Skip to main content

Full text of "Principles of geology"

See other formats 


Peay ais 
Bem: AT E 


t 


PRINCIPLES 


GEOLOGY. 


VOL. II. 


Lid a00W WALYD]1 


Z l g 
A 
<E 
A i 
(©) 

=] |È 
oE 
ea 

< 

< Pa 


4% 
\ ay / y 
aN ; Ri, 
RN Ñ AX w 


i| + FRANCISCVS DARWIN + jf 


Marry Soare dige 


Lonpon : 


Printed by A. SPOTTISWOODE, 
New-Street-Square. 


PRINCIPLES 


OF 


GEOLOGY: `’ 


BEING 


“AN INQUIRY HOW FAR THE FORMER CHANGES OF 
THE EARTH’S SURFACE 


ARE REFERABLE TO CAUSES NOW IN OPERATION. 


BY 


CHARLES LYELL, Esa. F.R.S. 


PRESIDENT OF THE GEOLOGICAL SOCIETY OF LONDON. 


“ Veré scire est per causas scire.” ` 


IN FOUR VOLUMES. 


VOL. II. 


THE FIFTH EDITION. 


LONDON: 
JOHN MURRAY, ALBEMARLE STREET. 
1837. 


PRINCIPLES OF GEOLOGY. 


BOOK II. 
Aqueous CAUSES — continued. 


CHAPTER VII. 
ACTION OF TIDES AND CURRENTS — continued. 


Action of tides and currents, continued — Inroads of the sea upon 
the delta of the Rhine in Holland — changes in the arms of the 
Rhine— Estuary of the Bies Bosch, formed in 1421 — Zuyder 
Zee, in the 13th century — Islands destroyed — Delta of the 
Ems converted into a bay — Estuary of the Dollart formed 
(p. 7.) — Encroachment of the sea on the coast of Sleswick — 
Qn shores of North America — Tidal wave, called the Bore — 
Influence of tides and currents on the mean level of seas — 
Action of currents in inland lakes and seas — Baltic — Cimbrian 
deluge (p. 13.) — Straits of Gibraltar— No under-current 
there — Whether salt is precipitated in the Mediterranean — 
Waste of shores of Mediterranean. 


Inroads of the sea at the mouths of the Rhine.— Tue 
line of British coast considered in the preceding 
chapter offered no example of the conflict of two 
great antagonist forces; the entrance, on the one 
hand, of a river draining a large continent, and on the 
other, the flux and reflux of the tide, aided by a strong 
current. But when we pass over by the Straits of 
Dover to the Continent, and proceed northwards, we 
find an admirable illustration of such a contest, where 
VOL, IL B 


2 INROADS OF THE SEA IN HOLLAND. [Book If, 


the Rhine and the ocean are opposed to each other, 
each disputing the ground now occupied by Holland ; 
the one striving to shape out an estuary, the other to 
form a delta. ‘There was evidently a period when the 
river obtained the ascendency, when the shape of the 
coast and set of the tides were probably very different ; 
but for the last two thousand years, during which man 
has witnessed and actively participated in the struggle, 
the result has been in favour of the ocean ; the area of 
the whole territory having become more and more 
circumscribed; natural and artificial barriers having 
given way, one after another; and many hundred thou- 
sand human beings having perished in the waves. 

Changes in the arms of the Rhine.— The Rhine, 
after flowing from the Grison Alps, copiously charged 
with sediment, first purifies itself in the Lake of Con- 
Stance, where a large delta is formed: then, swelled 
by the Aar and numerous other tributaries, it flows 
for more than six hundred miles towards the north : 
when, entering a low tract, it divides into two arms, 
north of Cleves, a little below the village of Pannerden 
— a point which must therefore be considered the head 
of its delta. In speaking of the delta Ido not mean to 
assume that all that part of Holland which is com- 
prised within the several arms of the Rhine can be 
called a delta in.the strictest sense of the term; be- 
cause some portion of the country thus circumscribed, 
as, for example, a part of Gelderland and Utrecht, 
consists of strata which may have been deposited in 
the sea before the Rhine existed. These older tracts 
may either have been raised like the Ullah Bund in 
Cutch, during the period when the sediment of the 
Rhine was converting a part of the sea into land, or 
they may have constituted islands previously. 


Ch, VIIJ INROADS OF THE SEA IN HOLLAND. a 


When the river divides north of Cleves, the left arm 
takes the name of the Waal; and the right, retaining 
that of the Rhine, is connected, a little farther to the 
north, by an artificial canal with the river Yssel. Still 
lower down, the Rhine takes the name of the Leck, a 
name which was given to distinguish it from another 
arm called the old Rhine, which was sanded up until 
after the year 1825, when a channel was cut for it, by 
which it now enters the sea at Catwyck. It is common, 
in all great deltas, that the principal channels of dis- 
charge should shift from time to time; but in Hol- 
land so many magnificent canals have been constructed, 
and have so diverted, from time to time, the course of 
the waters, that the geographical changes in this delta 
are endless, and their history, since the Roman era, 
forms a complicated topic of antiquarian research. The 
present head of the delta is about forty geographical 
miles from the nearest part of the gulf called the Zuy- 
der Zee, and more than twice that distance from the 
general coast-line. The present head of the delta of 
the Nile is about eighty or ninety geographical miles 
from the sea; that of the Ganges, as we before stated, 
two hundred and twenty; and that of the Mississippi 
about one hundred and eighty, reckoning from the 
point where the Atchafalaya branches off, to the ex- 
tremity of the new tongue of land in the Gulf of 
Mexico. But the comparative distance between the 
heads of deltas and the sea affords scarcely any data 
for estimating the relative magnitude of the alluvial 
tracts formed by their respective rivers. For the 
ramifications depend on many varying and temporary 
circumstances, and the area over which they extend 
does not hold any constant proportion to the volume 
of water in the river. 


BZ 


INROADS OF THE SEA IN HOLLAND. [Book H, 


The Rhine therefore has at present three mouths. 
About two-thirds of its waters flow to the sea by the 
Waal, and the remainder is carried partly to the Zuy- 
der Zee by the Yssel, and partly to the ocean by the 
Leck. As the whole coast to the south, as far as 
Ostend, and on the north, to the entrance of the 
Baltic, has, with few exceptions, from time immemorial, 
yielded to the force of the waves, it is evident that 
the delta of the Rhine, if it had advanced, would have 
become extremely prominent; and even if it had re- 
mained stationary, would long ere this have projected 
far beyond the rounded outline of the coast, like that 
strip of land already described, at the mouth of the 
Mississippi. But we find, on the contrary, that the 
islands which skirt the coast have not only lessened in 
size, but in number also, while great bays have been 
formed in the interior by incursions of the sea. I shall 
confine myself to the enumeration of some of the lead- 
ing facts, in confirmation of these views, and begin 
with the southernmost part of the delta, where the 
Waal enters, which is at present united with the 
Meuse, in the same manner as an arm of the Po, be- 
fore mentioned, has become confluent with the Adige. 
The Meuse itself had once a common embouchure 
with the Scheldt, by Sluys and Ostburg, but this 
channel was afterwards sanded up, as were many others 
between Walcheren, Beveland, and other islands, at 
the mouths of these rivers. The new accessions were 
almost all within the coast line, and were far more 
than counterbalanced by inroads of the sea, whereby 
large tracts of land, and dunes of blown sand, together 
with towns and villages, were swept away between 
the fourteenth and eighteenth centuries. Besides 
parts of Walcheren, Beveland, and several populous 


Ch. VIL] FORMATION OF THE ZUYDER ZEE. , 5 


districts in Kadzand, the island Orisant was in the 
year 1658 entirely annihilated. 

Inroads of the sea in Holland. —One of the most 
memorable irruptions occurred in 1421, where the 
tide, pouring into the mouth of the united Meuse and 
Waal, burst through a dam in the district named 
Bergse-Veld, and overflowed seventy-two villages, 
forming a large sheet of water called the Bies Bosch. 
Thirty-five of the villages were irretrievably lost, and 
no vestige, even of their ruins, was afterwards seen. 
The rest were redeemed, and the site of the others, 
though still very generally represented on maps as an 
estuary, has in fact been gradually filled up by alluvial 
deposits, and is now, as I am informed by Professor 
Moll, an immense plain, yielding abundant crops of 
hay, though still uninhabited. To the north of the 
Meuse is a long line of shore covered with sand dunes, 
where great encroachments have taken place from 
time to time, in consequence chiefly of the prevalence 
of south-easterly winds which blow down the sands 
towards the sea. The church of Scheveningen, not 
far from the Hague, was once in the middle of the 
village, and now stands on the shore; half the place 
having been overwhelmed by the waves in 1570. 
Catwyck, once far from the sea, is now upon the 
shore; two of its streets having been overflowed, and 
land torn away to the extent of two hundred yards in 
1719. It is only by aid of embankments, that Petten, 
and several other places farther north, have been 
defended against the sea. 

Formation of the Zuyder Zee and Straits of Staveren. 
— Still more important are the changes which have 
taken place on the coast opposite the right arm of the 

B 3 


G + FORMATION OF THE ZUYDER ZEE [Book II. 


Rhine, or the Yssel, where the ocean has burst through 
a large isthmus, and entered the inland lake Flevo, 
which, in ancient times, was, according to Pomponius 
Mela, formed by the overflowing of the Rhine over cer- 
tain low lands. It appears that, in the time of Tacitus, 
there were several lakes in the present site of the 
Zuyder Zee, between Friesland and Holland. The 
successive inroads by which these, and a great part 
of the adjoining territory, were transformed into a 
great gulf, began about the commencement, and were 
completed towards the close of the thirteenth cen- 
tury. Alting gives the following relation of the 
occurrence, drawn from manuscript documents of 
contemporary inhabitants of the neighbouring pro- 
vinces. In the year 1205, the island now called 
Wieringen, to the south of the Texel, was still a 
part of the mainland, but during several high floods, 
of which the dates are given, ending in December, 
1251, it was separated from the continent. By sub- 
sequent incursions, the sea consumed great parts of 
the rich and populous isthmus, a low tract which 
stretched on the north of Lake Flevo, between Staveren 
in Friesland, and Medemblick in Holland, till at length 
a breach was completed about the year 1282, and 
afterwards widened. Great destruction of land took 
place when the sea first broke in, and many towns 
were swept away ; but there was afterwards a reaction 
to a certain extent, large tracts at first submerged 
having been gradually redeemed. The new straits 
south of Staveren are more than half the width of 
those of Dover, but are very shallow, the greatest 
depth not exceeding two or three fathoms. The new 
bay isof a somewhat circular form, and between thirty 
and forty miles in diameter. How much of this space 


Ch. VIIJ THE DOLLART FORMED. _ a 


may formerly have been occupied by Lake Flevo, is 
unknown. i 
Destruction of Islands.— A series of islands stretch- 
ing from the Texel to the mouths of the Weser and 
Elbe, are evidently the last relics of a tract once con- 
tinuous. They have greatly diminished in size, and 
have lost about a third of their number since the time 
of Pliny; for that naturalist counted twenty-three 
islands between the Texel and Eider, whereas there 
are now only sixteen, including Heligoland and Neu- 
werk.* Heligoland, at the mouth of the Elbe, began 
in the year 800 to be much consumed by the waves. 
In the years 1300, 1500, and 1649, other parts were 
swept away, till at last a small portion only of the 
original island remained, consisting of a rock of red 
marl (of the keuper formation of the Germans), about 
200 feet high. Since 1770, a current has cut a passage 
no less than ten fathoms deep through this remaining 
portion, and has formed two islands, Heligoland and 
Sandy Island.+ ‘The fact of the new channel being laid 
down in all the charts as sixty feet deep is important, 
as showing the excavating power of marine currents 
under favourable circumstances. On the other hand 
some few islands have extended their bounds in one 
‘direction, or become connected with others, by the 
sanding-up of channels ; but even these, like Juist, 
have generally given way as much on the north 
towards the sea as they have gained on the south, or 
land side. 
The Dollart formed.— While the delta of the Rhine 
has suffered so materially from the movements of the 
ocean, it can hardly be supposed that minor rivers on 


* Von Hoff, vol. i. p. 364. + Id. p.57. 
BA 


8. COAST OF SLESWICK. [Book II. 


the same coast should have been permitted to extend 
their deltas. It appears, that in the time of the Ro- 
mans there was an alluvial plain of great fertility, 
where the Ems entered the sea by three arms. This 
low country stretched between Groningen and East 
Friesland, and sent out a peninsula to the north-east 
towards Emden. A flood, in 1277, first destroyed part 
of the peninsula. Other inundations followed at differ- 
ent periods throughout the fifteenth century. In 1507, 
a part only of Torum, a considerable town, remained 
standing ; and in spite of the erection of dams, the 
remainder of that place, together with market-towns, 
villages, and monasteries, to the number of fifty, were 
finally overwhelmed. The new gulf, which was called 
the Dollart, although small in comparison to the 
Zuyder Zee, occupied no less than six square miles at 
first ; but part of this space was, in the course of the 
two following centuries, again redeemed from the sea. 
The small bay of Leybucht, farther north, was formed 
in asimilar manner in the thirteenth century ; and the 
bay of Harlbucht, in the middle of the sixteenth. Both 
of these have since been partially reconverted into 
dry land. Another new estuary, called the Gulf of 
Jahde, near the mouth of the Weser, scarcely inferior 
in size to the Dollart, has been gradually hollowed 
out since the year 1016, between which era and 1651 
a space of about four square miles has been added to 
the sea. The rivulet which now enters this inlet is 
very small; but Arens conjectures, that an arm of the 
Weser had once an outlet in that direction. 

Coast of Sleswick.— Farther north we find so many 
records of waste on the western coast of Sleswick, as 
to lead us to anticipate, that, at no distant period in 
the history of the physical geography of Europe, 


Ch. VILJ COAST OF AMERICA UNDERMINED. g 


Jutland may become an island, and the ocean may 
obtain a more direct entrance into the Baltic. So 
late as 1825 the sea made a breach and entered the 
Lym-Fiord, so that the northern extremity of Jutland 
was converted into an island ; and this passage is still 
open (1835). 

Destruction of Northstrand by the sea.— North- 
strand, up to the year 1240, was, with the islands 
Sylt and Föhr, so nearly connected with the mainland 
as to appear a peninsula, and was called North Fries- 
land, a highly cultivated and populous district. It 
measured from nine to eleven geographical miles from 
north to south, and six to eight from east to west. In 
the above-mentioned year it was torn asunder from 
the continent, and in part overwhelmed. The Isle of 
Northstrand, thus formed, was, towards the end of 
the sixteenth century, only four geographical miles in 
circumference, and was still celebrated for its cul- 
tivation and numerous population. After many losses, 
it still contained nine thousand inhabitants. At last, 
in the year 1634, on the evening of the 11th of 
October, a flood passed over the whole island, whereby 
1300 houses, with many churches, were lost ; fifty 
thousand head of cattle perished, and above six thou- 
sand men. ‘Three small islets, one of them still called 
Northstrand, alone remained, which are now conti- 
nually wasting. 

Inroads of the sea on the eastern shores of North 
America.— After so many authentic details respecting 
the destruction of the coast in parts of Europe best 
known, it will be unnecessary to multiply examples of 
analogous changes in more distant regions of the 
world. It must not, however, be imagined that our 
own seas form any exception to the general rule. 

BO 


10 TIDAL WAVE CALLED “ THE BORE.” [Book II. 


Thus, for example, if we pass over to the eastern 
coast of North America, where the tides rise to a great 
elevation, we find many facts attesting the incessant 
demolition of land. At Cape May, for example, on 
the north side of Delaware Bay, in the United States, 
the encroachment of the sea was shown by observ- 
ations made consecutively for sixteen years, from 1804 
to 1820, to average about nine feet a year *; and at 
Sullivan’s Island, which lies on the north side of the 
entrance of the harbour of Charlestown, in South 
Carolina, the sea carried away a quarter of a mile of 
land in three years, ending in 1786.+ 

Tidal wave called “ the Bore.” — Before concluding 
my remarks on the action of the tides, I must not 
omit to mention the wave called “the Bore,” which is 
sometimes produced in a river where a large body of 
water is made to rise suddenly, in consequence of the 
contraction of the channel. This wave terminates âb- 
ruptly on the inland side; because the quantity of 
water contained in it is so great, and its motion so 
rapid, that time is not allowed for the surface of the 
river to be immediately raised by means of transmitted 
pressure. A tide wave thus rendered abrupt has a 
close analogy, observes Mr. Whewell, to the waves 
which curl over and break on a shelving shore. 

The Bore which enters the Severn, where the 
phenomenon is of almost daily occurrence, is some- 
times nine feet high, and at spring tides rushes up the 
estuary with extraordinary rapidity. The same phe- 
nomenon is frequently witnessed in the principal 
branches of the Ganges, and in the Megna. “In the 
Hoogly, or Calcutta river,” says Rennell, “the Bore 

* New Monthly Mag., vol. vi. p. 69. 

t Von Hoff, vol. i, p. 96, ł Phil. Trans., 1833, p. 204. 


Ch. VILJ ACTION OF CURRENTS IN THE BALTIC. 11l 


commences at Hoogly Point, the place where the 
river first contracts itself, and is perceptible above 
Hoogly Town; and so quick is its motion, that it 
hardly employs four hours in travelling from one to 
the other, though the distance is nearly seventy miles. 
At Calcutta it sometimes occasions an instantaneous 
rise of five feet; and both here, and in every other 
part of its track, the boats, on its approach, imme- 
diately quit the shore, and make for safety to the 
middle of the river. In the channels, between the 
islands in the mouth of the Megna, the height of the 
Bore is said to exceed twelve feet; and is so terrific 
in its appearance, and dangerous in its consequences, 
that no boat will venture to pass at spring tide.” * 
These waves may sometimes cause inundations, under- 
mine cliffs, and still more frequently sweep away trees 
and land animals from low shores, so that they may 
be carried down, and ultimately imbedded in fluviatile 
or submarine deposits. 


ACTION OF CURRENTS IN INLAND LAKES AND SEAS. 


In such large bodies of water as the North American 
lakes, the continuance of a strong wind in one direc- 
tion often causes the elevation of the water, and its 
accumulation on the leeward side; and while the 
equilibrium is restoring itself, powerful currents are 
occasioned. In October 1833, a strong current in 
Lake Erie, caused partly by the set of the waters 
towards the outlet of the lake, and partly by the pre- 
vailing wind, burst a passage through the sandy isthmus 
called Long Point Peninsula, and soon excavated a 
channel more than nine feet deep and nine hundred 


* Rennell, Phil. Trans. 1781. 
B 6 


12 ACTION OF CURRENTS IN THE BALTIC. [Book II. 


feet wide. Its width and breadth have since increased, 
and a new and costly pier has been erected ; for it is 
hoped that the event will permanently improve the 
navigation of Lake Erie for steam-boats.* In the Black 
Sea, also, although free from tides, we learn from 
Pallas that there is a sufficiently strong current to 
undermine the cliffs in many parts, and particularly in 
the Crimea. 

The redundancy of river water in the Baltic, espe- 
cially during the melting of ice and snow in spring, 
causes in general an outward current through the 
channel called the Cattegat. But after a continuance 
of north-westerly gales, especially during the height of 
the spring tides, the Atlantic rises; and, pouring a flood 
of water into the Baltic, commits dreadful devastations 
on the isles of the Danish Archipelago. This current 
even acts, though with diminished force, as far east- 
ward as the vicinity of Dantzic.¢ Accounts written 
during the last ten centuries attest the wearing down 
of promontories on the Danish coast, the deepening of 
gulfs, the severing of peninsulas from the main land, 
and the waste of islands, while in several cases marsh 
land, defended for centuries by dikes, has at last been 
overflowed, and thousands of the inhabitants whelmed 
in the waves. 

Thus the island Barsoe, on the coast of Sleswick, 
has lost, year after year, an acre atatime. The island 
Alsen suffers in like manner. The peninsula Zingst 
was converted into an island in 1625. There is a 
tradition that the isle of Rugen was originally torn by 
a storm from the main land of Pomerania: and it is 
known, in later times, to have lost ground, as in the 
* MS. of Capt. Bayfield, R. N. 

t See examples in Von Hoff, vol. i. p. 73., who cites Pisansky. 


Ch. VILI CIMBRIAN DELUGE. 13: 


year 1625, when a track of land was carried away. 
Some of these islands consist of ancient alluvial accu- 
mulations, containing blocks of granite, which are also 
spread over the neighbouring main land. The Marsh 
Islands are mere banks, like the lands formed of the 
“warp” in the Humber, protected by dikes. Some of 
them, after having been inhabited with security for 
more than ten centuries, have been suddenly over- 
whelmed. In this manner, in 1216, no less than ten 
thousand of the inhabitants of the Eyderstede and Dit- 
marsch perished; and on the 11th of October, 1634, 
the islands and the whole coast, as far as Jutland, 
suffered by a dreadful deluge. 

Cimbrian Deluge. —I have before enumerated the 
ravages of the ocean on the western shores of Sles- 
wick, and there are memorials of a series of like 
catastrophes on the eastern coast of that peninsula. 
Jutland was the Cimbrica Chersonesus of the ancients, 
and was then evidently the theatre of similar calamities; 
for Florus says, “ Cimbri, Theutoni, atque Tigurini, 
ab extremis Galliz profugi, cùm terras eorum inun- 
dasset Oceanus, novas sedes toto orbe querebant.”* 
Some have wished to connect this “ Cimbrian Deluge” 
with the bursting of the isthmus between England and 
France, and with other supposed convulsions; but 
when we consider the fate of Heligoland and North- 
strand, and the other terrific inundations in Jutland 
and Holstein since the Christian era, wherein thou- 
sands have perished, we need not resort to any such 
extraordinary catastrophes to account for the historical 
relation. The wave which in 1634 devastated the 
whole coast of Jutland committed such havoc, that we 


* Lib, iii. cap. 3. 


14 CURRENT IN THE STRAITS OF GIBRALTAR. [Book II. 


must be cautious how we reject hastily the traditions 
of like events on the coasts of Kent, Cornwall, Pem- 
brokeshire, and Cardigan; for, however sceptical we 
may be as to the amount of territory destroyed, it is 
very possible that former inroads of the sea may have 
been greater on those shores than any Witnessed in 
modern times. 

Straits of Gibraltar. — That the level of the Medi- 
terranean is from twenty to thirty feet lower than that 
of the Red Sea, at Suez, has been already stated. * 

It is well known that a powerful current sets con- 
stantly from the Atlantic into the Mediterranean, 
and its influence.extends along the whole southern 
borders of that sea, and even to the shores of Asia 
Minor. Captain Smyth found, during his survey, 
that the central current ran constantly at the rate of 
from three to six miles an hour eastward into the 
Mediterranean, the body of water being three miles 
and a half wide. But there are also two lateral 
currents — one on the European, and one on the 
African side ; each of them about two miles and a half 
broad, and flowing at about the same rate as the cen- 
tral stream. These lateral currents ebb and flow with 
the tide, setting alternately into the Mediterranean 
and into the Atlantic. The excess of water constantly 
flowing in is very great, and there is only one cause to 
which this can be attributed, the loss of water in the 
Mediterranean by evaporation. That the level of this 
sea should be considerably depressed by this means is 
quite conceivable, since we know that the winds blow- 
ing from the shores of Africa are hot and dry; and 
hygrometrical experiments recently made in Malta 
and other places, show that the mean quantity of 


# See Vol. I. p., 387, 


Ch. VIL] CURRENT IN THE STRAITS OF GIBRALTAR. 15 


moisture in the air investing the Mediterranean, is 
equal only to one half of that in the atmosphere of 
England. The temperature also of the great inland 
sea is upon an average higher, as was before stated, 
by 33° of Fahrenheit, than the western part of the 
Atlantic ocean, which must greatly promote its eva- 
poration. The Black Sea being situated in a higher 
latitude, and being the receptacle of rivers flowing 
from the north, is much colder, and its expenditure far 
less; accordingly, it does not draw any supply from 
the Mediterranean, but, on the contrary, contributes 
to it by a current flowing outwards, for the most part 
of the year, through the Dardanelles. The discharge, 
however, at the Bosphorus is so small when compared 
to the volume of water carried in by rivers as to imply 
a great amount of evaporation even in the Black Sea. 

Whether salt be precipitated in the Mediterranean.— 
It is, however, objected, that evaporation carries away 
only fresh water, and that the current from the At- 
lantic is continually bringing in salt water: why, then, 
do not the component ‘parts of the waters of the Me- 
diterranean vary? or how can they remain so nearly 
the same as those of the ocean? Some have imagined 
that the excess of salt might be carried away by an 
under-current running in a contrary direction to the 
superior ; and this hypothesis appeared to receive con- 
firmation from a late discovery that the water taken 
up about fifty miles within the Straits, from a depth 
of 670 fathoms, contained a quantity of salt four times 
greater than the water of the surface. Dr. Wollaston*, 
who analysed this water obtained by Captain Smyth, 
truly inferred that an amnder-current of such denser 
water, flowing outward, if of equal breadth and depth 


* Phil. Trans., 1829, part, i, p. 29. 


16 — PRECIPITATION OF SALT ' [Book II. 


with the current near the surface, would carry out as 
much salt below as is brought in above, although it 
moved with less than one fourth part of the velocity, 
and would thus prevent a perpetual increase of saltness 
in the Mediterranean beyond that existing in the 
Atlantic. It was also remarked by others, that the 
result would be the same if, the swiftness being equal, 
the inferior current had only one fourth of the volume 
of the superior. At the same time there appeared 
reason to conclude that this great specific gravity was 
only acquired by water at immense depths ; for two 
specimens of the water, taken at the distance of some 
hundred miles from the Straits, and at depths of 400, 
and even 450 fathoms, were found by Dr. Wollaston 
not to exceed in density that of many ordinary sam- 
ples of sea-water. Such being the case, we can now 
prove that the vast amount of salt brought into the 
Mediterranean does not pass out again by the Straits ; 
for it appears by Captain Smyth’s soundings, which 
Dr. Wollaston had not seen, that between the Capes 
of Trafalgar and Spartel, which are twenty-two miles 
apart, and where the Straits are shallowest, the deepest 
part, which is on the side of Cape Spartel, is only 220 
fathoms. It is therefore evident that if water sinks in 
certain parts of the Mediterranean, in consequence of 
the increase of its specific gravity, to greater depths 
than 220 fathoms, it can never flow out again into the 
Atlantic, since it must be stopped by the submarine 
barrier which crosses the shallowest part of the Straits 
of Gibraltar. 

The idea of the existence of a counter-current, at 
a certain depth, first originated in the following cir- 
cumstance:— M. De l'Aigle, commander of a privateer 
called the Phoenix, of Marseilles, gave chase to a 


Ch. VIIL] IN THE MEDITERRANEAN. i 


Dutch merchant-ship, near Ceuta Point, and coming 
up with her in the middle of the gut, between Tariffa 
and Tangier, gave her one broadside, which directly 
sunk her. A few days after, the sunk ship, with her 
cargo of brandy and oil, was cast ashore near Tangier, 
which is at least four leagues to the westward of the 
place where she went down, and directly against the 
strength of the central current.* This fact, however, 
affords no evidence of an under-current, because the 
ship, when it approached the coast, would necessarily 
be within the influence of a lateral current, which, 
running westward twice every twenty-four hours, 
might have brought back the vessel to Tangier. 

What, then, becomes of the excess of salt? — for 
this is an enquiry of the highest geological interest. 
The Rhone, the Po, and many hundred minor streams 
and springs, pour annually into the Mediterranean 
large quantities of carbonate of lime, together with 
iron, magnesia, silica, alumina, sulphur, and other 
mineral ingredients, in a state of chemical solution. 
To explain why the influx of this matter does not alter 
the composition of this sea has never been regarded 

a difficulty ; for it is known that calcareous rocks 
are forming in the delta of the Rhone, in the Adriatic, 
on the coast of Asia Minor, and in other localities. 
Precipitation is acknowledged to be the means where- 
by the surplus mineral matter is disposed of, after the 
consumption of a certain portion in the secretions of 
testacea, zoophytes, and other marine animals. But 
before muriate of soda can, in like manner, be pre- 
cipitated, the whole Mediterranean ought, it is said, 
to become as much saturated with salt as Lake Aral, 
the Dead Sea, or the brine-springs of Cheshire. 

* Phil, Trans, 1724. 


18 PRECIPITATION OF SALT [Book ÏI. 


It is undoubtedly true, in regard to small bodies of 
water, that every particle must be fully saturated with 
muriate of soda, before a single crystal of salt can be 
formed; such is probably the case in all natural 
salterns: such, for example, as those described by 
travellers as occurring on the western borders of the 
Black Sea, where extensive marshes are said to be 
covered by thin films of salt after a rapid evaporation 
of sea-water. The salt étangs of the Rhone, where 
salt has sometimes been precipitated in considerable 
abundance, have been already mentioned. But whether 
it be necessary that every part of a sea of enormous 
depth should be fully saturated before any precipitate 
can take place is a question of some difficulty. In the 
narrowest part of the Straits of Gibraltar, where they 
are about nine miles broad, between the Isle of Tariffa 
and Alcanzar Point, the depth varies from 160 to 500 
fathoms: but between Gibraltar and Ceuta, Captain 
Smyth sounded to the enormous depth of 950 fathoms ; 
where he found a gravelly bottom, with fragments of 
broken shells. Saussure sounded to the depth of two 
thousand feet, within a few yards of the shore, at Nice; 
and M. Bérard has lately fathomed to the depth of 
more than six thousand feet in several places without 
reaching the bottom. * l 

The central abysses of this sea are, in all likelihood, 
at least as deep as the Alps are high; and, as at the 
depth of seven hundred fathoms only, water has been 
found to contain a proportion of salt four times greater 
than at the surface, we may presume that the excess 
of salt may be much greater at the depth of two or 
three miles. After evaporation, the surface water 


f 
} 


* Bull. de la Soc. Géol. de France. — Résumé, p. 72. 1832, 


Ch, VILJ IN THE MEDITERRANEAN. 19 


becomes impregnated with a slight excess of salt, and 
its specific gravity being thus increased, it instantly 
falls to the bottom, while lighter water rises to the 
top, or flows in laterally, being always supplied by 
rivers and the current from the Atlantic. The heavier 
fluid, when it arrives at the bottom, cannot stop if it 
can gain access to any lower part of the bed of the 
sea, not previously occupied by water of the same 
density. In this manner the bottom of the nether- 
most submarine abysses must annually receive new 
supplies of brine, while the water at the surface, being 
incessantly renewed by rivers and the current from 
the ocean, can never become saturated. 

How far this accumulation of brine» can extend 
before the inferior strata will part with any of their 
salt, and what difference in such a chemical process 
the immense pressure of the incumbent ocean might 
occasion, are questions which cannot be answered in 
the present state of science. ‘There is also another 
curious topic of speculation; what changes may be 
effected by volcanic heat, so active in many parts of 
the bottom of the Mediterranean. A submarine hot- 
spring or stufa would give rise to a new set of pheno- 
mena. Perhaps it may be said that their effect would 
only be to cause ascending and descending currents, 
and thereby to promote the intermixture of the upper 
and lower waters of the sea. A solfatara, or rent 
through which inflammable gases are continually es- 
caping, might certainly convert sea-water into steam ; 
andin this case salt would be precipitated in the space 
from which the steam was expelled. Additional sup- 
plies of water might then find their way into the fis- 
sure, being injected into every pore of the rock by 
the vast pressure of the incumbent ocean. If, by a 


i 
i) 

| 

| | 
| 

i 

ij 

i 


m 


20 PRECIPITATION OF SALT. [Book If, 


repetition of this process, the cavity was filled with 
salt, other crystals of the same mineral would more 
easily be formed from a solution, and might then 
spread along the bottom of the sea, Yet even in this 
case it should seem that the fluid must first be fully 
saturated. It is certainly most difficult to explain on 
chemical principles how a deposit of salt may take 
place at the bottom of the Mediterranean, but it is 
nevertheless a fact that the waters of that sea, notwith- 
standing the constant influx of salt-water from the 
Atlantic, contain but a slight excess of muriate of 
soda above the ordinary waters of the ocean. 

In regard to the probable origin of those continu- 
ous masses *of rock-salt which we find in Poland, 
Hungary, Transylvania, and Spain, geologists have 
entertained very different opinions; but the theory 
which has obtained most favour in later times attri- 
butes them not to precipitation from an aqueous men- 
struum, but to sublimation from volcanic exhalations 
rising from below, which insinuate themselves into 
rents and vacuities, caused by the fracture and decom- 
position of rocks. 

The straits of Gibraltar are said to become gradually 
wider by the wearing down of the cliffs on each side 
at many points ; and the current sets along the coast 
of Africa, so as to cause considerable inroads in various 
parts, particularly near Carthage. Near the Canopic 
mouth of the Nile, at Aboukir, the coast was greatly 
devastated in the year 17 84, when a small island was 
nearly consumed. By a series of similar operations, 
the old site of the cities of Nicopolis, Taposiris, Parva, 
and Canopus, have become a sand-bank. * 

* Clarke’s Travels in Europe, Asia, arid Africa, vol. iii. 
pp- 340. and 363. 4th edition. 


Ch. VILJ SAND HILLS. 21 


Sand-Hills.—It frequently happens, where the sea 
is encroaching on a Coast, that perpendicular cliffs of 
considerable height, composed of loose sand, supply, 
as they crumble away, large quantities of fine sand, 
which, being in mid-air when detached, are carried 
by the winds to great distances, covering the land or 
barring up the mouths of estuaries. This is exempli- 
fied in Poole Bay, in Hampshire, and in many points 
of the coast of Norfolk and Suffolk. But a violent 
wind will sometimes drift the sand of a sea beach, and 
carry it up with fragments of shells to great heights, 

‘as in the case of the sands of Barry, at the northern 
side of the estuary of the Tay, where hills of this 
origin attain the height of 140 feet. 

On the coast of France and Holland long chains of 
these dunes have been formed in many parts, and 
often give rise to very important geological changes, 
by damming up the mouths of estuaries, and prevent- 


ing the free ingress of the tides, or free efflux of river 
water. 


CHAPTER VIII. 
REPRODUCTIVE EFFECTS OF TIDES AND CURRENTS. 


Reproductive effects of tides and currents— Silting up of es- 
tuaries does not compensate the loss of land on the borders of 
the ocean — Bed of the German Ocean (p. 29.) — Composition 
and extent of its sand-banks — Strata deposited by currents on 
the southern and eastern shores of the Mediterranean — Trans- 
portation by currents of the sediment of the Amazon, Orinoco, 
and Mississippi (p. 32.) — Stratification. 


From the facts enumerated in the last chapter, it ap- 


pears that, on the borders of the ocean, currents and 
tides co-operating with the waves of the sea are most 
powerful instruments in the destruction and transport- 
ation of rocks; and as numerous tributaries discharge 
their alluvial burden into the channel of one great 
river, so we find that many rivers deliver their earthy 
contents to one marine current, to be borne by it to a 
distance, and deposited in some deep receptacle of the 
ocean. The current not only receives this tribute of 
sedimentary matter from streams draining the land, 
but acts also itself on the coast, as does a river on the 
cliffs which bound a valley. The course of currents on 
the British shores is ascertained to be as tortuous as 
that of ordinary rivers. Sometimes they run between 
sand-banks, which consist of matter thrown down at 
_certain points where the velocity of the stream had 
been retarded; but it very frequently happens, that as 


Ch. VIIL] FORMATION OF ESTUARIES. 23 


in a river one bank is made of low alluvial gravel, 
while the other is composed of some hard and lofty 
rock constantly undermined, so the current, in its 
bends, strikes here and there upon a coast, which then 
forms one bank, while a shoal under water forms the 
other. If the coast be composed of solid materials, it 
yields slowly ; so also if it be of great height, for in that 
case a large quantity of matter must be removed before 
the sea can penetrate to any distance. But the open- 
ings where rivers enter are generally the points of 
least resistance, and it is here, therefore, that the 
ocean makes the widest and deepest breaches, 

A current alone cannot shape out and keep open an 
estuary, because it holds in suspension, like the river, 
during certain seasons of the year, a large quantity of 
sediment ; and where the ‘waters, flowing in opposite 
directions, meet, this matter subsides. For this reason, 
in inland seas, and even on the borders of the ocean, 
where the rise of the tide happens to be slight, it is 
scarcely possible to prevent a harbour from silting up ; 
and it is often expedient to carry out a jetty beyond 
the point where the marine current and the river neu- 
tralize each other's force ; for beyond this point a free 
channel is maintained by the superior strength of the 
current. 

Estuaries, how formed. —The formation and keeping 
open of large estuaries are due to the combined influ- 
ence of the tidal currents and rivers ; for when the 
tide rises, a large body of water suddenly enters the 
mouth of the river, where, becoming confined within 
narrower bounds, while its momentum is not destroyed, 
it is urged on, and, having to pass through a contracted 
channel, rises and runs with increased velocity, just as 
a stream, when it reaches the arch of a bridge scarcely 


24 l TIDES IN ESTUARIES. [Book IT, 


large enough to give passage to its waters, rushes with 
a steep fall through the arch. During the ascent of 
the tide, a body of fresh water, flowing down in an 
opposite direction from the higher country, is arrested 
in its course for several hours; and thus a large lake 
of brackish water is accumulated, which, when the sea 
ebbs, is let loose, as on the removal of an artificial 
sluice or dam. By the force of this retiring water, the 
alluvial sediment both of the river and of the sea is 
swept away, and transported to such a distance from 
the mouth of the estuary, that a small part only can 
return with the next tide. 

It sometimes happens, that during a violent storm a 
large bar of sand is suddenly made to shift its position, 
so as to prevent the free influx of the tides, or efflux of 
river water. Thus about the year 1500 the sands at 
Bayonne were suddenly thrown across the mouth of 
the Adour. That river, flowing back upon itself, 
soon forced a passage to the northward, along the 
sandy plain of Capbreton, till at last it reached the 
sea at Boucau, at the distance of seven leagues from 
the pomt where it had formerly entered. It was not 
till the year 1579 that the celebrated architect Louis 
de Foix, undertook, at the request of Henry III., to 
re-open the ancient channel, which he at last effected 
with great difficulty. * 

Tides in Estuaries.—In the estuary of the Thames 
at London, and in the Gironde, the tide flows five 
hours and ebbs seven, and in all estuaries the water 
requires a longer time to run down than up; so that 
the preponderating force is always in the direction 


~ * Nouvelle Chronique de la Ville de Bayonne, pp. 113. 139. 
1827, 


Ch, VIII] SILTING UP OF ESTUARIES. 25 


which tends to keep open a deep and broad passage. 
But as both the river and the tidal current are ready 
to part with their sediment whenever their velocity is 
checked, there is naturally a tendency in all estuaries 
to silt up partially, since eddies, and backwaters, and 
points where Opposing streams meet, are very numer- 
ous, and constantly change their position. 

Silting up of estuaries does not compensate for loss of 
coasts. — Many writers have declared that the gain on 
our eastern coast, since the earliest periods of history, 
has more than counterbalanced the loss ; but they have 
been at no pains to calculate the amount of loss, and 
have often forgotten that, while the new acquisitions are 
manifest, there are rarely any natural monuments to 
attest the former existence of the land that has been 
carried away. They have also taken into their account 
those tracts artificially recovered, which are often of 
great agricultural importance, and may remain secure, 
perhaps, for thousands of years, but which are only a 
few feet above the mean level of the sea, and are 
therefore exposed to be overflowed again by a small 
proportion of the force required to: remove cliffs of 
considerable height on our shores. If it were true 
that the area of land annually abandoned by the sea 
in estuaries were equal to that invaded by it, there 
would still be no compensation tn kind. 

It will seem, at first sight, somewhat paradoxical, 
but it is nevertheless true, that the greater number of 
estuaries, although peculiarly exposed to the invasion 
of the sea, are usually contracting in size, even where 
the whole line of coast is giving way. But the fact is, 
that the inroads made by the ocean upon estuaries, 
although extremely great, are completed during periods 


of comparatively short duration ; and in the intervals 
VOL. If. - ¢ 


26 REPRODUCTIVE EFFECTS OF ` [Book IE 


between these irruptions, the mouths of rivers, like 
other parts of the coast, usually enjoy a more or less 
perfect respite. All the estuaries, taken together, 
constitute but a small part of a great line of coast 2 dt 
is, therefore, most probable, that if our observations 
extend toa few centuries only, we shall not see any; 
and very rarely all, of this small part exposed to the 
fury of the ocean. The coast of Holland, and Fries- 
land, if studied for several consecutive centuries since 
the Roman era, would generally have led to the con- 
clusion that the land was encroaching fast upon the 
sea, and that the aggrandizement within the estuaries 
far more than compensated the losses on the open 
coast. But when our retrospect embraces the whole 
period, an opposite inference is drawn: and we find 
that the Zuyder Zee, the Bies Bosch, Dollart, and 
Yahde, are modern gulfs and bays, and that these 
points have been the principal theatres of the retreat, 
instead of the advance, of the land. If we possessed 
records of the changes on our coast for several thousand 
years, they would probably present us with similar 
results; and although we have hitherto seen our 
estuaries, for the most part, become partially con- 
verted into dry land, and bold cliffs intervening be- 
tween the mouths of rivers consumed by the sea, this 
has merely arisen from the accidental set of the cur- 
rents and tides during a brief period. 

The current which flows round from the north-west; 
and bears against the eastern coast of England, trans- 
ports, as we have seen, materials of various kinds. 
Aided by the winds and waves, it undermines and 
sweeps away the granite, gneiss, trap rocks, and sand- 
stone of Shetland, and removes the gravel and loam of 
the cliffs of Holderness, Norfolk, and Suffolk, which 


2 
Ch, VIIJ TIDES AND’ CURRENTS. 27 


are between fifty and two hundred feet in height, and 
which waste at the rate of from one to six yards an- 


nually. It also bears away, in co-operation with the 
Thames and the tides, 


coast of Essex and § 


continuously on the 


commits annual rav h-water beds, 


flints, in Hamp- 

ions of the Port- 

during the rainy 

sand, and mud, 

Grampians, Che- 

send down to the sea. To 

all this matter consigned? It 

Is not retained in mechanical Suspension by the waters 


a state of 
—it is deposited somewhere, yet 
certainly not in the immediate neighbourhood of our 
shores; for, in that case, there would soon be a ces- 
sation of the encroachment of the sea, 
of low land, like Romney Marsh, wou 
where encircle our island. 

As there is now a depth of water, exceedj 
feet, in some spots where cities flourished 
centuries ago, it is clear that the 
carries far away the materials of the 
removes also the ruins of many of + 
at the bottom of the sea. 

So great is the quantit 
sion by the tidal current 


of the ocean, nor does it mix with them in 


chemical solution, 


and large tracts 
Id almost every 


ng thirty 
but a few 
current not only. 
wasted cliffs, but 
he regular strata 


d by repeating 
warping,” for two or 
c2 


28 $ REPRODUCTIVE EFFECTS OF [Book II. 


a 


three years, considerable tracts have been raised, in 
the estuary of the Humber, to the height of about six 
feet. Ifa current, charged with such materials, meets 
with deep depressions in the bed of the ocean, it must 
often fill them up; just as a river, when it meets with 
a lake in its course, fills it gradually with sediment. 

But in the one case, the sheet of water is converted 
into land; whereas, in the other, a shoal only is raised, 
overflowed at high water, or at least by spring tides. 
The only records which we at present possess of the 
gradual shallowing of seas are confined, as might be 
expected, to estuaries, havens, and certain channels of 
no great depth ; and to some inland seas, as the Baltic, 
Adriatic, and Arabian Gulf. It is only of late years, 
that accurate surveys and soundings have afforded 
data of comparison in very deep seas, of which future 
geologists will avail themselves. 

An extraordinary gain of land is described to have 
taken place at the head of the Red Sea, the Isthmus 
of Suez having doubled in breadth since the age of 
Herodotus. In his time, and down to that of Arrian, 
Heroopolis was on the coast; now it is as far distant 
from the Red Sea as from the Mediterranean.* 
Suez in 1541 received into its harbour the fleet of 
Solyman II. ; but it is now changed into a sand-bank. 
The country called Tehama on the Arabian side of 
the Gulf has increased from three to six miles since 
the Christian era. Inland from the present ports are 
the ruins of more ancient towns, which were once on 
the sea-shore, and bore the same names. It is said 
that the blown sand from the deserts supplies some 


* Danville, Mém. sur l’Egypte, p. 108. — Von Hoff, vol. i. 
p- 390. 


Ch. VIILJ TIDES AND CURRENTS. 29 


` part of the materials of this new land, and that the 
rest is composed of shells and corals, of which the 
growth is very rapid. 

Filling up of the German Ocean. — The German 
Ocean is deepest on the Norwegian side, where the 
soundings give 190 fathoms ; but the mean depth of 
the whole basin may be stated at no more than thirty- 
one fathoms.* The bed of this sea is traversed by 
several enormous banks, one of which, occupying a 
central position, trends from the Frith of Forth, in a 
north-easterly direction, to a distance of 110 miles ; 
others run from Denmark and Jutland upwards of 105 
miles to the north-west; while the greatest of all, the 
Dogger Bank, extends for upwards of 354 miles from 
north to south. The whole superficies of these enor- 
mous shoals is equal to about one fifth of the whole 
area of the German Ocean, or to about one third of 
the whole extent of England and Scotland.+ The 
average height of the banks measures, according to 
Mr. Stevenson, about seventy-eight feet; the upper 
portion of them consisting of fine and coarse siliceous 
“sand, mixed with comminuted corals and shells, $ 

It has been supposed by some writers, that these 
vast submarine hills are made up bodily of drift sand, 
and other loose materials, principally supplied from 
the waste of the English, Dutch, and other coasts. 
But the late survey of the North Sea, conducted by 
Captain Hewett, affords ground for suspecting that 
this opinion is very erroneous. If such immense 
mounds of sand and mud had been accumulated under 


* Stevenson on the Bed of the German Ocean, O North Sea, 
— Ed. Phil. Journ. No, V. p. 44. 1820. 


+ Ibid., p. 47. + Ibid. 
Clg 


30 STRATA DEPOSITED BY CURRENTS. [Book IL 


the influence of currents, the same causes ought nearly 
to have reduced to a level the entire bottom of the 
German Ocean ; instead of which some long narrow 
ravines are found to intersect the banks. One of these 
varies from seventeen to forty-four fathoms in depth, 
and has very precipitous sides: in one part, called the 
“Inner Silver Pits,” it is fifty-five fathoms deep. The 
shallowest parts of the Doggerbank were found to be 
forty-two feet under water, except in one place, where 
the wreck of a ship had caused a shoal; so that we 
may suppose the-currents, which vary in their velocity 
from a mile to two miles and a half per hour, to have 
power to prevent the accumulation of drift matter in 
places of less depth. It seems, then, that the great 
banks above alluded to, and the ravines which intersect 
them, cannot be due to the tides and currents now ex- 
isting in this sea. They may, however, have been 
caused in great part by the movements of the ocean 
at some former period, when the bed of this sea, and 
the surface of the land adjoining, assumed its actual 
configuration. 

Strata deposited by currents. — It appears extraor- 
dinary, that in some tracts of the sea, adjoining the 
coast of England, where we know that currents are 
not only sweeping along rocky masses, thrown down, 
from time to time, from the high cliffs, but also occasion: 
ally scooping out channels in the regular strata, there 
should exist fragile shells and tender zoophytes in 
abundance, which live uninjured by these violent move- 
ments. ‘The ocean, however, is in this respect a coun- 
terpart of the land; and as, on the continents, rivers 
may undermine their banks, uproot trees, and roll 
along sand and gravel, while their waters are inhabited 
by testacea and fish, and their alluvial plains are 


Ch. VIIL] STRATA DEPOSITED BY CURRENTS. ot 


adorned with rich vegetation and forests, so the sea 
may be traversed by rapid currents, and its bed 
may here and there suffer great local derangement, 
without any interruption of the general order and 
tranquillity. 

One important character in the formations produced 
by currents, is, the immense extent over which they 


may be the means of diffusing homogeneous mixtures, 
for these are often co-extensive with a great line of 
coast, and, by comparison with their deposits, the 
deltas of rivers must shrink into insignificance. In the 
Mediterranean, the same current which is rapidly de- 
stroying many parts of the African coast, between the 
Straits of Gibraltar and the Nile, preys also upon the 
delta of the Nile, and drifts the sediment of that great 
river to the eastward. To this source may be attri- 
buted the rapid accretions of land on parts of the 
Syrian shores where rivers do not enter. 
It is the opinion of M. Girard, one of the scientific 
men who accompanied Napoleon’s expedition to Egypt, 
and who were employed on the survey of the ancient 
canal of Amron, communicating between the Nile and 
the Red Sea, that the isthmus of Suez itself is merely 
a bar formed by the deposition of this current and of 
the Nile, and that the two seas were formerly united. * 


It is certain, as before stated, that the isthmus is daily 
gaining in width by the accession of fresh deposits on 
the shores of the Mediterranean. + 

The ruins of ancient Tyre are now far inland, and 
those of ancient Sidon are two miles distant from the 


* Description de l'Egypte, Mémoires, tom. i, pe 88) 
+ Quarterly Review, No. lxxxvi. p. 445, 


c4 


32, REPRODUCTIVE EFFECTS OF [Book If, 


coast, the modern town having been removed towards 
the sea.*. But the south coast of Asia Minor affords 
far more striking examples of advances of the land 
upon the sea, where small streams co-operate with the 
current before mentioned. Captain Beaufort, in his 
Survey of that coast, has pointed out the great alter- 
ations effected on these shores since the time of Strabo, 
where havens are filled up, islands joined to the main- 
land, and where the whole continent has increased 
many miles in extent. Strabo himself, on comparing 
the outline of the coast in his time with its ancient 
state, was convinced, like our countryman, that it had 
gained very considerably upon the sea. The new- 
formed strata of Asia Minor consist of stone, not of 
loose, incoherent materials. Almost all the streamlets 
and rivers, like many of those in Tuscany and the 
south of Italy, hold abundance of carbonate of lime in 
solution, and precipitate travertin, or sometimes bind 
together the sand and gravel into solid sandstones and 
conglomerates: every delta and sand bar thus acquires 
solidity, which often prevents streams from forcing 
their way through them, so that their mouths are con- 
stantly changing their position. + 

Distribution of the sediment of the Amazon by cur- 
rents. Among the greatest deposits now in progress, 
and of which the distribution is chiefly determined by 
currents, we may class those between the mouths of 
the Amazon and the southern coast of North America. 
It has been before stated that a great current flows 
along the coast of Africa, from the south, which, when 


* Von Hoff, vol. i. p. 253. 
+ Karamania, or a brief Description of the Coast of Asia 
Minor, &c. London, 1817. 


Ch. VIIL] TIDES. AND CURRENTS. ` 33 


it reaches the head of the Gulf of Guinea, and is 
opposed by the waters brought to the same spot by 
the Guinea current, streams off in a westerly direction, 
and pursues its rapid course quite across the Atlantic 
to the continent of South America. Here one portion 
proceeds along the northern coast of Brazil to the 
Caribbean Sea and the Gulf of Mexico. Captain Sa- 
bine found that this current was running with the 
astonishing rapidity of four miles an hour where it 


crosses the stream of the Amazon, which river pre- 


Serves part of its original impulse, and has its waters 
not wholly mingled with those of the ocean at the dis- 
tance of three hundred miles from its mouth.* The 
sediment of the Amazon is thus constantly carried to 
the north-west as far as to the mouths of the Orinoco, 
and an immense tract of swamp is formed along the 
coast of Guiana, with a long range of muddy shoals 


bordering the marshes, and becoming converted into 
land. The sediment of the Orinoco is partly de- 
tained, and settles near its mouth, causing the shores 
of Trinidad to extend rapidly, and is partly swept 
away into the Caribbean Sea by the Guinea current. 
According to Humboldt, much sediment is carried 
again out of the Caribbean Sea into the Gulf of Mex- 
ico, The rivers, also, which descend from the high 
platform of Mexico, betweén the mouths of the Norte 
and Tampico, when they arrive, swollen by tropical 
rains, at the edge of that platform, bear down an enor- 
mous quantity of rock and mud to the sea; but the 


* Experiments to determine the Fi 
p. 445. 


t Lochead’s Observations on the Nat. Hist. of Guiana. Edin. 
Trans., vol, iv, 


gure of the Earth, &c 


c 5 


anaran aa x -a i 


34 REPRODUCTIVE EFFECTS OF [Book II. 


current, setting across their mouths, prevents the 
growth of deltas, and preserves an almost uniform 
curve in that line of coast.* It must, therefore, exert 
a great transporting power, and it cannot fail to sweep 
away part of the matter which is discharged from the — 
mouths of the Norte and the Mississippi. . 

Area over which strata may be formed by currents. — 
In regard to the distribution of sediment by cur- 
rents, it may be observed, that the rate of subsidence 
of the finer mud carried down by every great river into 
the ocean, must be extremely slow; for the more 
minute the separate particles of mud, the slower will 
they sink to the bottom, and the sooner will they 
acquire what is called their terminal velocity. It is 
well known that a solid body, descending through a 
resisting medium, falls by the force of gravity, which 
is constant, but its motion is resisted by the medium 
more and more as its velocity increases, until the 
resistance becomes sufficient to counteract the further 
increase of velocity. For example, a leaden ball, one 
inch diameter, falling through air of density as at the 
earth’s surface, will never acquire greater velocity 
than 260 feet per second, and, in water, its greatest 
velocity will be 8 feet 6 inches per second. If the 
diameter of the ball were +15 of an inch, the terminal 
velocities in air would be 26 feet, and in water ‘86 of a 
foot per second. 

Now, every chemist is familiar with the fact, that mi- 
nute particles descend with extreme slowness through 
water, the extent of their surface being very great 
in proportion to their weight; and the resistance of 
the fluid depending on the amount of surface. A pre- 


* This coast has been recently examined by Captain Vetch. — 
See also Bauza’s new chart of the Gulf of Mexico. 


Ch; VIIL] TIDES AND CURRENTS. 35 


cipitate of sulphate of baryta, for example, will some- 
times require more than five or six hours to subside 
one inch*; while oxalate and phosphate of lime re- 
quire nearly an hour to subside about an inch and a 
half and two inches respectively +, so exceedingly 
small are the particles of which these substances 
consist. 

When we recollect that the depth of the ocean is 
supposed frequently to exceed three miles, and that 
currents run through different parts of that ocean at 
the rate of four miles an hour, and when at the same 
time we consider that some fine mud carried down by 
rivers, as well as the impalpable powder showered 
down by volcanos, may subside at the rate of only an 
inch per hour, we shall be prepared to find examples 
of the transportation of sediment over areas of inde- 
finite extent. 

It is not uncommon for the emery powder used in 
polishing glass to take more than an hour to sink ‘one 
foot. Suppose mud, composed of particles twice as 
coarse, to fall at the rate of two feet per hour, and 
these to be discharged into that part of the Gulf 
Stream which preserves a mean velocity of three 
miles an hour for a distance of two thousand miles ; 
in twenty-eight days these particles will be carried 
2016 miles, and will have fallen only to a depth of 
224 fathoms. 

In this example, however, it is assumed that the 
current retains its superficial velocity at the depth of 
224 fathoms, for which we have as yet no data. Ex- 
periments should be made to ascertain the rate of 


* On the authority of Mr. Faraday. 
t On the authority of Mr. R. Phillips. 
c 6 


36 REPRODUCTIVE EFFECTS, ETC. [Book TI. 


currents at considerable distances from the surface, 
and the time taken by the finest river sediment to 
settle in sea-water of a given depth, and then the 
geologist may determine the area over which homo- 
geneous mixtures may be simultaneously distributed 
in certain seas. 

Stratification. — In regard to the internal arrange- 
ment of formations deposited in the deep sea by cur- 
rents far from the land, we may infer that in them, as 
in deltas, there is usually a division into strata ; for, in 
both cases, the accumulations are successive, and, for 
the most part, interrupted. The waste of cliffs on the 
British coast is almost entirely confined to the winter 
months ; so that running waters in the sea, like those 
on the land, are periodically charged with sediment, 
and again become pure. 


CHAPTER Ix, 
Iengeous Causss. 


Changes of the inorganic world, continued — Igneous causes — 
Division of the subject — Distinct volcanic regions — Region 
ofthe Andes— System of volcanos extending from the Aleutian 
isles to the Moluccas (p. 47.) — Polynesian archipelago — 
Volcanic region extending from the Caspian Sea to the Azores 
— Former connection of the Caspian, Lake Aral, and Sea of 
Azof — Tradition of deluges on the shores of the Bosphorus, 
Hellespont, and Grecian isles (p. 52.) — Periodical alternation 
of earthquakes in Syria and Southern Italy — Western limits of 
the European region (p. 59.) — Earthquakes rarer and more 
feeble as we recede from the centres of volcanic action — Ex- 
tinct volcanos not to be included in lines of active vents, _ 


We have hitherto considered the changes wrought, 
since the times of history and tradition, by the conti- 
nued action of aqueous causes on the earth’s surface ; 
and we have next to examine those resulting from 
igneous agency. As the rivers and springs on the land, 
and the tides and currents in the sea, have, with some 
slight modifications, been fixed and constant to certain 
localities from the earliest periods of which we have 
any records, so the volcano and the earthquake have, 
with few exceptions, continued, during the same lapse 
of time, to disturb the same regions. But as there are 
signs, on almost every part of our continent, of great 


38 POSITION OF VOLCANIC VENTS. [Book II, 


power having been exerted by running water on the 
surface of the land, and by waves, tides, and currents 
on cliffs bordering the sea, where, in modern times, no 
rivers have excavated, and no waves or tidal currents 
undermined—so we find signs of volcanic vents and 
violent subterranean movements in places where the 
_ action of fire has long been dormant. We can explain 
why the intensity of the force of aqueous causes should 
be developed in succession in different districts. Cur- 
rents, for example, tides, and the waves of the sea, 
cannot destroy coasts, shape out or silt up estuaries, 
break through isthmuses, and annihilate islands, form 
shoals in one place and remove them from another, 
without the direction and position of their destroying 
and transporting power becoming transferred to new 
localities. Neither can the relative levels of the earth’s 
crust, above and beneath the waters, vary from time 
to time, as they are admitted to have varied at former 
periods, and as it will be demonstrated that they still 
do, without the continents being, in the course of ages, 
modified, and even entirely altered, in their external 
configuration. Such events must clearly be accom- 
panied by a complete change in the volume, velocity, 
and direction of the streams and land floods to which 
certain regions give passage. That we should find, 
therefore, cliffs where the sea once committed ravages, 
and from which it has now retired — estuaries where 
high tides once rose, but which are now dried up— 
valleys hollowed out by water, where no streams now 
flow, is no more than we should expect ;— these and 
similar phenomena are the necessary consequences of 
physical causes now in operation; and, if there be no 
instability in the laws of nature, similar fluctuations’ 
must recur again and again in time to come. 


Ch. IX.] ` POSITION OF VOLCANIC VENTS. 39 


But, however natural it may be that the force of 
running water in numerous valleys, and of tides and 
currents in many tracts of the ‘sea, should now be 
spent, it is by no means so easy to explain why the 
violence of the earthquake and the fire of the volcano 
should also have become locally extinct, at successive 
periods. We can look back to the time when the ma- 
rine strata, whereon the great mass of Etna rests, had 
no existence ; and that time is extremely modern in 
the earth’s history. This alone affords ground for 
anticipating that the eruptions of Etna will one day 
cease. 


Nec que sulfureis ardet fornacibus Ætna 


Ignea semper erit, neque enim fuit ignea semper, 


are the memorable words which are put into the mouth 
of Pythagoras by the Roman poet, and they are fol- 
lowed by speculations as to the cause of volcanic vents 
_ shifting their positions. : Whatever doubts the philoso- 
pher expresses as to the nature of these causes, it is 
assumed, as incontrovertible, that the points of erup- 
tion will hereafter vary, because they have Sormerly 
done so. Te 

I have endeavoured to show, in former chapters, 
that this principle of reasoning has been too much set 
at naught by some modern schools of geology, which 
not only refuse to conclude that great revolutions ins 
the earth’s surface are now in progress, or that th ey 
will take place hereafter, because they have often been 
repeated in former ages, but even assume the impro- 
bability of such a conclusion, and throw the whole 
weight of proof on those by whom that doctrine is 
embraced. 

Division of the subject.— Volcanic action may be de- 


40 POSITION OF VOLCANIC VENTS. [Book II. 


fined to be “ the influence exerted by the heated in- 
terior of the earth on its external covering.” If we 
adopt this definition, without connecting it as Hum- 
boldt has done, with the theory of secular refrigeration, 
or the cooling down of an original heated and fluid 
nucleus, we may then class under a general head all 
the subterranean phenomena, whether of volcanos, or 
earthquakes, or those insensible movements of the 
land, by which, as will afterwards appear, large districts 
may be depressed or elevated, without convulsions. 
According to this view, I shall consider first, the 
volcano ; secondly, the earthquake ; thirdly, the rising 
or sinking of land in countries where there are no 
volcanos or earthquakes ; fourthly, the probable causes 
of the changes which result from subterranean agency. 
It is a very general opinion, that earthquakes and 
volcanos have a common origin ; for both are confined 
to certain regions, although the subterranean move- 
ments are least violent in the immediate proximity of 
volcanic vents, especially where the discharge of 
aériform fluids and melted rock is made constantly 
from the same crater. But as there are particular 
regions, to which both the points of eruption and the 
movements of great earthquakes are confined, I shall 
begin by tracing out the geographical boundaries of 
some of these, that the reader may be aware of the 
magnificent scale on which the agency of subterranean 
fire is now simultaneously developed. Over the whole 
of the vast tracts alluded to, active volcanic vents 
are distributed at intervals, and most commonly ar- 
ranged in a linear direction. Throughout the inter- 
mediate spaces there is abundant evidence that the 
subterranean fire is at work continuously, for the 


Ch. 1X.] VOLCANIC REGIONS. 4l 


ground is convulsed from time to time by earthquakes ; 
gaseous vapours, especially carbonic acid gas, are dis- 
engaged plentifully from the soil; springs often issue 
at a very high temperature, and their waters are 
usually impregnated with the same mineral matters as 
are dischaged by volcanos during eruptions. 


DISTINCT REGIONS OF SUBTERRANEAN DISTURBANCE. 


Region of the Andes.—Of these great regions, that 
of the Andes is one of the best defined. Respecting 
its southern extremity, we are still in need of more 
accurate information, doubts being entertained by some 
whether it extends into Tierra del Fuego. Captain 
Hall, however, had a distant view from his ship, in 
1822, of appearances which seem clearly to indicate 
an eruption of a volcano placed near the Beagle Chan- 
nel (50° 48’ S. lat., 68° W. long.). . Several volcanos 
are said to exist in the Andes of Patagonia, and 
no less than nineteen points of eruption are well 
known in Chili, situated in a continuous line from 
south to north, and forming lofty mountains. The 
number may hereafter be greatly augmented when 
the country has been more carefully examined, and 
throughout a longer period. How long an inter- 
val of rest may entitle us to consider a volcano as 
extinct, is not easily determined; but we know that, 
in Ischia, there intervened, between two consecutive 
eruptions, a pause of seventeen centuries ; and a much 
longer period, perhaps, elapsed between the eruptions 
of Vesuvius before the earliest Greek colonies settled 
in Campania, and the renewal of its activity in the 


49 GEOGRAPHICAL BOUNDARIES [Book 11. 


reign of Titus. It will be necessary, therefore, to 
wait for at least six times as many centuries as have 
elapsed since the discovery of America, before any 
one of the dormant craters of the Andes can be pre- 
sumed to be entirely spent, unless where there are 
some geological proofs that the latest eruptions must 
have belonged to a remote era. 

From the observations of Humboldt it appears, that 
all the volcanos of the Andes, whether extinct or 
active, have burst through basalts and trachytes, or 
through some igneous rocks of a porphyritic structure. 
All the loftiest summits of the range are composed of 
trachyte, with which abundance of obsidian is occa- 
sionally associated, and large accumulations of pumice 
and tuff, the latter formed of fragments of lava and 
, cinders agglutinated together. 
| illarica, in lat. 39° 8’ §., one of the principal of 
the Chilian volcanos, continues burning without inter- 
mission; and is so high that it may be distinguished at 
the distance of 150 miles. A year never passes in 
this province without some slight shocks of earth- 
quakes; and about -once in a century, or oftener; tre- 
mendous convulsions occur, by which, as will be after- 
wards seen, the land has been shaken from one 
extremity to the other; and continuous tracts, in- 
cluding part of the bed of the Pacific, have been 
permanently raised from one to twenty feet or more 
above their former level. Hot springs are numerous 
in this district, as well as springs of naphtha and 
petroleum, and mineral waters of various kinds. 

If we pursue our course northwards, we findin Peru | 
only one active volcano as yet known; but the pro- 
vince is so subject to earthquakes, that scarcely a 
week happens without a shock, and many of these 


Ch. IX. OF VOLCANIC REGIONS. 43 


have been so considerable as to create great changes 
of the surface. 

Proceeding farther north, we find the most consi- 
derable volcanos of the Andes situated in the province 
of Quito, where that chain attains its highest eleva- 
tion. These volcanos, occurring between the second 
degree of south and the third degree of north lat., 
are, Cayambe, Cotopaxi, Pichincha, Antisana, L’ Altar, 
and Tunguragua. The form of Cayambe, whose sum- 
mit is crossed by the line of the equator, is that of a 
truncated cone, which rises to the immense height of 
19,625 feet. The Indians of Lican have a tradition 
that the mountain called L’Altar, or Capac Urcu, 
which means “the chief,” was once the highest of 
those near the equator, being higher than Chimborazo, 
but in the reign of Ouainia Abomatha, before the dis- 
covery of America, a prodigious eruption took place, 
which lasted eight years, and broke it down. The 
fragments of trachyte, says M. Boussingault, which | 
once formed the conical summit of this celebrated 
mountain, are at this day spread over the plain.* 
Cotopaxi is the most lofty of all the South American 
volcanos which have been in a state of activity in 
modern times, its height being 18,858 feet; and its 
eruptions have been more frequent and destructive 
than those of any other mountain. It is a perfect 
cone, usually covered with an enormous bed of snow, 
which has, however, been somtimes melted suddenly 
during an eruption; as in Jan. 1803, for example, 
when the snows were dissolved in one night. 

Deluges are often caused in the Andes by the lique- 
faction of great masses of snow, and sometimes by the 


* Bull. dela Soc. Géol., tom. vi. p. 55. 


44 GEOGRAPHICAL BOUNDARIES | [Book IF, 


rending open, during earthquakes, of subterranean 
cavities filled with water. In these inundations, fine 
volcanic sand, loose stones, and other materials which 
the water meets with in its descent, are swept away, 
and a vast quantity of mud, called “moya,” is thus 
formed and carried down into the lower regions. 
Mud derived from this Source descended, in 1797, 
from the sides of Tunguragua, and filled valleys a 
thousand feet wide to the depth of six hundred feet, 
forming barriers by which rivers were dammed up, 
and lakes occasioned. In these currents and lakes of 
moya thousands of small fish are sometimes enveloped 
which, according to Humboldt, have lived and mul- 
tiplied in subterranean cavities, So great a quantity 
of these fish were ejected from the volcano of Imba- 
buru in 1691, that fevers, which prevailed at the pe- 
riod, were attributed to the efluvia arising from the 
putrid animal matter. 

In Quito, many important revolutions in the physical 
features of the country are said to have resulted, within 
the memory of man, from the earthquakes by which 
it has been convulsed. M. Boussingault declares his 
belief, that if a full register had been kept of all the 
convulsions experienced here and in other populous 
districts of the Andes, it would be found that the 
trembling of the earth had been incessant. The fre- 
quency of the movement, he thinks, is not due to 
volcanic explosions, but to the continual falling in of 
masses of rock’ which have been fractured and up- 
heaved in a solid form at a comparatively recent epoch. 
According to the same author, the height of several 
mountains of the Andes has diminished in modern times.* 


* Bull. de la Soc. Géol. de France, tom. vi. p. 56. 


T > 45 
Ch. 1X7 OF VOLCANIC REGIONS. 


If we continue our investigations still farther to the 
north, we find in the same line three volcanos in the 
province of Pasto, and three others in that of Popayan. 
In the provinces of Guatimala and Nicaragua, which 
lie between the isthmus of Panama and Mexico, there 
are no less than twenty-one active volcanos, all of them 
contained between the tenth and fifteenth degrees of 
north latitude. 

The great volcanic chain, after having thus pursued 
its course for several thousand miles from south to 
north, turns off in a side direction in Mexico, in the 
parallel of the city of that name, and is prolonged in 
a great platform, between the eighteenth and twenty- 
second degrees of north latitude. This high table 
land is said to owe its present form to the circumstance 
of an ancient system of valleys, in a chain of granitic 
mountains, having been filled up to the depth of many 
thousand feet, with various volcanic products. Five 
active volcanos traverse Mexico from west to east — 


Tuxtla, Orizaba, Popocatepetl, Jorullo, 


and Colima. 
Jorullo, 


which is in the centre of the great platform, 
is no less than 120 miles from the nearest ocean—an 
important circumstance, as showing that the 


. proximity | 
of the sea is not a necessary 


condition, although cer- 
tainly a very general characteristic, of the position of 


active volcanos. The extraordinary eruption of this 
mountain, in 1759, will be described in 
the line which connects these five v 
ina westerly direction, it cuts the 
islands, called the Isles of Revil] 

To the north of Mexico ther 
ing to some five, volcanos, 
but of these we have at 


the sequel. If 
ents be prolonged, 
volcanic group of 
agigedo. 

€ are three, or accord- 
in the peninsula of California, 
present no detailed account. 


I have before mentioned the violent earthquakes which 


4G GEOGRAPHICAL BOUNDARIES [Book 13. 


in 1812 convulsed the valley of the Mississippi at New 
Madrid, for the space of three hundred miles in length. 
As this happened exactly at the same time as the 
great earthquake of Caraccas, it is probable that these 
two points are parts of one continuous volcanic region ; 
for the whole circumference of the intervening Carib- 
bean Sea must be considered as a theatre of earth- 
quakes and volcanos. On the north lies the island of 
Jamaica, which, with a tract of the contiguous sea, 
has often experienced tremendous shocks; and these 
are frequent along a line extending from Jamaica to 
St. Domingo, and Porto Rico. On the south of the 
same basin the shores and mountains of Colombia are 
perpetually convulsed. On the west, is the volcanic 
chain of Guatimala and Mexico, before traced out ; 
and on the east the West India isles, where, in St. 
Vincent’s and Guadaloupe, are active vents. 

Thus it will be seen that volcanos and earthquakes 
occur uninterruptedly, from Chili to the north of 
Mexico ; and it seems probable, that they will here- 
after be found to extend from Cape Horn to California, 
or even to New Madrid, in the United States—a 
distance upon the whole as great as from the pole to 
the equator. In regard to the western limits of the 
region, they lie deep beneath the waves of the Pacific, 
‘and must continue unknown to us. On the east they 
are not prolonged, except where they include the 
West Indian islands, to a great distance ; for there 
seem to be no indications of volcanic disturbances in 
Guiana, Brazil, and Buenos Ayres. 

Canada.— Although no volcanos have been dis- 
covered in the northern regions of the new continent, 
we have authentic accounts of frequent earthquakes 
in Canada, and some of considerable violence have 


Doma : 


D 
A 


in op 


l 2 
Salanga y oH 
g 


i 
e 


P? Battooa Q 


P? Sebeerx DS 


Good Fortu ES 
N Pog 
r Por! 
TES 


Rin 


Tantalanı 


VA 


Hainan 


pul 


Mindor 


Gilamianes 


Palawan 


Ci Natuna Q 


> 
Alil Anambas 


< 
o 


Ww Binti 2 
A 


Volemo 
& 


Zed 2 


Lhersria 


saphe 


Volcanic Band, 
of the 
* Greek Islands. 


B 


Sambas 
o 


T 


Balabac o 


9 QBanatey 


ẹę Mematitha 


GV KN ££ 


o 


VOLCANIC BAND, 
of ‘the 
MOLTCCA 3 
and 
SUNDA ISLANDS. 


Reduced trom Maps of 
LEOPOLD VON BUCH. 


e a cones an 


Banka 


ae 


Billiton 


ž 


Benjermassin 


Sir ‘Laut 


Kangelano 

os! 5 

TOPR ok 
“s z: yw o 


teliltuibao 


Morty 


€ m 
amacmore AY ka 
« 
a A? 
~ 
A> ? 
00 


Ph eae’ 
a swage’ 
N 


SS 


Sandd Wood A 


no 


Longitude Kast from Greemwich, 


Ch. IX.) OF VOLCANIC REGIONS. AT 


Occurred, as that of 1663, hereafter to be described. 
A large part. of the estuary of the St. Lawrence and 
the surrounding country has been shaken from time to 
time; and we learn from Captain Bayfield’s Memoirs, 
that along the shores of the estuary and Gulf of St. 
awrence horizontal. banks of recent shells appear at 
Various heights, from ten to one hundred feet above 
igh water mark, and inland beaches of sand and 
Shingle with similar. shells, as also elevated limestone 
rocks Scooped. out by the waves, and. showing lines of 
lithodomous perforations, facts which indicate most 
Clearly the successive upheaving of the land since the 
‘ea was inhabited by the existing species of testacea.* 
Volcanic region from the Aleutian Isles to the Moluc- 
“as.— On a scale, which equals, or surpasses, that of the 
Andes, is another continuous line of volcanic action, 
Which commences, on the north, with the Aleutian Isles 
in Russian America, and extends, first in a westerly 
direction for nearly two hundred geographical miles, 
and then southwards, without interruption, throughout 
à Space of between 60° and 70° of latitude to the 
oluccas, where it branches off in different directions 
oth towards the east and north-west. + Thenorthern 
extremity of this volcanic region is the Peninsula of 
Alaska in about the fifty-fifth degree of latitude. From 
"hence the line is continued through the Aleutian or 
x Islands, to Kamtschatka. In: that archipelago 
eruptions are frequent ; and a new island rose in 1814, 
Which, according to some reports, is three thousand 


a Proceedings of Geol. Soc. No. 33. p. 5. and Trans. of Lit. 
SCHOE Quebec, vols. i. ii. 


t See map of volcanic lines which I have reduced and cor- 
rected from Von\Buch’s work on the Canaries. 


48 GEOGRAPHICAL BOUNDARIES [Book If, 


feet high and four miles round.* Langsdorf also 
mentions a rock of equal height, consisting of trachyte, 
said to have made its appearance at once from the 
bottom of the sea in the year 1795. t Earthquakes of 
the most terrific description agitate and alter the bed of 
the sea and surface of the land throughout this tract. 
The line is continued in the southern extremity of the 
peninsula of Kamtschatka, where there are seven active 
volcanos, which, in some eruptions, have scattered 
ashes to immense distances. The Kurile chain of 
islands constitutes the prolongation of the range, where 
a train of volcanic mountains, nine of which are 
known to have been in eruption, trends in a southerly 
direction. In these, and in the bed of the adjoining 
sea, alterations of level have resulted from earthquakes 
since the middle of the last century. The line is then 
continued to the south-west in the great island of 
Jesso, where there are active volcanic vents, as also in 
Nipon, the principal of the Japanese group, where the 
number of burning mountains is very great ; slight 
shocks of earthquakes being almost incessant, and 
violent ones experienced at distant intervals. Be- 
tween the Japanese and Philippine Islands, the com- 
munication is preserved by several small insular vents. 
Sulphur Island, in the Loo Choo archipelago, emits 
sulphureous vapour ; and Formosa suffers greatly from 
earthquakes. _ In Luzon, the most northern and largest 
of the Philippines, are three active volcanos ; Mindinao 
also was in eruption in 1764. The line is then pro- 
longed through Sanguir and the north-eastern extre- 
mity of Celebes, by Ternate and Tidore, to the Moluc- 


* Von Hoff, vol. ii. p. 414. 
t Referred to by Daubeny, Encycl. Metr, Part. 38, P 725. 


Ch. TX.} OF VOLCANIC REGIONS. eG 49 
Cas, and, amongst ‘the ‘rest, Sumbawa. Here a great 
transverse line may be said to run from east to west. 
On the west it passes through the whole of Java, 
where there are thirty-eight large volcanic mountains, 
many of which continually discharge smoke and sul- 
Phureous vapours. In the volcanos of Sumatra, the 
Same linear arrangement is preserved; but the line 
inclines gradually to the north-west in such a manner 
aS ‘toi point to the active volcano in Barren Island, in 
the Bay of Bengal, in about the twelfth degree of 
North latitude. (See plate of Volcanic Band of Molucca 
and Sunda ‘Islands, p-47.) \In another direction the 
Volcanic range is prolonged’ through Borneo, Celebes, 
Banda, and New Guinea; and farther eastward in New 
Britain, New Ireland, and various parts of the Poly- 
nesian archipelago. The Pacific Ocean, indeed, seems, 
ìn equatorial latitudes, to be one vast theatre of igneous 
action ; and its innumerable archipelagos, such as the 
New Hebrides, Friendly and Georgian Islands, are all 
Composed either of coralline limestones, or volcanic 
rocks, with active vents here and there interspersed. 
The abundant production of carbonate of lime in so- 
lution, would alone raise a strong presumption of the 
Volcanic constitution of these tracts, even if there were 
_ Not more positive proofs of igneous agency. 
Volcanic region from the Caspian to the Azores.—If 
We now turn our /attention to the principal region in 
the Old World, which, from time immemorial, has been 
agitated by earthquakes, and has given vent, at certain 
Points, to subterranean fires, we find that it possesses 
the Same general characters. This region extends 
from east to west for the distance of about one thou- 
Sand geographical miles, from the Caspian Sea to the 


Azores ; including within its limits the greater part of 


VOL. IL D 


1 


“e aaia ee ny a Se a aiae = . - 
=e $$ 


iced 


50 VOLCANIC REGION EXTENDING FROM [Book Il. 


the Mediterranean, and its most prominent peninsulas. 
From south to north, it reaches from about the thirty- 
fifth to the forty-fifth degree of latitude. Its northern 
boundaries are Caucasus, the Black Sea, the mountains 
of Thrace, Transylvania, and Hungary —the Aus- 
trian, Tyrolian, and Swiss Alps — the Cevennes and 
Pyrenees, with the mountains which branch off from 
the Pyrenees westward, to the north side of the Tagus. 
Its western limits are the ocean, but it is impossible to 
determine how far it may be prolonged in that direc- 
tion ; neither can we assign with precision its extreme 
eastern limit, since the country beyond the Caspian 
and the Sea of Aral is little known. Capt. A. Burnes, 
in his recent expedition through the valley of the 
Oxus, found that the whole basin of that river had a 
few weeks before he passed through it been convulsed 
by a tremendous earthquake, which had thrown down 
buildings and obstructed the courses of rivers. 

The great steppe of Tartary is unexplored ; and we 
are almost equally ignorant of the physical constitution 
of China, in which country many violent earthquakes 
have been felt. The southern boundaries of the region 
include the most northern parts of Africa, and part of 
the Desert of Arabia.* We may trace, through the 
whole area comprehended within these extensive | 
limits, numerous points of volcanic eruptions, hot 
springs, gaseous emanations, and other signs of ig- 
neous agency; while few tracts, of any extent, have 
been entirely exempt from earthquakes throughout 
the last three thousand years. 

Borders of the Caspian. — To begin on the Asiatic 
side, we find that, on the western shores of the Cas- 


* Von Hoff, vol. ii. p. 99. 


Ch. 1X,] THE CASPIAN TO THE AZORES. 5l 
pian, in the country round Baku, there is a tract called 
the Field of Fire, which continually emits inflammable 
gas, while springs of naphtha and petroleum occur in 
the same vicinity, as also mud volcanos. In the chain 
of Elburs, to the south of this sea, is a lofty mountain, 
which, according to Morier, sometimes emits smoke, 
and at the base of which are several small craters, 
where sulphur and saltpetre are procured in sufficient 
abundance to be used in commerce. Violent subter- 
ranean commotions have been experienced along the 
borders of the Caspian ; and, according to Engelhardt 
and Parrot, the bottom of that sea has, in modern 
times, varied in form; and they say that, near the 

south coast, the Isle of Idak, north from Astrabat, for- 
merly high land, has now become very low.* Any 
indications of a change in the relative levels of the 
land in this part of Asia, are of more than ordinary 
interest ; because it has been supposed that the level 
of the Caspian is much lower than that of the Black 
Sea, although much doubt has recently been thrown 
on the observations from which this conclusion was 
deduced.t 

Steppes of the Caspian.— A low and level tract, 
called the Steppe, abounding in saline plants, and 
Composed of tertiary strata containing many shells of 
Species now common in the adjoining sea, skirts the 
north-western shores of the Caspian. This plain often 
terminates abruptly by a line of inland cliffs, at the 
base of which runs a kind of beach, consisting of frag- 
Ments of limestone and sand, cemented together into 

* Travels in the Crimea and Caucasus, in 1815, vol. i. pp. 257. 


264, — Von Hoff, vol. i. p. 137. 
t See Book iv. chap. 19. 


D 2 


52 VOLCANIC REGION EXTENDING FROM {[Book II. 


a conglomerate. Pallas has endeavoured to show that 
there is an old line of sandy country, which indicates 
the ancient. bed of a strait, by which the Caspian was 
once united to the sea of Azof. On similar grounds, 
itis inferred that the salt lake Aral was formerly 
connected with the Caspian. 

Tradition of deluges on the shores of the Bosphorus, 
&c.— The convulsions which have produced the phe- 
nomena of the steppes may be very modern in the 
earth’s history, and yet a small portion of them only 
may have happened in the last twenty or thirty cen- 
turies. Remote traditions have come down to us of 
inundations, in which the waters of the Euxine were 
forced through the Thracian Bosphorus, and through 
the Hellespont, into the Aigean; and in the deluge of 
Samothrace, it appears that that small island, and the 
adjoining coast of Asia, were inundated. In the Ogy- 
gian also, which happened at a different time, Beotia 
and Attica were overflowed. Notwithstanding the 
mixture of fable, and the love of the marvellous, in 
those rude ages, and the subsequent inventions of 
Greek poets and historians, it may be distinctly per- 
ceived that the floods alluded to were local and tran- 
sient, and. that they happened in succession near the 
borders of that chain of inland seas. They may, per- 
haps, have been nothing more than great waves, which, 
about fifteen centuries before our era, devastated the 
borders of the Black Sea, the Sea of Marmora, the 
Archipelago, and neighbouring coasts, in the same 
manner as the western shores of Portugal, Spain, and 
Northern Africa were inundated, during the great 
earthquake at Lisbon, by a wave which rose, in some 
places, to the height of fifty or sixty feet; or as 
happened in Peru, in 1746, where two hundred violent 


Ch. 1X.] THE CASPIAN TO THE AZORES. 53 


shocks followed each other in the space of twenty-four 
hours, and the ocean broke with impetuous force upon 
the land, destroying the town of Callao, and four other 
Seaports, and permanently converted a considerable 
tract of inhabited country, which had perhaps sunk 
down below its former level, into a bay. Diodorus 
Siculus, in his account of the Samothracian deluge, 
informs us that the inhabitants had time to take refuge 
in the mountains, and save themselves by flight; he 
also relates that, long after the event, the fishermen of 
the island drew up in their nets the capitals of columns, 
Which, he says, were the remains of cities submerged 
by that terrible catastrophe.* These statements 
. Scarcely leave any doubt that the event consisted of a 
Subsidence of the coast, accompanied by a series of 
earthquakes, and successive inroads of the sea. 
In the country between the Caspian and the Black 
Seas, and in the chain of Caucasus, numerous earth- 
quakes have, in modern times, caused fissures and 
Subsidences of the soil, especially at Tiflis} The Cau- 
Casian territories abound in hot-springs and mineral 
Waters, So late as 1814, a new island was raised by 
Volcanic explosions, in the Sea of Azof; and Pallas 
Mentions that, in the same locality, epposite old Tem- 
Tuk, a submarine eruption took place in 1799, accom- 
panied with dreadful thundering, emission of fire and 
smoke, and the throwing up of mire and stones. Vio- 
lent earthquakes were felt at the same time at great 
Istances from Temruk. The country around Erzerum 
exhibits similar phenomena, as does that around Tauris 
and the lake of Urmia, in which latter we have already 


* Book v. chap. 46. See letter of M. Virlet, Bulletin de la 
Soc. Géol. de France, vol. ii. p. 341. 
T Von Hoff, vol. ii. p: 210. 


D 3 


54 VOLCANIC REGION EXTENDING FROM [Book Il. 


remarked the rapid formation of travertin. The lake 
of Urmia, which is about 280 English miles in circum- 
ference, resembles the Dead Sea, in having no outlet, 
and in being more salt than the ocean. Between the 
Tigris and Euphrates, also, there are numerous springs 
of naphtha, and frequent earthquakes agitate the 
country. 

Syria and Palestine abound in volcanic appearances, 
and very extensive areas have been shaken, at different 
periods, with great destruction of cities and loss of 
lives. Continual mention is made in history of the 
ravages committed by earthquakes in Sidon, Tyre, 
Berytus, Laodicea, and Antioch, and in the island of 
Cyprus. The country around the Dead Sea appears 
evidently, from the accounts of modern travellers, to 
be volcanic. A district near Smyrna, in Asia Minor, 
was termed by the Greeks Catacecaumene, or the 
burnt, where there is a large arid territory, without 
trees, and with a cindery soil.* 

Periodical alternation of Earthquakes in Syria and 
Southern Italy. — It has been remarked by Von Hoff, 
that from the commencement of the thirteenth to the 
latter half of the seventeenth century, there was an 
almost entire cessation of earthquakes in Syria and 
Judea; and, during this interval of quiescence, the 
Archipelago, together with part of the adjacent coast 
of Lesser Asia, as also Southern Italy and Sicily, suf- 
fered greatly from earthquakes; while volcanic erup- 
tions were unusually frequent in the same regions. A 
more extended comparison, also, of the history of the 
subterranean convulsions of these tracts seems to con- 
firm the opinion, that a violent crisis of commotion never 


* Strabo, Ed. Fal., p. 900. 


Ch. 1X.] THE CASPIAN TO THE AZORES. 55 


visits both at the same time. It is impossible for us to 
declare, as yet, whether this phenomenon is constant 
in this and other regions, because we can rarely trace 
back a connected series of events farther than a few 
centuries; but it is well known that, where numerous 
vents are clustered together within a small area, as in 
many archipelagos for instance, two of them are never 
m violent eruption at once. If the action of one be- 
Comes very great for a century or more, the others |; 
assume the appearance of spent volcanos. It is, there- |`) 
fore, not improbable that separate provinces of the same 
great range of volcanic fires may hold a relation to one 
deep-seated focus, analogous to that which the aper- 
tures of a small group bear to some more superficial rent 
or cavity. Thus, for example, we may conjecture that, 
at a comparatively small distance from the surface, Is- 
chia and Vesuvius mutually communicate with certain 
fissures, and that each affords relief alternately to elastic 
fluids and lava there generated. So we may suppose 
Southern Italy and Syria to be connected, at a much 
Sreater depth, with a lower part of the very same system 
of fissures ; in which case any obstruction occurring in 
one duct may have the effect of causing almost all the 
vapour and melted matter to be forced up the other, 
and if they cannot get vent, they may be the cause of 
Violent earthquakes. 

Grecian Archipelago. — Proceeding westwards, we 
reach the Grecian Archipelago, where Santorin, after- 
wards to be described, is the grand centre of volcanic 
action. To the north-west of Santorin is another vol- 
cano in the island of Milo, of recent aspect, having a 
very active solfatara in its central crater, and many 
Sources of boiling water and steam. Continuing the 
same line, we arrive at that part of the Morea, where 

p4 


56 VOLCANIC REGION EXTENDING FROM ` (Book II. 


we learn, from ancient writers, that Helice and Bura 
were, in the year 373 B. C., submerged beneath the 
sea by am earthquake; and the walls, according: to 
Ovid, were to be seen beneath. the waters. Near the 
same spot, in our. times (1817), Vostizza: was. laid. in 
ruins by a subterranean. convulsion.* At Methone, 
also (now Modon), in Messenia, about three centuries 
before. our era, an eruption threw up a great volcanic 
mountain, which is represented- by Strabo as being 
nearly four thousand feet. in height; but the magni- 
tude of the hill requires confirmation. Some suppose 
that the accounts. of: the formation of a hill near 
Treezene, of, which, the date is unknown, may refer to 
the same event. 

It was: Von Buch’s opinion that the volcanos. of 
Greece were arranged in a line running N: N. W. and 
S. S. E., as represented in. the map, Pl. 3.; and that 
they afforded the only example, in Europe of active 
volcanos having alinear direction.+ But-observations 
made during the late French expedition to the Morea 
have by-no means confirmed this view. On the con- 
trary, M. Virlet: announces as the result of his. in- 
vestigations, that there is no one determinate line of 
direction for the volcanic phenomena in Greece, 
whether. we follow. the points of eruptions, or the 
earthquakes, or any other signs of igneous agency. 

Macedonia, Thrace, and Epirus, have always. been 
subject. to earthquakes, and. the Ionian Isles are cons 
tinually convulsed, Respecting Southern Italy, Sicily, 
and the Lipari Isles, it is unnecessary to enlarge here, 
as the existence of volcanos in that region is known to 


* Von Hoff, vol. ii. p. 179, 
t Seerplate of volcanic bands, p. 47. 


Ch. 1X.) THE CASPIAN TO THE AZORES. 5T 


all, and I shall have occasion again to allude to them. 
I may mention, however, that Dr. Daubeny has traced 
a band of volcanic action across the Italian Peninsula, 
from Ischia to Mount Vultur, in Apulia, the com- 
mencement of the line being found in the hot springs 
Of Ischia, after which it is prolonged through Vesu- 
vius to the Lago d’Ansanto, where gases similar to 
those of Vesuvius are evolved. Its farther extension 
Strikes Mount Vultur, a lofty cone composed of tuff 
and laya, from one side of which carbonic acid and 
Sulphuretted hydrogen are emitted.* 

The north-eastern portion of Africa, including Egypt, 
Which lies six or seven degrees south of the volcanic 
ine ‘already traced, has been almost always exempt 
from earthquakes: but the north-western portion, 
especially Fez and Morocco, which fall within the 
line, suffer greatly from time to time. The southern 
Part of Spain also, and Portugal, have generally been 
€xposed to the same scourge simultaneously with 

orthern Africa. The provinces of Malaga, Murcia, 
and Granada, and in Portugal, the country round 
Lisbon, are recorded at several periods to have been 
devastated by great earthquakes. It will be seen, 
from Michell’s account of the great Lisbon shock in 
1755, that the first movement proceeded from the bed 
of the ocean ten or fifteen leagues from the coast. So 
late as February 2. 1816, when Lisbon was vehemently 
Shaken, two ships felt a shock in the ocean west from 

z isbon ; one of them at the distance of 120, and the 
other 262 French leagues from the coast +—a fact 

iat Daubeny on Mount Vultur, Ashmolean Memoirs. Oxford, 
35. 


tT Verneur, Journal des Voyages, vol. iv. p. 111. Von Hoff, 
Vol. ii. p. 275, 


DS 


58 VOLCANIC REGIONS. [Book II. 


which is the more interesting, because a line drawn 
through the Grecian archipelago, the volcanic region 
of Southern Italy, Sicily, Southern Spain, and Portu- 
gal, will, if prolonged westward through the ocean, 
strike the volcanic group of the Azores, which has, 
therefore, in all probability, a submarine connection 
with the European line. How far the island of Ma- 
deira, which has been subject to violent earthquakes, 
and the Canary Islands, in which volcanic eruptions 
have been frequent, may communicate beneath the 
waters with the same great region, must for the pre- 
sent be mere matter of conjecture. 

Besides the continuous spaces of subterranean dis- 
turbance, of which we have merely sketched the 
outline, there are other disconnected volcanic groups, 
of which the geographical extent is as yet very im- 
perfectly known. Among these may be mentioned 
Iceland, which belongs, perhaps, to the same region 
as the volcano in Jan Mayen’s Island, situated 5° to 
the north-east. With these, also, part of the nearest 
coast of Greenland, which is sometimes shaken by 
earthquakes, may be connected. 

Tn another hemisphere the island of Bourbon belongs 
to a theatre of volcanic action, of which Madagascar 
probably forms a part, if the alleged existence of 
burning volcanos in that island shall, on further ex- 
amination, be substantiated. In following round the 
borders of the Indian Ocean to the north, we find the 
volcano of Gabel Tor, within the entrance of the 
Arabian Gulf. In the province of Cutch earthquakes 
are frequent, and at Mhurr, twenty-five miles from 
Luckput, there is an active volcano, or at least a sol- 
fatara.* In Malwa, as also in Chittagong, in Bengal, 


* On the authority of Capt. A. Burnes. 


Ch. 1X,] VOLCANIC REGIONS. 59 


there have been violent earthquakes within the his- 
torical period. ) 

Volcanic regions of Southern Europe. —Respecting 
the volcanic system of Southern Europe, it may be 
observed, that there is a central tract where the 
greatest earthquakes prevail, in which rocks are shat- 
tered, mountains rent, the surface elevated or de- 
pressed, and cities laid in ruins. On each side of this 
line of greatest commotion there are parallel bands of 
Country, where the shocks are less violent. Ata still 
Sreater distance (as in Northern Italy, for example, 
€xtending to the foot of the Alps), there are spaces 
Where the shocks are much rarer and more feeble, 
Yet possibly of sufficient force to cause, by continued 
repetition, some appreciable alteration in the external 
form of the earth’s crust. Beyond these limits, again, 
all countries are liable to slight tremors at distant in- 
tervals of time, when some great crisis of subterranean 
Movement agitates an adjoining volcanic region ; but 
these may be considered as mere vibrations, pro- 
Pagated mechanically through thé external covering 
of the globe, as sounds travel almost to indefinite dis- 
tances through the air. Shocks of this kind have 

€en felt in England, Scotland, Northern France, and 
Germany —particularly during the Lisbon earthquake- 
But these countries cannot, on this account, be sup- 
Posed to constitute parts of the southern volcanic 
region, any more than the Shetland and Orkney 
Islands can be considered as belonging to the Icelandic 
circle, because the sands ejected from Hecla have been 
wafted thither by the winds. 

Lines of active and extinct Volcanos not to be con- 
founded, —We must also be careful to distinguish 
between lines of extinct and active volcanos, even 

D 6 


60 VOLCANIC REGIONS, [Book II, 


where they appear to run in the same direction ; for 
ancient and modern systems may cross and interfere 
with each other. Already, indeed, we have proof that 
this is the case ; so that it is not by geographical posi- 
tion, but by reference to the species of organic beings 
alone, whether aquatic or terrestrial, whose remains 
occur in beds. interstratified with lavas, that we can 
clearly distinguish the relative age of volcanos of which 
no eruptions are recorded. Had Southern Italy been 
known to civilized nations. for as short a period as 
America, we should have had no record of eruptions 
in Ischia; yet we might have assured ourselves that 
the lavas of that isle had flowed since. the Mediter- 
ranean was inhabited by the species of testacea now 
living in the Neapolitan seas.* With this assurance 
it would not have been rash to include. the numerous 
vents of that island in the modern volcanic group of 
Campania. 

On similar grounds we may infer, without much 
hesitation, that the eruptions of Etna and the modern 
earthquakes of Calabria, are a continuation. of that 
action, which, at a somewhat earlier period, produced 
the submarine lavas of the Val. di Noto in. Sicily. + 
But the lavas of the Euganean hills and the Vicentin, 
although not wholly beyond. the range of earthquakes 
in Northern Italy, must not be confounded with any 
existing volcanic system ; for when they flowed, the 
seas were inhabited by animals almost all of them dis- 
tinct from those now known to live, whether. in. the 
Mediterranean or other parts of the globe. But an 
examination of these topics would, carry us to events: 
anterior to the times of history ; we must therefore 
defer their consideration to the 4th Book; 


*) See account of Ischia, book iv, chap, 10. 
+ Boek iv, ch. 6. 


vmn TIS: 


opeuodum) Pad i 
ch XO 


LORDLSTIG OINVO TOA 


Optog Ip odo) 


DPVWOLT 


-W uoj 


VUSIJAV 5p 


“unuosıpr Sf? 


CHAPTER X. 
VOLCANIC DISTRICT OF NAPLEs. 


History of the voleanic eruptions in the district round Naples — 
Early convulsions in the island of Ischia—— Numerous cones 
thrown up there— Epomeo not an habitual volcano — Lake 
Avernus — The Solfatara — Renewal of the eruptions of Vesu- 
vius, A.n. 79—Pliny’s description of the phenomena (p. 67.) 
— Remarks on his silence respecting the destruction of Hercu- 
laneum and Pompeii — Subsequent history of Vesuvius — Lava 
discharged in Ischia in 1802 — Pause in the eruptions of Vesu- 
vius — Monte Nuovo thrown up (p. 72.)—Uniformity of the 
Volcanic operations of Vesuvius and the Phlegrzan Fields in 
ancient and modern times. 


I suant next give.a sketch of the history of some of 
the volcanic vents dispersed throughout the great re- 
ions before described, and consider the composition 
and arrangement of their lavas and. ejected matter. 
The only volcanic region known to the ancients was): 
that. of which the Mediterranean forms a part; and 
even of this they have transmitted to us very imper- 
fect records relating to the eruptions of the three 
Principal districts, namely, that round Naples, that of. 
Sicily and its isles, and that of the Grecian Archipe- 
ago. By far the most connected. series of records 
throughout a long period relates to the first of these 
Provinces: and these cannot be too attentively con- 
sidered, as much historical information is indispensable 


62 VOLCANIC ERUPTIONS IN ISCHIA. [Book If. 


in order to enable us to obtain a clear view of the 
connection and alternate mode of action of the different 
vents in a single volcanic group. 

Early convulsions in the Island of Ischia.— The 
Neapolitan volcanos extend from Vesuvius, through the 
Phlegrzan Fields, to Procida and Ischia, in a somewhat 
linear arrangement, ranging from the north-east to the 
south-west, as will be seen in the annexed map of the 
volcanic district of Naples (plate 4.). Within the space 
above limited, the volcanic force is sometimes deve- 
loped in single eruptions from a considerable number 
of irregularly scattered points ; but a great part of its 
action has been confined to one principal and habitual 
vent, Vesuvius or Somma. Before the Christian era, 
from the remotest periods of which we have any tra- 
dition, this principal vent was in a state of inactivity. 
But terrific convulsions then took place from time to 
time in Ischia (Pithecusa), and seem to have extended 
to the neighbouring isle of Procida (Prochyta) ; for 
Strabo * mentions a story of Procida having been torn 
asunder from Ischia; and Pliny + derives its name 
from its having been poured forth by an eruption from 
Ischia. 

The present circumference of Ischia along the wa- 
ter’s edge is eighteen miles, its length from west to 
east about five, and its breadth from north to south 
three miles. Several Greek colonies which settled there 
before the Christian era were compelled to abandon 
it in consequence of the violence of the eruptions. 
First the Erythraans, and afterwards the Chalcidians, 
are mentioned as having been driven out by earth- 


*YEABs Vi í + Nat. Hist., lib. iii. c. 6. 


Ch..X.] VOLCANIC ERUPTIONS IN ISCHIA. 63 


quakes and igneous exhalations. A colony was after- 
wards established by Hiero, king of Syracuse, about 
380 years before the Christian era; but when they 
had built a fortress, they were compelled by an erup- 
tion to fly, and never again returned. Strabo tells us 
that Timeus recorded a tradition, that, a little before 
his time, Epomeus, the principal mountain in the 
Centre of the island, vomited fire during great earth- 
quakes ; that the land between it and the coast had 
ejected much fiery matter, which flowed inte the sea, 
and that the sea receded for the distance of three 
Stadia, and then returning, overflowed the island. This 
eruption is supposed by some to have been that which 
Ormed the crater of Monte Corvo on one of the 
higher flanks of Epomeo, above Foria, the lava-current 
of which may still be traced, by aid of the scorize on 
its surface, from the crater to the sea. 

To one of the subsequent eruptions in the lower 
Parts of the isle, which caused the expulsion of the 
first Greek colony, Monte Rotaro has been attributed, 
and it bears every mark of recent origin. The cone 
18 remarkably perfect, and has a crater on its summit 
Precisely resembling that of Monte Nuovo; but the 
hill is larger, and resembles some of the more con- 
Siderable cones of single eruption near Clermont in 
Auvergne, and, like some of them, it has given vent 
to a lava-stream at its base, instead of its summit. A 
Small ravine swept out by a torrent exposes the struc- 
ture of the cone, which is composed of innumerable 
inclined and slightly undulating layers of pumice, 
Scoriæ, white lapilli, and enormous angular blocks of 
trachyte. These last have evidently been thrown out 

` by violent explosions, like those which in 1822 launched 


64 ~ VOLCANIC ERUPTIONS IN ISCHIA. [Book If. 


from Vesuvius a mass of augitic lava, of many tons 
weight, to the distance of three miles, which fell in 
the garden of Prince Ottajano. The cone of Rotaro 
is covered with the arbutus, and other beautiful ever- 
greens. Such is the strength of the virgin soil, that 
the shrubs have become almost arborescent; and the 
growth of some of the smaller wild plants has been so 
vigorous, that botanists have scarcely been able to 
recognize the species. 

The eruption which dislodged the Syracusan colony 
is supposed. to have given rise to that mighty current 
which forms the promontory of Zaro and Caruso. The 
surface of these lavas is still very arid and bristling, 
and is covered, with black scoriz; so that it is not 
without great labour that human industry has re- 
deemed some small spots, and converted them into 
vineyards. Upon the produce of these vineyards the 
population of the island is almost entirely supported. 
It amounts at present to about. twenty-five thousand,” 
and ison the increase. 

From the date of the great eruption last alluded to, 
down to our own time, Ischia has enjoyed tranquillity, 
with the exception of one emission of lava hereafter 
to be described, which, although it occasioned much 
local damage, does not appear to have devastated the 
whole country, in the manner of more ancient ex- 
plosions.. There are, upon the whole, on different 
parts of Epomeo, or scattered through the lower tracts 
of Ischia, twelve considerable volcanic cones, which 
have been thrown up since the island was raised above 
the surface of the deep; and many streams of lava 
may have flowed, like that of ‘ Arso’ in 13802, without 
cones having been produced; so that this island may; 
for ages before the period of the remotest traditions, 


Ch. X.] AVERNUS — SOLFATARA. 65 


have served as a safety-valve to the whole Terra di 
Lavoro, while the fires of Vesuvius were dormant.* 

Lake Avernus.—It seems-also clear, that Avernus, 
a- circular lake near Puzzuoli, about half a mile in 
diameter, which is now'a salubrious and cheerful spot, 
once exhaled mephitic vapours; such as are often 
emitted by. craters after eruptions. There is no 
reason for discrediting the account of Lucretius, that 
birds could not fly over it without being stifled, al- 
though they: may now frequent it uninjured. There 
must have been a time when this crater was in action ; 
and for many centuries afterwards it may have de- 
Served the appellation of ‘atri janua Ditis,” emitting, 
Perhaps, gases as destructive of animal life as those 
suffocating vapours given out by Lake Quilotoa, in 
Quito, in 1797, by which whole herds of cattle on its 
Shores were killed}, or as those deleterious eman- 
ations which annihilated all the cattle in the island 
of Lancerote, one of the Canaries, in 1730.§ Bory 
St. Vincent, mentions, that in the same isle birds fell 
lifeless. to. the ground; and Sir William Hamilton 
informs us that he picked up dead birds on Vesuvius 
during an eruption. 

Solfatara.— The Solfatara, near Puzzuoli, which 
May be considered as a nearly extinguished crater, 
appears, by the accounts of Strabo and others, to have 
been before the Christian era in very much the same 
State as at presént, giving vent continually to aqueous 


* For an account of the geology of Ischia, see book iv. ch. 10. 

t. De Rerum Nat., vi. 740. — Forbes, on Bay of Naples, Edin. 
Journ of Sci., No. iii. new series, p. 87. Jan. 1830. 

¢ Humboldt, Voy., p. 317. 


$ Von Buch , Uber einen vulcanischen Ausbruch auf der Insel 
Lanzerote, 


66 ERUPTION OF VESUVIUS, A. D. 79. [Book II. 


vapour, together with sulphureous and muriatic acid 
gases, like those evolved by Vesuvius. 

Ancient history of Vesuvius.— Such, then, were the 
points where the subterranean fires obtained vent, from 
the earliest period to which tradition reaches back, . 
down to the first century of the Christian era; but we 
then arrive at a crisis in the volcanic action of this 
district — one of the most interesting events witnessed 
by man during the brief period throughout which he has 
observed the physical changes on the earth’s surface. 
From the first colonization of Southern Italy by the 
Greeks, Vesuvius afforded no other indications of its 
volcanic character than such as the naturalist might 
infer, from the analogy of its structure to other vol- 
canos. These were recognized by Strabo, but Pliny 


did not include the mountain in his list of active 


vents. The ancient cone was of a very regular form, 


terminating, not as at present, in two peaks, but with 
a flattish summit, where the remains of an ancient 
crater, nearly filled up, had left a slight depression, 
covered in its interior by wild vines, and with a sterile 
plain at the bottom. On the exterior, the flanks of 
the mountains were clothed with fertile fields richly 
cultivated, and at its base were the populous cities of 
Herculaneum and Pompeii. But the scene of repose 
was at length doomed to cease, and the volcanic fire 
was recalled to the main channel, which, at some 
former unknown period, had given passåge to repeated 
streams of melted lava, sand, and scoriz. . 
Renewal of its eruptions.—The first symptom of the 
revival of the energies of this volcano was the occur- 
rence of an earthquake in the year 63 after Christ, 
which did considerable injury to the cities in its 
vicinity. From that time to the year 79 slight shocks 


Ch. X.] ERUPTION OF VESUVIUS, A. D. 79. 67 


were frequent ; and in the month of August of that 
year they became more numerous and violent, till they 
ended at length in an eruption. The elder Pliny, who. 
commanded the Roman fleet, was then stationed at 
Misenum ; and in his anxiety to obtain a near view of 
the phenomena, he lost his life, being suffocated by 
sulphureous vapours. His nephew, the younger Pliny, 
remained at Misenum, and has given us, in his Let- 
ters, a lively description of the awful scene. A dense 
Column of vapour was first seen rising vertically from 
Vesuvius, and then spreading itself out laterally, so that 
its upper portion resembled the head, and its lower 
the trunk of the pine which characterizes the Italian 
landscape. This black cloud was pierced occasionally 
by flashes of fire as vivid as lightning, succeeded by 
darkness more profound than night. Ashes fell even 
Upon the ships at Misenum, and caused a shoal in one 
Part of the sea—the ground rocked, and the sea re- 
ceded from the shores, so that many marine animals 
Were seen on the dry sand. The appearances above 
described agree perfectly with those witnessed in more 
recent eruptions, especially those of Monte Nuovo in 
1538, and of Vesuvius in 1822. 

Silence of Pliny respecting the destruction of Hercu- 
laneum and Pompeii.—In all times and countries, 
indeed, there is a striking uniformity in the volcanic 
Phenomena; but it is most singular that Pliny, although 
giving a circumstantial detail of so many physical facts, 
and describing the eruption, earthquake, and shower of 
ashes which fell at Stabiæ, makes no allusion to the 
sudden overwhelming of two large and populous cities, 
Herculaneum and Pompeii. All naturalists who have 
searched into the memorials of the past for records 
of physical events, must have been surprised at the 


68 ERUPTION OF VESUVIUS, A. D. 79, [Book II. 


indifference with which the most memorable occur- 
rences are often passed by; in the works of writers of 
enlightened periods ; as also of the extraordinary ex- 
aggeration which usually displays: itself in the tradi- 
tions of’ similar events, in ignorant and superstitious 
ages. But no omission is more remarkable than that 
now under consideration : nor has the circumstance, we 
think, been at all explained by the suggestion that the 
chief object of the younger Pliny was to give Tacitus 
a full account of the particulars of his uncle’s death. 
We have no hesitation in saying, that had the buried 
Cities never been discovered, the accounts transmitted 
to us of their tragical'end would have been discredited 
by the majority; so vague and general are the narra- 
tives, or so long subsequent to the event. Tacitus, 
the friend and contemporary of Pliny, when adverting 
in general terms to the convulsions, says merely that 
“cities were consumed or buried,” * 

Suetonius, although he alludes to the eruption inci- 
dentally, is silent as to the cities, They are mentioned 
by Martial, in an epigram, as immersed in cinders ; 
but the first historian who alludes to them by name is 
Dion Cassius t, who flourished about a century and a 
half after Pliny. He appears to have derived his 
information from the traditions of the inhabitants, and 
to have recorded, without discrimination, all the facts 
and fables which he could collect. He tells us, “that 
during the ernption a multitude of men of superhuman 
Stature, resembling giants, appeared, sometimes on 
the mountain, and sometimes in the environs —that 
Stones and smoke were thrown out, the sun was hidden, 


* Haustæ aut obrute urbes., — Hist., lib. i. 
T Hist. Rom., lib. lxvi. 


Ch. XJ ERUPTION OF VESUVIUS, A.D. 79. 69 


and then the giants seemed to rise again, while the 
Sounds of trumpets were heard, &c. &c. ; and finally,” 
he relates, “two entire cities, Herculaneum and Pom- 
Peli, were buried under showers of ashes, while all the 
People were sitting in the theatre.” That many of 
these circumstances were invented would have been 
obvious, even without the aid of Pliny’s letters ; and 
the examination of Herculaneum and Pompeii enables 
Us to prove, that none of the people were. destroyed 
in the theatres, and, indeed, that there were very few 
of the inhabitants who did not escape from, both cities. 
Yet some lives were lost, and there was ample founda- 
tion for the tale in its most essential particulars. 

This case may often serve as.a caution ;to the 
$eologist, who has frequent occasion to. weigh, in like 
Manner, negative evidence derived from the silence of 
€minent writers, against the obscure but. positive testi- 
mony of popular traditions. Some authors, for ex- 
ample, would have us call in question the reality of 
the Ogygian deluge, because Homer and Hesiod say 
nothing of it. But they were poets, not historians, 
and they lived many centuries after the latest date 
assigned to the catastrophe. Had they even lived at 
the time of that flood, we might still contend that 
their silence ought, no more than Pliny’s, to avail 
against the authority of tradition, however much ex- 
@ggeration we may impute to the traditional narrative 
of the event. 

It does not appear that in the year 79 any lava 
flowed from Vesuvius ; the ejected substances, per- 
haps, consisted entirely of Japilli, sand, and fragments 
of older lava, as when Monte Nuovo was thrown up in 
1538. The first era at which we have authentic ac- 
Counts of the flowing of a stream of lava, isthe year 


70 ERUPTION IN ISCHIA, A.D. 1302. [Book II. 


1036, which is the seventh eruption from the revival 
of the fires of the volcano. A few years afterwards, 
in 1049, another eruption is mentioned, and another 
in 1138 (or 1139), after which a great pause ensued 
of 168 years. During this long interval of repose, 
two minor vents opened at distant points. First, it 
is on tradition that an eruption took place from the 
Solfatara in the year 1198, during the reign of Frederic 
I., Emperor of Germany ; and although no circum- 
stantial detail of the event has reached us from those 
dark ages, we may receive the fact without hesitation.* 
Nothing more, however, can be attributed to this 
eruption, as Mr. Scrope observes, than the discharge 
of a light and scoriform trachytic lava, of recent 
aspect, resting upon the strata of loose tuff which 
covers the principal mass of trachyte. + 

Volcanic eruption in Ischia, 1302.—The other oc- 
currence is well authenticated,—the eruption, in the 
year 1302, of a lava-stream from a new vent on the 
south-east side of the Island of Ischia. During part 
of 1301, earthquakes had succeeded one another with 
fearful rapidity ; and they terminated at last with the 
discharge of a lava-stream from a point named the 
Campo del Arso, not far from the town of Ischia. 
This lava ran quite down to the sea—a distance of 
about two miles ; in colour it varies from iron grey to 
reddish black, and is remarkable for the glassy felspar 
which it contains. Its surface is almost as sterile, 
after a period of five centuries, as if it had cooled 


* The earliest authority, says Mr. Forbes, given for this fact, 
appears to be Capaccio, quoted in the Terra Tremante of Bonito. 
` — Edin. Journ. of Sci. &c. No. I., N. S., p. 127. July, 1829. 
t Geol, Trans., second series, vol. ii, p. 346. 


Ch. X] SUBSEQUENT HISTORY OF VESUVIUS. - 71 
down yesterday. A few scantlings of wild thyme, and 
two or three other dwarfish plants, alone appear in the 
interstices of the scoriz, while the Vesuvian lava of 
1767 is already covered with a luxuriant vegetation. 
P Ontanus, whose country-house was burnt and over- 
Whelmed, describes the dreadful scene as having 
lasted two months.* Many houses were swallowed 
Up, and a partial emigration of the inhabitants followed. 
This eruption produced no cone, but only a slight de- 
Pression, hardly deserving the name of a crater, where 
aps of black and red scoriz lie scattered around. 
ntil this eruption, Ischia is generally believed to 
ave enjoyed an interval of rest for about seventeen 
Centuries ; but Julius Obsequens +, who flourished 
A.D. 214, refers to some volcanic convulsions in the 
Year 662 after the building of Rome (ot Reyes 
liny, who lived a century before Obsequens, does not 
numerate this among other volcanic eruptions, the 
Statement of the latter author is supposed to have 
een erroneous; but it would be more consistent, for 
reasons before stated, to disregard the silence of Pliny, 
and to conclude that some kind of subterranean com- 
Motion, probably of no great violence, happened at the 
Period alluded to. 

History of Vesuvius after 1138.—To return to Ve- 
Suvius:—the next eruption occurred in 1306; be- 
‘ween which era and 1631 there was only one other 
(in 1500), and that a slight one. It has been re- 
Marked, that throughout this period Etna was ina 
State of such unusual activity as to lend countenance 
to the idea that the great Sicilian volcano may some- 


* Lib. vi. de Bello Neap. in Grævii Thesaur. 
+ Prodig. libell., c. cxiv. 


LO FORMATION OF MONTE: NUOVO. [Book IL 


times serve as a channel of discharge to elastic fluids 
and lava that would otherwise rise ‘to the vents in 
Campania. 

Formation of Monte Nuovo, 1538.—The:great pause 
was also marked by a memorable. event in the Phle- 
grean Fields— the sudden formation of a new moun- 
tain in 1538, of which we ‘have received authentic 
accounts from contemporary writers. Frequent earth- 
quakes, for two years preceding, disturbed the neigh- 
bourhood of Puzzuoli ; but it was not until the 27th 
and 28th of September, 1538, that they became alarm- 
ing, when not less than twenty shocks were expe- 
rienced in twenty-four hours. At length, on the night 
of the 29th, two hours after sunset, a gulf opened 
between the little town of Tripergola, which once 
existed on the site of the Monte Nuovo, and the baths 
in its suburbs, which were. much frequented. This 
watering-place contained an hospital for those who 
resorted thither for the benefit of the thermal springs, 
and it appears that there were no fewer than three 
inns in the principal street. A large fissure approached 
the town with a tremendous noise, and with the emis- 
sion of flame; and began to discharge mud composed 
of pumice-stones and ashes mixed with water, with 
some blocks of solid stone. The ashes, by which the 
town was entirely overwhelmed, fell in immense quan- 
tities, even at. Naples ; while the neighbouring Puz- 
zuoli was. deserted by its: inhabitants. The:sea retired 
suddenly for two hundred yards, and: a portion of its 
bed was left dry. The whole coast, from Monte Nuovo 
to beyond Puzzuoli, was at that time upraised to the 
height of many feet above the bed of the Mediter- 
ranean, and has ever since remained permanently 
elevated. The proofs of this remarkable event will 


MONTE NUOVO FORMED A. D. 1538. 73 


be considered at length when the phenomena of the 
Temple of Serapis are described.* On the 3d of 
October the eruption ceased, so that the hill (1. fig. 22.), 
the great mass of which was thrown up in a day and a 
night, was accessible ; and those who ascended re- 
Ported that they found a funnel-shaped crater on its 
Summit. (9. fig . 22.) 

The height of Monte Nuovo has recently been de- 
termined, by the Italian mineralogist Pini, to be 440 
English feet above the level of the bay ; its base is 
about eight thousand feet, or nearly a mile and a half, 
in circumference. According to Pini, the depth of the 
“rater is 421 English feet from the summit of the hill, 
50 that its bottom is only nineteen feet above the level 


Monte Nuovo, formed in the Bay of Baia, Sept. 29th, 1538. 
Cone of Monte Nuovo. 2. Brim of crater of ditto. 
8. Thermal spring, called Baths of Nero, or Stufe di Tritoli. 


2 


* See chap. xvi. 


v 
OL. II, E 


7A VOLCANOS OF THE PHLEGREAN FIELDS. [Book II. 


of the sea. No lava flowed from this cavity, but the 
ejected matter consisted of pumiceous mud with some 
masses of trachyte, many of them schistose, and re- 
sembling clinkstone. The Monte Nuovo is declared, 
by the best authorities, to stand partly on the site of 
the Lucrine Lake (4. fig. 23*), which was nothing 
more than the crater of a pre-existent volcano, and was 
almost entirely filled during the explosion of 1538. 
Nothing now remains but a shallow pool, separated 
from the sea by an elevated beach, raised artificially. 


The Phlegrean Fields. 


1. Monte Nuovo. 2. Monte Barbaro. 
3. Lake Avernus. 4. Lucrine Lake. 
5. The Solfatara. 6. Puzzuoli. 

7. Bay of Baie. 


* This representation of the Phlegrzan Fields is reduced from 
part of Plate xxxi. of Sir William Hamilton’s great work, 
“. Campi Phlegrzi.” The faithfulness of his coloured delineations 
of the scenery of that country cannot be too highly praised. 


Ch.X.] VOLCANOS OF THE PHLEGREAN FIELDS. ‘75 

Volcanos of the Phlegrean Fields. — Immediately 
adjoining Monte Nuovo is the larger volcanic cone of 
Monte Barbaro (2. fig. 23.), the Gaurus inanis of Ju- 


venal — an appellation given to it probably from its 
q 


‚“eep circular crater, which is about a mile in diameter. 

arge as is this cone, it was probably produced by a 
single eruption; and it does not, perhaps, exceed in 
magnitude some of the largest of those formed. in 
Ischia, within the historical era. It is composed 
chiefly of indurated tufa, like Monte Nuovo, stratified 
conformably to its conical surface. This hill was once 
very celebrated for its wines, and is still covered with 
vineyards ; but when the vine is not in leaf it has a 
Sterile appearance, and, late in the year, when seen 
from the beautiful bay of Baiæ, it often contrasts so 
Strongly in verdure with Monte Nuovo, which is always 
clothed with arbutus, myrtle, and other wild ever- 
sreens, that a stranger might well imagine the cone 
‘Of older date to be that thrown up in the sixteenth 
Century, * 

There is nothing, indeed, so calculated to instruct 
the geologist as the striking manner in which the 
T€cent volcanic hills of Ischia, and that now under 
Consideration, blend with the surrounding landscape. 

othing seems wanting or redundant ; every part of 
Oe ticture. isin such perfect harmony with the rest, 
that the whole has the appearance of having been 
Called into existence by a single effort of creative 
Power. Yet what other result could we have anti- 
Cipated, if Nature has ever been governed by the same 


* Hamilton (writing in 1770) says, “ The new mountain pro- 


uces as yet but a very slender vegetation.” — Campi Phlegrai, 
P: 69, 


This remark was no longer applicable when I saw it, in 
1898, 


E 2 


76 VOLCANOS OF THE PHLEGREAN FIELDS. [Book IL 


laws? Each new mountain thrown up — each new 
tract of land raised or depressed by earthquakes — 
should be in perfect accordance with those previously 
formed, if the entire configuration of the surface has 
been due to a long series of similar disturbances. 
Were it true that the greater part of the dry land 
originated simultaneously in its present state, at some 
era of paroxysmal convulsion, and that additions were 
afterwards made slowly and successively during a 
period of comparative repose; then, indeed, there 
might be reason to expect a strong line of demarca- 
tion between the signs of ancient and modern changes. 
But the very continuity of the plan, and the perfect 
identity of the causes, are to many a source of decep- 
tion’; since, by producing a unity of effect, they lead 
them to exaggerate the energy of the agents which 
operated in the earlier ages. In the absence of all 
historical information, they are as unable to separate 
the dates of the origin of different portions of our 
continents, as the stranger is to determine, by their 
physical features alone, the distinct ages of Monte 
Nuovo, Monte Barbaro, Astroni, and the Solfatara. 
The vast scale and violence of the volcanic opera- 
tions in Campania, in the olden time, has been a theme 
of declamation, and has been contrasted with the com- 
parative state of quiescence of this delightful region in 
the modern era. Instead of inferring, from analogy, 
that the ancient Vesuvius was always at rest when the 
craters of the Phlegraean Fields were burning, — that 
each cone rose in succession, — and that many years, 
and often centuries, of repose intervened between dif- 
ferent eruptions, — geologists seem to have generally 
conjectured that the whole group sprung up from the 
ground at once, like the soldiers of Cadmus when he 


Ch. X.J MODERN ERUPTIONS OF VESUVIUS. fe 


Sowed the dragon’s teeth. As well might they en- 
deavour to persuade us that on these Phlegrzean Fields, 
as the poets feigned, the giants warred with Jove, ere 
yet the puny race of mortals were in being. 

Modern Eruptions of Vesuvius. — For nearly a 
Century after the birth of Monte Nuovo, Vesuvius 
Continued in a state of tranquillity. There had then 

een no violent eruption for 492 years ; and it appears 
that the crater was then exactly in the condition of 
the present extinct volcano of Astroni, near Naples. 

racini, who visited Vesuvius not long before the erup- 
tion of 1631, gives the following interesting description 
of the interior :— “The crater was five miles in circum- 
“tence, and about a thousand paces deep; its sides 
Were covered with brushwood, and at the bottom there 
Was a plain on which cattle grazed. In the woody 
Parts wild boars frequently harboured. In one part 
of the plain, covered with ashes, were three small 
Pools, one filled with hot and bitter water, another 
Salter than the sea, and a third hot, but tasteless.” * 

ut at length these forests and grassy plains were 
Consumed, being suddenly blown into the air, and their 
Se ered to the winds. In December, 1631, 
Seven streams of lava poured at once from the crater, 
and overflowed several villages on the flanks and at 

© foot of the mountain. Resina, partly built over 
the ancient site of Herculaneum, was consumed by 
the fiery torrent. Great floods of mud were as de- 
Structive as the lava itself, — no uncommon occur- 
Tence during these catastrophes; for such is the vio- 
ence of rains produced by the evolution of aqueous 
vapour, that torrents of water descend the cone, and, 


y Hamilton’s Campi Phlegræi, folio, vol. i. p. 62.; and 
"eslak, Campanie, tome i. p- 186. 


E 3 


sð 


78 MODERN ERUP IONS OF VESUVIUS [Book II. 


becoming charged with impalpable volcanic dust, and 
rolling along loose ashes, acquire sufficient consistency 
to deserve their ordinary appellation of “ aqueous 
lavas.” ; 

_ A brief period of repose ensued, which lasted only 
until the year 1666, from which time to the present 
there has been a constant series of eruptions, with 
rarely an interval of rest exceeding ten years. Dur- 
ing these three centuries no irregular volcanic agency 
has convulsed other points in this district. Brieslak 
remarked, that such irregular convulsions had occurred 
in the Bay of Naples in every second century; as, for 
example, the eruption of the Solfatara in the twelfth, 
of the lava of Arso, in Ischia, in the fourteenth, and 
of Monte Nuovo in the sixteenth: but the eighteenth 
has formed an exception to this rule, and this seems 
accounted for by the unprecedented number of erup- 
tions of Vesuvius during that period; whereas, when 
the new vents opened, there had always. been, as we 
have seen, a long intermittance of activity in the 
principal volcano. 


CHAPTER XI. 
VOLCANIC DISTRICT OF NAPLES — continued. 


Volcanic District of Naples, continued — Dimensions and struc- 
ture of the cone of Vesuvius — Dikes in the recent cone 
(p. 85.) — Section through Vesuvius and Somma — Vesuvian 
lavas and minerals (p. 89.) — Effects of decomposition of 
lavas — Alluviums called “aqueous lavas” — Origin and com- 
Position of the matter enveloping Herculaneum and Pompeli— 
Controversies on the subject — Condition and contents of the 
buried cities (p. 100.) — Small number of Skeletons — State of 
Preservation of animal and vegetable substances — Rolls of 
Papyrus — Probability of future discoveries of MSS, — Stabiæ 
(P. 106.) — Torre del Greco — Concluding remarks on the 
Campanian volcanos, 


Structure of the cone of Vesuvius. — BETWEEN the end 
of the eighteenth century and the year 1822, the 
teat crater of Vesuvius has been gradually filled by 
ava boiling up from below, and by scoriz falling from 
the explosions of minor mouths which were formed at 
Intervals on its bottom and sides. In place of a regular 
Cavity, therefore, there was a rough and rocky plain, 
covered with blocks of lava and scoriz, and cut’ by 
numerous fissures, from which clouds of vapour were 
evolved. But this state of things was totally changed 
by the eruption of October, 1822, when violent explo- 
Sions, during the space of more than twenty days, 
roke up and threw out all this accumulated mass, so 
48 to leave an immense gulf or chasm, of an irregular, 
E A 


80 STRUCTURE OF THE CONE [Book IT. 


but somewhat elliptical shape, about three miles in 
circumference when measured along the very sinuous 
and irregular line of its extreme margin, but somewhat 
Jess than three quarters of a mile in its longest dia- 
meter, which was directed from N. E. to S. W.* The 
depth of this tremendous abyss has been variously esti- 
mated; for from the hour of its formation it decreased 
daily by the dilapidation of its sides. It measured, at 
first, according to the account of some authors, two 
thousand feet in depth from the extreme part of the 
existing summit +; but Mr. Scrope, when he saw it, 
soon after the eruption, estimated its depth at less 
than half that quantity. More than eight hundred 
feet of the cone was carried away by the explosions, 
so that the mountain was reduced in height from about 
4200 to 3400 feet. + 

As we ascend the sloping sides, the volcano appears 
a mass of loose materials——.a mere heap of rubbish, 
thrown together without the slightest order; but on 
arriving at the brim of the crater, and obtaining a view 
of the interior, we are agreeably surprised to discover 
that the conformation of the whole displays in every 
part the most perfect symmetry and arrangement. 
The materials are disposed in regular strata, slightly 
undulating, appearing, when viewed in front, to be 
disposed in horizontal planes. But, as we make the 
- circuit of the edge of the crater, and observe the cliffs 
by which it is encircled projecting or receding in sa- 
lient or retiring angles, we behold transverse sections 


* Account of the Eruption of Vesuvius in October, 1822, by 
G. P. Scrope, Esq., Journ. of Sci., &c. vol. xv. p. 175. 

t Mr. Forbes, Account of Mount Vesuvius, Edin. Journ. of 
Sci., No. xviii. p. 195. Oct. 1828, 

+ Ibid., p. 194. 


Ch. X1.) OF VESUVIUS. 81 


of the currents of Java and beds of sand and scorie, 
and recognize their true dip. We then discover that 
they incline outwards from the axis of the cone, at 
angles varying from 30° to 45°. The whole cone, in 
fact, is composed of a number of concentric coatings of 
alternating lavas, sand, and scorie. Every shower of 
ashes which has fallen from above, and every stream 
of lava descending from the lips of the crater, have 
Conformed to the outward surface of the hill, so that 
ne conical envelope may be said to have been succes- 
sively folded round another, until the aggregation of 
the whole mountain was completed. The marked separ- 
ation into distinct beds results from the different 
Colours and degrees of coarseness in the sands, scoriz, 
and lava, and the alternation of these with each other. 

he greatest difficulty, on the first view, is to conceive 

OW so much regularity can be produced, notwith- 
Standing the unequal distribution of sand and scoriz, 

riven by prevailing winds in particular eruptions, and 
the small breadth of each sheet of lava as it first flows 
Out from the crater. 

But on a closer examination, we find that the appear- 
ance of extreme uniformity is delusive, for when a 
umber of beds thin out gradually, and at different 
Points, the eye does not without difficulty recognize 
the termination of any one stratum, but usually sup- 
Poses it continuous with some other, which at a short 

‘stance may lie precisely in the same plane. The 
slight undulations, moreover, produced by inequalities 
On the sides of the hill on which the successive layers 
Were moulded, assist the deception. As countless 

eds of sand and scoriæ constitute the greater part of 
the whole mass, these may sometimes mantle conti- 
nuously round the whole cone; and even lava-streams 


E 5 


89 FLUID LAVA. [Book I. 


may be of considerable breadth when first they over- 
flow, and, since in some eruptions a considerable part 
of the upper portion of the cone breaks down at once, 
may form a sheet extending as far as the space which 
the eye usually takes in in a single section. 

The high inclination of some of the beds, and the 
firm union of the particles even where there is evi- 
dently no cement, is another striking feature in the 
volcanic tuffs and breccias, which seems at first not 
very easy of explanation. But the last great eruption 
afforded ample illustration of the manner in which 
these strata are formed. Fragments of lava, scorie, 
pumice, and sand, when they fall at slight distances 
from the summit, are only half cooled down from a 
state of fusion, and are afterwards acted upon by the 
heat from within, and by fumeroles or small crevices 
in the cone through which hot vapours are disengaged. 
Thus heated, the ejected fragments cohere together 
strongly ; and the whole mass acquires such consistency 
in a few days, that fragments cannot be detached 
without a smart blow of the hammer. At the same 
time sand and scoriz, ejected to a greater distance, 
remain incoherent.* 

Sir William Hamilton, in his description of the erup- 
tion of 1779, says, that jets of liquid lava, mixed 
with stones and scoria, were thrown up to the height 
of at least ten thousand feet, having the appearance 
of a column of fire.+ Some of these were directed 
by the winds towards Ottaiano, and some of them, 
falling almost perpendicularly, still red-hot and 
liquid, on Vesuvius, covered its whole cone, part of 


* Monticelli and Covelli, Storia di Fenon. del Vesuv., en 
1821-2-3.  - + Campi Phlegrzi. 


Ch, XL] FLUID LAVA. 83 


the mountain of Somma, and the valley -between 
them. The falling matter being nearly as vividly 
inflamed as that which was continually issuing fresh 
from the crater, formed with it one complete body of 
fire, which could not be less than two miles and a 
half in breadth, and of the extraordinary height above 
Mentioned, casting a heat to the distance of at least 
Sıx miles around it. Dr. Clarke, also, in his account 
of the eruption of 1793, says that millions of red-hot 
Stones were shot into the air full half the height of 
the cone itself, and then bending, fell: all round in a 
ne arch. On another occasion he says that, as they 
fell, they covered nearly half the cone with fire. 
The same author has also described the. different 
appearance of the lava at its source, and at some 
distance from it, when it had descended into the 
Plains below. At the point where it issued, in 1793, 
from an arched chasm in the side of the mountain, 
the vivid torrent rushed with the velocity of a flood. 
t was in perfect fusion, unattended with any scoriæ 
On its Surface, or any gross materials not in a state of 
Complete solution. - It flowed with the translucency of 
Shey, “in regular channels, cut finer than art can 
Mitate, and glowing with all the splendour of the 
Sun.” —< Sir William Hamilton,” he continues, “ had 
Conceived that no stones thrown upon a current of 
lava would make any impression. I was soon’ con- 
Yinced of the contrary. Light bodies, indeed, of five, 
ten, and fifteen pounds weight made little or no im- 
Pression even at the source; but bodies of sixty, 
Seventy, and eighty pounds were seen to form a kind 
ot bed on the surface of the lava, and float away with 
't. A stone of three hundred weight, that had been 
thrown out, by. the crater, lay near the source of the 
E 6 


84 FLUID LAVA. [Book II. 


current of lava: I raised it upon one end, and then 
let it fall in upon the liquid lava; when it gradually 
sunk beneath the surface, and disappeared. If I 
wished to describe the manner in which it acted upon 
the lava, I should say that it was like a loaf of bread 
thrown into a bowl of very thick honey, which gradually 
involves itself in the heavy liquid, and then slowly 
sinks to the bottom. 

“The lava, at a small distance from its source, 
acquires.a darker tint upon its surface, is less easily 
acted upon, and, as the stream widens, the surface, 
having lost its state of perfect solution, grows harder 
and harder, and cracks into innumerable fragments of 
very porous matter, to which they give the name of 
scoriz, and the appearance of which has led many to 
suppose that it proceeded thus from the mountain. 
There is, however, no truth in this. All lava, at its 
first exit from its native volcano, flows out in a liquid 
state, and all equally in fusion. The appearance of 
the scoriz is to be attributed only to the action of the 
external air, and not to any difference in the materials 
which compose it, since any lava whatever, separated 
from its channel, and exposed to the action of the 
external air, immediately cracks, becomes porous, and 
alters its form. As we proceeded downward, this 
became more and more evident; and the same lava 
which at its original source flowed in perfect solution, 
undivided, and free from encumbrances of any kind, 
a little farther down had its surface loaded with scoriz 
in such a manner, that, upon its arrival at the bottom 
of the mountain, the whole current resembled nothing 
so much as a heap of unconnected cinders from an 
iron-foundry.” In another place he says, that “ the 
rivers of lava in the plain resembled a vast heap of 
cinders, or the scoriz of an iron-foundry, rolling 


Ch. XIJ RECENT DIKES, 85 


slowly along, and falling with a rattling noise over one 
another,” + i 

It appears that the intensity of the light and heat 
of the lava varies considerably at different periods of 
the same eruption, as in that of Vesuvius in 1819 and 
1820, when Sir H. Davy remarked different degrees 
of vividness in the white heat at the point where the 
lava originated. t 

When the expressions “flame” and “smoke” are 
used in describing volcanic appearances, they must 
8enerally be understood in a figurative sense. The 
Clouds of apparent smoke consist usually of aqueous 
and other vapours, or of that impalpable dust which is 
formed of finely comminuted volcanic scoriæ. The 
Columns of flame are very rarely if ever derived from 
inflammable gases, but consist of showers of incan- 
“scent or red-hot fragments of lava, illuminated by 
that vivid light which is emitted from the crater 
elow, where the lava is said to glow with the splen- 
Our of the sun. 

Dikes in the recent cone, how formed.— The inclined 
Strata before mentioned which dip outwards in all 
irections from the axis of the cone of Vesuvius, are 
intersected by veins or dikes of compact lava, for the 
Most part in a vertical position. In 1828 these were 
Seen to be about seven in number, some of them not 
less than four or five hundred feet in height, and 
thinning out before they reached the uppermost part 
of the cone. Being harder than the beds through 
Which they pass, they have decomposed less rapidly, 
and therefore stand out in relief. § 

* Otter’s Life of Dr. Clarke. 

t Phil. Trans., 1828, p. 241. ł See Book 4. chap, 10. 
` $ When I visited Vesuvius, in Nov. 1828, I was prevented 


from descending into the crater by the constant ejections then 


86 SECTION OF VESUVIUS [Book II. 


There can be no doubt that these dikes have been 
produced by the filling up of open fissures with liquid 
lava; but of the date of their formation we know 
nothing further than that they are all subsequent to 
the year 79, and, relatively speaking, that they are 
more modern than all the lavas and scoriæ which they 
intersect. A considerable number of the upper strata, 
not traversed by them, must have been due to later 
eruptions, if the dikes were filled from below, and if 
lava: rose in them to the surface. That the earth- 
quakes, which almost invariably precede eruptions, 
occasion rents in the mass is well known; and, in 
1822, three months before the lava flowed out, open 
fissures, evolving hot vapours, were numerous. It is 
clear that such rents must be injected with melted 
matter when the column of lava rises, so that the 
origin of the dikes is easily explained, as also the 


great solidity and crystalline nature of the rock com- 
posing them, which has been formed by lava cooling 
slowly under great pressure. 

Section through Vesuvius and Somma.— In the an- 
nexed diagram (Fig. 24.) it will be seen that, on the 
side of Vesuvius opposite to that where a portion of 


thrown out. I only got sight of three of the dikes; but Signor 
Monticelli had previously had drawings made of the whole, which 
he showed me. The veins which I saw were on that side of the 
cone which is encircled by Somma. In March of the year before 
mentioned, an eruption began at the bottom of the deep gulf 
formed in 1822. The ejected matter had filled up nearly one 
third of the original abyss in November, and the same operation 
was still in progress, a single black cone being seen at the bottom 
in almost continual activity. I found the lava of 1822 not yet 
cool on the north side of the cone, and evolving much heat and 
vapour from crevices. It was then upwards of six years since it 
flowed out. 


; 400} UO BUDD OF 
puaose 0} aiudard Loy} uayM 3104} SINUI PUL SISLOY I1ƏY} BUTALI HIƏJ[ƏAVI} WOY PaT|¥9 OS » 
*"SNIANSA A JO JUOD JUaIAI OY} Sunoasioyur sI. YY 
eewwuog SunoəsIəzur sıq, F‘? 
"134819 BIAS ay} JO WOyOq J} 78 “8S8T ul dn umosy} auUOd [jeug of 
‘SSSI Jo uondnaa Áq yoy 107219 *2 “p 
x OPA) [ap OLY “9 
‘aDIS ynos ay} UO ‘SsNIARSAaA JO JUOD yUadaL 
ayy JO aseq əy} BSurpostoue ‘uonsefoad oyr[-aovasa, e ‘euruoMepeg AL 9 
'SNIANSƏA JO OUD JUIVUL OY} JO SUIEUA IYJ IO “BUIUIOg JUO V 
epuuog pun sntansəd fo uoaas pasoddng 


ins, is a pro-. 
hich some have 
i from 

It 


ldistant 


ina, w 


ti, precisely equ 


carpment of Somma and the Pedamentina. 


< 
= 
a 
© 
mn 
A 
zZ 
= 


iscon 


ing to V 


the axis of the present cone of Vesuvius 


accord 


. 
? 


een objected that, if the Pedamentina and the 


jection (6) called the Pedament 
*Scarpment of Somma were the remains of the original 


edge of which the lavas of the modern Vesuvius have 
Poured 

the es 

has b 


Crater broken down towards the sea, and over the 
being, 


Supposed to be part of the circumference of the ancient 


the ancient cone of Somma (a) still rema 


88 SECTION OF VESUVIUS AND SOMMA. [Book 1I. 


crater, that crater must have been many miles in 
diameter, and more enormous than almost any one 
known on the globe. In answer to this, it may be 
suggested, that probably the ancient mountain was 
higher than Vesuvius (which, comparatively speaking, 
is a volcano of no great height), and that the explo- 
sions of the year 79 caused it not merely to disgorge 
the contents of its crater, which had long been choked - 
up, but blew up a great part of the cone itself: so 
that the wall of Somma, and the ridge or terrace of 
the Pedamentina, were never the margin of a crater 
of eruption, but are the relics of a ruined and trun- 
cated cone. 

It will be seen in the diagram that the slanting beds 
of the cone of Vesuvius become horizontal in the Atrio 
del Cavallo (at c), where the base of the new cone 
meets the precipitous escarpment of Somma; for when 
the lava flows down to this point, as happened in 1822, 
its descending course is arrested, and it then runs in 
another direction along this small valley, circling round 
the base of the cone. Sand and scoriæ, also, blown 
by the winds, collect at the base of the cone, and are 
then swept away by torrents; so that there is always 
here a flattish plain, as represented. In the same 
manner the small interior cone ( f ) must be composed 
of sloping beds, terminating in a horizontal plain ; for, 
while this monticule was gradually gaining height by 
successive ejections of lava and scorie, in 1828, it was 
always surrounded by a flat pool of semi-fluid lava, 
into which scoriz and sand were thrown. 

The escarpment of Somma exhibits a structure pre- 
cisely similar to that of the cone of Vesuvius, but the 
beds are intersected by a much greater number of 
dikes. The formation of this older cone does not be- 


Ch. Xr} VESUVIAN LAVAS. © 89 


long to the historical era, and must not, therefore, be 
enlarged upon in this place; but I shall have occasion 
Presently to revert to the subject, when speaking of a 
favourite doctrine of some modern geologists, con- 
cerning « craters of elevation” (Erhebungscratere), 
Whereby, in defiance’ of analogy, the origin of the 
“Identical disposition of the strata and dikes in Vesu- 
vius and Somma has been referred to a mode of oper- 
ation extremely dissimilar. 
Vesuvian Lavas.— The modern lavas of Vesuvius 
are characterized by a large proportion of augite (or 
Pyroxene). They are often porphyritic, containing 
'sSeminated crystals of augite, leucite, or some other 
mneral, imbedded in a more earthy base.* In regard 
to the structure of these lavas on a great scale, there 
are no natural sections of sufficient depth to enable us 
» draw fair comparisons between them and the pro- 
ucts of extinct volcanos. At the fortress near Torre 
© Greco a section is exposed, fifteen feet in height, 
°F a current which ran into the sea; and it evinces, 
“specially, in the lower part, a decided tendency to 
vide into rude columns. A still more striking ex- 
pie Ple may be seen to the west of Torre del Annun- 
ziata, near Forte Scassato, where the mass is laid open 
by the Sea to the depth of twenty feet. In both these 
cases, however, the rock may rather be said to be 
vided into numerous perpendicular fissures, than to 
p Prismatic, although the same picturesque effect is 
Produced, In the lava-currents of Central France 
those of the Vivarais, in particular), the uppermost 
Portion, often forty feet or more in thickness, is an 
amorphous mass passing downwards into lava irregu- 


* See Book 4, chap. 10. 


90. EFFECTS OF DECOMPOSITION ON LAVAS. [Book II. 


larly prismatic ; and under this, there is a foundation 
of regular and vertical columns, but these lavas are 
often one hundred feet or more in thickness. We can 
scarcely expect to discover the same phenomenon in 
the shallow currents of Vesuvius, where the lowest 
part has cooled more rapidly, although it may be 
looked for in modern streams in Iceland, which exceed 
even those of ancient France in volume. 

Mr. Scrope mentions that, in the cliffs encircling 
the modern crater of Vesuvius, he saw many currents 
offering a columnar division, and some almost as re- 
gularly prismatic as any ranges of the older basalts ; 
and he adds, that in some the spheroidal concretionary 
structure, on a large scale, was equally conspicuous.* 
Brieslak + also informs us that, in the siliceous lava of 
1737, which contains augite, leucite, and crystals of 
felspar, he found very regular prisms in a quarry 
near Torre del Greco; an observation confirmed by 
modern authorities. ¢ 

Effects of decomposition on lavas.—The decompo- 
sition of some of the felspathic lavas, either by simple 
weathering, or by gaseous emanations, converts them 
from a hard to a soft clayey state, so that they no 
longer retain the smallest resemblance to rocks cooled 
down from a_state of fusion. The exhalations of 
sulphuretted hydrogen and muriatic acid, which are 
disengaged continually from the Solfatara, also produce 
curious changes on the trachyte of that nearly extinct. 
volcano: the rock is bleached and becomes porous, 
fissile, and honeycombed, till at length it crumbles 


* Journ. of Sci., vol. xv. p. 177. 
+ Voy. dans la Campanie, tomei. p. 201. 
+ Mr. Forbes; Edin. Journ. of Sci., No. xviii., Oct. 1828. 


Ch. XI.) VESUVIAN MINERALS. 9T 


into a white siliceous powder.* Numerous: globular 
concretions, composed of concentric laminæ, are also: 
formed by the same vapours in this decomposed 
Tock, + 
They who have visited the Phlegrzean Fields and 
the Volcanic regions of Sicily, and who are aware of 
© many problematical appearances which igneous 
rocks of the most modern origin assume, especially 
after decomposition, cannot but be astonished at the 
Confidence with which the contending Neptunists 
and Vulcanists in the last century dogmatized on 
the origin of certain rocks of remote antiquity. 
stead of having laboured to acquire an accurate 
*¢quaintance with the aspect of known volcanic rocks, 
‘nd the transmutations which they undergo subse- 
ently to their first consolidation, the adherents of 
Oth parties seem either to have considered themselves 
œn with an intuitive knowledge of the effects of 
volcanic operations, or to have assumed that they 
“quired no other analogies than those which a labo- 
ratory or furnace might supply. 
esuvian Minerals. — A great variety of minerals 
àre found in the lavas of Vesuvius and Somma: for 
x many are common to both, that it is unnecessary to 
Separate them. Augite, leucite, felspar, mica, olivine, 
pa: Sulphur, are most abundant. It is an extraordinary 
act, that, in an area of three square miles round Ve- 
Suvius, a greater number of simple minerals have been 
und than in any spot of the same dimensions on the 
Surface of the globe. Häuy enumerated only 380 
‘Pecies of simple minerals as known to him ; and no 


wie 
aubeny on Volcanos, p. 169. 
Scrope, Geol. Trans., second series, vol. il. p. 346.. 


a 


n 


92 VESUVIAN MINERALS. [Book II. 


less than eighty-two had been found on Vesuvius 
and in the tuffs on the flanks of Somma before the end 
of the year 1828.* Many of these are peculiar to 
that locality. Some mineralogists have conjectured 
that the greater part of these were not of Vesuvian 
origin, but thrown up in fragments from some older 
formation, through which the gaseous explosions burst. 
But none of the older rocks in Italy, or elsewhere, 
contain such an assemblage of mineral products; and 
the hypothesis seems to have been prompted by a dis- 
inclination to admit that, in times so recent in the 
earth’s history, the laboratory of Nature could have 
been so prolific in the creation of new and rare com- 
pounds. Had Vesuvius been a volcano of high an- 
tiquity, formed when Nature 


Wanton’d as in her prime, and played at will 

Her virgin fancies, 
it would have been readily admitted that these, or a 
much greater variety of substances, had been sublimed 
in the crevices of lava, just as several new earthy and 
metallic compounds are known to have been produced 
by fumeroles, since the eruption of 1822. But a 
violent hypothesis appears to have been resorted to, 
in order to explain away facts which would imply the 
unimpaired energy of reproductive causes in our own 
times. 

Formation of Tuffs. — The above remarks apply 
simply to the structure of the cone; but a small part 
only of the ejected matter remains so near to the vol- 
canic orifice. A large portion of sand and scoriz is 
borne by the winds and scattered over the surrounding 
plains: part falls into the sea; and still more is swept 


* Monticelli and Covelli, Prodom. della Mineral. Vesuv. 


Ch. XL] FLOWING OF LAVA UNDER WATER. 93 


down by torrents into the deep, during the intervals, 
often Protracted for many centuries, between erup- 
tions. In this case horizontal deposits of tufaceous 
Matter become intermixed with other kinds of sedi- 
Ment, and with shells and corals, so that rocks of a 
Mixed character are formed, such as tuffs, peperinos, 
and volcanic conglomerates. 
lowing of lava under water.— Some of the lavas, 
> of Vesuvius reach the sea, as do those of almost 
all volcanos; since they are generally in islands, or 
bordering the coast. Here they find a bottom, often 
evelled by operations analogous to those which form 
deltas; so that instead of being highly inclined, as 
around the cone, or in narrow bands, as in a valley, 
€y may spread out in broad horizontal sheets. It is _ 
not improbable, as Dr. Daubeny has suggested, that 
8Y retain their fluidity for a considerable time longer i 
“neath the sea than in the open air; for the rapidity 
With which heated bodies are cooled by being plunged 
‘nto Water arises chiefly from the conversion of the 
Wer Portions of water into steam, which steam ab- 
= ing much heat immediately ascends, and is recon- 
verted into water. But under the pressure of an ocean 
sufficiently deep to prevent the formation of steam, the 
“at of the lava would be carried off more slowly, and 
— by the circulation of ascending and descending 
Currents of water, those portions nearest the source of 
fat becoming specifically lighter, and consequently 
'splacing the water above. This kind of circulation 
Would take place with much less rapidity than in the 
*tmosphere, inasmuch as the expansion of water by 


“Mal increments of heat is less considerable than that 
OF air | 


also 


= See Daubeny’s Volcanos, p. 400. 


94 VOLCANIC ALLUVIUMS. [Book 1 


Volcanic alluviums.— In addition to the ejection§ 
which fall on the cone, and that much greater mass 
-which finds its way gradually to the neighbouring sea 
there is a third portion, often of no inconsiderable 
thickness, composed of alluviums, spread over the 
valleys and plains at small distances from the volcano. 
Aqueous vapours are evolved copiously from a crate! 
during eruptions, and often for a long time subse- 
quently to the discharge of scoriæ and lava: these 
vapours are condensed in the cold atmosphere sur- 
rounding the high volcanic peak, and heavy rains are 
thus caused in countries where, at the same season 
and under ordinary circumstances, such a phenomeno? 
is entirely unknown. The floods thus occasioned sweep 
along the impalpable dust and light scoriz, till 4 
current of mud is produced, which is called, in Cam 
pania, “lava d’ acqua,” and is often more dreaded tha? 
an igneous stream (lava di fuoco), from the greate! 
velocity with which it moves. So late as the 27th of 
October, 1822, one of these alluviums descended thé 
cone of Vesuvius, and, after overspreading much cul- 
tivated soil, flowed suddenly into the villages of St. 
Sebastian and Massa, where, filling the streets and 
interior of some of the houses, it suffocated seven pet 
sons. It will therefore happen very frequently, that 
towards the base of a volcanic cone, alternations wil 
be found of lava, alluvium, and showers of ashes. 

Mass enveloping Herculaneum and Pompeii, — To 
which of these two latter divisions the mass envelop 
ing Herculaneum and Pompeii should be referred, ha 
been a question of the keenest controversy ; but thé 
discussion might have been shortened, if the combat 
ants had reflected that, whether volcanic sand a? 
ashes were conveyed to the towns by running wate! 


Ch. X1] HERCULANEUM. AND POMPEII. 5 
or through the air, during an eruption, the interior of 
uildings, so long as the roofs remain entire, together 
With all underground vaults and cellars, could be filled 
only by an alluvium. We learn from history, that a 
€avy shower of sand, pumice, and lapilli, sufficiently 
steat to render Pompeii and Herculaneum uninhabit- 
able, fell for eight successive days and nights in the 
year 79, accompanied by violent rains. We ought, 
therefore, to find a very close resemblance between 
€ strata covering these towns, and those composing 
e minor cones of the Phlegrzean Fields, accumulated 
rapidly, like Monte Nuovo, during a continued shower 
ot ejected matter; with this difference, however, that 
© strata incumbent on the cities would be horizontal, 
whereas those in the cones are highly inclined, and that 
arge angular fragments of rock, which are thrown out 
Mear the vent, would be wanting at a distance, where 
Small lapilli only can be found. Accordingly, with these 
€X¢eptions, no identity can be more perfect than the 
orm and distribution of the matter at the base of 
nte Nuovo, as laid open by the encroaching sea, 
and the appearance of the beds superimposed on 
°Mpeii, That city is covered with numerous alter- 
nitions of different horizontal beds of tuff and lapilli, 
or the most part thin, and subdivided into very fine 
ayers. I observed the following section near the Am- 
Phitheatre, in November, 1828 — (descending series). 
Feet. Inches. 

l. Black sparkling sand from the eruption of 

1822, containing minute regularly formed 
Crystals of augite and tourmaline, from . 2 to 3* 


* ° 
he great eruption, in 1822, caused a covering only a few 


Mcheg thick on Pompeii. Several feet are mentioned by Mr. 
orbes, — Eq, Journ. of Science, No. xix. -p. 131. Jan. 1829, 


96 MASS ENVELOPING [Book 1. 


Feet. Inches. 
2. Vegetable mould . : i ‘i sik S 


3. Brownincoherent tuff, full of pisolitic globules 
in layers, from half an inch to three inches 
in thickness : 

. Small scoriz and white lapilli 

Brown earthy tuff, with numerous pisolitic 
globules . , 

6. Brown earthy tuff, with aii divided into 
layers : 

7. Layer of whitish lapilli 

8. Grey solid tuff 

9. Pumice and white lapilli 


Many of the ashes in these beds are vitrified and 
harsh to the touch. Crystals of leucite, both fresh 
and farinaceous, have been found intermixed.* The 
depth of the bed of ashes above the houses is variable; 
but seldom exceeds twelve or fourteen feet, and it is 
said that the higher part of the Amphitheatre always 
projected above the surface ; though, if this were the 
case, it seems inexplicable that the city should neve! 
have been discovered till the year 1750. It will be 
observed, in the above section, that two of the brow? 
half-consolidated tuffs are filled with small pisolitic 
globules. It is surprising that this circumstance is not 


But he must have measured in spots where it had drifted. The 
dust and ashes were five feet thick at the top of the crater, and 
decreased gradually to ten inches at Torre del Annunziata. The 
size and weight of the ejected fragments diminished very regu- 
larly in the same continuous stratum, as the distance from the 
centre of projection was greater. 

* Forbes, ibid. p. 130. 


Ch. XL] HERCULANEUM AND POMPEII. 97 
alluded to in the animated controversy which the 
oyal Academy of Naples maintained with one of 
their members, Signor Lippi, as to the origin of the 
Strata incumbent on Pompeii. The mode of aggre- 
gation of these globules has been fully explained by 
Mr. Scrope, who saw them formed in great numbers, 
™ 1822, by rain falling during the eruption on fine 
volcanic sand, and sometimes, also, produced like hail 
In the air, by the mutual attraction of the minutest 
Particles of fine damp sand. ‘Their occurrence, there- 
fore, agrees remarkably well with the account of heavy 
Tain, and showers of sand and ashes, recorded in his- 
tory, and is opposed to the theory of an alluvium 

‘Ought from a distance by a flood of water. 

Lippi entitled his work, “ Fu il fuoco o l’ acqua che 
Sotterrd Pompei ed Ercolano?” * and he contended 
that neither were the two cities destroyed in the year 
79, nor by a volcanic eruption, but purely by the 
agency of water charged with transported matter. 

is Letters, wheréin he endeavoured to dispense, as 
ar as possible, with igneous agency, even at the foot 
or the volcano, were dedicated, with great propriety, 
® Werner, and afford an amusing illustration of the 
Polemic style in which geological writers of that day 
"Wleed themselves. His arguments were partly of 
an historical nature, derived from the silence of con- 
emporary historians, respecting the fate of the cities 
Wich; as we have already stated, is most remarkable, 
and Partly drawn from physical proofs. He pointed 
ut with great clearness the resemblance of the tufa- 
eous matter in the vaults and cellars at Herculaneum 
and Pompeii to aqueous alluviums, and its distinctness 


* Napoli, 1816. 


VOL. I. F 


98 i MASS ENVELOPING ` [Book If 


from ejections which had fallen through the air: 
Nothing, he observed, but moist pasty matter could 
have received the impression of a woman’s breast; 
which was found in a vault at Pompeii, or have given 
the cast of a statue discovered in the theatre at Her- 
culaneum. It was objected to him, that the heat of 
the tuff in Herculaneum and Pompeii was proved by 
the carbonization of the timber, corn, papyrus-rolls, 
and other vegetable substances there discovered: but 
Lippi replied with truth, that the papyri would have 
been burnt up, if they had come in contact with fire, 
and that their being only carbonized was a clear de- 
monstration of their having been enveloped, like fossil 
wood, in a sediment deposited from water. The Aca- 
demicians, in their report on his pamphlet, assert, 
that when the Amphitheatre was first cleared out, the 
matter was arranged, on the steps, in a succession of 
concave layers, accommodating themselves to the 
interior form of the building, just as snow would lie if 
it had fallen there. This observation is highly interest- 
ing, and points to the difference between the stratifica- 
tion of ashes in an open building, and of mud derived 
from the same in the interior of edifices and cellars. 
Nor ought we to call the allegation in question, be- 
‘cause it could not be substantiated at the time of the 
controversy, after the matter had been all removed ; 
although Lippi took advantage of this removal, and met 
the argument of his antagonists by requiring them to 
prove the fact. 

Pompeii not destroyed by lava. There iis. decisive 
evidence that no stream of lava has ever reached 
Pompeii since it was first built, although the found- 
ations of the town stand upon the old leucitic lava of 
Somma; several streams of which; with tuff interposed, 


Ch. X1] HERCULANEUM AND POMPEII. . 99 


have been cut through in excavations, At Hercula- 
neum the case is different, although the substance 
Which fills-the interior of the houses and the vaults 
must have been introduced in a state of mud, like that 
found in similar situations in Pompeii; yet the super- 
incumbent mass differs wholly in composition and 
thickness, Herculaneum was situated several miles 
nearer to the volcano, and has, therefore, been always 
More exposed to be covered, not only by showers of 
ashes, but by alluviums and streams of lava. Accord- 
mely, masses of both have accumulated on each other 
above the city, to a depth of nowhere less than 70, and 
m many places of 112 feet.* 

The tuff which envelopes the buildings consists of 
“omminuted volcanic ashes, mixed with pumice. .A 
Mask imbedded in this matrix has left a cast, the 
Sharpness of which was compared by Hamilton to 

ose in plaster of Paris; nor was the mask in the 
“ast degree scorched, as if it had been imbedded in 

fated matter. This tuff is porous; and, when first 
“XCavated, is soft and easily worked, but acquires a 
“onsiderable degree of induration on exposure to the 
alr. Above this lowest stratum is placed, according to 
Hamilton, “the matter of six eruptions,” each separ- 
ated from the other by veins of good soil. In these 
Soils Lippi states. that he collected a considerable 
number of Jand shells—an observation which is no 
°ubt correct ; for many snails’ burrow in soft soils, and 
“ome Italian species descend, when they hybernate, to 

© depth of five feet and more from the surface. 
Yella Torre also informs us that there is in one part 


Ak e 


w Hamilton, Observ. on Mount Vesuvius, p. 94. London, 
4 - 


E2 


100 OBJECTS PRESERVED IN [Book If. 


of this superimposed mass a bed of true siliceous lava 
(lava di pietra dura); and, as no such current is 
believed to have flowed till near one thousand years 
after the destruction of Herculaneum, we must con- 
clude, that the origin of a large part of the covering of 
Herculaneum was long subsequent to the first inhu- 
mation of the place. That city, as well as Pompeii; 
was a seaport. Herculaneum is still very near the 
shore, but a tract of land, a mile in length, intervenes 
between the borders of the Bay of Naples and Pompeii. 
In both cases the gain of land is due to the filling up 
of the bed of the sea with volcanic matter, and not to 
elevation by earthquakes, for there has been no change 
in the relative level of land and sea. Pompeii stood 
on a slight eminence composed of the lavas of the 
ancient Vesuvius, and flights of steps led down to the 
water’s edge. The lowermost of these steps are said 
to be still on an exact level with the sea. 

Condition and contents of the buried cities, — After 
these observations on the nature of the strata envelop- 
ing and surrounding the cities, we may proceed to 
consider their internal condition and contents, so far 
at least as they offer facts of geological interest. Not- 
withstanding the much greater depth at which Hercu- 
laneum was buried, it was discovered before Pompeii; 
by the accidental circumstance of a well being sunk; 
in 1713, which came right down upon the theatre; 
where the statues of Hercules and Cleopatra were 
soon found. Whether this city or Pompeii, both of 
them founded by Greek colonies, was the most con-. 
siderable, is not yet. determined ; but both are men- 
tioned by ancient authors as among the seven most 
flourishing cities in Campania, The walls of Pompeii 
were three miles in circumference ; but we have, a$ 


Ch. X1] HERCULANEUM AND POMPEII. 101 


yet, no certain knowledge of the dimensions of Her- 
Culaneum. In the latter place the theatre alone is 
pen for inspection; the Forum, Temple of Jupiter, 
and other buildings, having been filled up with rubbish 
as the workmen proceeded, owing to the difficulty of 
removing it from so great a depth below ground. 
Even the theatre is only seen by torchlight, and the 
Most interesting information, perhaps, which the geo- 
logist obtains there, is the continual formation of 
Stalactite in the galleries cut through the tuff; for 
there is a constant percolation of water charged with 
Carbonate of lime mixed with a small portion of mag- 
nesia, Such mineral waters must, in the course of 
time, create great changes in many rocks; especially 
în lavas, the pores of which they may fill with calcareous 
Spar, so as to convert them into amygdaloids. Some — 
Scologists, therefore, are unreasonable when they 
expect that volcanic rocks of remote eras should 
àccord precisely with those of modern date ; since it 
'S obvious that many of those produced in our own 
time will not long retain the same aspect and internal 
Composition. 

Both at Herculaneum and Pompeii, temples have 
ĉen found with inscriptions commemorating the re- 
uilding of the edifices after they had been thrown 

-own by an earthquake.* This earthquake happened 
m the reign of Nero, sixteen years before the cities 
Were overwhelmed. In Pompeii, one fourth of which 
IS now laid open to the day, both the public and pri- 
vate buildings bear testimony to the catastrophe. The 
walls are rent, and in many places traversed by fissures 
still open. Columns are lying on the ground only half 
* Swinburne and Lalande. Paderni, Phil. Trans. 1758, 
Vol. 1. p. 619, 


F 3 


102 OBJECTS PRESERVED IN ` [Book 11. 


hewn from huge blocks of travertin, and the temple 
for which they were designed is seen half repaired. 
In some few places the pavement had sunk in, but in 
general it was undisturbed, consisting of large irregu- 
lar flags of lava joined neatly together, in which the 
carriage wheels have often worn ruts an inch and 2 
half deep. In the wider streets, the ruts are numerous 
and irregular ; in the narrower, there are only two, one 
on each side, which are very conspicuous. It is im- 
possible not to look with some interest even on these 
ruts, which were worn by chariot wheels more than 
seventeen centuries ago; and, independently of their 
antiquity, it is remarkable to see such deep incisions 
so continuous in a stone of great hardness. We ob- 
serve nothing of the kind in the oldest pavements of 
modern cities. 

Small number of skeletons. —A very small number 
of skeletons have been discovered in either city; and 
it is clear that most of the inhabitants not only found 
time to escape, but also to carry with them the prin- 
cipal part of their valuable effects. In the barracks at 
Pompeii were the skeletons of two soldiers chained to 
the stocks, and in the vaults of a country-house in the 
suburbs were the skeletons of seventeen persons, who 
appear to have fled there to escape from the shower 
of ashes. They were found inclosed in an indurated 
tuff, and in this matrix was preserved a perfect cast of 
a woman, perhaps the mistress of the house, with an 
infant in her arms. Although her form was imprinted 
on the rock, nothing but the bones remained. To 
these a chain of gold was suspended, and on the 
fingers of the skeleton were rings with jewels. Against 


the sides of the same vault was ranged a long line of 
earthen amphore. . 


Ch. XI] HERCULANEUM AND POMPEII. 103 


The writings scribbled by the soldiers on the walls 
of their barracks, and the names of the owners of 
€ach house written over the doors, are still perfectly 
legible. The colours of fresco paintings on the stuc- 
Coed walls in the interior of buildings are almost as 
Vivid as if they were just finished. There are public 
fountains decorated with shells laid out in patterns in 
the same fashion as those now seen in the town of 
Naples; and in the room of a painter; who was perhaps 
a naturalist, a large collection of shells was found, 
Comprising a great variety. of Mediterranean species, 
ìn as good a state of preservation as if they had 
remained for the same number of years in a museum. 
A comparison of these remains. with those found so 
Senerally in a fossil state would not assist us in obtain- 
Ing the least insight into the time required to produce 
à Certain degree of decomposition or mineralization > 
for, although under favourable circumstances, much 
Sreater alteration might doubtless have been brought 
about in a shorter period, yet the example before us 
Shows that an inhumation of seventeen centuries. may 
Sometimes effect nothing towards the reduction of 
Shells to the state in which fossils are usually found. 

The wooden beams in the houses at Herculaneum 
are black on the exterior, but when cleft open they 
appear to be almost in the state of ordinary wood, and 
the progress made by the whole mass towards the 
State of lignite is scarcely appreciable. Some animal 
and vegetable substances of more perishable kinds 

ave of course suffered much change and decay, yet 

the state of conservation of these is truly remarkable. 

Fishing-nets are very abundant in both. cities, often 

quite entire; and their number at Pompeii is the more 

interesting from the sea being now, as we stated, a 
F 4 


104 PAPYRI IN HERCULANEUM. [Book II. 


mile distant. Linen has been found at Herculaneum, 

with the texture well defined ; and in a fruiterer’s shop 

in that city were discovered vessels full of almonds, 

chestnuts, walnuts, and fruit of the “ carubiere,” all 

distinctly recognizable from their shape. A loaf, also, 

still retaining its form, was found in a baker's shop, 

with his name Stamped upon it. On the counter of 
an apothecary was a box of pills converted into a fine 

earthy substance ; and by the side of it a small cylin- 

drical roll, evidently prepared to be cut into pills. By 

the side of these was a jar containing medicinal herbs. 

In 1827, moist olives were found in a square glass 

case, and “ caviare,” or roe of a fish, in a state of won- 

derful preservation. An examination of these curious ; 
condiments has been published by Covelli, of Naples, 

and they are preserved hermetically sealed in the 

museum there.* 

Papyri.— There is a marked difference in the con- 
dition and appearance of the animal and vegetable 
substances found in Pompeii and Herculaneum ; those 
of Pompeii being penetrated by a grey pulverulent 
tuff, those in Herculaneum seeming to have been first 
enveloped by a paste which consolidated round them, 
and then allowed them to become slowly carbonized. 
Some of the rolls of papyrus at Pompeii still retain 
their form ; but the writing, and indeed almost all the 
vegetable matter, appear to have vanished, and to have 
been replaced by volcanic tuff somewhat pulverulent. 
At Herculaneum the earthy matter has scarcely ever 
penetrated ; and the vegetable substance of the papy- 
rus has become a thin friable black matter, almost 
resembling in appearance the tinder which remains 


ea is 


>. . 
SA 


* Mr. Forbes, Edin. Journ. of:Sci., No. xix. p- 130, Jan. 1829. 


Ch. XL] PAPYRI IN HERCULANEUM. 105 


when stiff paper has been burnt, in which the letters. 
may still be sometimes traced. The small bundles of 
papyri, composed. of five or six rolls tied up together, 
had sometimes Jain horizontally, and were pressed in 
that direction, but sometimes they had been placed in 
_ à vertical position. Small tickets were attached to 
each bundle, on which the title of the work was in- 
scribed. In one case only have the sheets been found 
With writing on both sides of the pages. So numerous 
are the obliterations and corrections, that many must 
have been original manuscripts. The variety of hand- 
Writings is quite extraordinary : nearly all are written 
in Greek, but there are afew in Latin. They were 
almost all found in a suburban villa in the library of 
One private individual; and the titles of four hundred 
of those least injured, which have been read, are found 
to be unimportant works, but all entirely new, chiefly 
relating to music, rhetoric, and cookery. There are 
two volumes of Epicurus “ On Nature,” and the others 
are mostly by writers of the same school, only one 
fragment having been discovered, by an opponent of 
the Epicurean system, Chrysippus.* 

Probability of future discoveries of MS'S.—In the 
Opinion of some antiquaries, not one hundredth part of 
the city has yet been explored ; and the quarters 
hitherto cleared out, at a great expense, are those 
Where there was the least probability of discovering 
Manuscripts. As Italy could already boast her splen- 
did Roman amphitheatres and Greek temples, it was a 


* In one of the manuscripts which was`in the hands of the 
interpreters when I visited the museum, the author indulges in 
the speculation that all the Homeric personages were allegorical — 
that Agamemnon was the ether, Achilles the sun, Helen the 
earth, Paris the air, Hector the moon, &c. 


F 5 


106 PAPYRI IN HERCULANEUM. [Book 11. 


matter of secondary interest to add to their number 
those in the dark and dripping galleries of Hercula- 
neum ; and having so many of the masterpieces of 
ancient art, we could have dispensed with the inferior 
busts and statues which could alone have been ex- 
pected to reward our researches in the ruins of a pro- 
vincial town. But from the moment that it was ascer- 
tained that rolls of papyrus preserved in this city could 
still be deciphered, every exertion ought to have been 
steadily and exclusively directed towards the discovery 
of other libraries. Private dwellings should have been 
searched, before so much labour and expense were 
consumed in examining public edifices. A small por- 
tion of that zeal and enlightened spirit which prompted 
the late French and Tuscan expedition to Egypt 
might, long ere this, in a country nearer home, have 
snatched from oblivion some of the lost works of 
the Augustan age, or of eminent Greek historians and 
philosophers. A single roll of papyrus might have dis- 
closed more matter of intense interest than all that 
was ever written in hieroglyphics.* 

Stabie. — Besides the cities already mentioned, 
Stabiæ, a small town about six miles from Vesuvius, 
and near the site of the modern Castel-a-Mare (see 


* During my stay at Naples, in 1828, the Neapolitan govern- 
ment, after having discontinued operations for many years, cleared 
out a small portion of Herculaneum, near the sea, where the 
covering was least thick. After this expense had been incurred, 
it was discovered that the whole of the ground had been previously 
examined, near a century before, by the French Prince d’Elbeeuf, 
who had removed every thing of yalue! Such is the want of 
system with which operations have always been, and still are, 
carried on here, that we may expect similar blunders to be made 
continually. 


Ch. XL] DESTRUCTION OF .TORRE DEL GRECO. 107 


map of volcanic district of Naples), was overwhelmed 
during the eruption of 79. Pliny mentions that, when 
his uncle was there, he was obliged to make his escape, 
So great was the quantity of falling stones and ashes. 
In the ruins of this place, a few skeletons have been 
found buried in volcanic ejections, together with some 
antiquities of no great value, and rolls of papyrus, 
which, like those of Pompeii, were illegible. 

Torre del Greco overflowed by lava.—Of the towns 
hitherto mentioned, Herculaneum alone has been over- 
flowed by a stream of melted matter; but this did not, 
as we have seen, enter or injure the buildings which 
were previously enveloped or covered over with tuff. 
But burning torrents have often taken their course 
through the streets of Torre del Greco, and consumed 
or inclosed a large portion of the town in solid rock. It 
seems probable that the destruction of three thousand 
of its inhabitants, in 1631, which some accounts attri- 
bute to boiling water, was principally due to one of 
those alluvial foods which we before mentioned: but, 
‘in 1737, the lava itself flowed through the eastern side 
of the town, and afterwards reached the sea; and, in 
1794, another current, rolling over the western side, 
filled the streets and houses, and killed more than 
four hundred persons. The main street is now quar- 
tied through this lava, which supplied building stones 
for new houses erected where others had been anni- 
hilated. The church was half buried in a rocky mass, 
but the upper portion served as the foundation of a 
New edifice. 

The number of the population at present is estimated 
at fifteen thousand; and a satisfactory answer may 
readily be returned to those who inquire how the in- 
habitants can be so “inattentive to the voice: of time 

F 6 


108 DESTRUCTION OF TORRE DEL GRECO. [Book TI, 


and the warnings of nature*,” as to rebuild. their 
dwellings on a spot so often devastated. No neigh- 
bouring site unoccupied by a town, or which would not 
be equally insecure, combines the same advantages of 
proximity to the capital, to the sea, and to the rich 
lands on the flanks of Vesuvius. If the present popu- 
lation were exiled, they would immediately be replaced 
by another, for the same reason that the Maremma of 
Tuscany and the Campagna di Roma will never be 
depopulated, although the malaria fever commits more 
havoc in a few years than the Vesuvian lavas in as 
many centuries. The district around Naples supplies 
one, amongst innumerable examples, that those re- 
gions where the surface is most frequently renewed, 
and where.the renovation is accompanied, at different 
intervals of time, by partial destruction of animal and 
vegetable life, may nevertheless be amongst the most 
habitable and delightful on our globe. 

I have already made a similar remark when speak- 
ing of tracts where aqueous causes are now most 
active ; and the observation applies as-well to parts 
of the surface which are the abode of aquatic animals, 
as to those which support terrestrial species. The 
sloping sides of Vesuvius give nourishment to a vigor- 
ous and healthy population of about eighty thousand 
souls ; and the surrounding hills and plains, together 
with several of the adjoining isles, owe the fertility of 
their soil to matter ejected by prior eruptions. Had 
the fundamental limestone of the Apennines remained 
uncovered throughout the whole area, the country 
could not have sustained a twentieth part of its pre- 
sent inhabitants. This will be apparent to every geo- 
logist who has marked the change in the agricultural 


* Sir H. Davy, Consolations in Travel, p. 66. 


€h. XLI REFLECTIONS ON THE. BURIED CITIES. 109 


character of the soil the moment he has passed the 
utmost boundary of the volcanic ejections, as when, 
for example, at the distance of about seven miles from 
Vesuvius, he leaves the plain and ascends the declivity 
of the Sorrentine Hills. 

Concluding remarks. — Yet, favoured as this region 
has been by Nature from time immemorial, the signs 
of the changes imprinted on it during the period that 
It has served as the habitation of man may appear in 
after-ages to indicate a series of unparalleled disasters. 
Let us suppose that at some future time the Mediter- 
ranean should form a gulf of the great ocean, and that 
the tidal current should encroach on the shores of 
Campania, as it now advances upon the eastern coast 
of England; the geologist will then behold the towns 
already buried, and many more which will evidently 
be entombed hereafter, laid open in the steep cliffs, 
Where he will discover buildings superimposed above 
€ach other, with thick intervening strata of tuff or 
ava— some unscathed by fire, like those of Hercula- 
neum and Pompeii; others half melted down, as in 
Torre del Greco ; and many shattered and thrown 
about in strange confusion, as in Tripergola. Among 
the ruins will be seen skeletons of men, and impres- 
sions of the human form stamped in solid rocks of tuff, 

or will the signs of earthquakes be wanting. The 
Pavement of part of the Domitian Way, and the Tem- 
Ple of the Nymphs, submerged at high tide, will be 
uncovered at low water, the columns remaining erect 
and uninjured. Other temples which had once sunk 
down, like that of Serapis, will be found to have been 
‘praised again by subsequent movements. If they who 
study these phenomena, and speculate on their causes, 
assume that there were periods when the laws of Na- 


\ 


110 REFLECTIONS ON THE BURIED CITIES. [Book It 


ture differed from those established in their own time; 
they will scarcely hesitate to refer the wonderful 
monuments in question to those primeval ages. When 
they consider the numerous proofs of reiterated cata- 
strophes to which the region was subject, they may; 
perhaps, commiserate the unhappy fate of beings con- 
demned to inhabit a planet during its nascent and 
chaotic state, and feel grateful that their favoured race 
has escaped such scenes of anarchy and misrule. 

Yet what was the real condition of Campania during 
those years of dire convulsion? “ A climate where 
heaven’s breath smells sweet and wooingly — a vigorous 
and luxuriant nature unparalleled in its productions — 
a coast which was once the fairy land of poets, and the 
favourite retreat of great men. Even the tyrants of 
the creation’ loved this alluring region, spared it, 
adorned it, lived in it, died in it.”* The inhabitants, 
indeed, have enjoyed no immunity from the calamities 
which are the lot of mankind; but the principal evils 
which they have suffered must be attributed to moral, 
not to physical, causes—to disastrous events over 
which man might have exercised a control, rather than 
to the inevitable catastrophes which result from sub- 
terranean agency. When Spartacus encamped his 
army of ten thousand gladiators in the old extinct 
crater of Vesuvius, the volcano was more justly a 
subject of terror to Campania, than it has ever been 
since the rekindling of its fires. 


* Forsyth’s Italy, vol. ii. 


-CHAPTER XII. - 


ETNA — SKAPTAR JOKUL — JORULLO. 


External physiognomy of Em Lateral cones — Their succes- 
sive obliteration — Early eruptions of Etna — Monti Rossi in 
1669 — Great Fissure of S. Lio — Towns’ overflowed by Java 
— Part of Catania destroyed (p. 118.) — Mode of advance of a 
current of lava — Excavation of a church under lava — Subter- 
ranean caverns — Linear direction of cones formed. in 1811 
and 1819 — Flood produced in 1755 by the melting of snow 
during an eruption— A glacier covered by lava on Etna — 
Volcanic eruptions in Iceland (p. 126.) — New island thrown 
up in 1783 — Lava currents of Skaptar Jokul in same year — 
Their immense volume — Eruption of Jorullo in Mexico 
(P. 133.) — Humboldt’s Theory of the convexity of the Plain 
of Malpais. 


External physiognomy of the, cone. — Havine entered 
into a detailed historical account of the changes in 
the volcanic district round Naples, I shall allude in a 
More cursory manner to some of the circumstances of 
Principal interest in the history of other volcanic 
Mountains. After Vesuvius, our most authentic records 
relate to Etna, which rises near the sea in solitary: 
Standeur to the height of nearly eleven thousand feet”, 


oth In 1815, Captain Smyth ascertained, trigonometrically, that 
the height of Etna was 10,874 feet. The Catanians, disappointed 
that their mountain had lost nearly 2000 feet of the height assigned 
to it by Recupero, refused to. acquiesce in the decision. After- 
Wards, in 1824, Sir J. Herschel, not being aware of Captain 


ee a ee en Se eee =—— 


cece: 


BLZ ETNA. , [Book II. 


the mass being chiefly composed of volcanic matter 
ejected above the surface of the water. The base of 
the cone is almost circular, and eighty-seven English 
miles in circumference ; but if we include the whole 
district over which its lavas extend, the circuit is 
probably twice that extent. 

Divided into three regions. —The cone is divided by 
nature into three distinct zones, called the Jertile, the 
woody, and the desert regions. The first of these, com- 
prising the delightful country around the skirts of the 
mountain, is well cultivated, thickly inhabited, and 
covered with olives, vines, corn, fruit-trees, and aro- 
matic herbs. Higher up, the woody region encircles 
the mountain —an extensive forest, six or seven miles 
in width, affording pasturage for numerous flocks. The 
trees are of various species, the chestnut, oak, and 
pine being most luxuriant ; while in some tracts are 
groves of cork and beech. Above the forest is the 
desert region, a waste of black lava and scorie ; where, 
on a kind of plain, rises the cone to the height of 
about eleven hundred feet, from which sulphureous 
vapours are continually evolved. The most grand and 
original feature in the physiognomy of Etna is the 
multitude of minor cones which are distributed over its 
flanks, and which. are most abundant in the woody 
region. These, although they appear but trifling ir- 
regularities when viewed from a distance as subordi- 
nate parts of so imposing and colossal a mountain, 


Smyth’s conclusions, determined, by careful barometrical measure- 
ment, that the height was 10,8723 feet. This singular agreement 
of results so differently obtained was spoken of by Herschel as ‘‘a 
happy accident ;” but Dr. Wollaston remarked that “ it was one 
of those accidents which would not have happened to two fools.” 


Ch. XIL] MINOR VOLCANOS ON ETNA. 113 


would, nevertheless, be deemed hills of considerable 
altitude in almost any other region. 

Cones produced by lateral eruptions. — Without enu- 
Merating numerous monticules of ashes thrown out at 
different points, there are about eighty of these secon- 
dary volcanos, of considerable dimensions ; fifty-two 
M the west and north, and twenty-seven on the east 
side of Etna. One of the largest, called Monte Mi- 
nardo, near Bronte, is upwards of 700 feet in height, 
and a double hill near Nicolosi, called Monti Rossi, 
formed in 1669, is 450 feet high, and the base two 
miles in circumference ; so that it somewhat exceeds 
in size Monte Nuovo, before described. Yet it ranks 
only as a cone of the second magnitude amongst those 
Produced by the lateral eruptions of Etna. On look- 
Ing down from the lower borders of the desert region, 
these volcanos present us with one of the most de- 
lightful and characteristic scenes in Europe. They 
afford every variety of height and size, and are arranged 
în beautiful and picturesque groups. However uniform 
they may appear when seen from the sea, or the plains 

elow, nothing can be more diversified than their 
shape when we look from above into their craters, one 
side of which is generally broken down. There are, 
Indeed, few objects in nature more picturesque than a 
Wooded volcanic crater. The cones situated in the 
higher parts of the forest zone are chiefly clothed with 
lofty pines ; while those at a lower elevation are 
adorned with chestnuts, oaks, beech, and holm. 

Successive obliteration of these cones. —The history 
of the eruptions of Etna, imperfect and interrupted as 
it is, affords, nevertheless, a full insight into the manner 
in which the whole mountain has successively attained 
its present magnitude and internal structure. The 


114 BURIED CONES ON ETNA. (Book II. 


principal cone has more than once fallen in and beer 
reproduced. In 1444 it was 320 feet high, and fell in 
after the earthquakes of 1537. In the year 1693, 
when a violent earthquake shook the whole of Sicily; 
and killed sixty thousand persons, the cone lost so 
much of its height, says Boccone, that it could not be 
seen from several places in Valdemone, from which it 
was before visible. The greater number of eruptions 
happen either from the great crater, or from lateral 
Openings in the desert region. When hills are thrown 
up in the middle zone, and project beyond the general 
level, they gradually lose their height during subse- 
quent eruptions ; for when lava runs down from the 
upper parts of the mountain, and encounters any of 
these hills, the stream is divided, and flows round them 
so as to elevate the gently sloping grounds from which 
they rise. In this manner a deduction is often made 
at once of twenty or thirty feet, or even more, from 
their height. Thus, one of the minor cones, called 
Monte Peluso, was diminished in. altitude by a great 
lava stream which encircled it in 1444; and another 
current has recently taken the same course — yet this 
hill still remains four or five hundred feet high. 

There is a cone called Monte Nucilla, near Nicolosi, 
round the base of which several successive currents 
have: flowed, and showers of ashes have fallen, since 
the time of history, till at last, during an eruption in 
1536, the surrounding plain was so raised, that the top 
of the cone alone was left projecting above the general 
level. Monte Nero, situated above the Grotta dell’ 
Capre, was in 1766 almost submerged by a current; 
and Monte Capreolo afforded, in the year 1669, a 
curious example of one of the last stages of obliter- 
ation : for a lava stream, descending on a high ridge. 


Ch. XIL] EARLY ERUPTIONS OF ETNA. 115 


which had been built up by the continued superposi- 
tion of successive lavas, flowed directly into the crater, 
and nearly filled it. The lava, therefore, of each new 
lateral cone tends to detract from the relative height 
of lower cones above their base: so that the flanks of 
Etna, sloping with a gentle inclination, envelop in suc- 
cession a great multitude of minor volcanos, while new 
Ones spring up from time to time ; and this has given 
to the older parts of the mountain, as seen in some 
Sections two or three thousand feet perpendicular, a 
complex and highly interesting internal structure. 
Early eruptions of Etna.— Etna appears to have 
been in activity from the earliest times of tradition ; for 
Diodorus Siculus mentions an eruption which caused 
a district to be deserted by the Sicani before the Tro- 
jan war. Thucydides informs us, that in the sixth 
Year of the Peloponnesian war, or in the spring of the 
Year 425 B.C., a lava stream ravaged the environs of 
Catania, and this, he says, was the third eruption which 
had happened in Sicily since the colonization of that 
island by the Greeks.* The second of the three erup- 
tions alluded to by the historian took place in the year 
475 B. c., and was that so poetically described by 
Pindar, two years afterwards, in his first Pythian ode :— 


LOY 
poe 
A ovpavia ouvexes 
; ; 
Nigoero Aitya, TAVETEÇ 


Xuovos dEerag tibnya’ 


In these and the seven verses which follow, a gra- 
Phic description is given of Etna, such as it appeared 
five centuries before the Christian era, and such as it 


.* Book iii., at the end, 


116 ERUPTION OF ETNA, A.D, 1669. [Book II. 


-has been seen when in eruption in modern times. The 
poet is only making a passing allusion to the Sicilian 
volcano, as the mountain under which Typheeus lay 
buried, yet by a few touches of his master hand every 
striking feature of the scene has been faithfully pour- 
trayed. We are told of «the snowy Etna, the pillar 
of heaven,—the nurse of everlasting frost, in whose 
deep caverns lie concealed the fountains of unap- 
proachable fire — a stream of eddying smoke by day 
— a bright and ruddy flame by night; and burning 
rocks rolled down with loud uproar into the sea.” 
Eruption of 1669— Monti Rossi formed. — The great 
eruption which happened in the year 1669 is the first 
which claims particular attention. An earthquake 
had levelled to the ground all the houses in Nicolosi, a 
town situated near the. lower margin of the woody 
region, about twenty miles from the summit of Etna, 
and ten from the sea at Catania. Two gulphs then 
opened near that town, from whence sand and scoriæ 
were thrown up in such quantity, that, in the course 
of three or four months, a double cone was formed, 
called Monti Rossi, about 450 feet high. But the 
most extraordinary phenomenon occurred at the com- 
mencement of the convulsion in the plain of S. Lio. 
A fissure six feet broad, and of unknown depth, opened 
with a loud crash, and ran in a somewhat tortuous 
course to within a mile of the summit of Etna. Its 
direction was from north to south, and its length twelve 
miles. It emitted a most vivid light. Five other pa- 
rallel fissures of considerable length afterwards opened 
one after the other, and emitted smoke, and gave out 
bellowing sounds which were heard at the distance of 
forty miles. This case seems to present the geologist 
with an illustration of the manner in which those con- 


ERUPTION OF ETNA, A. D. 1669. 


Minor cones onthe flanks of Etna. 


1. Monti Rossi, near Nicolosi, formed in 1669. 
2. Vampeluso? * 


tinuous dikes of vertical porphyry were formed which 
are seen to traverse some of the older lavas of Etna; 
ar the light emitted from the great rent of S. Lio ap- 
p ted to indicate that the fissure was filled to a certain 
eight with incandescent lava probably to the height 
of an orifice not far distant from Monti Rossi, which 
at that time opened and poured out a lava current. 
hen the melted matter in such a rent has cooled, it 
Must become a solid wall or dike, intersecting the 
older rocks of which the mountain is composed. 
The lava current above alluded to soon reached in its 
course a minor cone called Mompiliere, at the base of 


7 The hill which I have here introduced was called by my 
i ie Vampolara, but the name given in the text is the nearest to 
's which I find in Gemmellaro’s Catalogue of Minor Cones, 


Speers teaseeain-etentemnasssieales 


a 
Í 

4 | 
f. 

a | 
a 
| 
| 


118 “ERUPTION OF ETNA, A. D. 1669. [Book IL 


which it entered a subterranean grotto, communicating 
with a suite of those caverns which are so common 
in the lavas of Etna. Here it appears to have melted 
down some of the vaulted foundations of the hill, s0 
that the whole of that cone became slightly depressed 
and traversed by numerous open fissures. 

Part of Catania destroyed. — The lava, after over- 
flowing fourteen towns and villages, some having 2 
population of between three and four thousand inhabit- 
ants, arrived at length at the walls of Catania. These 
had been purposely raised to protect the city ; but the 
burning flood accumulated till it rose to the top of the 
rampart, which was sixty feet in height, and then it 
fell in a fiery cascade and overwhelmed part of the 


city. The wall, however, was not thrown down, but - 


was discovered long afterwards, by excavations made 
in the rock by the Prince of Biscari; so that the tra- 
veller may now see thé solid lava curling over the top 
of the rampart as if still in the very act of falling. 
This great current had performed a course of fifteen 
miles before it entered the sea, where it was still six 
hundred yards broad, and forty feet deep. It covered 
some territories in the environs of Catania, which had 
never before been visited by the lavas of Etna. While 
moving on, its surface was in general a mass of solid 
rock; and its mode of advancing, as is usual with lava 
streams, was by the occasional fissuring of the solid 
walls. A gentleman of Catania, named Pappalardo, 
desiring to secure the city from the approach of the 
threatening torrent, went out with a party of fifty 
men whom he had. dressed in skins to protect them 
from the heat, and armed with iron crows and hooks- 
They broke open one of the solid walls which flanked 


Ch. X1] ERUPTION OF ETNA, A.D, 1669. 119 


the current near Belpasso, and immediately forth issued 
à rivulet of melted matter which took the direction 
of Paternò; but the inhabitants of that town, being 
alarmed for their safety, took up arms and put a stop 
to farther operations.* if. 

As another illustration of the solidity of the walls 
of an advancing lava stream, I may mention an adven- 
ture related by Recupero, who, in 1766, had ascended 
4 small hill formed of ancient volcanic matter, to: be- 
hold the slow and gradual approach of a fiery current, 
two miles and a half broad; when suddenly two small 
threads of liquid matter issuing from a crevice detached 
themselves from the main stream, and ran rapidly 
towards the hill. He and his guide had just time to 
“scape, when they saw the hill, which was fifty feet in 

eight, surrounded, and in a quarter of an hour melted 
“own into the burning mass, so as to flow on with it. 

But it must not be supposed that this complete 

Usion of rocky matter coming in contact with lava is 
of universal, or even common, occurrence. It probably 
lappens when fresh portions of incandescent matter 
“ome successively in contact with fusible materials. In 
many of the dikes which intersect the tuffs and lavas 
of Etna, there is scarcely any perceptible alteration 
effected by heat on the edges of the horizontal beds, 

-W contact with the vertical and more crystalline mass. 
On the site of Mompiliere, one of the towns overflowed 
m the great eruption above described, an excavation 
Was made in 1704; and by immense labour the work- 
Men reached, at the depth of thirty-five feet, the gate 
of the principal church, where there were three statues, 

eld in high veneration. One of these, together with 


* Ferrara, Descriz. dell’. Etna, p. 108, 


aD 
ib 7 
i i { 
Hd 
Mee |, 
i f 
it ý 
‘a 
ae 
ry j 
| oe 
mt 
(a | 
H 
i i 
i 


ee 


120 SUBTERRANEAN CAVERNS ON ETNA. [Book Il- 


a bell, some money, and other articles, were extracted 
in a good state of preservation from beneath a great 
arch formed by the lava. It seems very extraordinary 
that any works of art, not encased with tuff, like those 
in Herculaneum, should have escaped fusion in hollow 
spaces left open in this lava current, which was so hot 
at Catania eight years after it entered the town, that 
it was impossible to hold the hand in some of the 
crevices, 

Subterranean caverns on Etna.— Mention was made 
of the entrance of a lava stream into a subterranean 
grotto, whereby the foundations of a hill were partially 
undermined. Such underground passages are among 
the most curious features on Etna, and appear to have 
been produced by the hardening of the lava, during 
the escape of great volumes of elastic fluids, which 
are often discharged for many days in succession, after 
the crisis of the eruption is over. Near Nicolosi, not 
far from Monti Rossi, one of these great openings may 
be seen, called the Fossa della Palomba, 625 feet in 
circumference at its mouth, and seventy-eight deep- 
After reaching the bottom of this, we enter another 
dark cavity, and then others in succession, sometimes 
descending precipices by means of ladders. At length 
the vaults terminate in a great gallery ninety feet long, 
and from fifteen ‘to fifty broad, beyond which there is 
still a passage, never yet explored; so that the extent 
of these caverns remains unknown.* The walls and 
roofs of these great vaults are composed of rough and 
bristling scorize, of the most fantastic forms. 

Eruption of 1811.—1 shall now proceed to offer 
some observations on the two last eruptions in 1811 


* Ferrara, Descriz. dell’ Etna. Palermo, 1818. 


Ch. XIL] ERUPTIONS OF 1811 AND 1819. | PAI 


and 1819.* It appears, from the relation of Signor 
Gemmellaro, who witnessed the phenomena, that the 
reat crater in 1811 first testified, by its loud detona- 
tions, that the lava had ascended to near the summit 
of the mountain. A violent shock was then felt, and 
è stream broke out from the side of the cone, at no 
great distance from its apex. Shortly after this had 
Ceased to flow, a second stream burst forth at another 
Opening, considerably below the first; then a third 
Still lower, and so on till seven different issues had 
been thus successively formed, all lying upon the same 
Straight line. It has been supposed that this line was 
a perpendicular rent in the internal framework of the 
Mountain, which rent was probably not produced at 
One shock, but prolonged successively downwards, by 
the lateral pressure and intense heat of the internal 
Column of lava, as it subsided by gradual discharge 
through each vent. t 
Eruption of 1819.—In 1819 three large mouths or 
Caverns opened very near those which were formed in 
the eruptions of ,1811, from which flames, red-hot 
Cinders, and sand, were thrown up with loud explo- 
sions, A few minutes afterwards another mouth 
Opened below, from which flames and smoke issued ; 
and finally a fifth, lower still, whence a torrent of lava 
flowed, which spread itself with great velocity over the 
deep and broad valley called “ Val del Bove.” This 
Stream flowed two miles in the first twenty-four hours, 
and nearly as far in the succeeding day and night. 


* Since this was written for the 1st edition of this work, another 
eruption has occurred. In 1832, the lava flowed down on the 
West side of Etna to within two miles of Bronte. 

Tt Scrope on Volcanos, p. 153. 

VOL. II, . G 


122. MODE OF ADVANCE OF THE LAVA. [Book I, 


The three original mouths at length united into one 
large crater, and sent forth lava, as did the infe- 
rior apertures, so that an enormous torrent poured 
down the “ Val del Bove.” When it arrived at a vast 
and almost perpendicular precipice, at the head of the 
valley of Calanna, it poured over in a cascade, and, 
being hardened in its descent, made an inconceivable 
crash as it was dashed against the bottom. So im- 
mense was the column of dust raised by the abrasion 
of the tufaceous hill over which the hardened mass 
descended, that the Catanians were in great alarm, 
supposing a new eruption to have burst out in the 
woody region, exceeding in violence that near the 
summit of Etna. 

Mode of advance of the lava. — Of the cones thrown 
up during this eruption, not more than two are of suf- 
ficient magnitude to be numbered among those eighty 
which were before described as adorning the flanks of 
Etna. The surface of the lava which deluged the 
“Val del Bove” consists of rocky and angular blocks, 
tossed together in the utmost disorder. Nothing can 
be more rugged, or more unlike the smooth and even 
superficies which those who are unacquainted with 
volcanic countries may have pictured to themselves, 
in a mass of matter which had consolidated from a 
liquid state. Mr.-‘Scrope observed this current in the 
year 1819, slowly advancing down a considerable slope, 
at the rate of about a yard an hour, nine months after 
its first emission. The lower stratum being arrested 
by the resistance of the ground, the upper or central 
part gradually protruded itself, and being unsupported 
fell down. This in its turn was covered by a mass of 
more liquid lava, which swelled over it from above. 

` The current had all the appearance of a huge heap of 


3 = = 
=F A 
Ww 
WE (i 
4 t 
HE! 
by j 
{ 
NEA : 
irp | 
i i 
mn 
1$. 
le BZ 
f Y i 
Eo 
os 
ii y 
IE 
i 
ai t 
ijj 
| i 
r le 
f 
4 
h | 
i { 
i i \ 
y 
H 
ji 
i 
ii 
| 
‘ 


2r- 


a D 


Ch. XIL] FLOODS ON ETNA. 123 
"ough and large cinders rolling over and over upon 
itself by the effect of an extremely slow propulsion 
from behind. The contraction of the crust as it solidi- 
fied, and the friction of the scoriform cakes against one 
‘nother, produced a crackling sound. Within the cre- 
Vices a dull red heat might be seen by night, and vapour 
‘SSuing in considerable quantity was visible by day.* 
Flood produced by the melting of snow by lava. — 
‘ he erosive and transporting power of running water 
1s rarely exerted on Etna with great force, the rain 
Which falls being immediately imbibed by the porous 
“vas ; so that, vast as is the extent of the mountain, 
t feeds only a few small rivulets, and these, even, are 
dry throughout the greater portion of the year. The 
enormous rounded boulders, therefore, of trachyte and 
asalt, a line of which can be traced from the sea, 
from near Giardini, by Mascali, and Zafarana, to the 
“Val del Bove,” would offer a perplexing problem to 
$ € geologist, if history had not preserved the memo- 
nals of a tremendous flood which happened in this 
istrict in the year 1755. It appears that two streams 
of lava flowed in that year, on the 2d of March, from 
the highest crater : they were immediately precipitated 
Upon an enormous mass of snow which then covered 
the whole mountain, and was extremely deep near the 
Summit. The sudden melting of this frozen mass, by 
3 fiery torrent three miles in length, produced a 
frightful inundation, which devastated the sides of the 
Mountain for eight miles in length, and afterwards 
Covered the lower flanks of Etna, where they were less 
Steep, together with the plains near the sea, with great 
€posits of sand, scoriæ, and blocks of lava. 


* Scrope on Volcanos, p. 102. 


G 2 


124 GLACIER COVERED BY LAVA. > [Book II- 


Many absurd stories circulated in Sicily respecting 
this event, such as that the water was boiling, and that 
it was vomited from the highest crater ; that it was as 
salt as the sea, and full of marine shells; but these 
were mere inventions, to which Recupero, although he 
relates them as tales of the mountaineers, seems tO 
have attached rather too much importance. 

Floods of considerable violence have also been pro- 
duced on Etna by the fall of heavy rains, aided, 
probably, by the melting of snow. By this cause alone, 
in 1761, sixty of the inhabitants of Acicatena were 
killed, and many of their houses swept away.* 

Glacier covered by a lava stream.— A remarkable 
discovery was made on Etna in 1828 of a great 
mass of ice, preserved for many years, perhaps for 
centuries, from melting, by the singular accident of a 
current of red-hot lava having flowed over it. The 
following are the facts in attestation of a phenomenon 
which must at first sight appear of so paradoxical a 
character. The extraordinary heat experienced in the 
South of Europe, during the summer and autumn of 
1828, caused the supplies of snow and ice which had 
been preserved in the spring of that year, for the use 
of Catania and the adjoining parts of Sicily and. the 
island of Malta, to fail entirely. Great distress was 
consequently felt for want of a commodity regarded 
in those countries as one of the necessaries of life 
rather than an article of luxury, and the abundance of 
which contributes in some of the larger cities to the 
salubrity of the water and the general health of the 
community. The magistrates of Catania applied to 
Signor M. Gemmellaro, in the hope that his local 


= 


3| 
SPE SA rane a me eS) 
s A, 


e ny een 


* Ferrara, Descriz. dell’ Etna, p. 116. 


Ch. XIL] GLACIER COVERED BY LAVA. 125 


knowledge of Etna might enable him to point out 

Some crevice or natural grotto on the mountain, where 

drift snow was still preserved. Nor were they dis- 

appointed ; for he had long suspected that a small mass ` 
of perennial ice at the foot of the highest cone was 

Part. of a large and continuous glacier covered by a 

lava current. Having procured a large body of work- 

men he quarried into this ice, and proved the super- 

Position of the lava for several hundred yards, so as 

Completely to satisfy himself that nothing but the sub- 

Sequent flowing of the lava over the ice could account 

for the position of the glacier. Unfortunately for the 

Seologist, the ice was so extremely hard, and the ex- 

Cavation so expensive, that there is no probability of 
the operations being renewed. 

On the first of December, 1828, I visited this spot, 
Which is on the south-east side of the cone, and not 
far above the Casa Inglese ; but the fresh snow had 
already nearly filled up the new opening, so that it 

ad only the appearance of the mouth of a grotto. I 
do not, however, question the accuracy of the con- 
Clusion of Signor Gemmellaro, who, being well ac- 
qainted with all the appearances of drift snow in the 
fissures and cavities of Etna, had recognized, even 
before the late excavations, the peculiarity of the po- 
Sition of the ice in this locality. We may suppose that 
at the commencement of the eruption, a deep mass of 
drift snow had been covered by volcanic sand showered 
down upon it before the descent of the lava. A dense 
Stratum of this fine dust mixed with scoriæ is well 

nown to be an extremely bad conductor of heat; and 

the shepherds in the higher regions of Etna are accus- 

tomed to. provide water for their flocks during sum- 

mer, by strewing a layer of volcanic sand a few inches 
G 3 


126 VOLCANIC ERUPTIONS IN ICELAND. [Book Il 


thick over the snow, which effectually prevents the 
heat of the sun from penetrating. 

Suppose the mass of snow to have been preserved 
from liquefaction until the lower part of the lava had 
consolidated, we may then readily conceive that a gla- 
cier thus protected, at the height of ten thousand feet 
above the level of the sea, would endure as long as the 
snows of Mont Blanc, unless melted by volcanic heat 
from below. When I visited the great crater in the 
beginning of winter, (December Ist, 1828,) I found 
the crevices in the interior encrusted with thick ice, 
and in some cases hot vapours were actually streaming 
out between masses of ice and the rugged and steep 
walls of the crater. 

After the discovery of Signor Gemmellaro, it would 
not be surprising to find in the cones of the Icelandic 
volcanos, which are covered for the most part with 
perpetual snow, repeated alternations of lava streams 
and glaciers. 

Volcanic eruptions in Iceland.— With the exception 
of Etna and Vesuvius, the most complete chronologi- 
cal records of a series of eruptions are those of Iceland; 
for their history reaches as far back as the ninth cen- 
tury of our era; and, from the beginning of the twelfth 
century, there is clear evidence that, during the whole 
period, there has never been an interval of more than 
forty, and very rarely one of twenty years, without 
either an eruption or a great earthquake. So intense 
is the energy of the volcanic action in this region, that 
some eruptions of Hecla have lasted six years without 
ceasing. Earthquakes have often shaken the whole 
island at once, causing great changes in the interior, 
such as the sinking down of hills, the rending of 
mountains, the desertion by rivers of their channels, 


Ch. XIL] NEW ISLAND THROWN UP, A. D. 1783. 127 


and the appearance of new lakes.* New islands have 
often been thrown up near the coast, some of which 
still exist ; while others have disappeared, either by 
subsidences or the action of the waves. 

In the interval between eruptions, innumerable hot 
Springs afford vent to subterranean heat, and solfataras 
discharge copious streams of inflammable matter. The 
volcanos in different parts of this island are observed, 
like those of the Phlegreean Fields, to be in activity 
by turns, one vent often serving for a time as a safety- 
valve to the rest. Many cones are often thrown up in 
one eruption, and in this case they take a linear direc- 
tion, running generally from north-east to south-west, 
from the north-eastern part of the island, where the 
Voleano Krabla lies, to the promontory Reykianas. 

New island thrown up in 1783.— The convulsions of 
the year 1783 appear to have been more tremendous 
than any recorded in the modern annals of Iceland ; 
and the original Danish narrative of the catastrophe, 
drawn up in great detail, has since been substantiated 
by several English travellers, particularly in regard to 
the prodigious extent of country laid waste, and the 
Volume of lava produced.+ About a month previous 


* Von Hoff, vol. ii. p. 393. 

+ The first narrative of the eruption was drawn up by Stephen- 
sen, then Chief Justice in Iceland, appointed Commissioner by 
the King of Denmark, for estimating the damage done to the 
Country, that relief might be afforded to the sufferers. Henderson 
Was enabled to correct some of the measurements given by Ste- 
Phensen, of the depth, width, and length of the lava currents, by 
reference to the MS. of Mr. Paulson, who visited the tract in 
1794, and examined the lava with attention. (Journal of a Re- 
Sidence in Iceland, &c. p. 229.) Some of the principal facts are 
also corroborated by Dr. Hooker, in his ‘ Tour in Iceland,” 
vol. ii, p. 128. | 


G 4 


128 ERUPTION OF SKAPTAR JOKUL, [Book I, 


to.the eruption on the main land, a submarine volcano 
burst forth in the sea in lat. 63° 251 N. long. 23° 44’ W. 
at a distance of thirty miles in a south-west direction 
from Cape Reykianas, and ejected so much pumice, 
that the ocean was covered with that substance to the 
distance of 150 miles, and ships were considerably im- 
peded in their course. A new island was thrown up, 
consisting of high cliffs, within which fire, smoke, and 
pumice were emitted from two or three different points. 
This island was claimed by his Danish Majesty, who 
denominated it Nyöe, or the New Island; but before a 
year had elapsed, the sea resumed its ancient domain, 
and nothing was left but a reef of rocks from five to 
thirty fathoms under water. 

Great eruption of Skaptár Jokul.— Earthquakes, 
which had long been felt in Iceland, became violent on 
the 11th of June, when Skaptar Jokul, distant nearly 
two hundred miles from Nyée, threw out a torrent of 
lava which flowed down into the river Skapta, and 
completely dried it up. The channel of the river was 
between high rocks, in many places from four hundred 
to six hundred feet in depth, and near two hundred in 
breadth. Not only did the lava fill up this great defile 
to the brink, but it overflowed the adjacent fields to a 
considerable extent. The burning flood, on issuing 
from the confined ‘rocky gorge, was then arrested for 
some time by a deep lake, which formerly existed in 
the course of the river, between Skaptardal and Aa, 
which it entirely filled. The current then advanced 
again, and reaching some ancient lava full of subter- 
raneous caverns, penetrated and melted down part of 
it ; and in some places, where the stream could not 
gain vent, it blew up the rock, throwing fragments to 
the height of more than 150 feet. On the 18th of 


Ch- XIL] IN ICELAND, A.D. 1783. 129 


June, another ejection of liquid lava rushed from the 
volcano, which flowed down with amazing velocity over 
the surface of the first stream. By the damming up 
of the mouths of some of the tributaries of the Skapta, 
Many villages were completely overflowed with water, 
and thus great destruction of property was caused. 
The lava, after flowing for several days, was preci- 
Pitated down a tremendous cataract called Stapafoss, 
Where it filled a profound abyss, which that great 
Waterfall had been hollowing out for ages, and, after 
this, the fiery current again continued its course. 

On the 3d of August, fresh floods of lava still pouring 
from the volcano, a new branch was sent off in a dif- 
ferent direction ; for the channel of the Skapta was now 
So entirely choked up, and every opening to the west 
and north so obstructed, that the melted matter was 
forced to take a new course, so that it ran in a south- 
€ast direction, and discharged itself into the bed of the 
river Hverfisfliot, where a scene of destruction scarcely 
inferior to the former was occasioned. These Ice- 
landic lavas (like the ancient streams which are met 
With in Auvergne, and other provinces of Central 
France, ) are stated by Stephensen to have accumu- 
lated to a prodigious depth in narrow rocky gorges ; 
but when they came to wide alluvial plains, they spread 
themselves out into broad burning lakes, sometimes 
from twelve to fifteen miles wide, and one hundred feet 
deep, When the “fiery lake” which filled up the lower 
Portion of the valley of the Skapta had been augmented 
by new supplies, the lava flowed up the course of the 
river to the foot of the hills from whence the Skapta 
takes itsrise. This affords a parallel case to one which 
can be shown to have happened at a remote era in the 
Volcanic region of the Vivarais in France, where lava 

G 5 


130 ERUPTION OF SKAPTAR JOKUL. [Book Il. 


issued from the cone of Thueyts, and while one branch 
ran down, another more powerful stream flowed up the 
channel of the river Ardéche, 

The sides of the valley of the Skapta present superb 
ranges of basaltic columns of older lavas, resembling 
those which are laid open in the valleys descending 
from Mont Dor in Auvergne, where more modern 
lava currents, on a scale very inferior in magnitude to 
those of Iceland, have also usurped the beds of the 
existing rivers. The eruption of Skaptar Jokul did not 
entirely cease till the end of two years; and when 
Mr. Paulson visited the tract eleven years afterwards, 
in 1794, he found columns of smoke still rising from 
parts of the lava, and several rents filled with hot 
water.* 

Although the population of Iceland was very much 
scattered, and did not exceed fifty thousand, no less 
than twenty villages were destroyed, besides those 
inundated by water; and more than nine thousand 
human beings perished, together with an immense 
number of cattle, partly by the depredations of the 
lava, partly by the noxious vapours which impregnated 
the air, and, in part, by the famine caused by showers 
of ashes throughout the island, and the desertion of 
the coasts by the fish. 

Immense volume of the lava.— But the extraordinary 
volume of melted matter produced in this eruption 
deserves the particular attention of the geologist. Of 
the two branches, which flowed in nearly opposite 
directions, the greatest was fifty, and the lesser forty 
miles in Jength. The extreme breadth which the 
Skapta branch attained in the low countries was from 


* Henderson’s Journal, &c. p. 228. 


Ch. XIL] IMMENSE VOLUME OF THE LAVA. 131 


twelve to fifteen miles, that of the other about seven. 
The ordinary height of both currents was one hundred. 
feet, but in narrow defiles it sometimes amounted to 
six hundred. A more correct idea will be formed of 
the dimensions of the two streams, if we consider how 
Striking a feature they would now form in the geology 
of England, had they been poured out on the bottom 
of the sea after the deposition, and before the eleva- 
tion of our secondary and tertiary rocks. The same 
causes which have excavated valleys through parts of 
our marine strata, once continuous, might have acted 
With equal force on the igneous rocks, leaving, at the 
Same time, a sufficient portion undestroyed to enable 
Us to discover their former extent. ` Let us, then, 
imagine the termination of the Skapta branch of lava 
to rest on the escarpment of the inferior and middle 
oolite, where it commands the vale of Gloucester. The 
reat platform might be one hundred feet thick, and 
from ten to fifteen miles broad, exceeding any which 
can be found in Central France. We may also sup- 
Pose great tabular masses to occur at intervals, capping 
the summit of the Cotswold Hills between Gloucester 
and Oxford, by Northleach, Burford, and other towns. 
The wide valley of the Oxford clay would then occa- 
Sion an interruption for many miles ; but the same 
Tocks might recur on the summit of Cumnor and Shot- 
Over Hills, and all the other oolitic eminences of that 
district. On the chalk of Berkshire, extensive plateaus, 
six or seven miles wide, would again be formed; and, 
lastly, crowning the highest sands of Highgate and 
Hampstead, we might behold some remnants of the 
current five or six hundred feet in thickness, causing 
those hills to rival, or even to surpass, in height, 
Salisbury Craigs and Arthur’s Seat. 
G 6 


132 ANCIENT -AND MODERN LAVAS COMPARED. [Book II. 


The distance between the extreme points here indi- 
cated would not exceed ninety miles in a direct line; 
and we might then add, at the distance of nearly two 
hundred miles from London, along the coast of Dorset- 
shire and Devonshire for example, a great mass of 
igneous rocks, . to represent those of contemporary 
origin, which were produced beneath the level of the 
sea, where the island of Nyöe rose up. 

Volume of ancient and modern flows of lava com- 
pared.— Yet, gigantic as must appear the scale of 
these modern volcanic operations, we must be content 
to regard them as perfectly insignificant in comparison 
to currents of the primeval ages, if we embrace the 
theoretical views of some geologists of great celebrity. 
Thus, we are informed by Professor Brongniart, in his 
last work, that “aux époques g¢ognostiques anciennes, 
tous les phénomènes géologiques se passoient dans 
des. dimensions centuples de celles qu’ils présentent 
aujourd’hui.”* Had Skaptér Jokul therefore been a 
volcano of the olden time, it would have poured forth 
lavas at.a single eruption, a hundred times more volu- 
minous than those which were witnessed by the present 
generation in 1783. But this can never have been 
intended by M. Brongniart ; for were we to multiply 
the two currents before described by a hundred, and 
first assume that their height and breadth remain the 
same, they would. stretch out to the length of nine. 
thousand miles, or about half as far again as from the 
pole to the equator. If, on the other hand, we suppose 
their length and breadth to remain the same, and 
multiply their height in an equal proportion, the mean 


*. Tableau des Terrains qui composent l’Ecorce du Globe, p, 52. 
Paris, 1829. 


Ch. XH] ERUPTION OF JORULLO, A. D. 1759. 133 


elevation of the volcanic mass becomes ten thousand 
feet, and its greatest more than double that ofthe 
imalaya mountains. It will immediately be granted 
that, among the older formations, no igneous rock of 
such colossal magnitude has yet been met with; nay, 
it would be most difficult to point out a mass of ancient 
date distinctly referable to a single eruption, which 
Should even rival in volume the matter poured out 
from Skaptár Jokul in 1783. 
Eruption of Jorullo in 1759.— As another example 
of the stupendous scale of modern volcanic eruptions, 
May mention that of Jorullo in Mexico, in 1759. 
he great region to which this mountain belongs has 
already been described. The plain of Malpais forms 
Part of an elevated platform, between two and three 
thousand feet above the level of the sea, and is bounded 
y hills composed of basalt, trachyte, and volcanic 
tuff, clearly indicating that the country had previously, 
though probably at a remote period, been the theatre 
ot igneous action. From the era of the discovery of 
the New World to the middle of the last century, the 
district had remained undisturbed, and the space, now 
the site of the volcano, which is thirty-six leagues 
distant from the nearest sea, was occupied by fertile 
fields of sugar-cane and indigo, and watered by the 
two brooks Cuitimba and San Pedro. In the month 
of June, 1759, hollow sounds of an alarming nature 
Were heard, and earthquakes succeeded each other 
for two months, until, in September, flames issued 
from the ground, and fragments of burning rocks were 
thrown to prodigious heights. Six volcanic cones, 
Composed of scoriz and fragmentary lava, were formed 
on the line of a chasm which ran in the direction from 
N.E: to S.8.W. The least of these cones was 300 


134 ERUPTION OF JORULLO, A.D. 1759. [Book IL. 


feet in height ; and Jorullo, the central volcano, was 
elevated 1600 feet above the level of the plain. It 
sent forth great streams of basaltic lava, containing 
included fragments of granitic rocks, and its ejections 
did not cease till the month of February, 1760. 
Humboldt visited the country more than 40 years 
after this occurrence, and was informed by the Indians, 
that when they returned, long after the catastrophe, 
to the plain, they found the ground uninhabitable 
from the excessive heat. When he himself visited the 
place, there appeared, around the base of the cones, 
and spreading from them, as from a centre, over an 
extent of four square miles, a mass of matter of a 
convex form, about 550 feet high at its junction with 
the cones, and gradually sloping from them in all 


directions towards the plain. This mass was still in a 
Fig. 26. 


a, Summit of Jorullo; b, c, inclined plane sloping at angle of 
6° from the base of the cones. 

Hesiod state, the temperature in the fissures being on 
the decrease from year to year, but in 1780 it was 
still sufficient to light a cigar at the depth of a few 
inches. On this slightly convex protuberance, the slope 
of which must form an angle of about 6° with the 
horizon, were thousands of flattish conical mounds, 
from six to nine feet high, which, as well as large 
fissures traversing the plain, acted as fumeroles, giving 
out clouds of sulphuric acid and hot aqueous vapour. 
The two small rivers before mentioned disappeared 
during the eruption, losing themselves below the eastern - 
extremity of the plain, and reappearing as hot springs 
at its western limit. 


Ch. XII] CONVEXITY OF THE PLAIN OF MALPAIS. 135 


Cause of the convexity of the plain of Malpais.— 
Humboldt attributed the convexity of the plain to 
inflation from below ; supposing the ground, for four 
Square miles in extent, to have risen up in the shape 
of a bladder to the elevation of 550 feet above the 
Plain in the highest part. But this theory is by no 
Means borne out by the facts described ; and it is the 
More necessary to scrutinize closely the proofs relied 
on, because the opinion of Humboldt appears to have 
been received as if founded on direct observation, and 
has been made the groundwork of other bold and ex- 
‘taordinary theories. Mr. Scrope has suggested that 
the phenomena may be accounted for far more natur- 
ally, by supposing that lava flowing simultaneously 
Tom the different orifices, and principally from Jorullo, 
United into a sort of pool or lake. As they were 
Poured forth on a surface previously flat, they would, 
if their liquidity was not very great, remain thickest 
and deepest near their source, and diminish in bulk 
from thence towards the limits of the space which they 
Covered. Fresh supplies were probably emitted suc- 
“essively during the course of an eruption which lasted 
@ year; and some of these, resting on those first 
mitted, might only spread to a small distance from 
the foot of the cone, where they would necessarily 
accumulate to a great height. 

The showers, also, of loose and pulverulent matter 
Tom the six craters, and principally from Jorullo, 
Would be composed of heavier and more bulky par- 
ticles near the cones, and would raise the ground at 
their base, where, mixing with rain, they might have 
given rise to the stratum of black clay which is 

scribed as covering the lava. The small conical 
Mounds (called “hornitos,” or little ovens) may re- 


136 CONVEXITY OF THE PLAIN OF MALPAIS. [Book Il. 


semble those five or six small hillocks which existed 
in 1823 on the Vesuvian lava, and sent forth columns 
of vapour, having been produced by the disengage- 
ment. of elastic fluids heaving up small dome-shaped 
masses of lava. The fissures mentioned by Humboldt 
as of frequent occurrence, are such.as might naturally 
accompany the consolidation of a thick bed of lava, 
contracting as it congeals; and the disappearance of 
rivers is the usual result of the occupation of the 
lower part of a valley or plain by lava, of which there 
are many beautiful examples in the old lava-currents 
of Auvergne. The heat of the “hornitos” is stated 
to have diminished from the first; and Mr. Bullock, 
who visited the spot many years after Humboldt, 
found the temperature of the hot spring very low, — a 
fact which seems clearly to indicate the gradual con- 
gelation of a subjacent bed of lava, which from its 
immense thickness may have been enabled to retain 
its heat for half a century. The reader may be re- 
minded, that when we thus suppose the lava near the 
volcano to have been, together with the ejected ashes, 
more than five hundred feet in depth, we merely 
assign a thickness which the current of Skaptar Jokul 
attained in some places in 1783. , 
Hollow sound of the plain when struck. — Another 
argument adduced in support of the theory of inflation 
from below, was, the hollow sound made by the steps 
of a horse upon the plain; which, however, proves 
nothing more than that the materials of which the 
convex mass is composed are light and porous. The. 
sound called “rimbombo” by the Italians is. very 
commonly returned by: made. ground when. struck 
sharply ; and has been observed not only on the sides 
of Vesuvius and other volcanic.cones where there is 


è 


Ch. XIL] ERUPTION OF JORULLO. 137 


a cavity below, but in plains such as the Campagna di 

oma, composed in a great measure of tuff and porous 
volcanic rocks. The reverberation, however, may 
Perhaps be assisted by grottos and caverns, for these 
May be as numerous in the lavas of Jorullo as in many 
of those of Etna; but their existence would lend no 
Countenance to the hypothesis of a great arched 
Cavity, four square miles in extent, and in the centre 
550 feet high. * 

No recent eruptions of Jorullo.— In a former edition 
I stated that I had been informed by Captain Vetch, 
that in 1819 a tower at Guadalaxara was thrown 
down by an earthquake, and that ashes, supposed to 
have come from J orullo, fell at the same time at Guan- 
axuato, a town situated 140 English miles from the 
Volcano. There appears, however, to have been a 
Mistake in the statement; for Mr. Burkart, a German 
director of mines, who examined Jorullo in 1827, as- 
Certained that there had been no eruption there since 
Humboldt’s visit in 1803. He went to the bottom of 
the crater, and observed a slight evolution of sul- 
Phurous acid vapours, but the “ hornitos ” had entirely 
Ceased to send forth steam. During the twenty- 
Our years intervening between his visit and that of 

umboldt, vegetation had made great progress on the 
flanks of the new hills, the rich soil of the surrounding 
Country was once more covered with luxuriant crops 
of Sugar-cane and indigo, and there was an abuudant 


Stowth of natural underwood on all the uncultivated 
tracts. + 


* See Scrope on Volcanos, p. 267. 
+ Leonhard and Bronn’s Neues Jahrbuch, 1835, p. 36. 


CHAPTER XIII. 


Volcanic archipelagos — The Canaries — Eruptions in Teneriffe 
— Cones thrown up in Lancerote in 1730-36 — Pretended 
distinction between ancient and modern lavas — Recent oolitic 
travertin in Lancerote — Submarine volcanos (p. 145.) — 
Graham Island formed in 1831 — Von Buch’s Theory of 
“ Elevation Craters” considered (p. 152.) — Santorin and its 
contiguous isles — Isle of Palma, a supposed ‘ Crater of Ele- 
vation” — Barren Island in the Bay of Bengal (p. 159.) — 
Mineral composition of volcanic products (p. 177.) — Specu- 
lations respecting igneous rocks produced at great depths by 
modern volcanic eruptions. 


Volcanic archipelagos. — IN our chronological sketch 


of the changes which have happened within the tra- 
ditionary and historical period in the volcanic district 
round Naples, we described the renewal of the fires of 
a central and habitual crater, and the almost entire 
cessation of a series of irregular eruptions from minor 
and independent vents. Some volcanic archipelagos 
offer interesting examples of the converse of this 
phenomenon ; the great habitual vent having become 
almost sealed up, and eruptions of great violence now 
proceeding, either from different points in the bed of 
the ocean, or from adjoining islands, where, as for- 
merly in Ischia, new cones and craters are formed 
from time to time. Of this state of things the Canary 
Islands now afford an example. 

Peak of Teneriffe.— The highest crater of the Peak 
of Tenerife has been in the state of a solfatara ever 
since it has been known to Europeans ; but several 


Ch. XIILJ ERUPTION IN LANCEROTE, 1730—36. 139 


eruptions have taken place from the sides of the 
Mountain; one in the year 1430, which formed a 
small hill, and another in 1704 and the two following 
years, accompanied with great earthquakes, when the 
lava overflowed a town and harbour. Another erup- 
tion happened in June, 1798, not far from the summit 
of the peak. But these lateral emissions of lava, at 
distant intervals, may be considered as of a subor- 
dinate kind, and subsidiary to the great discharge 
which has taken place in the contiguous isles of 
Palma and Lancerote; and the occasional activity of 
the peak may be compared to the irregular eruptions 
before mentioned, of the Solfatara, of Arso in Ischia, 
and of Monte Nuovo, which have broken out since 
the renewal of the Vesuvian fires in 79. 

Eruption in Lancerote, 1730 to 1736. — The effects - 
of one of these insular eruptions in the Canaries, which 
happened in Lancerote, between the years 1730 and. 
1736, were very remarkable ; and a detailed descrip- 
tion has been published by Von Buch, who had an 
pportunity, when he visited that island in 1815, of 
Comparing the accounts transmitted to us of the 
event, with the present state and geological appear- 
ances of the country.* On the first of September, 
1730, the earth split open on a sudden two leagues 
from Yaira. In one night a considerable hill of 
ejected matter was thrown up; and a few days later, 
another vent opened, and gave out a lava-stream, 
Which overran Chinanfaya and other villages. It 
flowed first rapidly, like water, but became afterwards 


* This account was principally derived by Von Buch from the 

S. of Don Andrea Lorenzo Curbeto, Curate of Yaira, the point 
Where the eruption began. — Uebe einen vulcanischen Ausbruch 
auf der Insel Lanzerote. 


140 THIRTY NEW CONES THROWN UP. [Book Il. 


heavy and slow, like honey. On the 7th of September 
an immense rock was protruded from the bottom of 
the lava, with a noise like thunder, and the stream 
was forced to change its course from N. to N. W., so 
that St. Catalina and other villages were overflowed. 

Whether this mass was protruded by an earthquake, 
or was a mass of ancient lava, blown up like that be- 
fore mentioned in 1783 in Iceland, is not explained. 

On the 11th of September more lava flowed out, 
and covered the village of Maso entirely, and, for the 
space of eight days, precipitated itself with a horrible 
roar into the sea. Dead fish floated on the waters in 
indescribable multitudes, or were thrown dying on the 
shore. After a brief interval of repose, three new 
openings broke forth immediately from the site of the 
consumed. St.. Catalina, and sent out an enormous 
quantity of lapilli, sand, and ashes. On the 28th of 
October, the cattle throughout the whole country 
dropped lifeless to the ground, suffocated by putrid 
vapours, which condensed and fell down in drops. 
On the 1st of December a lava stream reached the 
sea, and formed an island, round which dead fish were 
strewed. 

Number of cones thrown up.—It is unnecessary here 
to give the details of the overwhelming of other places 
by fiery torrents, or of a storm which was equally new 
and terrifying to the inhabitants, as they had never 
known one in their country before. On the 10th of 
January, 1731, a high hill was thrown up, which, on 
the same day, precipitated itself back again into its 
own crater; fiery brooks of lava flowed from it to 
the sea. On the 3rd of February a new cone arose. 
Others were thrown up in March, and poured forth 
Java-streams. Numerous other volcanic cones were 


Ch. XIIL]. HEIGHT OF NEW CONES. 141 


Subsequently formed in succession, till at last their 
number amounted. to about thirty. In June, 1731, 
during a renewal of the eruptions, all the banks and 
shores in the western part of the island were covered 
With dying fish, of different species, some of which 
had never before been seen. Smoke and flame arose 
from the sea, with loud detonations. These dreadful 
“ommotions lasted without interruption for five. suc- 
Cessive years, so that a great emigration of the inha- 
bitants became necessary. 

Their linear direction. — As to the height of the 
new cones, Von Buch was assured that the formerly 
steat and flourishing St. Catalina lay buried under 

ills 400 feet in height; and he observes that. the 
Most elevated cone of the series rose 600 feet above 
its base, and 1378 feet above the sea, and that several 
others were nearly as high. The new vents were.all 
arranged in one line, about two geographical miles 
long, and in a direction nearly east and west. If we 
admit the probability of Von Buch’s conjecture, that 
these vents opened along the line of a cleft, it seems 
Necessary to suppose that this subterranean fissure 
Was only prolonged upwards to the surface by degrees, 
and that the rent was narrow at first, as is usually the 
“ase with fissures caused by earthquakes. Lava and 
elastic fluids might escape from some point on the rent 
Where there was least resistance, till, the first aperture 

“Coming obstructed by ejections and the consolidation 
of lava, other orifices burst open in succession, along 
the line of the original fissure. Von Buch found that 
ach crater was lowest on that side on which lava had 
‘sued ; but some craters were not breached, and were 
Without any lava-streams. In one of these were open 

Ssures, out of which hot vapours rose, which in 1815 


142 ANCIENT AND MODERN LAVAS. [Book II. 


raised the thermometer to 145° Fahrenheit, and was 
probably at the boiling point lower down. The ex- 
halations seemed to consist of aqueous vapour ; yet 
they could not be pure steam, for the crevices were 
encrusted on either side by siliceous sinter (an opal- 
like hydrate of silica of a white colour), which ex- 
tended almost to the middle. This important fact 
attests the length of time during which chemical pro- 
cesses continue after eruptions, and how open fissures 
may be filled up laterally by mineral matter, sublimed 
from volcanic exhalations. The lavas of this eruption 
covered nearly a third of the whole island, often form- 
ing on slightly inclined planes great horizontal sheets 
several square leagues in area, resembling very much 
the basaltic plateaus of Auvergne. 

Pretended distinction between ancient and modern 
lavas. — One of the new lavas was observed to contain 
masses of olivine of an olive-green colour, resembling 
those which occur in one of the lavas of the Vivarais. 
Von Buch supposes the great crystals of olivine to 
have been derived from a previously existing basalt 
melted up by the new volcanos; but he gives no suf- 
ficient data to bear out such a conjecture. The older 
rocks of the island consist, in a great measure, of 
that kind of basaltic lava called dolerite, sometimes co- 
lumnar, and partly of common basalt and amygdaloid. 
Some recent lavas assumed, on entering the sea, a 
prismatic form, and so much resembled the older lavas 
of the Canaries, that the only geological distinction 
which Von Buch appears to have been able to draw 
between them was, that they did not alternate with 
conglomerates, like the ancient basalts. Some modern 
writers have endeavoured to discover, in the abundance 
of these conglomerates, a proof of the dissimilarity of 


Ch. XIIL] ANCIENT AND MODERN LAVAS, 143 


the voleanic action in ancient and modern times; 
but this character is more probably attributable to the 
difference between submarine operations and those on 
the land. All the blocks and imperfectly rounded 
fragments of lava, transported, during the intervals 
of eruption, by rivers and torrents, into the adjoining 
Sea, or torn by the continued action of the waves 
rom cliffs which are undermined, must accumulate in 
Stratified breccias and conglomerates, and, be covered 
"ain and again by other lavas. This is now taking 
Place on the shores of Sicily, between Catania and 
rezza, where the sea breaks down and covers the 
“tore with blocks and pebbles of the modern lavas of - 
tna; and on parts of the coast of Ischia, where 
“merous currents of trachyte are in like manner 
‘ndermined in lofty precipices. So often then as an 
‘Sland is raised in a volcanic archipelago by earth- 
quakes from the deep, the fundamental and (relatively 
to all above) the oldest lavas will often be distinguish- 

€ from those formed by subsequent eruptions on 

ty land, by their alternation with beds of sandstone 
te fragmentary rocks. 

he supposed want of identity then between the 

vo canic phenomena of different epochs resolves itself 
"nto the marked difference between the operations 
“thultaneously in progress, above and below the 
Waters, Such, indeed, is the source, as was before 
Psa the First Book (Chap. V.), of many of our 
“Ongest theoretical prejudices in geology. No sooner 
0 We Study and endeavour to explain submarine ap- 
Pearances, than we feel, to use a common expression, 
ut of our element ; and, unwilling to concede that our 
“Xtreme ignorance of processes now continually going 


144: ERUPTION OF. LANCEROTE, A. D. 1824. [Book 11- 


on can be the cause of our perplexity, we take refuge 
in a “ pre-existent order of nature.” 

Recent formation of oolitic travertin in Lancerote.— 
Throughout a considerable part of Lancerote, the old 
lavas are covered by a thin stratum of limestone, from 
an inch to two feet in thickness. It is of a hard sta 
lactitic nature, sometimes oolitic, like the Jura lime- 
stone, and contains fragménts of lava and terrestrial 
shells, chiefly helices and spiral bulimi. Von Buch 
imagines, that this remarkable superstratum has bee? 
produced by the furious north-west storms, which in 
winter drive the spray of the sea in clouds over the 
whole island; from whence calcareous particles may 
be deposited stalactitically.. If this explanation be 
correct, and it seems highly probable, the fact is inter- 
esting, as attesting the quantity of matter held in solu- 
tion by the sea-water, and ready to precipitate itself 
in the form of solid rock. At the bottom of such 4 
sea, impregnated, as in the neighbourhood of all activé 
volcanos, with mineral matter in solution, lavas must 
be converted into calcareous amygdaloids, a form 1” 
which the igneous rocks so frequently appear in the 
older European formations. I may mention that recent 
crevices in the rocks of Trezza, one of the Cyclopia® 
isles at the foot of Etna, are filled with a kind of tra- 
vertin, as high as the spray of the sea reaches ; and 
included in this hard veinstone I have seen fragments 
and even entire specimens, of recent shells, perhaps 
thrown up by the waves. 

- Recent eruption in Lancerote.— From the year 1736 
to 1815, when Von Buch visited Lancerote, there had 
been no eruption; but, in August, 1824, a crate 
opened near the port of Rescif, and formed, by its 


Ch. XIIL] SUBMARINE VOLCANOS. 145 


ejections, in the space of twenty-four hours, a consi- 
derable hill. Violent earthquakes preceded and accom- 
panied this eruption.* . 

Submarine volcanos.— Although we have every 
Teason to believe that volcanic eruptions as well as 
€arthquakes are common in the bed of the sea, it was 
Not to be expected that many opportunities would 
occur to scientific observers of witnessing the phe- 
nomena. The crews of vessels have sometimes 
reported that they have seen in different places sul- 
Phureous smoke, flame, jets of water, and steam, rising 
Up from the ‘sea, or they have observed the waters 
8reatly discoloured, and in a state of violent agitation 
as if boiling. New shoals have also been encountered, 
or a reef of rocks just emerging above the surface, 
Where previously there was always supposed to have 
been deep water. On some few occasions the gradual 
formation of an island by a submarine eruption has 
been observed, as that of Sabrina, in the year 1811, 
off St, Michael’s, in the Azores. The throwing up ot 
ashes in that case, and the formation of a cone about 
three hundred feet in height, with a crater in the 
Centre, closely resembled the phenomena usually ac- 
Companying a volcanic eruption on land. Sabrina was 
Soon washed away by the waves. Previous eruptions 
m the same part of the sea were recorded to have 
happened in 1691 and 1720. The rise of Nyée, also, 
a small island off the coast of Iceland, in 1783, has 
already been alluded to, and another volcanic isle was 


4 Férussac, Bulletin des Sci. Nat., tome v. p.45. 1825. 


he volcano was still burning when the account here cited was 
Written, 


VOL. 11. H 


nn 


a 


aoe 


pen 


146 GRAHAM ISLAND. [Book Il. 


produced by an eruption near Reikiavig, on the same 
coast, in June, 1830.* 

Graham Island+,1831.—We have still more recent 
and minute information respecting the appearance, i? 
1831, of a new volcanic island in the Mediterranean, 
between the S. W. coast of Sicily and that projecting 
part of the African coast where ancient Carthage 
stood. The site of the island was not any part of the 
great shoal, or bank, called “ Nerita,” as was first 
asserted, but a spot where Captain W. H. Smyth had 
found, in his survey a few years before, a depth of 
more than one hundred fathoms’ water. $ 

The position of the island (lat. 37° 8’ 30” N., long: 
12° 49’ 15” E.) was about thirty miles S. W. of Sci- 
acca in Sicily, and thirty-three miles N. E. of Pantel- 
laria.§ On the 28th of June, about a fortnight before 
the eruption was visible, Sir Pulteney Malcolm, in 
passing over the spot in his ship, felt the shocks of an 
earthquake, as if he had struck on a sand-bank ; and 
the same shocks were felt on the west coast of Sicily, 
in a direction from S.W. to N.E. About the 10th of 
July, John Corrao, the captain of a Sicilian vessel; 


* Journ. de Géol., tome i. 

+ In a former edition, I selected the name of Sciacca out of 
seven which had been proposed; but the Royal and Geographical 
Societies have now adopted Graham Island; a name given by 
Captain Senhouse, R. N., the first who succeeded in landing on it- 
The seven rival names are, Nerita, Ferdinanda, Hotham, Graham; 
Corrao, Sciacca, Julia. As the isle was visible for only about 
three months, this is an instance of a wanton multiplication of 


synonyms which has scarcely ever been outdone even in the annals 
of zoology and botany. i 
4 Phil. Trans. 1832, p. 255. 
§ Journ. of Roy. Geograph. Soc. 1830-31. 


A 


Ch. XIIL] GRAHAM ISLAND. 147 


reported that, as he passed near the place, he saw a 
Column of water like a water-spout, sixty feet high, 
and eight hundred yards in circumference, rising from 
the sea, and soon afterwards a dense steam in its 
Place, which ascended to the height of 1800 feet. 

he same Corrao, on his return from Gergenti, on the 
18th of July, found a small island, twelve feet high, 
With a crater in its centre, ejecting volcanic matter, 
and immense columns of vapour; the sea around 
being covered with floating cinders and dead fish. 

he scoriæ were of a chocolate colour, and the water 
Which boiled in the circular basin was of a dingy red. 
The eruption continued with great violence to the end 
of the same month; at shia time the island was 
Visited by several persons, and, among others, by 
Captain Swinburne, R. N., and M. Hoffmann, the 
Prussian geologist. It was then from fifty to ninety 


feet in height, and three quarters of a mile in circum- 
ference, By the 4th of August it became, according 


Fig. 27. 


LOD aA 


are o 


Form of the cliffs of Graham Island, as seen from S. S. E., distant one mile, 
Ith August, 1831. * 


to Some accounts, above 200 feet high, and three miles 
™ circumference; after which it began to diminish in 
Size by the action of the waves, and was only two 


* Phil. Trans. .» partii., 1832, reduced from drawings by Cap- 
tain Wodehouse, R. N. 


H 2 


148 GRAHAM ISLAND. ‘Book I. 


miles round on the 25th of August; and.on the 3d of 
September, when it was carefully examined by Captain 
Wodehouse, only three-fifths of a mile in circum- 
ference, its greatest height being then 107 feet. At 
this time the crater was about 780 feet in circum- 
ference. On the 29th of September, when it was 
visited by Mons. C. Prevost, its circumference was 
reduced to about seven hundred yards. It was com- 


View of the interior of Graham Island, 29th Sept. 1831. 
posed entirely of incoherent ejected matter, scoriæ, 
pumice, and lapilli, forming regular strata, some of 
which are described as having been parallel to the 
steep inward slope of the crater, while the rest were 
inclined outwards, like those of Vesuvius.* When 
the arrangement of the ejected materials has been 
determined by their falling continually on two steep 
slopes, that of the external cone and that of the crater; 
which is always a hollow inverted cone, a transverse 
section would probably resemble that given in the an- 


* See memoir by M. C. Prevost, Ann. des Sci. Nat., tom. xxiv 


GRAHAM ISLAND. 


Graham Island, 23th Sept. 1831. * 
nexed figure (30.). But when I visited Vesuvius, in 
1898, I saw no beds of scoriz inclined towards the 
Fig. 30. 


axis of the cone (see fig. 24. p. 87.). Such may have 
Once existed; but the explosions, or subsidences, or 
Whatever causes produced the great crater of 1822, 
had possibly destroyed them. 

Few of the pieces of stone thrown out from Graham 
sland exceeded.a foot in diameter. Some fragments 
of dolomitic limestone were intermixed; but these 
Were the only non-volcanic substances. During the 
Month of August, there occurred on the S. W. side 
of the new island a violent ebullition and agitation 
of the sea, accompanied by the constant ascension 
of a column of dense white steam, indicating the ex- 

* In the annexed sketch (fig. 29.), drawn by M. Joinville, 
Who accompanied M. C. Prevost, the beds seem to slope towards 
the centre of the crater; but I am informed by Mr. Prevost that 


these lines were not intended by the artist to represent the dip of 
the beds, 


H 3 


neon » 
pa Se a e AE 


150 GRAHAM ISLAND. [Book IÍ. 


istence of a second vent at no great depth from the 
surface. Towards the close of October, no vestige of 
the crater remained, and the island was nearly levelled 
with the surface of the ocean, with the exception, at 
one point, of a small monticule of sand and scoriæ. It 
was reported that, at the commencement of the year 
following (1832), there was a depth of 150 feet where 
the island had been: but this account was quite er- 
roneous ; for in the early part of that year Captain 
Swinburne found a shoal and discoloured water there, 
and towards the end of 1833 a dangerous reef existed; 
of an oval figure, about three-fifths of a mile in extent. 
In the centre was a black rock, of the diameter of 
about twenty-six fathoms, from nine to eleven feet 
under water; and round this rock are banks of black 
volcanic stones and loose sand. At the distance of sixty 
fathoms from this central mass, the depth increased 
rapidly. There was also a second shoal at the dis- 
tance of 450 feet S. W. of the great reef, with fifteen 
feet water over it, also composed of rock surrounded 
by deep sea. We can scarcely doubt that the rock 
in the middle of the larger reef is solid lava which 
rose up in the principal crater, and that the second 
shoal marks the site of the submarine eruption ob- 
served in August, 1831, to the S. W. of the island. 
From the whole of the facts above detailed, it ap- 
pears that a hill eight hundred feet or more in height 
was formed by a submarine volcanic vent, of which the 
upper part (only about two hundred feet high) emerged 
above the waters, so as to form an island. This cone 
must have been equal in size to one of the largest of 
the lateral volcanos on the flanks of Etna, and about 
half the height of the mountain Jorullo in Mexico, 
which was formed in the course of nine months, 1” 
1759. In the centre of the new volcano a large cavity 


Ch, XHI.] GRAHAM |ISLAND. 151 


Was kept open by gaseous discharges, which threw out 
Scoriz ; and fluid Java probably rose up in this cavity. 
It is not uncommon for small subsidiary craters to open 
Near the summit of a cone, and one of these may have 
been formed in the case of Graham Island; a vent, 
Perhaps, connected with the main channel of discharge 
Which gave passage in that direction’ to elastic fluids, 
Scoriz, and melted lava. It does not appear that, 
either from this duct, or from the principal vent, there 
Was any overflowing of lava; but melted rock may 
have flowed from the flanks or base of the cone (a 
common occurrence on land), and may have spread in 
a broad sheet over the bottom of the sea. 
` Fig. 31. 


Si) LZ 
BW 
LY ABW NG 
The dotted lines in the annexed figure are an imagi- 
nary restoration of the upper part of the cone, now 
"emoved by the waves: the strong lines represent the 
Part of the volcano which is still under water. In the 
Centre is a great column, or dike, of solid lava, two 
hundred feet in diameter, supposed to fill the space by 
Which the gaseous fluids rose ; and on each side of the 
ike is a stratified mass of scoriz and fragmentary lava. 
he solid nucleus of the reef where the black rock is 
now found withstands the movements of the sea; 
While the surrounding loose tuffs are cut away to a 
Somewhat lower level. In this manner the lava, which 
Was the lowest part of the island, or to speak more 
Correctly, which scarcely ever rose above the level of 
H 4 


152 THEORY OF ELEVATION CRATERS. [Book II. 


the sea when the island existed, has now become the 
highest point in the reef. 

No appearances observed, either during the eruption 
or since the island disappeared, give the least support 
to the opinion promulgated by some writers, that part 
of the ancient bed of the sea had been lifted up bodily’ 

The solid products, says Dr. John Davy, whether 
they consisted of sand, light cinders, or vesicular lava, 
differed more in form than in composition. The lava 
contained augite ; and the specific gravity was 2-07 and 
2°70. When the light spongy cinder, which floated on 
the sea, was reduced to fine powder by trituration, and 
the greater part of the entangled air got rid of, it was 
found to be of the specific gravity 2°64; and that of 
some of the sand which fell in the eruption was 2°75 *? 
so that the materials equalled ordinary granites in 
weight and solidity. The only gas evolved in any 


considerable quantity was carbonic acid.+ 

Theory of Elevation Craters. { — Before quitting the 
subject of submarine volcanos, it will be necessary to 
say something of an opinion which has been promul- 
gated by Leopold Von Buch, respecting what he has 


* Phil. Trans. 1832, p. 243. t Ibid. p. 249. 

¢ The view which I now give of the theory of elevation craters; 
although more full; is substantially the same which I published i” 
the first edition, printed in 1829, after I had examined Vesuvius 
and Etna, and compared them with the Mont Dor and the Plomb 
du Cantal. The late Professor Hoffmann of Berlin set out on his 
travels through Italy and Sicily in 1829, with a strong expectatio® 
of finding every where the clearest illustrations of the « Erbe 
bungscratere ; °” but when he had explored the Lake Albano, nea! 
Rome, as well as Vesuvius, Etna, Stromboli, and the other Lipari 
Islands, he was compelled reluctantly to abandon the doctrine 
(Bulletin de la Soc. Géol. de France, tom. iii. p.170.). A” 
examination of the same countries led M. C. Prevost, as it ha 
done Mr. Scrope and myself, to similar conclusions. 


Ch XIIL] THEORY OF ELEVATION CRATERS. 153 


termed elevation craters (Erhebungscratere). He has 
attempted to explain, by a novel hypothesis, the origin 
of certain large cavities, and the peculiar conical dis- 
Position of the masses of volcanic matter which sur- 
Tound them. 

According to this view such cones as the ancient 
Vesuvius (or Somma), and the greater part even of the 
modern Vesuvius, as well as the nucleus of Etna, and 
Many other mountains of similar form, have not derived 
the actual arrangement of their materials from suc- 
Cessive eruptions as above described (p. 80.); but 
their mode of origin is thus explained: Beds of pumice, 
breccia, trachyte, basalt, scoriz, and other substances 
Were first accumulated in a horizontal position, and 
then lifted up by the force of pent-up vapours, which 
burst open a cavity in the middle of the upraised mass. 
By this elevation the beds were so tilted as to dip out- 
Wards, in every direction from the central cavity or 
crater, at various angles of between 12 and 35 degrees. 
In this way, says Von Buch, Monte Nuovo itself ori- 
ginated, being formed of the same marine pumiceous 
tuff which occurs at Posilippo and the country round 
Naples. He supposes that, previously to 1538, this 
tuf stretched uninterruptedly to the site of Monte 
Nuovo in nearly horizontal beds, until, at that period, 
it was upheaved and made to constitute a hill more 
than 400 feet in height, with a crater of nearly equal 
depth in the centre. In the unbroken walls surround- 
ing the crater appear the upper ends of the beds of 
tuff, which are there seen to be inclined every where 
from within outwards.* 

Before the publication of these opinions it had always 
been inferred, from the accounts of eye-witnesses, that 
* Poggendorf’s Annalen, 1836, p. 181. 

a 5 


» 


154 THEORY OF ELEVATION CRATERS. [Book IL 


Monte Nuovo was produced, in 1538, in the same 
manner as Graham Island in 1831. Those who beheld 
the eruption relate that a gulf opened on the site of 
the small town of Tripergola, near Puzzuoli, close 
to the sea, from which jets of mud, mingled with 
pumice and stones, were vomited for a day and a night. 
These substances, falling down on all sides of the vent, 
caused a conical hill, on which several petsons as- 
cended a few days after the eruption, and found a deep 
funnel-shaped crater on the summit. (See p. 72. and 
fig. 22. of Monte Nuovo.) There is no difficulty in 
conceiving that the pumiceous mud, if so thrown out, 
may have set intoa kind of stone on drying, just as 
some cements, composed of volcanic ashes, are known 
to consolidate with facility. 

One of the first objections which naturally suggest 
themselves to the notion of a cone like Monte Nuovo 
being the effect of the sudden uplifting of horizontal 
beds of rock, has been well stated by Mons. C. Prevost, 
who remarks, that if beds of solid and non-elastic ma- 
terials had yielded to a violent pressure directed from 
below upwards, we should find not simply a deep empty 
cavity, but an irregular opening where many rents 

Fig. 32.0 converged, and these rents 
would be seen to break 
through the walls of the 
crater. They would also be 

> widest at top and diminish 

downwards. (See fig. 32. 

a,b.)* But not a single 

fissure of this kind is ob- 

servable in the interior of Monte Nuovo, where the 
walls of the crater are quite continuous and entire. 


* Mém. dela Soc. Géol. de France, tom. ii. p. 91. 


Ch. XIIL] ISLE OF PALMA. 155 


Isle of Palma.— As the theory of elevation 
craters was first invented for the Canary Islands, it will 
be desirable to give them our first consideration ; and 
when treating of this subject we must not forget how 
much we are indebted to the talents and zeal of Leopold 
Von Buch for his faithful description of these islands, 
as well as for his numerous other works on Geology. 

Nearly in the centre of Palma is an 
immense circular cavity, called the 
Caldera or basin, which forms the hollow 
axis of the entire island. A lofty 
Mountain ridge runs round this axis, 
and presents in all directions, towards 
the Caldera, a perpendicular precipice 
of no less than four thousand feet in le of Laima. 
height, while on the outside the slope is gentle towards 


Fig. 34, 


View of the Isle of Palma, and of the Caldera in its centre. 


the sea. The middle of the Caldera is more than two - 
thousand feet above the level of the ocean; the sur- 
rounding borders (“ cumbre,” or “crest” in Spanish, ) 
are of various heights, attaining at one point an eleva- 
tion of 7234 feet. The diameter of the Caldera is about 
six miles; and so steep are the cliffs by which it is 
environed, that there is not a single pathway down the 
rocks; and the only entrance is by the ravine, or 
H 6 


{ 
Í 
{ 
i i 
| 
i | 
| j 
i VE I 
ig i 
i fi 
i 
E | 
i - 
| 
| Í 
1 
4 ' 
pi 
EEN 
ts 
a l! 
k i 
Bpi 
i et 
mi |) 
wii 
Si 
We bib: 
ti 
i f 
nF 
| 
i 1 
aii 
| 
k ii 
l F 
i ail 
|i lait 
i | 
Bi 


ta 
} 


j 
i 
f 


156 ISLE OF PALMA. [Book 1I. 


« baranco,” which runs from the great circus down to 
the sea, intersecting all the rocks of which the island 
is composed. In this section are exposed strata of tuff, 
alternating with beds of basalt; and below are con- 
glomerates, composed of fragments of granite, quartz, 
syenite, and other crystalline rocks, some of which 
appear in one place in situ. Volcanic dikes, or veins, 
are seen cutting through all these formations in the 
precipice on each side of the baranco, and these in- 
crease in number as we pass up the gorge, and approach 
nearer to the Caldera. The veins often cross one 
another, and at length form a perfect net-work. In the 
cliffs encircling the Caldera itself are various volcanic 
rocks, traversed by basaltic dikes, most of which are 
perpendicular, and appear to hold together the more 
incoherent masses through which they cut. The sloping 
sides of the island, which has much the appearance of a 
flattened and hollow cone, are furrowed by numerous 
minor ravines, in which beds of red and yellow scorie 
are exposed to view. The ravines are deep near the 
sea, but they terminate before reaching the Caldera. 
From this description I find it impossible to draw 
any other inference than that we have here the re- 
mains of a great volcanic mountain, formed by suc- 
cessive eruptions,.the first of which burst through 
granitic rocks. A great cone having, in the course of 
ages, been built up, the higher parts of it were after- 
wards destroyed, and the central crater enlarged by 
gaseous explosions; at the same time that a falling in, 
or engulphment, of large masses may have taken place, 
But, according to the theory of “ elevation craters,” ve 
are called upon to suppose, that a series of horizontal 
beds of volcanic matter were first accumulated over 
each other, to the enormous depth of more than four 


Ch, XIIL] THEORY OF ELEVATION CRATERS. 157 


thousand feet, after which the expansive force was 
directed on a given point with such extraordinary 
energy, as to lift up bodily the whole mass, so that it 
tose in some parts to the height of seven thousand feet 
above the sea, while a great void or cavity was formed 
M the middle. Yet, notwithstanding this prodigious 
effort of gaseous explosions, concentrated on so small 
à point, the beds, instead of being shattered, contorted, 
and thrown into the utmost disorder, have acquired that 
Tegular and symmetrical arrangement which charac- 
terizes the flanks of the large cone of Etna! Earth- 
quakes, when they act on extensive tracts of country, 
May certainly elevate and depress them without de- 
tanging considerably the relative position of hills, val- 
€ys, and ravines. But if the aeriform fluids should 
break through a mere point, as it were, of the earth’s 
Crust, and that, too, where the beds were not com- 
Posed of soft yielding clay, or incoherent sand, but 
M great part of solid trachyte and basalt, thousands 
of feet thick, is it possible to conceive that such 
Masses of rock could be heaved up, so as to attain the 
eight of seven thousand feet, or more, without being 
fissured and fractured in every direction ? 

But there is another difficulty which the advocates 
of « elevation craters” appear to have overlooked. 
Numerous dikes or veins of igneous rock are observed 
m the walls of the craters of Palma, Somma, Strom- 

oli, and other volcanic masses. It is agreed on all 
ands that such dikes were once fissures, at first empty 
and afterwards filled up with melted matter. It must 
also be conceded that the fluid was introduced at dif- 
ferent periods, for after the cooling and consolidation 
of Some dikes, new rents have occasionally been made 
nto which other lavas have entered and solidified. 


158 GREAT CANARY. [Book It. 


Now these phenomena imply the successive rise of 
lava from the interior towards the surface, precisely 
in the region where the height of the volcanic moun- 
tain is greatest, and where, in perfect accordance 
with the eruption theory, the quantity of igneous rock 
and tuff are in excess. It cannot be said in reply: 
that the dikes were all produced at once during the 
upheaving of the mass, or, in other words, that fissures 
were both caused and filled at the moment when the 
uplifting force was exerted, and when the cone and 
crater were formed; for.had this been the case, there 
would have been a large quantity of melted matter 
ready to flow down into the crater, which would then 
have been partially choked up, at the same time that 
the fissures would have been left partially empty. 
Great Canary.— The form of the Great Canary is 
very analogous to that of Palma, there being here also 
a caldera and a principal ravine leading out of it, on 
the south side. The rocks are tuff, conglomerate, 
basalt, and trachyte. In.some of the borders of the 
island are marls and conglomerates containing recent 
marine shells, from three to four hundred feet above 
the level of the sea, and presenting an appearance’ 
says Von Buch, as if the level of the ocean had sub- 
sided at successive periods. These are doubtless the 
effects. of elevation, and at the base of Etna marine 
strata are in like manner discoverable ; but their occut- 
rence does not prove an upheaving of that kind from 
which cones and craters would result. It is also stated 
that between masses of basalt in the Great Canary * 
marine shells have been found, 500 or 600 feet abov® 
the sea, all of which is what we should now expect t° 


* See Berthelot and Webb, cited by De Beaumont, Descrip: 
Géol. de la France, tom. iii. p. 254. 


Ch, XIIL] THEORY OF ELEVATION CRATERS. 159 


arise on the flanks of Stromboli. For a great number 
of alternating beds of lava, and deposits containing 
Shells mixed with volcanic sand and scoriz, may have 
*ecumulated on the flanks of that half-submerged cone, 
ad may, one day, be raised up in the same manner 
38 continents and islands have risen from the deep. 
Teneriffe. —The Peak of Teneriffe rises out of a 
valley surrounded by precipitous cliffs, which vary in 
height from 1000 to 1800 feet, and which are given as 
an exemplification of the “ Erhebungscratere.” The 
“eak stands, says Von Buch, like a tower encircled by 
‘ts fosse and bastion. The volcanic rocks resemble, in 
Seneral, those found in the other Canary Islands. 
Barren Island.—Barren Island, in the Bay of Ben- 
gal, is also proposed as a striking illustration of the 
thebungscratere ; and here, it is said, we have the 


Advantage of being able to contrast the ancient crater 
of elevation with a cone and crater of eruption in its 


entre. When seen from. the ocean, this island pre- 


‘ents, on almost all sides, a surface of bare rocks, 

rising, with a moderate acclivity, towards the interior ; 

ùt at one point there is a cleft, by which we can 

Penetrate into the centre, and there discover that it is. 

*ecupied by a great circular basin, filled by the waters 
Fig. 35. 


160 THEORY OF ELEVATION CRATERS. [Book 1. 


of the sea, and bordered all around by steep rock® 
in the midst of which rises a volcanic cone, very 
frequently in eruption. The summit of this cone 15 
1690 French feet in height, corresponding to that of 
the circular border which incloses the basin; so that 
it can be seen from the sea only through the ravines 
which precisely resembles the deep gorge of thé 
caldera of the Isle of Palma, and of: which an equ 
valent, more or less decided in its characters, is sai 

to occur in all elevation craters. It is most probable 
that the exterior inclosure of Barren Island, c, d, 
(Fig. 36.) is nothing more than the remains of a tru?” 
cated cone, ¢, a, b, d, a great portion of which has bee? 
carried away, partly by the action of the waves, and 
partly by explosions which preceded the formation 0 
the new interior cone, f, e, g. 


Supposed section of Barren Island, in the Bay of Bengal. 


Santorin.— We may next consider the island of 
Santorin, in the Grecian Archipelago, as its structu? 
has been frequently appealed to by both parties dur 
ing the controversy now under consideration. 

The three islands of Santorin, Therasia, and Asp? 
nisi surround an almost circular gulf of about tW° 
leagues in diameter from south to north, and a leagu? 
and a half from east to west. The island of Santor? 
itself forms more than two thirds of the circuit, and ¥ 
composed entirely of volcanic matter, with the excep" 
tion of its southern part, which rises to three times the 


Ch. XIIL] ‘  SANTORIN. 161 


height of the igneous rocks in the island, and is formed 
of granular limestone and argillaceous schist.* This 
Mountainous part is the original and fundamental nu- 
cleus of the isle ; and, according to M. Bory de St. Vin- 
cent, its strata have the same direction as those of the 
other isles of the Grecian archipelago, from N.N.W. 
to S.S.E. Their inclination and fractures have no 
relation to the position of the newer volcanic rocks, of 


Fig. 37. 


Autom ate 


prf )r isi 


y llli . 
i ; Li Santor’ 
Micra Kameni EER an autorin 
j Ny 
LZ. 


La ay 
“i Ly 


4 Z y 
p, T LOLU 


which the remainder of the group of islands is exclu- 
sively composed. The volcanic mass, which must be 


* Virlet, Bull. de la Soc. Géol. de France, tom. iii. p. 103. 


162 THEORY OF ELEVATION CRATERS. [Book II. 


considered as quite an independent formation, consists 
of alternating beds of trachytic lava, tuff, and conglo- 
merate, which dip on every side from the centre of 
the gulf to the circumference. Towards the gulf they 
present uniformly a high and steep escarpment, the 
precipices in Santorin rising to the height of more than 
eight hundred feet, and plunging at once into a sea 
from eight hundred to a thousand feet deep. Each of 
the islands is capped by an enormous mass of white 
tufaceous conglomerate, from forty to fifty feet in thick- 
ness; which is not pumice, as has often been stated- 
The beds of lava and tuff, above mentioned, are accu- 
mulated in great numbers one upon another, and of 
unequal thickness: although disposed with great regu- 
larity, when viewed as a whole, they are found to be 
discontinuous, as in Vesuvius, when any particular mass 
is traced to some distance. 

Before discussing the merits of the theory proposed 
to account for the structure of this volcanic group, it 
will be desirable to give a brief sketch of its history, s0 
far‘as it is known. Pliny relates that the separation 
of Therasia from Thera, or Santorin, took place after 2 
violent earthquake, in the year 233 before the Christian 
era. From his work, and other authorities, we also 
learn that the year 196 8.c. gave birth, in the middle of 
the gulf, to Hiera, or the Sacred Isle, still called Hiera- 
Nisos, or sometimes Palaia Kameni (Old Burnt Island). 
There seems to have been no eruption then, but simply 
an upheaving of solidlava. In the year 19 of our era 
Thia (the Divine) made its appearance above the sur- 
face of the waters. This small island has no longer 4 
separate existence, having been joined to Hiera, from 
which it was only 250 paces distant : Hiera itself in- 
creased in size in 726 and in 1427. In 1573, the small 


Ch. XIIL] ISLAND OF SANTORIN. 163 


island of Micra-Kameni appeared, a small cone and 
crater, one hundred feet high, raised by successive 
ejections. 

f On the 27th of September, 1650, there was an erup- 
tion three or four miles north of Santorin, altogether 
Outside of the gulf, immediately after violent earth- 
quakes, It gave rise to no new islet, but greatly 
elevated the bottom of the sea on the spot. The 
ruption lasted three months ; many houses on San- 
torin were destroyed ; and the vapours of sulphur and 
hydrogen killed more than fifty persons, and more than 
One thousand domesticated animals. A wave fifty feet 
high broke upon the rocks of the Isle of Nio, about 
four leagues distant, and advanced 350 yards into the 
Interior of the island of Sikino, which is seven leagues 
of. The sea also broke upon Santorin, overthrew two 
Churches, and exposed to view a village on each side 
of the mountain of St. Stephen, both of which must 
have been overwhelmed by showers of volcanic matter 
during some former eruption.* 

Lastly, in 1707 and 1709, Nea Kameni was pro- 
duced between Palaia and Micra (old and lesser) Ka- 
Menis. This isle was composed originally of two dis- 
tinct parts, the first which rose was called the White 
Island — a mass of pumice, extremely porous. Goree 
the Jesuit, who was then in Santorin, says that the 
rock « cut like bread,” and that, when the inhabitants 
landed on it, they found a multitude of full-grown 
fresh oysters adhering to it, which they eat.+ This 
island was afterwards covered, in great part, by the 
Matter ejected from the crater of the second island, 
Produced at the same time, called “ Black Island,” be- 


* Virlet, Bull. de la Soc. Géol. de France, tom. iii. p. 103. 
: t Phil. Trans., No. 332. 


164 THEORY OF ELEVATION CRATERS. [Book II. 


ing composed partly of brown trachyte. This volcano, 
now named Nea (or New) Kameni, continued in erup- 
tion, at intervals, during 1711 and 1712, and formed 2 
cone 330 feet above the level of the sea: there are 
now, therefore, two channels of direct communication 
between the atmosphere and volcanic foci beneath the 
group of Santorin ; namely, the craters of New and 
Little Kameni. . 
A curious fact is mentioned by M. Virlet, respecting 
the supposed slow and progressive rise of a solid ridge 
at. the bottom of the sea. Twenty years ago there 
was a depth of fifteen fathom water between the lesse! 
Kameni and the port of Phira in Santorin. In 1830, 
when MM. Virlet and Bory visited the spot, there 
was only a depth of between three and four fathoms; 
and they found that the bottom consisted of a hard 
rock, probably trachyte, measuring about eight hun- 
dred yards from E. to W. and five hundred only from 
N. to S. Beyond this the sea deepens rapidly on all 
sides. From these facts, and from information obtained 
on the spot, M. Virlet infers that the bed of the sea is 
rising gradually, and that, in all probability, a new 
island may one day appear without commotion above 
the surface. He suggests that the solid crust of rock 
now slowly rising may resemble a.cork carried up by 
the fermentation of the liquor on which it floats.* 
After the explanation before offered} of the mode 
in which the semicircular escarpment of Somma ori- 
ginated, it is almost needless to say that I regard the 
three islands which encircle the gulf of Santorin a5 
nothing more than the ruins of a great volcanic cone 
the summit of which, like that of the ancient Vesuvius, 


* See M. Virlet’s Memoir, before cited. 
t Above, p. 87. 


Ch. XIIL] THEORY OF ELEVATION CRATERS. — 165 


or of Barren Island, has been destroyed ; and as to 
the small volcanic islets thrown up since the historical 
fra, in the centre of the gulf, they may be compared 
to the modern cone, or rather cones, of Vesuvius. 
Von Buch supposes that a solid dome of trachyte is 
now rising in the centre of the bay, and that the ex- 
Pansive force from below will, one day, burst an open- 
‘ng, and cause the uplifted rocks to dip on all sides 
om within outwards.* It would be an unprofitable 
task to speculate on the mode in which the water may 
ow be shoaling in the centre of the gulf of Santorin, 
r on the possible forms which the uplifted mass may 
assume, Undoubtedly the porous mass of white 
Pumice upheaved in 1707 (see p. 163.) implies the 
Partial elevation of solid matter, and may be compared 
Perhaps to the solid crust of scoria, which is often 
Capable of supporting heavy weights on the surface of 
ava currents still in motion. Such data are far too 
Scanty and obscure to form a solid foundation for the 
i ĉory now under discussion. 
- It is naturally objected by M. Virlet, that if a mass 
ike Santorin, which, including its submarine founda- 
tions, must be from 1700 to 2000 feet in thickness, 
Was suddenly and violently heaved up from a horizontal 
Position, we might expect to find the rocks traversed 
Sery where with rents which would diverge from the 
Principal centre of movement to the circumference of 
€ circular area. But these rents are wanting, as are 
l signs of the shattering and dislocation of the mass. 
t the same time he adduces a fact which must surely 
Prove conclusive against the notion of the island’s 
aving been formed in any other mode than that by 
which an ordinary cone is accumulated. In examining 


* Poggendorf’s Annalen, 1836, p. 183. 


166 THEORY OF ELEVATION CRATERS. [Book 1. 


the various currents of lava (the existence of which 
was unknown to Von Buch, who had not visited San- 
torin), it was found that the vesicles, or pores which 
abound in them, are lengthened in the several dires- 
tions in which they would naturally be drawn out, if 
the melted matter had flowed towards different point 
of the compass from the summit of a conical mountain, 
of which the present islands were the base. The force 
of this argument will be appreciated by those who arë 
aware that bubbles of confined gas in a fluid in motio” 
assume an oval form, and that the direction of the 
longer axis coincides always with that of the stream 
It is also observed by M. Virlet, that the deep stratu™ 
of white tufaceous conglomerate by which all thé 
islands are uniformly covered, may well be supposed 
to have resulted from heavy showers of ejected matte! 
which fell during that paroxysmal explosion by which 
the great cone was originally blown up, truncated, and 
emptied in its interior. 

The manner in which the external walls were sep?” 
rated into three distinct islands is easily conceived: 
The principal breaches are to the N. W., the quarte" 
most exposed to the waves and currents. On this 
side, the earthquake of 233 B.c., mentioned by Pliny» 
may have caused a fissure, which allowed the wave 
and currents to penetrate and sweep away the inc0- 
herent tuffs and conglomerates, just as they washed 
away Graham Island; and if there happened to bê 
little or no lava at certain points, the waves would ip 
such places readily force a passage.* 

The dimensions of the Gulf of Santorin, or the Cal 
dera of the Isle of Palma, are not greater than we may 


s 


* Virlet, ibid. 


Ch. XIIL] TRUNCATION OF VOLCANIC CONES. ' 167 


Suppose to result from the truncation and evacua- 
tion of ordinary volcanic cones. We shall afterwards 
See that Papandayang, formerly one of the loftiest 
volcanos in Java, lost, in 1772, about four thousand 
feet of its‘ former height.* During an eruption in 
M444, accompanied by a tremendous earthquake, the 
Summit of Etna was destroyed, and an enormous 
“tater was left, from which lava flowed. The segment 
of that crater may still be seen near the Casa Inglese, 
and, when complete, it must have measured several 
Miles in diameter. The cone was afterwards re- 
Paired; but this might not so easily have happened, 
ad the summit of Etna, like Stromboli or Santorin, 
ĉen placed in a deep sea; for in that case the vent 
might have become choked up with strata of sand and 
“Onglomerate, swept in by waves and currents; and 

ese obstructions, by augmenting the repressive force, 
Would have increased the violence of subsequent ex- 
Plosions. There is, unquestionably, a much greater 
Probability when the volcanic vent communicates with 
“atmosphere that a channel will be kept open by 
astic fluids, whereby currents of lava may escape 
Without resistance, and without causing any violent 
Commotion. Let us suppose the large Etnean crater 
of 1444. to have been choked up, and again truncated 
°wn to the upper margin of the woody region; a 
“tcular basin would thus have been formed, thirty 
talian miles in circumference, exceeding by five or 
SX miles the circuit of the Gulf of Santorin, Yet 
© know, by numerous sections, that the strata of 
trachyte, basalt, and trachytic breccia, would, in that 
Part of the great cone of Etna, dip on all sides off 


* See chap. xvi. 


168 THEORY OF ELEVATION CRATERS. [Book 11. 


from the centre, at a gentle angle, to every point of 
the compass, except where irregularities were occa- 
sioned, at certain points, by the occurrence of the 
small buried cones before mentioned. If this gulf 
were, then, again choked up, and the vent obstructed 
so that new explosions of great violence should trun- 
cate the cone once more down to the inferior borde 
of the forest zone of Etna, the circumference of the 
gulf would be fifty Italian miles.* Yet even then the 
ruins of the cone of Etna might form a circular island, 
entirely composed of volcanic rocks, sloping gently 
outwards on all sides, at a very slight angle ; and this 
island might be between seventy and eighty English 
miles in its exterior circuit, rivalling Palma in fertility ' 
while the circular bay within might be between forty 
and fifty miles round. 

If a difference in size alone were a sufficient reas” 
for seeking a difference in origin, we should then b° 
called upon to refer the innermost cone of Vesuvius 
thrown up in 1828, to a mode of action distinct from 
that by which the larger cone of the year 79 was 
formed; and the shape and structure of this, again 
might be attributed to a series of operations distinct 
from those to which the outermost cone and escatP" 
ment of Somma were due. It is extraordinary thal 
after the identity of the form and structure of Vest” 
vius and Somma had been so clearly demonstrated by 
M. Necker +, one of these cones should actually havé 
been considered by some of the followers of Von Bu? 


* For the measurements of different parts of the cone of Eto 
see Trattato dei Boschi del’ Etna, Scuderi, Acti dell’ Acad. GIO” 
de Catan., vol. i. 

+ Mémoire sur le Mont Somma, Mém. de la Soc. de Phys: o 
d’Hist. Nat. de Généve, tom. ii. parti, p. 155. 


Ch. XIIL] THEORY OF ELEVATION CRATERS. 169 


as an “ erhebungscratere,” and the other as a cone of 
eruption. (See fig. 24. p. 87.) 

Had there been any foundation for the theory, that 
Violent explosions of gas could exert the power of 
raising up horizontal strata symmetrically round a cen- 
tral cavity, numerous examples would, ere this, have 
been adduced of strata other than volcanic elevated in 
this way round some active volcano. But where do we 
find an instance of inner cones with craters like those 
of Vesuvius, Santorin, Barren Island, and others, en- 
circled by precipices of rocks exclusively of lacu8trine 
or marine origin, and in which the strata have the 
quaqua-versal dip, characteristic of all cones of erup- 
tion? If such could be pointed out, we might un- 
doubtedly be forced to concede, that the cone and 
Crater-like configuration may be the result of two dis- 
tinct modes of formation. It is not pretended that, on 
the whole face of the globe, a single example of this 
kind can be pointed out. Are we then called upon to 
believe that, whenever elastic fluids generated in the 
Subterranean regions burst through horizontal strata, 
So as to upheave them in the peculiar manner before 
adverted to, they always select, as if from choice, those 
Spots of comparatively insignificant area where a cer- 
tain quantity of volcanic matter happens to lie; while 
they carefully avoid purely lacustrine and marine 
Strata, although they often lie immediately contigu- 
Sus? Why, on the southern borders of the Limagne 
d'Auvergne, where several eruptions burst through, 
and elevated the horizontal marls and limestones, did 
these fresh-water beds never acquire, in any instance, 
à conical and crateriform disposition? We have no 
lesitation, therefore, in adhering to the opinion, that all 
the central cavities of the volcanic mountains alluded 

VOL. IT: I 


I er 


170 THEORY OF ELEVATION: CRATERS. [Book II. 


to by Von Buch, are simply craters of paroxysmal 
explosion, as they have been very properly termed 
by Mr. Scrope. This class of craters, or cup-shaped 
hollows, have usually been formed where the earth's 
crust happened to be composed of volcanic matters 
but not always. Elastic fluids have sometimes burst 
through rents in other rocks, and have shattered them 
for a certain space, and blown their contents into the 
air. Thus in the volcanic region of the Eifel, explo- 
sions, sometimes unaccompanied by the emission of 
lava; have excavated craters in strata of sandstone and 
shale; but they have not raised the strata all round 
the central cavity. The distinctness of these pheno- 
mena from those appealed to in corroboration of the 
« erhebungscratere” will be pointed out in the fourth 
book.* 

An attempt has been made to adduce the ancient 
volcanos of Central France, the Mont Dor, and thé 
Plomb du Cantal, as illustrations of elevation craters 
but it has been found necessary to resort to a very 
complicated hypothesis in order to reconcile their for™ 
and structure to the conditions required by the eleva- 
tion theory. M. Prevost had remarked that the thick- 
ness of volcanic matter is much more considerable in 
the centre of these masses than at their circumferenc® 
for at the centre there are sections several hundred 
yards deep of trachyte and tufaceous breccias, while 
round the borders there are only thin deposits of tu 
and basalt covering the fundamental rocks, which 12 
the case of the Mont Dor are granite, in the Cantal 
tertiary marl and limestone, and granitic schist.+ Thes? 
fundamental rocks are themselves quite exposed at the 


* See Index, « Eifel.” 
+ Mém, de la Soc. Géol. de France, tom. ii. p. 91. 


Ch, XIIL] THEORY OF ELEVATION CRATERS. 171 


Surface, as at æ (fig. 38.), as soon as we recede from the 
borders of the volcanic region. We cannot, therefore, 


C e 


admit the actual configuration of Mont Dor and the 
Cantal to have been the effect of a violent upheaval of 
Volcanic materials, previously horizontal, unless we are 
prepared to suppose that these materials first filled 
deep basins or hollows of anearly circular form, of 
Which a, d, ¢ (fig. 39.) may be taken as a section, and 


HEF OER 
7 i hy 
oN eqns E 


afterwards the elevating force must have been applied 
Precisely at the point where the thickness of igneous 
Tock was greatest, or at d, and with such energy as 
to invert the original position of the cone, and to cause 
the mass to occupy the space. a, b, c, instead of a, d, e. 
These consequences were proposed as fatal objec- 
tions; but ‘Monsieur Elie de Beaumont, while fully 
admitting them, denies that they invalidate Von Buch’s 
theory, He assumes that in Auvergne, Cantal, and 
Velay, deep depressions did actually exist just in the 
‘Pots where the three volcanic mountains of Mont Dor, 
antal, and Mezen now rise. Eruptions took place at 
Scattered points near the margin or on the sides of these 
depressions, so. that trachyte, basalt, pumice, and 
SCorize were emitted from different vents. The fused 
Materials flowed down, and the ejected fragments and 
12 


ee 


SS ee ee eee 


172 THEORY OF ELEVATION CRATERS. [Book II. 


scoriz were washed by the rains, so as to accumulate 
in greatest thickness towards the central or deepest 
part of each basin. In this manner the conical or len- 
ticular forms of the future volcanic mountains were first 
cast as it were in a mould, sunk in granitic or tertiary 
rocks, until the time arrived when the gaseous power 
was so directed against the volcanic accumulations, 
that they were rent and thrust up, and made to present 
a convexity upwards instead of downwards. During 
this upheaval the beds acquired their actual dip on 
every side away from the principal point of elevation. 
It is not stated whether the concavity a, d, e (fig. 39.), 
which must have been occasioned by the uplifting of 
the igneous rocks, and their removal to a, b, c, remains 
at present an empty space, or whether the space has 
since been occupied by other matter, and if so, by what. 
Nor is any reason assigned why in every instance the 
lowest point of each basin, whether composed of granite 
or other rock, should happen to be the point of 
maximum elevation during a subsequent process of 
subterranean expansion. We might, perhaps, believe 
in one fortuitous coincidence of this kind, and grant 
that the deepest part of a pre-existing basin happened 
to be the point of least resistance in the whole neigh- 
bourhood, or might even imagine that it remained s0 
after it was loaded by the weight of a thousand feet oF 
more of solid basalt and breccia. But how can wé 
suppose that in several, nay, in hundreds of cases, the 
gaseous explosion should break forth precisely where 
some original depression was deepest, and where the 
surface was afterwards loaded with the greatest mas® 
of volcanic matter ? 

In cones and craters which we have seen produced; 
or which have been augmented in size by eruptions ° 


Ch, XIIL] THEORY OF ELEVATION CRATERS. 173 


lava and scoriæ, we know that the largest and heaviest 
fragments fall nearest to the principal vent, and that 
this is one cause of the conical form of the heap. We 
know also that lava currents are often insufficient in 
volume or fluidity to extend far from the point 
where they issue, and hence many currents stop short 
before approaching the circumference of a large cone. 
' This is another obvious cause of the peculiar shape 
of volcanic mountains, and the inclined position of 
their component beds of rock. In direct defiance of 
Such striking analogy, we are told that we must look 
for the point of eruption, not where lava and scoriæ are 
Now accumulated in the greatest abundance, but any- 
where and everywhere rather than at that point ! 

It has been said that the sheets of trachyte and ba- 
Salt on the Mont Dor and Cantal are too bread and too 
thick to have congealed on a slope which formed an 
angle of more than three degrees with the horizon, and 
that these ancient igneous rocks are more compact and 
less cellular than modern lava, and that the bubbles of 
gas inclosed in them would have been drawn out into 
more lengthened forms if they had flowed down an in- 
clined plane steeper than that above alluded to. It is also 
affirmed that modern lava streams, when they run down 
the sides of a cone, form only a narrow stream or 
thread of melted matter. In reply I may observe, that 
the number of accurate observations on the effects of 
modern eruptions is too scanty to enable a geologist to 
insist on such points of discordance, although we know 
enough to show that some of them have been exagge- 
rated, We learn from Mr. Abich, who witnessed the 
eruption of Vesuvius in 1833 and 1834, that lava con- 
Solidated on a very steep slope, and ‘that the beds 
flowing one over another preserved their parallelism 

I 3 


RE OES HT ee 


174 THEORY OF ELEVATION CRATERS. [Book If. 


from top to bottom of the cone, without any visible 
difference of thickness. He denies that they evinced 
any tendency to run off the cone, and states, as indeed 
others had stated, that. the amount of declivity on 
which lava is capable of becoming fixed or congealed, 
depends almost entirely on the degree of its original 
fluidity, which is exceedingly variable.* Sir W. Ha- 
milton had related that on Vesuvius in 1779 and 1793 ` 
the lava thrown up in jets into the air was still red hot 
when it fell down again upon the cones, which it in- 
vested with one complete body of fire. (See pp. 
$2, 83.) -From such showers may result continuous 
envelopes, if not of lava, at least of solid scoriz, the 
half-melted fragments being known to cohere together 
into one mass, as they cool around the vent. It is also 
stated that in some eruptions large portions of the 
upper rim of the crater broke down suddenly, so that 4 
broad sheet of lava descended the flanks of the cone. 

The sections seen on the flanks of Mont Dor and 
Cantal are not sufficiently numerous to enable a geologist 
to trace with certainty the continuity of the same 
flows, and to prove their precise identity at distant 
points.. The number of different beds is extremely 
great, especially near the centre and summit of each 
mountain ; and wé see tuffs alternating again and again 
with basalt and trachyte. Often on the opposite sides 
of the same valley in the Cantal the tuffs and lavas by 
no means coincide, bed for bed. 

As to the texture of the more ancient igneous rocks 
it may be admitted that they are generally more com- 
pact ; yet they are sometimes very porous, and occa- 
sionally exhibit signs of having been in motion. On 


* Bulletin de la Soc. Géol. de France, tom. vii. p. 40. 


Ch, XIIL] THEORY OF ELEVATION CRATERS. 175 


the other hand some modern lavas of Etna are ex- 
tremely compact. This character may probably be 
Modified in part by mineralogical composition, and the 
degree of fluidity of different varieties of lava and the 
quantity of gas contained in them, as well as by the 
declivity of the surface on which they cool. That the 
ancient lavas of France should differ in many respects, 
and particularly in composition, from those now flowing 
from Vesuvius and Etna, is natural, since we are told 
that the active volcanos of the Andes produce lavas 
quite distinct from those of Europe, both ancient and 
modern. According to Von Buch, the American vol- 
canic rocks contain generally albite instead of common 
felspar as a principal ingredient.* 

But may not Some large volcanic cones have been 
Subjected to a certain amount of forcible elevation pro- 
duced by the local earthquakes generally felt during 
and before eruptions? This may be conceded, for we 
frequently see that the same force which drives lava 
Up the central vent has power to rend the cone, and 
May therefore, in some cases, tilt the beds so as to 
Taise them and increase their original slope. Some 
Cones, therefore, may have had their central mass suc- 
Cessively upheaved to a certain extent, while they were 
thickened outwardly by new showers of scorize and lava 
Streams. But although this theory of elevation and 
Partial dislocation accompanying successive eruptions 
May be called in to explain certain phenomena, it may 
be regarded only as a subsidiary and subordinate hy- 
Pothesis, eruptions alone without upheaval being the 
Principal and often the sole cause of volcanic cones 
and craters. 


* Poggendorf’s Annalen, 1836, p. 190. 
l I 4 


— ght 


a aw 


=—— 


q 
j 
j 
| ie fi 
a i | 
? 
iy K 
ie g i 
| 
Can 
aia j 
i ie 
He i 
rie ie ow 
A ii Bid 
Ki EH 
i 
Fie ae 
f ? 
Es Wa 
| Ki 
f | 


ee RT a 


ee So E oa ee N 


176 THEORY OF ELEVATION CRATERS. [Book IT- 


It remains to consider how far the analogy of certain 
tracts which have a dome-shaped configuration, and 
have been called valleys of elevation, lend any support 
to the elevation-crater theory. The meaning attached 
to the term valleys of elevation will be fully under- 
stood by studying the 21st and 22d chapters of the 
fourth book. It is not disputed that horizontal strata 
have in this case been upheaved, in such a manner as 
to dip off in all directions from a central nucleus; but 
generally this phenomenon is only a modified form of 
that kind of linear upheaval to which mountain chains 
owe their origin. Such protuberances therefore are in 
their normal form elliptical, rather than circular, al- 
though occasionally they resemble or may even be 
identical in outward shape with certain volcanic cones 
But the analogy fails in many essential particulars. 
The volcanic mass (fig. 38.) is thickest towards the 
centre, and thins out round the circumference at x w.; 


Volcanic Mountain. Fig. 38. 


Elevation Valley. Fig. 40. 


but in the Elevation Valley (fig. 40.), there is no such 
thinning out of the formations found in the middle of 
the elevated tract. In the one case (fig. 38.) the funda- 
mental rocke makes its appearance at the surface at a, g; 
but in the other, on the contrary, (fig. 40.) the strata 
forming the nucleus ¢ are removed farthest from the 
surface below, x, æ. In both instances there may be 2 


Ch. XII] MINERAL COMPOSITION OF LAVAS. 177 


central depression, but in the Elevation Valley it is 
Caused partly by fracture and partly by denudation; 
and if the central mass or nucleus happens to be com- 
Posed of some hard rock, there is then a ridge or emi- 
Nence in the middle instead of a depression. Some- 
times a steep escarpment surrounds the valley of ele- 
Yation, but not always, and when such cliffs exist they 
are principally due to denudation. They are, more- 
Bier, usually intersected by open ravines, caused by 
Cross fractures and faults running at right angles to 
the longest diameter of the ellipse, which cross frac- 
tures are wanting, as before observed, in the so-called 
Craters of elevation. 

Mineral Composition of Volcanic Products. — The 
Mineral called felspar forms in general more than half 
of the mass of modern lavas. When it is in great 
€Xcess, lavas are called trachytic ; they consist gene- 
tally of a base of compact felspar, in which crystals of 
Slassy felspar are disseminated.* When augite (or 
Pyroxene) predominates, lavas are termed basaltic. 

Ut others of an intermediate composition occur, which 
from their colour have been called gray-stones. The 
abundance of quartz, forming distinct crystals or con- 
€retions, characterizes the granitic and other ancient 
tocks, now generally considered by geologists as of 
'Sneous origin: whereas that mineral is rarely exhibited 
a separate form in recent lavas, although silica enters 
‘argely into their composition. Hornblende, so common 
m hypogene rocks, or those commonly called “ pri- 
Mary,” is rare in modern lava; nor does it enter largely 
mto rocks of any age in which augite abounds. It 
Should, however, be stated, that the experiments of 


* See Glossary. 
15 


178 FREQUENCY OF VOLCANIC ERUPTIONS. [Book J 


M. Gustavus Rose have made it very questionable; 
whether the minerals called hornblende and augité 
can be separated as distinct species, as their different 
varieties seem to pass into each other, whether We 
consider the characters derived from their angles of 
crystallization, their chemical composition, or theif 
specific gravity. The difference in form of the tw? 
substances may be explained by the different circum- 
stances under which they have been produced; thé 
form of hornblende being the result of slower cooling 
Crystals of augite have been met with in the scorie of 
furnaces, but never those of hornblende; and crystals 
of augite have been obtained by melting hornblende - 
in a platina crucible, but hornblende itself has not 
been formed artificially.* Mica occurs plentifully # 
some recent trachytes, but is rarely present wher 
augite is in excess. 

Frequency of eruptions, and nature of subterranea™ 
igneous rocks. — When we speak of the igneous rock 
of our own times, we mean that small portion which, 
in violent eruptions, is forced up by elastic fluids t° 
the surface of the earth,—the sand, scoriz, and lav% 
which cool in the open air. But we cannot obtain ac 
cess to that which is congealed far beneath the surfac® 
under great pressure, equal to that of many hundred, 
or many thousand atmospheres. 

During the last century, about fifty eruptions at® 
recorded of the five European volcanic districts, ° 
Vesuvius, Etna, Volcano, Santorin, and Iceland; but 
many beneath the sea in the Grecian Archipelago a? 
near Iceland may doubtless have passed unnoticed. 
some of them produced no lava, others, on the co” 


* Bulletin de la Soc. Géol. de France, tom. ii. p. 206. 


Ch. XIII] SUBTERRANEAN VOLCANIC ROCKS. ` 179 


trary, like that of Skaptar Jokul, in 1783, poured out 
melted matter for five or six years consecutively ; 
Which cases, being reckoned as single eruptions, will 
Compensate for those of inferior strength. Now, if we 
Consider the active volcanos of Europe to constitute 
about a fortieth part of those already known on the 
globe, and calculate that, one with another, they are 
about equal in activity to the burning mountains in 
Other districts, we may then compute that there hap- 
Pen on the earth about two thousand eruptions in the 
Course of a century, or about twenty every year. 

However inconsiderable, therefore, may be the su- 
Perficial rocks which the operations of fire produce on 
the surface, we must suppose the subterranean changes 
Now constantly in progress to be on the grandest scale. 
The loftiest volcanic cones must be as insignificant, : 
when contrasted to the products of fire in the nether 
regions, as are the deposits formed in shallow estuaries 
when compared to submarine formations accumulating 
in the abysses of the ocean. In regard to the cha- 
tacters of these volcanic rocks, formed in our own 
` times in the bowels of the earth, whether in rents and 
caverns, or by the cooling of lakes of melted lava, we 
May safely infer that the rocks are heavier and less 
Porous than ordinary lavas, and more crystalline, 
although composed of the same mineral ingredients. 
As the hardest crystals produced artificially in the 
laboratory require the longest time for their formation, 
So we must suppose that where the cooling down of 
Melted matter takes place by insensible degrees, in 
the course of ages, a variety of minerals will be pro- 
duced far harder than any formed by natural processes 
Within the short period of human observation. 

These subterranean volcanic rocks, moreover, can- 

16 


180 SUBTERRANEAN VOLCANIC ROCKS. [Book If 


not be stratified in the same manner as sedimentary 
deposits from water, although it is evident that when 
great masses consolidate from a state of fusion, they 
may separate into natural divisions; for this is seen to 
be the case in many lava currents. We may also 
expect that the rocks in question will often be rent by 
earthquakes, since these are common in volcanic re- 
gions; and the fissures will be often injected with 
similar matter, so that dikes of crystalline rock will 
traverse masses of similar composition. It is also 
clear, that no organic remains can be included in such 
masses, as also that these deep-seated igneous form- 
ations considered in mass must underlie all the strata 
containing organic remains, because the heat proceeds 
from below upwards, and the intensity required to 
reduce the mineral ingredients to a fluid state must 
destroy all organic bodies in rocks included in the 
midst of them. 

If by a continued series of elevatory movements, 
such masses shall hereafter be brought up to the sur- 
face, in the same manner as sedimentary marine strata 
have, in the course of ages, been upheaved to the 
summit of the loftiest mountains, it is not difficult to 
foresee what perplexing problems may be presented to 
the geologist. He may then, perhaps, study in some 
mountain chain the very rocks produced at the depth 
of ‘several miles beneath the Andes, Iceland, or Java, ; 
in the time of Leibnitz, and draw from them the same 
conclusion which that philosopher derived from certain 
igneous products of high antiquity; for he conceived 
our globe to have been, for an indefinite period, in the 
state of a comet, without an ocean, and uninhabitable 
alike by aquatic or terrestrial animals. 


CHAPTER XIV. 


EARTHQUAKES AND THEIR EFFECTS. 


Earthquakes and their effects — Deficiency of ancient accounts— 
Ordinary atmospheric phenomena— Changes produced by earth- 
quakes in modern times considered in chronological order — 
Earthquake in Chili, 1835 — Isle of Santa Maria raised ten 
feet — Chili, 1822 — Extent of country elevated (p. 191.) — 
Aleppo and Ionian Isles — Earthquake of Cutch in 1819— 
Subsidence in the Delta of the Indus (p. 195.) — Island of 
Sumbawa in 1815 — Town of Tomboro submerged — Earth- 
quake of Caraccas in 1812— South Carolina in 1811 — 
Changes in the valley of the Mississippi (p. 203.) — Aleutian 
Islands in 1806 — Reflections on the earthquakes of the nine- 
teenth century — Earthquake in Quito, Quebec, &c, — Java, 
1786 — Sinking down of large tracts — Japan Isles, 1783. 


Ty, the sketch before given of the geographical bound- 
aies of volcanic regions, I stated, that although the 
Points of eruption are but thinly scattered, constituting 
ere spots on the surface of those vast districts, yet 

€ subterranean movements extend simultaneously 
Ver immense areas. We may now proceed to con- 
Sider the changes which these movements produce 
n the surface, and in the internal structure of the 
farth’s crust. 

Deficiency of ancient accounts. — It is only within 

© last century and a half, since Hooke first promul- 
8ated his views respecting the connexion between 
8eological phenomena and earthquakes, that the per- 


182 PHENOMENA ATTENDING EARTHQUAKES. [Book JL 


manent changes effected by these convulsions have 
excited attention. Before that time, the narrative of 
the historian was almost exclusively confined to thé 
number of human beings who perished, the number of 
cities laid in ruins, the value of property destroyed, 0 
certain atmospheric appearances which dazzled or tet 
rified the observers. The creation of a new lake, the 
engulphing of a city, or the raising of a new island, 
are sometimes, it is true, adverted to, as being t0 
obvious, or of too much geographical interest, to be 
passed over in silence. But no researches were made 
expressly with a view of ascertaining the amount of 
depression or elevation of tHe ground, or any particula! 
alterations in the relative position of sea and land ; aD 

very little distinction was made between the raising of 
soil by volcanic ejections, and the upheaving of it by 
forces acting from below. The same remark applies 
to a very large proportion of modern accounts ; and 
how much reason we have to regret this deficiency of 
information appears from this, that in every instanc? 
where a spirit of scientific inquiry has animated the 
eye-witnesses of these events, facts calculated ™ 
throw light on former modifications of the earths 
structure are recorded. 

Phenomena attending earthquakes. — As I shall con- 
fine myself almost entirely, in the following notice 
of earthquakes, to the changes brought about by the 
in the configuration of the earth’s crust, I may me? 
tion, generally, some accompaniments of these terri- 
ble events which are almost uniformly commemorated 
in history, that it may be unnecessary to advert t° 
them again. Irregularities in the seasons preceding 
or following the shocks; sudden gusts of wind, inte 
rupted by dead calms ; violent rains at unusual seasoD* 


Ch. XIV.] EARTHQUAKE IN CHILI, 1835. _ 183 


or in countries where such phenomena are almost 
unknown ; a reddening of the sun’s disk, and a hazi- 
Ness in the air, often continued for months ; an evolu- 
tion of electric matter, or of inflammable gas from the 
Soil, with sulphureous and mephitic vapours ; noises 
underground, like the running of carriages, or the dis- 
charge of artillery, or distant thunder ; animals utter- 
ing cries of distress, and evincing extraordinary alarm, 
being more sensitive than men of the slightest move- 
Ment; a sensation like sea-sickness, and a dizziness 
in the head, experienced by men : — these, and other 
Phenomena, which are still more remotely connected 
With our present subject as geologists, have recurred 
again and again at distant ages, and in all parts of 
the globe. 

I shall now begin the enumeration of earthquakes 
With the latest authentic narratives, and so carry back 


the survey retrospectively, that I may bring before the 
Teader, in the first place, the minute and circumstan- 
tial details of modern times, and thus enable him, by 
observing the extraordinary amount of change within 
the last 150 years, to perceive how great must be the 
deficiency in the meagre annals of earlier eras. 


EARTHQUAKES OF THE NINETEENTH CENTURY.* 


Chili, 1835. — The latest earthquake by which the 
Position of solid land is known to have been perma- 


* Since the publication of the first edition of this work, nume- 
Tous accounts of recent earthquakes have been published ; but as 
they do not illustrate any new principle, I cannot insert them all, 
as they would enlarge too much the size of my work. . Among 
the most violent may be mentioned those of March 1829, near 
Alicant in Murcia — that of Sept. 1827, at Lahore, East Indies 


Q] 
Va 


ea eel 
Idivia 
come 


1 


Ch. XIV. EARTHQUAKE IN CHILI, 1835. 185 


tently altered is that which occurred in South Ame- 
tica, on the 20th of February, 1835. It was felt at all 
Places between Copiapo and Chiloe, from north to 
South, and from Mendoza to Juan Fernandez, from east 
to west. « Vessels,” says Mr. Caldcleugh, “ navigating 
the Pacific, within 100 miles of the coast, experienced 
the shock with considerable force.’’* Conception, Tal- 
Cahuano, Chillan, and other towns were thrown down. 
From the account of Captain FitzRoy, R.N., who was 
then employed in surveying the coast, we learn that 
after the shock the sea retired in the bay of Concep- 
tion, and the vessels grounded, even those which had 
ĉen lying in seven fathoms water ; all the shoals were 
Visible, and soon afterwards a wave rushed in and then 
"etreated, and was followed by two other waves. The 
Vertical height of these waves does not appear to have 
€en much greater than from sixteen to twenty feet, 
although they rose to much greater heights when they 
roke upon a sloping beach. 

According to Mr. Caldcleugh, a great number of the 
Volcanos of the Chilian Andes were in a state of un- 
usual activity, both during the shocks and for some 
time preceding and after the convulsion, and lava was 
Seen to flow from the crater of Osorno. (See Map, 
fig. 41.) The island of Juan Fernandez, distant 360 


~of Jan. 15. 1832, which destroyed Foligno, in Italy, — June 24. 
1830, in China, in Tayming, North of Houan — March 9. 1830, 
in the Caucasus at Kislier — April 1833, Manilla — 1833, Isle of 
Missa in Adriatic, and Opus. Von Hoff has published, from 
time to time, in Poggendorf’s Annalen, lists of the earthquakes 
Which have happened since 1821 ; and, by consulting these, the 
reader will perceive that every month is signalized by one or many 
Convulsions in some part of the globe. 
* Phil. Trans., 1886, p. 21. 


186 EARTHQUAKE IN CHILI, 1895. [Book H- 


miles from Chili, was violently shaken at the same 
time, and devastated by a great wave. Flames rosé 
there from the sea about a mile from the shore, and 
illumined the whole island during the night, althoug! 
it was afterwards ascertained that there was a depth 
of sixty-nine fathoms water in the spot where tog 
flames had appeared. * 

“ At Conception, ” says Captain FitzRoy, “the earth 
opened and closed rapidly in numerous places. The 
direction of the cracks was not uniform, though gene 
rally from south-east to north-west. The earth was 
not quiet for three days after the great shock, and moré 


Fig. 42. 


r— 


PACIFIC = 


Ruins of 
o Penco 


a 


N Conception 


je E a 


Biot 


Y 
& 


* Phil. Trans., 1836, p. 25. 


Ch. xtv.] EARTHQUAKE IN CHILI, 1835. 187 


than three hundred shocks were counted between the 
20th of February and the 4th of March. The loose 
“arth of the valley of the Biobio was everywhere 
Parted from the solid rocks which bound the plain, 
there being an opening between them from an inch to 
à foot in width. 

“For some days after the 20th of February, the sea 
at Talcahuano,” says Captain FitzRoy, “did not rise to 
the usual marks by four or five feet vertically. When 
Walking on the shore even at high water beds of dead 
Mussels, numerous chitons, and limpets, and withered 
Sea-weed, still adhering, though lifeless, to the rocks 
M which they had lived, everywhere met the eye.” 

Ut this difference in the relative level of the land and 
Sea gradually diminished, till in the middle of April the 
Water rose again to within two feet of the former high 
Water mark. It might be supposed that these changes 
°f level merely indicated a temporary disturbance in 
the set of the currents or in the height of the tides at 

alcahuano; but on considering what occurred in the 
‘eighbouring island of Santa Maria, Captain FitzRoy 
Concluded that the land had been raised four or five 
ĉet in February, and that it had returned in April to 
Within two or three feet of its former level. 

Santa Maria, the island just alluded to, is about seven 
Niles long and two broad, and about twenty-five miles 
South-west of Conception. (See Map, fig.42.) The 
Phenomena observed there are most important. “It 
‘Ppeared,” says Captain Fitz Roy, who visited Santa 

aria twice, the first time at the end of March, and 
afterwards in the beginning of April, “that the south- 
a extremity of the island had been raised eight feet, 

€ middle nine, and the northern end upwards of ten 


188 EARTHQUAKE IN ISCHIA, 1998, [Book 1} 


feet. On steep rocks, where vertical measures could 
be correctly taken, beds of dead mussels were fou? 

ten feet above high water mark. One foot lower tha? 
the highest bed of mussels, a few limpets and chito” 
were seen adhering to the rock where they had grow™ 
Two feet lower than the same, dead mussels, chitoD% 
and limpets were abundant.” . 

“ An extensive rocky flat lies around the northe! 
parts of Santa Maria. Before the earthquake this fa’ 
was covered by the sea, some projecting rocks only 
showing themselves. Now, the whole flat is exposed, 
and square acres of it are covered with dead shell-fish» 
the stench arising from which is abominable. By tH 
elevation of the land the southern port of Santa Maria 
has been almost destroyed ; little shelter remaining 
there, and very bad landing.” The surrounding sea is 
also stated to have become shallower in exactly th? 
same proportion as the land had risen ; the sounding’ 
having diminished a fathom and a half everywhel? 
around the island. 

At Tubal, also, to the south-east of Santa Maria, the 
land was raised six feet, at Mocha two feet, but 2° 
elevation could be ascertained at Valdivia, northwa 
of Conception. wig 

Ischia, 1828. — On the 2d of February the whole 
island of Ischia was shaken by an earthquake, and ” 
the October following I found all the houses in Cas* 
micciol still without their roofs. On the sides of # 
ravine between that town and Forio, I saw masses ° 
greenish tuff, which had been thrown down. The ho! 
spring of Rita, which was nearest the centre of th? 
movement, was ascertained by M. Covelli to hav? 
increased in temperature, showing, as he observe” 


Ch, XIV] BOGOTA, 1827. — CHILI, 1822. 189 
that the explosion took place below the reservoirs 
Which heat the thermal waters.* 

Bogota, 1827. — On the 16th of November, 1827, 
the Plain of Bogota was convulsed by an earthquake, 
and a great number of towns were thrown down. 

rrents of rain swelled the Magdalena, sweeping 
along vast quantities of mud and other substances, 
Which emitted a sulphureous vapour and destroyed the 

Sh. Popayan, which is distant two hundred geogra- 
Phical miles S. S.W. of Bogota, suffered greatly. Wide 
crevices appeared in the road of Guanacas, leaving no 
doubt that the whole of the Cordilleras sustained a 
Powerful shock. Other fissures opened near Costa, in 
the plains of Bogota, into which the river Tunza im- 
mediately began to flow.t It is worthy of remark, 
that in all such cases the ancient gravel bed of a river 
'S deserted, and a new one formed at a lower level; so 
that a want of relation in the position of alluvial beds 
to the existing water-courses may be no test of the 
igh antiquity of such deposits, at least in countries 

abitually convulsed by earthquakes. Extraordinary 
rains accompanied the shocks before mentioned ; and 
two volcanos are said to have been in eruption in the 
Mountain-chain nearest to Bogota. 

Chili, 1822. — On the 19th of November, 1822, the 
Coast of Chili was visited by a most destructive earth- 
quake. The shock was felt simultaneously throughout 
à Space of 1200 miles from north to south. St. Jago, 
valparaiso, and some other places, were greatly in- 
Jured. When the district round Valparaiso was ex- 
amined on the morning after the shock, it was found 


* Biblioth. Univ., Oct. 1828, p. 157. ; and Férussac, Bulletin 
€, tome xi, p- 227. 
t Phil. Mag., July 1828, p. 37. 


190 EARTHQUAKE IN CHILI, 182. [Book Jf 


that the whole line of coast, for the distance of above 
one hundred miles, was raised above its former leve!” 
At Valparaiso the elevation was three feet, and ab 
Quintero about four feet. Part of the bed of the se 
says Mrs. Graham, remained bare and dry at high 
water, “with beds of oysters, muscles, and other shells 
adhering to the rocks on which they grew, the fis? 
being all dead, and exhaling most offensive effiuvia. T 

An old wreck of a ship, which before could not bê 
approached, became accessible from the land, althoug? 
its distance from the original sea-shore had not al 
tered. It was observed, that the water-course of # 
mill, at the distance of about a mile from the se% 
gained a fall of fourteen inches, in little more than on? 
hundred yards; and from this fact it is inferred that 
the rise in some parts of the inland country was fat 
more considerable than on the borders of the ocean$ 
Part of the coast thus elevated consisted of granite, in 
which parallel fissures were caused, some of which 
were traced for a mile and a half inland. (Cones ? 
earth, about four feet high, were thrown up in several 
districts, by the forcing up of water mixed with san 
through funnel-shaped hollows, —a phenomenon very 
common in Calabria, and the explanation of which wi! 
hereafter be considered.. Those houses in Chili of 
which the foundations were on rock were less damaged 
than such as were built on alluvial soil. 

Mr. Cruckshanks, an English botanist, who resided 
in the country during the earthquake, has informe 


* See Geol. Trans., vol. i., second series; and also Journ of 
Sci., 1824, vol. xvii. p. 40. 

+ Geol. Trans., vol. i., second series, p. 415, 4 Ibid. 

§ Journ. of Sci., vol. xvii. p. 42. 


Ch. XIV.] COAST OF CHILI ELEVATED. 191 


me that some rocks of greenstone at Quintero, a few 
hundred yards from the beach, which had always been 
Under water till the shock of 1822, have since been 
Uncovered when the tide is at half-ebb; and he states 
that, after the earthquake, it was the general belief of 
the fishermen and inhabitants of the Chilian coast, 
not that the land had risen, but that the ocean had 
Permanently retreated. 

Dr. Meyen, a Prussian traveller, who visited Valpa- 
Taiso in 1831, says that on examining the rocks both 
North and south of the town, nine years after the 
€vent, he found in corroboration of Mrs. Graham’s 
account, that remains of animals and sea-weed, the 
Lessonia of Bory de St. Vincent, which has a firm 
ligneous stem, still adhered to those rocks which in 
1899 had been elevated above high water mark. * 
According to the same author, the whole coast of 
Central Chili was raised about four feet, and banks of 
Marine shells were laid dry on many parts of the coast. 

e observed similar banks, elevated at unknown pe- 
tods, in several places, especially at Copiapo, where 
the species all agree with those now living in the 
Ocean. Mr. Freyer also, who resided some years in 
South America, has confirmed these statements t; 
but Mr. Cuming, a gentleman well known by his nu- 
Merous discoveries in conchology, and who resided at 

alparaiso during and after the earthquake, could de- 
tect no proofs of the rise of the Jand, nor any signs of 
à change of level. On the contrary; he remarked, that 
the water at spring tides rose after the earthquake to 
the same point on a wall near his house, which it had 


* Reise um die erde ; and see Dr. Meyen’s letter cited Foreign 
Quart. Rev. No. 33. p. 13. — 1836. 
T Geol, Soc. Proceedings, No. 40, p. 179., Feb, 1835. 


192 COAST OF CHILI ELEVATED. [Book I. 


reached before the shocks. The opinions of this gen- 
tleman well deserve attention from those who may 
have opportunities of minutely investigating the Chi- 
lian coast ; but after considering his objections to Mrs 
Graham’s account, even before the late convulsion, £ 
felt satisfied with the proofs of elevation in 1892. Had 
I still cherished any scepticism, it would have bee” 
removed by the coincidence of the facts related by 
Captain FitzRoy a shaving occurred in 1835, thirtee® 
years afterwards, in another part of the same country.” 

Extent of country elevated.—The area over which this 
permanent alteration of level is conjectured to have eX’ 
tended, in 1822, is 100,000 square miles.+ The whole 
country, from the foot of the Andes to a great dis 
tance under the sea, is supposed to have been raised 
the greatest rise being at the distance of about tw? 
miles from the shore. “The rise upon the coast w35 
from two to four feet:—at the distance of a mile 
inland it must have been from five to six, or seve? 
feet.” {| The soundings in the harbour of Valparaiso 
have been materially changed by this shock, and 
the bottom has become shallower. The shocks cor 
tinued up to the end of September, 1823 ; eve? 
then, forty-eight hours seldom passed without on 
and sometimes two or three were felt during twenty” 
four hours. Mrs. Graham observed, after the earth- 
quake of 1822, that, besides the beach newly raised 
above high-water mark, there were several olde" 
elevated lines of beach one above the other, consisting 
of shingle mixed with shells, extending in a parallel 


* Cuming, Geol. Proceedings, No. 42. p. 213. 
t Journ. of Sci., vol. xvii. 


ł Journ. of Sci., vol. xvii., pp. 40. 45. 


Ch. XIV.] COAST OF CHILI ELEVATED. T AOP 


direction to the shore, to the height of fifty feet above 
the sea. * 

In order to give some idea of the enormous amount 
of change which this single convulsion may have occa- 
Sioned, let us assume that the extent of country moved 
Was correctly estimated at 100,000 square miles, — an 
extent just equal to half the area of France, or about 
five-sixths of the area of Great Britain and Ireland. 
If we suppose the elevation to have been only three 
feet on an average, it will be seen that the mass of 
rock added to the continent of America by the move- 
Ment, or, in other words, the mass previously below 
the level of the sea, and after the shocks permanently 
above it, must have contained fifty-seven cubic miles 
in bulk; which would be sufficient to form a conical 
Mountain two miles high (or about as high as Etna), 
With a circumference at the base of nearly thirty-three 
miles. We may take the mean specific gravity of the 
rock at 2°655,—a fair average, and a convenient one 
in such computations, because at such a rate a cubic 
yard weighs two tons. Then, assuming the great Py- 
ramid of Egypt, if solid, to weigh, in accordance with 
an estimate before given, six million tons, we may state 
the rock added to the continent by the Chilian earth- 
quake to have more than equalled 100,000 pyramids. 

But it must always be borne in mind that the weight 
of rock here alluded to constituted but an insignificant 
Part of the whole amount which the volcanic forces 
had to overcome. The whole thickness of rock be- 
tween the surface of Chili and the subterranean foci of 
volcanic action, may be many miles or leagues deep. 
Say that the thickness was only two miles, even then 


* Geol. Trans., vol. i., second series, p. 415. 
VOL. IL K 


e ea 


r a 


194 EARTHQUAKE OF CUTCH, 1819. [Book I. 


the mass which changed place and rose three feet . 
being 200,000 cubic miles in volume, must have ex- 
ceeded in weight 363 million pyramids. 

It may be useful to consider these results in con- . 
nection with others already obtained froma different 
source, and to compare the working of two antagonist 
forces — the levelling power of running water, and the 
expansive energy of subterranean heat. How long, it 
may be asked, would the Ganges require, according t0 
data before explained, to transport to the seaa quantity 
of solid matter equal to that added to the land by the 
Chilian earthquake? The discharge of mud in one 
year by the Ganges equalled the weight of sixty py- 
ramids. In that case it would require seventeen cen- 
turies and a half befere the river could bear down from 
the continent into the sea a mass equal to that gained 
by the Chilian earthquake. In about half that number 
of centuries, perhaps, the united waters of the Ganges 
and Burrampooter might accomplish the operation. 

Aleppo, 1822.— Jonian Isles, 1820.— When Aleppo 
was destroyed by an earthquake in 1822, two rocks are 
reported to have risen from the sea near the island of 
Cyprus* ; andanew rocky island was observed in 1820 
not far from the coast of Santa Maura, one of the 
Ionian Islands, after violent earthquakes. + 

Cutch, 1819.—A violent earthquake occurred at 
Cutch, in the delta of the Indus, on the 16th of June; 
1819. (See Map, plate 5.) The principal town, Bhooj; 
was converted into a heap of ruins, and its stone 
buildings were thrown down. The shock extended t0 
Ahmedabad, where it was very destructive ; and at 
Poonah, four hundred miles farther, it was feebly felt. 


* Journ. of Sci., vol. xiv. p. 450. 
ft Von Hoff., vol. ii. p. 180. 


| SPUMJ P i d Ag L 

| WO AaNIS LO SA V a st ae ae f “Spool Brenty 

| PUP i > j Í FAN USAN < io opg QYLJO JOUUDY) JP 
5 r av UD $2 

| HOLA) 10 NNA ; 


a LS ES 


WL IU POOP PYZ 


rosd i 


H 
DYOM 
OA. 
uv APLK 
Me amp al | 
me ANUN 


p 


ee R 


aN EXO 


o 
DILNI 


SOT 


Ea n al I & 
a r A . j x prum? 


o 
Lood, apy ¢ 


Zi 


smpuy gO yn maq W 


SO 


ihe ee st ot 
tht! OAC vA ws 4 A 


SINCE SUBMERGED BY THE RARTHQUAKE OF 1819. 


2 


Prom a sketch taken on the spot ty Capt. Grindlay ar 1808. 


idan , Published 1834 by John M urray,Albemarle Street) 


Ch. XIV.] FORT AND VILLAGE SUBMERGED. ` 195 


At the former city, the great mosque erected by Sul- 
tan Ahmed nearly 450 years before, fell to the ground, 
attesting how long a period had elapsed since a shock 
of similar violence had visited that point. At Anjar, 
the fort, with its tower and guns, were hurled to the 
Sround in one common mass of ruin. The shocks 
Continued some days until the 20th ; when, thirty miles 
north-west from Bhooj, the volcano called Denodur 
is said to have burst out in eruption, and the convul- 
Sions ceased. 

Subsidence in the Delta of the Indus.— Although 
the ruin of towns was great, the face of nature in the 
inland country, says Captain Macmurdo, was not visibly 
altered. In the hills some large masses only of rock 
and soil were detached from the precipices ; but the 
astern and almost deserted channel of the Indus, 
Which bounds the province of Cutch, was greatly 
Changed. This estuary, or inlet of the sea, was, before 
the earthquake, fordable at Luckput, being only about 
a foot deep when the tide was at ebb, and at flood tide 
Never more than six feet ; but it was deepened at the 
fort of Luckput, after the shock, to more than eighteen 
Jeet at low water.* On sounding other parts of the ` 
Channel, it was found, that where previously the depth 
of the water at flood never exceeded one or two feet, 
it had become from four to ten feet deep. By these 
and other remarkable changes of level, a part of the 
Inland navigation of that country, which had been 
Closed for centuries, become again practicable. ` 

Fort and village submerged. + — The fort and village 


* Macmurdo, Ed. Phil. Journ., vol. iv. p. 106. 

t I am indebted to Captain Burnes for the accompanying 
“ngraving (Pl. VI.) of the Fort of Sindree, as it appeared eleven 
Years before the earthquake, 


go 


196 EARTHQUAKE OF CUTCH, 1819. [Book IL 


of Sindree, on the eastern arm of the Indus, above 
Luckput, are stated by the same writer. to have beer 
overflowed ; and, after the shock, the tops of the houses 
and wall were alone to be seen above the water, fot 
the houses, although submerged, were not cast dow). 
Had they been situated, therefore, in the interior, 
where so many forts were levelled to the ground, their 
site would, perhaps, have been regarded as having 
remained comparatively unmoved. Hence we may 
suspect that great permanent upheavings and depres- 
sions of soil may be the result of earthquakes, without 
the inhabitants being in the least degree conscious of 
any change of level. 

A more recent survey of Cutch by Capt. A. Burnes; 
who was not in communication with Capt. Macmurdo, 
confirms the facts above enumerated, and adds many 
important details.* That officer examined the delta 
of the Indus in 1826 and 1828, and from his account 
it appears that, when Sindree subsided in June, 1819; 
the sea flowed in by the eastern mouth of the Indus, 
and in a few hours converted a tract of land, 2000 
square miles in area, into an inland sea, or lagoon. 
Neither the rush of the sea into this new depression, 
nor the movement of the earthquake, threw down 
entirely the small fort of Sindree, one of the four 
towers, the north-western, still continuing to stand; 
and the day after the earthquake, the inhabitants, who 
had ascended to the top of this tower, saved them- 
selves in boats. t 


* This Memoir is now in the Library of the Royal Asiatic 
Society of London. 


+ I have been enabled, from personal communication with 
Captain Burnes, to add several particulars to my former account 
of this earthquake, 


Ch, XIV.] ELEVATION OF THE ULLAH BUND. 197 


Elevation of the Ullah Bund. — Immediately after 
the shock, the inhabitants of Sindree saw, at the dis- 
tance of five miles and a half from their village, a long 
elevated mound, where previously there had been a 
low and perfectly level plain. (See Map, Pl. 5.) To 
this uplifted tract they gave the name of “ Ullah 
Bund,” or the “Mound of God,” to distinguish it 
from several artificial dams previously thrown across 
the eastern arm of the Indus. 

Extent of country raised.—It has been already ascer- 
tained that this new-raised country is upwards of fifty 
miles in length from east to west, running parallel to 
that line of subsidence before mentioned which caused 
the grounds around Sindree to be flooded. The range 
of this elevation extends from Puchum Island towards 
Gharee ; its breadth from north to south is conjectured 
to be in some parts sixteen miles, and its greatest as- 
certained height above the original level of the delta 
is ten feet, —an elevation which appears to the eye to 
be very uniform throughout. 

For several years after the convulsion of 1819, the 
Course of the Indus was very unsettled, and at length, 
in 1896, the river threw a vast body of water into its 
eastern arm, that called the Phurraun, above Sinde ; 
and forcing its way in a more direct course to the sea, 
burst through all the artificial dams which had been 
thrown across its channel, and at length cut right 
through the «Ullah Bund,” whereby a natural sec- 
tion was obtained. In the perpendicular cliffs thus 
laid open, Captain Burnes found that the upraised 
lands consisted of clay filled with shells. The new | 
channel of the river where it intersected the “ bund” 
Was eighteen feet deep, and during the swells in 1826 
it was two or three hundred yards in width; but i 

KS 


198 EARTHQUAKE OF CUTCH, 1819. [Book 1 


1828 the channel was still further enlarged. The 
Indus, when it first opened this new passage, threw 
such a body of water into the new meer, or salt lagoon, 
of Sindree, that it became fresh for many months; but 
it had recovered its saltness in 1828, when the supply 
of river water was less copious, and finally it became 
more salt than the sea, in consequence, as the natives 
suggested to Captain Burnes, of the saline particles 
with which the “ Runn of Cutch” is impregnated. 

In 1828 Captain Burnes went in a boat to the ruins 
of Sindree, where a single remaining tower was seer 
in the midst of a wide expanse of sea. The tops of 
the ruined walls still rose two or three feet above the 
level of the water ; and standing on one of these, he 
could behold nothing in the horizon but water, except 
in one direction, where a blue streak of land to the 
_horth indicated the Ullah Bund. This scene presents 
to the imagination a lively picture of the revolutions 
now in progress on the earth—a waste of waters 
where a few years before all was land, and the only 
land visible consisting of ground uplifted by a recent 
earthquake. 

The Runn of Cutch, above alluded to, is a flat re- 
gion of a very peculiar character, and no less than 
7000 square miles in area; a greater superficial extent 
than Yorkshire, or about one fourth the area of Ireland. 
It is not a desert of moving sand, nor a marsh, but 
evidently the dried-up bed of an inland sea, which for 
a great part of every year has a hard and dry bottom 
uncovered by weeds or grass, and only supporting here 
and there a few tamarisks. But during the monsoons» 
` when the sea runs high, the salt water driven up from 
the Gulf of Cutch and the creeks at Luckput overflows 
a large part of the Runn, especially after rains, wher 


Ch. XIV. EARTHQUAKE OF CUTCH, 1819. 199 


the soaked ground permits the sea-water to spread 
rapidly. The Runn is also liable to be overflowed 
Occasionally in some parts by river-water ; and it is 
remarkable that the only portion which was ever highly 
cultivated (that anciently called Sayra) is now perma- 
hently submerged. The surface of the Runn is some- 
times encrusted with salt about an inch in depth, 
in consequence of the evaporation of the sea-water. 
Islands rise up in some parts of the waste, and the 
boundary lands form bays and promontories. 

The natives have a tradition that, about three cen- 
turies ago, the countries of Cutch and Sinde were 
Separated by the sea, thus giving rise to the district 
called the Runn. Towns far inland are still pointed 
Out as having once been ancient ports; and it is said 
that ships were wrecked and engulphed by the great 
Catastrophe. In confirmation of this account it was 
observed, in 1819, that, in the jets of black muddy 
Water thrown out of fissures in that region, there were 
Cast up numerous pieces of wrought iron and ship 
hails. * Cones of sand six or eight feet in height are 
Said to have been thrown up on these lands. 

We must not conclude without alluding to a moral 
Phenomenon connected with this tremendous cata- 
Strophe, which we regard as highly deserving the at- 
tention of geologists. It is stated by Captain Burnes, 
that «these wonderful events passed wnheeded by the 
inhabitants of Cutch ;” for the region convulsed, though 
Once fertile, had for a long period been reduced to 
Sterility by want of irrigation, S0 that the natives were 
indifferent as to its fate. Now it is to this profound 


* Capt. Burnes’s Account. 
+ Capt. Macmurdo’s Memoir, Ed. Phil. Journ., vol. iv. p.106. 


K 4 


200 VOLCANIC ERUPTION IN SUMBAWA, 1815, [Book 1f, 


apathy which all but highly civilized nations feel, in 
regard to physical events not having an immediate in- 
fluence on their worldly fortunes, that we must ascribe 
the extraordinary dearth of historical information con- 
cerning changes of the earth’s surface, which modern 
observations show to be by no means of rare occurrence 
in the ordinary course of nature. 

To the east of the line of this earthquake lies Oojain 
(called Ozene in the Peryplus Maris Erythr). Ruins 
of an ancient city are there found, a mile north of the 
present, buried in the earth to the depth of from fifteen 
to sixteen feet, which inhumation is known to have 
been the consequence of a tremendous catastrophe in 
the time of the Rajah Vicramaditya.* 

Island of Sumbawa, 1815. — In April, 1815, one of 
the most frightful eruptions recorded in history oc- 
curred in the mountain Tomboro, in the island of 
Sumbawa. It began on the 5th of April, and was 
most violent on the lith and 12th, and did not en- 
tirely cease till July. The sound of the explosions was 
heard in Sumatra, at the distance of 970 geographical 
miles in a direct line; and at Ternate, in an opposite 
direction, at the distance of 720 miles. Out of a 
population of twelve thousand, only twenty-six in- 
dividuals survived on the island. Violent whirlwinds 
carried up men, horses, cattle, and whatever else 
came within their influence, into the air, tore up the 
largest trees by the roots, and covered the whole sea 
with floating timber.+ Great tracts of land were 
covered by lava, several streams of which, ‘issuing 


* Von Hoff, vol. ii. p.454.; for further particulars, see book iii» 
chap. xiv. 


t Raffles’s Java, vol. i. p. 28. 


Ch. XIV] TOWN OF TOMBORO SUBMERGED. 201 
from the crater of the Tomboro mountain, reached 
the sea. So heavy was the fall of ashes, that they 
broke into the Resident’s house at Bima, forty miles 
fast of the volcano, and rendered it, as well as many 
Other dwellings in the town, uninhabitable. On the 
Side of Java the ashes were carried to the distance of 
300 miles, and 217 towards Celebes, in sufficient 
quantity to darken the air. The floating cinders to 
the westward of Sumatra formed, on the 12th of 
April, a mass two feet thick, and several miles in ex- 


tent, through which ships with difficulty forced their 
Way. 


The darkness occasioned in the daytime by the 
ashes in Java was so profound, that nothing equal to 
it was ever witnessed in the darkest night. Although 
this volcanic dust when it fell was an impalpable pow- 


der, it was of considerable weight when compressed, a 
Pint of it weighing twelve ounces and three quarters. 
Along the sea coast of Sumbawa, and the adjacent 
isles, the sea rose suddenly to the height of from two 
to twelve feet, a great wave rushing up the estuaries, 
and then suddenly subsiding. Although the wind at 
Bima was still during the whole time, the sea rolled in 
Upon the shore, and filled the lower parts of the houses 
With water a foot deep. Every prow and boat was 
forced from the anchorage, and driven on shore. 

The town called Tomboro, on the west side of the 
Volcano of Sumbawa, was overflowed by the sea, which 
€ncroached upon the shore so that the water remained 
Permanently eighteen feet deep in places where 
there was land before. Here we may observe, that the 
amount of subsidence of land was apparent, in spite of 
the ashes, which would naturally have caused the limits 
of the coast to be extended. 5 


K 5 


202 EARTHQUAKE OF CARACCAS, 1812. ' [Book IŁ 


The area over which tremulous noises and other 
volcanic effects extended, was one thousand English 
miles in circumference, including the whole of the 
Molucca Islands, Java, a considerable portion of Ce- 
lebes, Sumatra, and Borneo. In the island of Amboyna, 
in the same month and year, the ground opened, 
threw out water, and then closed again.* 

In conclusion, I may remind the reader, that but for ` 
the accidental presence of Sir Stamford Raffles, then 
governor of Java, we should scarcely have heard in 
Europe of this tremendous catastrophe. He required 
all the residents in the various districts under his au- 
thority to send in a statement of the circumstances 
which occurred within their own knowledge ; but, 
valuable as were their communications, they are often 
calculated to excite rather than to satisfy the curiosity 
of the geologist. They mention, that similar effects, 
though in a less degree, had, about seven years before, 
accompanied an eruption of Carang Assam, a volcano 
in the island of Bali, west of Sumatra ; but no particu- 
lars of that great catastrophe are recorded.+ 

Caraccas, 1812.—On the 26th of March, 1812, 
several violent shocks of an earthquake were felt in 
Caraccas. The surface undulated like a boiling liquid, 
and terrific sounds were heard underground. The 
whole city with its splendid churches was in an instant 
a heap of ruins, under which ten thousand of the in- 
habitants were buried. On the 5th of April, enormous 
rocks were detached from the mountains. It was be- 
lieved that the mountain Silla lost from 300 to 360 feet 


See E 


| 
i 


VM 
Hi 
ih: 
| 

i 

i 

f 

| 
Ha 


i f 
Le || 
l 

j 

| 


Sh, ae 


a 


—— 


ee eee 


* Rafiles’s Hist. of Java, vol.i. p.25.— Ed. Phil, Journ. 
vol. iii. p. 389. 

tł Life and Services of Sir Stamford Raffles, pi 241. London 
1830. 


Ch. XIV.] EARTHQUAKE OF SOUTH CAROLINA. 203 


of its height by subsidence ; but this was an opinion 
not founded on any measurement. On the 27th of 
April, a volcano in St. Vincent’s threw out ashes; and 
on the 30th, lava flowed from its crater into the sea, 
While its explosions were heard at a distance equal to 
that between Vesuvius and Switzerland, the sound 
being transmitted, as Humboldt supposes, through the 
ground. During the earthquake which destroyed Ca- 
raccas, an immense quantity of water was thrown out 
at Valecillo, near Valencia, as also at Porto Cabello, 
through openings in the earth ; and in the Lake Mara- 
Caybo the water sank. Humboldt observed that the 
Cordilleras, composed of gneiss and mica slate, and the 
country immediately at their foot, were more violently 
Shaken than the plains.* 

South Carolina, 1811.— New Madrid.— Previous 
to the destruction of La Guayra and Caraccas, in 1812, 
South Carolina was convulsed by earthquakes; and 
the shocks continued till those cities were destroyed. 
The valley also of the Mississippi, from the village of 
New Madrid to the mouth of the Ohio in one direc- 
tion, and to the St. Francis in another, was convulsed 
to such a degree as to create lakes and islands. Flint, 
the geographer, who visited the country seven years 

after the event, informs us, that a tract of many miles 
in extent, near the Little Prairie, became covered with 
Water three or four feet deep; and when the water 
disappeared, a stratum of sand was left in its place. 

arge lakes of twenty miles in extent were formed in 
the course of an hour, and others were drained. The 
Srave-yard at New Madrid was precipitated into the 


* Humboldt’s Pers. Nar., vol.iv. p. 12.; and Ed, Phil. Journ., 
Vol. i. p. 272., 1819. 
K 6 


204 ALEUTIAN ISLANDS. —NEW ISLANDS. [Book H 


bed of the Mississippi ; and it is stated that the ground 
whereon the town is built, and the river bank for fifteen 
miles above, sank eight feet below their former level.* 
The neighbouring forest presented for some years 
afterwards “a singular scene of confusion; the trees 
standing inclined in every direction, and many having 
their trunks and branches broken. ” + 

The inhabitants relate that the earth rose in great 
undulations ; and when these reached a certain fearful 
height, the soil burst, and vast volumes of water, sand, 
and pit-coal were discharged as high as the tops of the 
trees. Flint saw hundreds of these deep chasms re- 
maining in an alluvial soil, seven years after. The 
people in the country, although inexperienced in such 
convulsions, had remarked that the chasms in the earth 
were in a direction from S.W. to N.E. ; and they accord- 
ingly felled the tallest trees; and laying them at right 
angles to the chasms, stationed themselves upon them. 
By this invention, when chasms opened more than once 
under these trees several persons were prevented from 
being swallowed up.{ At one period during this earth- 
_ quake, the ground not far below New Madrid swelled 
up so as to arrest the Mississippi in its course, and to 
cause a temporary reflux of its waves. The motion of 
some of the shocks was horizontal, and of others per- 
pendicular ; and the vertical movement is said to have 
been much less desolating than the horizontal. If this 
be often the case, those shocks which injure cities least 
may produce the greatest alteration of level. ` 

Aleutian Islands, 1806. — In the year 1806, a new 


* Cramer’s Navigator, p. 243. Pittsburgh, 1821. 
+ Long’s Exped. to the Rocky Mountains, iii. p. 184. 
+ Silliman’s Journ., Jan. 1829. 


Ch. XIV.] EARTHQUAKES OF NINETEENTH CENTURY. 205 


island, in the form of a peak, with some low conical 
hills upon it, rose from the sea among the Aleutian 
Islands, east of Kamtschatka. According to Langs- 
dorf*, it was four geographical miles in circumference ; 
and Von Buch infers, from its magnitude, and from its 
not having again subsided below the level of the sea, 
that it did not consist merely of ejected matter, but of 
a solid rock of trachyte upheaved.+ Another extra- 
ordinary eruption happened in the spring of the year 
1814, in the sea near Unalaschka, in the same archi- 
Pelago. A new isle was then produced of considerable 
Size, and with a peak three thousand feet high, which 
remained standing for a year afterwards, though with 
Somewhat diminished height. 
Although it is not improbable that earthquakes ac- 
Companying these tremendous eruptions may have 
eaved up part of the bed of the sea, yet the circum- 
Stance of the islands not having disappeared like 
Sabrina (see p. 145.) may have arisen from the emis- 
Sion of lava. If Jorullo, for example, in 1759, had 
risen from a shallow sea to the height of 1600 feet, 
instead of attaining that elevation above the Mexican 
Plateau, the massive current of basaltic lava which 
Poured out from its crater would have enabled it to 
Withstand, for a long period, the action of a turbulent 
Sea, 
Reflections on the earthquakes of the nineteenth cen- 
tury, — We are now about to pass on to the events of 
the eighteenth century; but, before we leave the con- 
Sideration of those already enumerated, let us pause 
for a moment, and reflect how many remarkable facts 


“i Bemerkungen auf einer Reise um die Welt., bd. ii. s. 209, 
+ Neue Allgem. Geogr. Ephemer., bd. iii. s. 348. 


ee ee 


eee 


206 EARTHQUAKE OF QUITO, 1797. [Book II. 


of geological interest are afforded by the earthquakes 
above described, though they constitute but a small 
part of the convulsions even of the last thirty years. 
New rocks have risen from the waters; the tempera- 
ture of a thermal spring has been raised; the coast of 
Chili has been twice permanently elevated; a consi- 
derable tract in the delta of the Indus has sunk down, 
and some of its shallow channels have become navi- 
gable; an adjoining part of the same district, upwards 
of fifty miles in length and sixteen in breadth, has 
been raised about ten feet above its former level ; the 
town of Tomboro has been submerged, and twelve 
thousand of the inhabitants of Sumbawa have been 
destroyed. Yet, with a knowledge of these terrific, 
catastrophes, witnessed during so brief a period by the 
present generation, will the geologist declare with 
perfect composure that the earth has at length settled 
into a state of repose? Will he continue to assert 
that the changes of relative level of land and sea, so 
common in former ages of the world, have now ceased? 
If, in the face of so many striking facts, he persists in 
maintaining this favourite dogma, it is in vain to hope 
that, by accumulating the proofs of similar convulsions 
during a series of antecedent ages, we shall shake his 
tenacity of purpose: — 


Si fractus illabatur orbis, 
Impavidum ferient ruinz. 


EARTHQUAKES OF THE EIGHTEENTH CENTURY. 


Quito, 1797. — On the morning of February 4th, 
1797, the volcano of Tunguragua in Quito, and the 
surrounding district, for forty leagues from south tO 
north, and twenty leagues from west to east, experi- 


Ch. XIV.] - CUMANA, 1797. 207 


enced an undulating movement, which lasted four 
minutes. The same shock was felt over a tract of 
170 leagues from south to north, from Piura to Po- 
payan ; and 140 from west to east, from the sea to 
the river Napo. In the smaller district first men- 
tioned, where the movement was more intense, every 
town was levelled to the ground; and Riobamba, 
Quero, and other places, were buried under masses 
detached from the mountains. At the foot of Tungura- 
gua the earth was rent open in several places; and 
Streams of water and fetid mud, called “ moya,” 
Poured out, overflowing and wasting every thing. In 
Valleys one thousand feet broad, the water of these 
floods reached to the height of six hundred feet‘ 
and the mud deposit barred up the course of the 
tiver, so as to form lakes, which in some places con- 
tinued for more than eighty days. Flames and suffo- 
Cating vapours escaped from the lake Quilotoa, and 
killed all the cattle on its shores. The shocks con- 
tinued all February and March ; and on the fifth of 
April they recurred with almost as much violence as 
at first. We are told that the form of the surface in 
the district most shaken was entirely altered, but no 
exact measurements are given whereby we may esti- 
Mate the degree of elevation or subsidence.* Indeed 
it would be difficult, except in the immediate neigh- 
bourhood of the sea, to obtain any certain standard of 
Comparison, if the levels were really as much altered 
as the narrations imply. 

Cumana, 1797. — In the same year, on the 14th of 

ecember, the small Antilles experienced subterra- 


4 Cavanilles, Journ. de Phys., tome xlix. p. 230, Gilbert’s 
Annalen, bd, vi. p. 67. Humboldt’s Voy., pe 317. 


208 QUEBEC, 1791.—CARACCAS, 1790. — SICILY, 1790, [Book I 


nean movements, and four-fifths of the town of CU 
mana was shaken down by a vertical shock. The form 
of the shoal of Mornerouge, at the mouth of the 
river Bourdones, was changed by an upheaving of the 
ground.* 

Quebec, 1791. — We learn from Captain Bayfield’ 
memoirs, that earthquakes are very frequent on the 
shore of the estuary of the St. Lawrence, of force 
sufficient at times to split walls and throw down chim- 
neys. Such were the effects experienced in Decembe!) 
1791, in St. Paul’s Bay, about fifty miles N. E. from 
Quebec ; and the inhabitants say, that about every 
twenty-five years a violent earthquake returns, which 
lasts forty days. In the History of Canada, it is stated 
that, in 1663, a tremendous convulsion lasted si% 
months, extending from Quebec to Tadeausac, — # 
distance of about 130 miles. The ice on the river was 
broken up, and many landslips caused.+ 

Caraccas, 1790. — In the Caraccas, near where thé 
Caura joins the Orinoco, between the towns San Pedro 
de Alcantara and San Francisco de Aripao, an earth- 
quake, on St. Matthew’s day, 1790, caused a sinking in 
of the granitic soil, and left a lake eight hundred yards 
in diameter, and from eighty to one hundred in depth- 
It was a portion of the forest of Aripao which sub- 
sided, and the trees remained green for several months 
under water. 

Sicily, 1790. — On the 18th of March in the same 
year, at S. Maria di Niscemi, some miles from Terra’ 
nuova, near the south coast of Sicily, the ground gra 


* Humboldt’s Voy., Relat. Hist., parti. p. 309. 
t Macgregor’s Travels in America. 
¢ Humboldt’s Voy., Relat. Hist., part ii. p. 632. 


oh. XIV. JAVA, 1786.—JAPAN ISLES, 1783. 209 


dually sank down for a circumference of three Italian 
miles, during seven shocks; and, in one place, to the 
depth of thirty feet. It continued to subside to the 
€nd of the month. Several fissures sent forth sulphur, 
Petroleum, steam, and hot water; and a stream of mud, 
Which flowed for two hours, and covered a space sixty 
feet long, and thirty broad. This happened far from 
both the ancient and modern volcanic district, in a 
Stoup of strata consisting chiefly of blue clay.* 

Java, 1786. — About the year 1786, an earthquake 
Was felt at intervals, for the period of four months, in 
the neighbourhood of Batur, in Java, and an eruption 
followed. Various rents were formed, which emitted 
à sulphureous vapour; separate tracts sunk away, and 
Were swallowed by the earth. Into one of these the 
rivulet Dotog entered, and afterwards. continued to 
follow a subterraneous course. The village of Jam- 
Pang was buried in the ground, with thirty-eight of its 
Inhabitants, who had not time to escape. We are in- 
debted to Dr. Horsfield for having verified the above- 
Mentioned facts.+ 

Japan Isles, 1783.—In the province of Sinano, in 
the Isle of Nifon, the volcanic mountain of Asama- 
Yama, situated north-east of the town of Komoro, was 
m violent eruption August 1. 1783. The eruption — 
Was preceded by a frightful earthquake; gulphs are 
Said to have opened every where, and many towns to 

ave been swallowed up, while others were subse- 
quently buried by lava. ¢ 


* Ferrara, Camp. fl., p. 51. 
t Batav. Trans., vol. viii. p. 141. 
ł Humboldt, Fragmens Asiatiques, &c., tom. i. p. 229. 


\ 


Fan aR PRES ge 


CHAPTER XV. 
EARTHQUAKE IN CALABRIA, 1783. 


Earthquake in Calabria, February 5. 1783 — Shocks continued t 
the end of the year 1786 — Authorities — Area convulsed— 
Geological structure of the district — Difficulty of ascertaining 
changes of level (p. 217.) — Subsidence of the quay at Messina 
— Shift or fault in the Round Tower of Terranuova — Mov 
ment in the stones of two obelisks — Opening and closing of 
fissures — Large edifices engulphed — Dimensions of ne 
caverns and fissures (p. 225.) — Gradual closing in of rents 
Bounding of detached masses into the air— Landslips— 
Buildings transported entire to great distances (p, 231, )—New 
lakes — Currents of mud — Funnel-shaped hollows in alluvi@ 
plains — Fall of cliffs, and shore near Scilla inundated — State 
of Stromboli and Etna during the shocks — How earthquake 
contribute to the formation of valleys (p. 237.) — Concluding 


remarks. 


Calabria, 1783.— Or the numerous earthquakes 
which have occurred in different parts of the glob 
during the last hundred years, that of Calabria, in 
1783, is almost the only one of which the geologist 
can be said to have such a circumstantial account as t0 
enable him fully to appreciate the changes which this 


cause is capable of producing in the lapse of age 


The shocks began in February, 1783, and lasted for 
nearly four years, to the end of 1786. Neither in 
duration, nor in violence, nor in the extent of territory 
moved, was this convulsion remarkable, when C0” 
trasted with many experienced in other countries 


Ch. XV] EARTHQUAKE IN CALABRIA, 1783. = eae 


both during the last and present century; nor were 
the alterations which it occasioned in the relative 
level of hill and valley, land and sea, so great as those 
effected by some subterranean movements in South 
America, in later times. The importance of the 
€arthquake in question arises from the circumstance, 
that Calabria is the only spot hitherto visited, both 
during and after the convulsions, by men possessing 
Sufficient leisure, zeal, and scientific information, to 
enable them to collect and describe with accuracy the 
Physical facts which throw light on geological ques- 
tions. 


\ ill Sy i 
“tt ZR MUM pay. 
BUNS NE 


b'Lerral 


J. Spartivento 


| 
i 
| 
| } 
| 

| 

i 


212 EARTHQUAKE IN CALABRIA, 1783. [Book I£ 


Authorities. — Among the numerous authorities, Vi- 
venzio, physician to the King of Naples, transmitted t0 
the court a regular statement of his observations during 
the continuance of the shocks; and his narrative 4 
drawn up with care and clearness.* Francesco AT- 
tonio Grimaldi, then secretary of war, visited the 
different provinces at the king’s command, and pub- 
lished a most detailed description of the permanent 
changes in the surface.+ He measured the length; 
breadth, and depth of the different fissures and gulpbs 
which opened, and ascertained their number in many 
provinces. His comments, moreover, on the reports 
of the inhabitants, and his explanations of their rela- 
tions, are judicious and instructive. Pignataro, 4 
physician residing at Monteleone, a town placed in 
the very centre of the convulsions, kept a register of 
the shocks, distinguishing them into four classes 
according to their degree of violence. From his work; 
it appears that, in the year 1783, the number was 949; 
of which 501 were shocks of the first degree of force; 
and in the following year there were 151, of which 98 
were of the first magnitude. 

Count Ippolito, also, and many others, wrote de- 
scriptions of the earthquake ; and the Royal Academy 
of Naples, not satisfied with these and other observ- 
ations, sent a deputation from their own body inte 
Calabria, before the shocks had ceased, who were 
accompanied by artists instructed to illustrate bY 
drawings the physical changes of the district, and thé 
state of ruined towns and edifices. Unfortunately 
these artists were not very successful in their repre- 

* Istoria de’ Tremuoti della Calabria del 1783. 


t Descriz. de? Tremuoti Accad. nelle Calabria nel 178% 
Napoli, 1784, 


Ch. Xv. EARTHQUAKE IN CALABRIA, 1783. 913 


Sentations of the condition of the country, particularly 
when they attempted to express, on a large scale, the 
extraordinary revolutions which many of the great and 
Minor river-courses underwent. But many of the 
Plates published by the Academy are valuable; and 
as they are little known, I shall frequently avail my- 
Self of them to illustrate the facts about to be de- 
Scribed.* 

In addition to these Neapolitan sources of inform. 
ation, our countryman, Sir William Hamilton, sur- 
veyed the district, not without some personal risk, 
before the shocks had ceased; and his sketch, pub- 
lished in the Philosophical Transactions, supplies many 
‘facts that would otherwise have been lost. He has 
*xplained in a rational manner many events which, 
4s related in the language of some eyewitnesses, 
appeared marvellous and incredible. Dolomieu also 
€xamined Calabria during the catastrophe, and wrote 
an account of the earthquake, correcting a mistake 
into which Hamilton had fallen, who supposed that 
à part of the tract shaken had consisted of volcanic 
tuff. It is, indeed, a circumstance which enhances 
the geological interest of the commotions which so 
often modify the surface of Calabria, that they are 
Confined to a country where there are neither ancient 
Nor modern rocks of volcanic or trappean origin ; so 
that at some future time, when the era of disturbance 
Shall have passed by, the cause of former revolutions 
Will be as latent as in parts of Great Britain now 
°ccupied exclusively by ancient marine formations. 


_ * Istoria de’ Fenomeni del Tremoto, &c. nell’ An. 1788, posta 
™ luce dalla Real. Accad., &c. di Nap. Napoli, 1784. fol. 


214 ‘EXTENT OF THE AREA CONVULSED. [Book IL 


Extent of the area convulsed.—The convulsion of 
the earth, sea, and air extended over the whole © 
Calabria Ultra, the south-east part of Calabria Citr® 
and across the sea to Messina and its environs ; ? 
district lying between the 38th and 39th degrees of 
latitude. The concussion was perceptible over a great 
part of Sicily, and as far north as Naples ; but the 
surface over which the shocks acted so forcibly as t0 
excite intense alarm did not generally exceed five 
hundred square miles in area. The soil of that part 
of Calabria is composed chiefly, like the southern part 
of Sicily, of calcareo-argillaceous strata of great thick- 
ness, containing marine shells. This clay is sometime 
associated with beds of sand and limestone. For thé 
most part these -formations resemble in appearance a? 
consistency the Subapennine marls, with their accom” 
panying sands and sandstones; and the whole group 
bears considerable resemblance, in the yielding natur? 
of its materials, to most of our tertiary deposits iD 
France and England. Chronologically considered, how” 
ever, the Calabrian formations are comparatively of 
very modern date, and abound in‘fossil shells referrible 
to species now living in the Mediterranean. 

We learn from Vivenzio that, on the 20th and g6th 
of March, 1783, earthquakes occurred in the islands 0 
Zante, Cephalonia, and St. Maura; and in the last- 
mentioned island several public edifices and- private 
houses were overthrown, and many people destroyed: 
It has been already shown that the Ionian Islands fal 
within the line of the same great volcanic regio” 
as Calabria; so that both earthquakes were probably 
derived from a common source, and it is not imp? 
bable that the bed of the whole intermediate sea W# 
convulsed. 


th. XV.J EARTHQUAKE IN CALABRIA, 1783. 9215 


If the city of Oppido, in Calabria; be taken asa 
Centre, and round that centre a circle be described, 
With a radius of twenty-two miles, this space will com- 
Prehend the surface of the country which suffered the 
Sreatest alteration, and where all the towns and vil- 
lages were destroyed. The first shock, of February 
Sth, 1783, threw down, in two minutes, the greater 
Part of the houses in all the cities, towns, and villages, 
from the western flanks of the Apennines in Calabria 

ltra to Messina in Sicily, and convulsed the whole 
Surface of the country. Another occurred on the 28th 
of March, with almost equal violence. The granitic 
Chain which passes through Calabria from north to 
South, and attains the height of many thousand feet, 
Was shaken but slightly by the first shock, but more 
tudely by some which followed. 

Some writers have asserted that the wavelike move- 
Ments which were propagated through the recent 
Strata, from west to east, became very violent when 
they reached the point of junction with the granite, 
as if a reaction was produced where the undulatory 
Movement of the soft strata was suddenly arrested by 
the more solid rocks. But the statement of Dolomieu 
n this subject is most interesting, and, perhaps, in a 
8€ological point of view, the most important of all the 
Observations which are recorded.* 

The Apennines, he says, which consist in great part 
of hard and solid granite, with some micaceous and 
argillaceous schists, form bare mountains with steep 
Sides, and exhibit marks of great degradation. At their 

ase newer strata are seen of sand and clay, mingled 


E Dissertation on the Calabrian Earthquake, &c., translated in 
tnkerton’s Voyages and Travels, vol. v. 


216 EARTHQUAKE IN CALABRIA, 1783. [Book IÈ 


with shells; a marine deposit containing such ingredi- 
ents as would result from the decomposition of granite. 
The surface of this newer (tertiary) formation consti- 
tutes what is called the plain of Calabria —a platfor™ 
which is flat and level, except where intersected bY 
narrow valleys or ravines, which rivers and torrents 
have excavated sometimes to the depth of six hundred 
feet. The sides of these ravines are almost perpe” 
dicular ; for the superior stratum, being bound togethe" 
by the roots of trees, prevents the formation of 4 
sloping bank. The usual effect of the earthquake, he 
continues, was to disconnect all those masses whic 
either had not sufficient bases for their bulk, or which 
were supported only by lateral adherence. Hence it 
follows that throughout almost the whole length of thé 
chain the soil which adhered to the granite at the bas? 
of the mountains Caulone, Esope, Sagra, and Aspr? 
monte, slid over the solid and steeply inclined nucleus 
and descended somewhat lower, leaving almost uni”? 
terruptedly from St. George to beyond St. Christina, * 
distance of from nine to ten miles, a chasm betwee? 
the solid granitic nucleus and the sandy soil. Many 
lands slipping thus were carried to a considerable dis- 
tance from their former position, so as entirely to covet 
others ; and disputes arose as to whom the property 
which had thus shifted its place should belong. 

From this account of Dolomieu we might anticipat® 
as the result of a continuance of such earthquakes, firsts 
a longitudinal valley following the line of junction ° 
the older and newer rocks ; secondly, greater distusb- 
ance in the newer strata near the point of contact 
than at a greater distance from the mountains ; phe- 
nomena very common in other parts of Italy at the 
junction of the Apennine and Subapennine formation® 


Ch. XV.] CHANGES OF RELATIVE LEVEL. ONT 


The surface of the country often heaved, like the 
billows of a swelling sea, which produced a swimming 
in the head, like sea-sickness. Itis particularly stated, 
in almost all the accounts, that just before each shock 
the clouds appeared motionless ; and, although no ex- 
planation is offered of this phenomenon, it is obviously 
the same as that observed in a ship at sea when it 
Pitches violently. The clouds seem arrested in their 
career as often as the vessel rises in a direction con- 
trary to their course ; so that the Calabrians must have 
experienced precisely the same motion on the land. 

Trees, supported by their trunks, sometimes bent 
during the shocks to the earth, and touched it with 
their tops. This is mentioned as a well-known fact by 
Dolomieu; and he assures us that he was always on 
his guard against the spirit of exaggeration in which 
the vulgar are ever ready to indulge when relating 
these wonderful occurrences. 

I shall now consider, in the first place, that class of 
Physical changes produced by the earthquake which 
are connected with alterations in the relative level of 
the different parts of the land ; and afterwards de- 
Scribe those which are more immediately connected 
With the derangement of the regular drainage of the 
Country, and where the force of running water co- 
operated with that of the earthquake. 

Difficulty of ascertaining changes of level. —In regard 
to alterations of relative level, none of the accounts 
establish that they were on a considerable scale; but 
t must always be remembered that, in proportion to 
the area moved is the difficulty of proving that the 
general level has undergone any change, unless the 
Sea-coast happens to have participated in the principal 
Movement. Even then it is often impossible to deter- 

VOL, Il. ie 


218 | EARTHQUAKE IN CALABRIA, 1783. [Book I. 


mine whether an elevation or depression even of seve- 
ral feet has occurred, because there is nothing tO 
attract notice in a band of shingle and sand of unequal 
breadth above the level of the sea running parallel to 
a coast; such bands generally marking the point reached 
by the waves during spring tides, or the most violent 
tempests. The scientific investigator has not sufficient 
topographical knowledge to discover whether the ex- 
tent of beach has diminished or increased; and he 
who has the necessary local information scarcely ever 
feels any interest in ascertaining the amount of the 
rise or fall of the ground. Add to this the great dif- 
ficulty of making correct observations, in consequence 
of the enormous waves which roll in upon a coast 
during an earthquake, and efface every landmark neat 
the shore. 

Subsidence of the Quay at Messina. — It is evidently 
in seaports alone that we can look for very accurate 
indications of slight changes of level; and when we 
find them, we may presume that they would not be 
rare at other points, if equal facilities of comparing 
relative altitudes were afforded. Grimaldi states (and 
his account is confirmed by Hamilton and others), that 
at Messina, in Sicily, the shore was rent; and the soil 
along the port, which before the shock was perfectly 
level, was found afterwards to be inclined towards the 
sea, — the sea itself near the “ Banchina ” becoming 
deeper, and its bottom in several places disordered. 
The quay also sunk down about fourteen inches below 
the level of the sea, and the houses in its vicinity were 
much fissured. (Phil. Trans. 1783.) 

Among various proofs of partial elevation and de- 
pression in the interior, the Academicians mention, i? 
their Survey, that the ground was sometimes on the 


Ch. Xv] CHANGES OF RELATIVE LEVEL. 219 


Same level on both sides of new ravines and fissures, 
but sometimes there had been a considerable shifting, 
either by the upheaving of one side, or the subsidence 
of the other. Thus, on the sides of long rents in the 
territory of Soriano, the stratified masses had altered 
their relative position to the extent of from eight to 
fourteen palms (six to ten and a half feet). 

Polistena. — Similar shifts in the strata are alluded 
to in the territory of Polistena, where there appeared 
innumerable fissures in the earth. One of these was 
of great length and depth; and in parts the level 
of the corresponding sides was greatly changed. (See 
Fig. 44.) 

Terranuova. — In the town of Terranuova some 
Ouses were seen uplifted above the common level, 
and others adjoining sunk down into the earth. In 
Several streets the soil appeared thrust up, and abutted 
against the walls of houses; a large circular tower of 
Solid masonry, part of which had withstood the gene- 


Deep fissure near Polistena, caused by the earthquake of \783. 
L 2 


220 EARTHQUAKE IN CALABRIA, 1783, [Book IL 


ral destruction, was divided by a vertical rent, and one 
side was upraised, and the foundations heaved out of 
the ground. It was compared by the Academicians- 
to a great tooth half extracted from the alveolus, with 
the upper part of the fangs exposed. (See Fig. 45-) 


Shift or “ fault” in the round tower of Terranuova in Calabria, occasioned bY 
the earthquake of 1783, 


Along the line of this shift, or “fault,” as it would 
be termed technically by miners, the walls were found 
to adhere firmly to each other, and to fit so well, that 
the only signs of their having been disunited was the 
want of correspondence in the courses of stone 0? 
either side of the rent. 

Dolomieu saw a stone well in the convent of the 
Augustins at Terranuova, which had the appearance 
of having been driven out of the earth. It resembled 
a small tower eight or nine feet in height, and a little 
inclined. This effect, he says, was produced by the 


Ch. xv.J CHANGES OF RELATIVE LEVEL. 991 


Consolidation and consequent sinking of the sandy soil 
m which the well was dug. 

Th some walls which had been thrown down, or 
“iclently shaken, in Monteleone, the separate stones 
Were parted from the mortar, so as to leave an exact 
mould where they had rested; whereas in other cases 
the mortar was ground to dust between the stones. 

It appears that the wave-like motions, and those 
Which are called vorticose or whirling in a vortex, 
often produced effects of the most capricious kind. 
Thus, in some streets of Monteleone, every house was 
thrown down but one; in others, all but two; and the 
buildings which were spared were often scarcely in 
the least degree injured. 

_ In many cities of Calabria, all the most solid build- 
ngs. were thrown down, while those which were 
slightly built escaped; but at Rosarno, as also at Mes- 
Sina in Sicily, it was precisely the reverse, the massive 
edifices being the only ones that stood. Two obelisks 
(Fig, 46.) placed at the extremities of a magnificent 


Shift in the stones of two obelisks in the Convent of S. Bruno. 


TO 


299 EARTHQUAKE IN CALABRIA, 1783. [Book I. 


façade in the convent of S. Bruno, in a small tow? 
called Stefano del Bosco, were observed to have under- 
. gone a movement of a singular kind. ‘The shock 
which agitated the building is described as having 
been horizontal and vorticose. The pedestal of each 
_ obelisk remained in its original place ; but the separate 
stones above were turned partially round, and removed 
Sometimes nine inches from their position without 
falling. 

Fissures.—It appears evident that a great part of 
the rending and fissuring of the ground was the effect 
of a violent motion from below upwards ; and in 2 
multitude of cases where the rents and chasms opened 
and closed alternately, we must suppose that the earth 
was by turns heaved up, and then let fall again. We 
may conceive the same effect to be produced on 4 
small scale, if, by some mechanical force, a pavement 
composed of large flags of stone should be raised up 
and then allowed to fall suddenly, so as to resume its 
original position. If any small pebbles happened to be 
lying on the line of contact of two flags, they would 
fall into the opening when the pavement rose, and be 
swallowed up, so that no trace of them would appeat 
after the subsidence of the stones. In the same mal 
ner, when the earth was upheaved, large houses, trees» 
cattle, and men were engulphed in an instant in chasms 
and fissures; and when the ground sank down again: 
the earth closed upon them, so that no vestige of them 
was discoverable on the surface. In many instances. 
individuals were swallowed up by one shock, and the? 
thrown out again alive, together with large jets of 
water, by the shock which immediately succeeded. 

At Jerocarne, a country which, according to the 
Academicians, was dacerated in a most extraordinary 


Ch. XV.] HOUSES ENGULPHED. 293 


Manner, the fissures ran in every direction “ like 
cracks on a broken pane of glass” (see Fig. 47 .); and, 


ca 


Fissures near Jerocarne, in Calabria, caused by the earthquake of 1783. 


as a great portion of them remained open after the 
Shocks, it is very possible that this country was perma- 
nently upraised. It was usual, as we learn from Dolo- 
mieu, for the chasms and fissures throughout Calabria 
to run parallel to the course of some pre-existing 
gorges in their neighbourhood. 

Houses engulphed.— In the vicinity of Oppido, the 
Central point from which the earthquake diffused its 
violent movements, many houses were swallowed up 
by the yawning earth, which closed immediately over 
them. In the adjacent district, also, of Cannamaria 
four farm-houses, several oil-stores, and some spacious 
dwelling-houses were so completely engulphed in one 
Chasm, that not a vestige of them was afterwards dis- 
Cernible. The same phenomenon occurred at Terra- 
nuova, S. Christina, and Sinopoli. The Academicians 
State particularly, that when deep abysses had opened 

L 4 


224 EARTHQUAKE IN CALABRIA 1783. [Book I. 


in the argillaceous strata of. Terranuova, and houses 
had sunk into them, the sides of the chasms closed 
with such violence, that, on excavating afterwards 0 
recover articles of value, the workmen found the con- 
tents and detached parts of the buildings jammed 
together so as to become one compact mass. It is 
unnecessary to accumulate examples of similar occut- 
rences; but so many are well authenticated during 
this earthquake in Calabria, that we may, without 
hesitation, yield assent to the accounts of catastrophes 
of the same kind repeated again and again in history» 
where whole towns are declared to have been en- 
gulphed, and nothing but a pool of water or tract of 
sand left in their place. 

Chasm formed near Oppido.— On the sloping side of 
a hill near Oppido a great chasm opened; and, although 
a large quantity of soil was precipitated into the abyss; 


together with a considerable number of olive-trees and 
part of a vineyard, a great gulph remained after the 
shock, in the form of an amphitheatre, 500 feet long 
and 200 feet deep. (See Fig. 48.) 


Chasm formed by the earthquake of 1783 near Oppido, in Calabria. 


Ch. Xv.) FORMATION OF NEW LAKES, 225 


_ Dimensions of new fissures and chasms.— Accord- 
‘ng to Grimaldi, many fissures and chasms, formed by 
the first shock of February 5th, were greatly widened, 
lengthened, and deepened by the violent convulsions 
of March 28th. In the territory of San Fili this ob- 
Server found a new ravine, half a mile in length, two 
feet and a half broad, and twenty-five feet deep ; and 
another of similar dimensions in the territory of Rosarno. 
A ravine nearly a mile long, 105 feet broad, and thirty 
feet deep, opened in the district of Plaisano, where, 

So, two gulphs were caused—one in a place called 

rzulle, three quarters of a mile long, 150 feet broad, 
wd above one hundred feet deep; and another at La 

ortuna, nearly a quarter of a mile long, above thirty 
feet in breadth, and no less than 225 feet deep. 

In the district of Fosolano three gulphs opened: one 
of these measured 300 feet square, and above 
thir ty feet deep; another was nearly half a mile 
ong, fifteen feet broad, and above thirty feet deep ; 
the third was 750 feet square. Lastly, a calcareous 
Mountain, called Zefirio, at the southern extremity of 
the Italian peninsula, was cleft in two for the length of 
Nearly half a mile, and an irregular breadth of many 
fet. Some of these chasms were in the form of a 
“escent. The annexed cut (Fig. 48.) represents one 
Y no means remarkable for its dimensions, which 
“emained open by the side of a small pass over the hill 
a Sts Angelo, near Soriano. The small river Mesima 
'S seen in the foreground. 

Formation of new lakes.—In the vicinity of Semi- 
Nara, a lake was suddenly formed by the opening of a 
Steat chasm, from the bottom of which water issued. 

his lake was called Lago del Tolfilo. It extended 

L5 


g 


EARTHQUAKE IN CALABRIA, 1783, [Book I 


Chasm in the hil of St. Angelo, near Soriano, in Calabria, caused by the 
earthquake of 1783. 

1785 feet in length, by 937 in breadth, and 52 iP 
depth. The inhabitants, dreading the miasma of this 
stagnant pool, endeavoured, at great cost, to drain ! 
by canals, but without success, as it was fed by springs 
issuing from the bottom of the deep chasm. A small 
circular subsidence occurred not far from Polistena, 0 
which a representation is given (fig. 50. p. 227.). 

Gradual closing in of fissures. —Sir W. Hamilto® 
was shown several deep fissures in the vicinity ° 
Mileto, which, although not one of them was above ê 
foot in breadth, had opened so wide during the garth- 
quake as to swallow up an ox and nearly one hundred 
goats. The Academicians also found, on their retur” 
through districts which they had passed at the co™- 
mencement of their tour, that many rents had, in that 
short interval, gradually closed in, so that their width 


CLOSING IN OF FISSURES, 


4 


Circular pond near Polistena, in Calabria, caused by the earthquake in 1783. 


had diminished several feet, and the opposite walls had 
Sometimes nearly met. It is natural that this should 
happen in argillaceous strata, while, in more solid 
Tocks, we may expect that fissures will remain open 
for ages. Should this be ascertained to be a general 
fact in countries convulsed by earthquakes, it may 
afford a satisfactory explanation of a common pheno- 
Menon in mineral veins. Such veins often retain their 
full size so long as the rocks consist of limestone, 
granite, or other indurated materials; but they con- 
tract their dimensions, become mere threads, or are 
€ven entirely cut off, where masses of an argillaceous 
Nature are interposed. If we suppose the filling up 
of fissures with metallic and other ingredients to be a 
Process requiring ages for its completion, it is obvious 
that the opposite walls of rents, where strata consist of 
Yielding materials, must collapse or approach very 
Near to each other before sufficient time is allowed for 
the accretion of a large quantity of veinstone. 
L6 


Se ae 
= —. 


-A 


ie 
Ho E 
ae 3 
$F 

i 
[i 1 
5 


228 EARTHQUAKE IN CALABRIA, 1783. [Book TI 


Thermal waters augmented.—It is stated by Gri- 
maldi, that the thermal waters of St. Eufemia, in 
Terra di Amato, which first burst out during the 
earthquake of 1638, acquired, in February, 1783, an 
augmentation both in quantity and degree of heat. 
This fact appears to indicate a connection between the 
heat of the interior and the fissures caused by the 
Calabrian earthquakes, notwithstanding the absence of 
volcanic rocks, either ancient or modern, in that district: 

Bounding of detached masses into the air.— The vio- 
lence of the movement of the ground upwards was 
singularly illustrated by what the Academicans call 
the ‘sbalzo,”: or bounding into the air, to the height 
of several yards, of masses slightly adhering to the 
surface. In some towns, a great part of the pave- 
ment stones were thrown up, and found lying with 
their lower sides uppermost., In these cases, we 
must suppose that they were propelled upwards by 
the momentum which they had acquired; and that the 
adhesion of one end of the mass being greater than 
that of the other, a rotatory motion had been commu- 
nicated to them. When the stone was projected to a 
sufficient height to perform somewhat more than a 
quarter of a revolution in the air, it pitched down on 
its edge, and fell with its lower side uppermost. 

Effects of earthquakes on the excavation of valleys.— 
The next class of effects to be considered, are those 
more immediately connected with the formation of 
valleys, in which the action of water was often com- 
bined with that of the earthquake. The country 
agitated was composed, as before stated, chiefly of . 
argillaceous strata, intersected by deep narrow valleys, 
sometimes from five to six hundred feet deep. AS 
the boundary cliffs were in great part vertical, it will 


Ch, XV.) 


LANDSLIPS, 229 


readily be conceived that, amidst the various move- 
ments of the earth, the precipices overhanging rivers, 
eing without support on one side, were often thrown 
down, We find, indeed, that inundations produced by 
obstructions in river-courses are among the most dis- 
astrous consequences of great earthquakes in all parts 
of the world; for the alluvial plains in the bottoms of 
Valleys are usually the most fertile and well-peopled 
Parts of the whole country; and whether the site of a 
town is above or below a temporary barrier in the 
Channel of a river, it is exposed to injury by the waters 
fither of a lake or flood. 
Landslips.— From each side of the deep valley or . 
‘avine of Terranuova, enormous masses of the adjoin- 
Ng flat country were detached, and cast down into the 
“ourse of the river, so as to give rise to great lakes. 
aks, olive-trees, vineyards, and corn, were often seen 
Stowing at the bottom of the ravine, as little injured 
aS their former companions, which still continued to 
flourish in the plain above, at least five hundred feet 
igher, and at the distance of about three quarters of 
a mile. In one part of this ravine was an enormous 
mass, two hundred feet high, and about four hundred 
feet at its base, which had been detached by some 
former earthquake. It is well attested, that this mass 
travelled down the ravine nearly four miles, having 
ĉen put in motion by the earthquake of the 5th of 
bruary. Hamilton, after examining the spot, de- 
Clared that this phenomenon might be accounted for 
Y the declivity of the valley, the great abundance of 
Tain. which fell, and the great weight of the alluvial 
Matter which pressed behind it. Dolomieu also al- 
ludes to the fresh impulse derived from other masses . 


230 EARTHQUAKE IN CALABRIA, 1783, [Book J: 


falling, and pressing upon the rear of those first set i? 
motion. 

The first account sent to Naples of the two great 
slides or landslips above alluded to, which caused 4 
great lake near Terranuova, was couched in these 
words :—«“ Two mountains on the opposite sides of 4 
valley walked from their original position until they 
met in the middle of. the plain, and there joining to- 
gether, they intercepted the course of a river,” &¢ 
The expressions here used resemble singularly thosé 
applied to phenomena, -probably very analogous, which 

are said to have occurred at Fez, during the grea 
Lisbon earthquake, as also in Jamaica and Java at 
other periods. 

Not far from Soriano, which was levelled to the 
ground by the great shock of February, a small valley» 
containing a beautiful olive-grove, called Fra Ramond 
underwent a most extraordinary revolution. Inno 
merable fissures first traversed the river-plain in all 
directions, and absorbed the water until the argilla- 
ceous substratum became soaked, so that a great part 
of it was reduced to a state of fluid paste. Strange 
alterations in the outline of the ground were the cor 
Sequence, as the soil to a great depth was easily 
moulded into any form. In addition to this change 
the ruins of the neighbouring hills were precipitated 
into the hollow ; and while many olives were uprooted; 
others remained growing on the fallen masses, and in- 
clined at various angles (see Fig. 51). The small rive? 
Caridi was entirely concealed for many days; aP? 
when at length it reappeared, it had shaped for itse! 
an entirely new. channel. 


en SS a ae e ES Tr Rape 
ee = = ne AES a ees SSE sae 


i 
ia 
ih 

| 

| 


f 

i 

i i 
l |i | 
f l 

W He A 


Saws 


7 = eae PEPER 


Ch. XV] BUILDINGS TRANSPORTED BY LANDSLIPS. 231 


Changes of the surface at Tek Tioti near Soriano, in Calabria. 
1. Portion of a hill covered with olives thrown down. 

2. New bed of the river Caridi. 3. Town of Soriano. 

Buildings transported entire to great distances. — 
Near Seminara, an extensive olive-ground and orchard 
were hurled to a distance of two hundred feet, into a 
valley sixty feet in depth. At the same time a deep 
chasm was riven in another part of the high platform 
from which the orchard had been detached, and the 
river immediately entered the fissure, leaving its for- 
mer bed completely dry. A small inhabited house, 
standing on the mass of earth carried down into the 
valley, went along with it entire, and without injury to 
the inhabitants. The olive trees, also, continued to 
grow on the land which had slid into the valley, and 
bore the same year an abundant crop of fruit. 

Two tracts of land on which a great part of the 
town of Polistena stood, consisting of some hundreds 


232 EARTHQUAKE IN CALABRIA, 1783. [Book II. 


of houses, were detached into a contiguous ravine; 
and nearly across it, about half a mile from their origi- 
nal site ; and what is most extraordinary, several of the 
inhabitants were dug out from the ruins alive and 
unhurt, 

Two tenements, near Mileto, called the Macini and 
Vaticano, about a mile long, and half a mile broad, 
were carried for a mile down a valley. A thatched 
cottage, together with large olive and mulberry trees, 
most of which remained erect, were carried uninjured 
to this extraordinary distance. According to Hamil- 
ton, the surface removed had been long undermined by 
rivulets, which were afterwards in full view on the bare 
spot deserted by the tenements. The earthquake seems 
to have opened a passage in the adjoining argillaceous 
hills, which admitted water charged with loose soil 
into the subterranean channels of the rivulets imme- 
diately under the tenements, so that the foundatiens 
of the ground set in motion by the earthquake were 
loosened. Another example of subsidence, where the 
edifices were not destroyed, is mentioned by Grimaldi, 
as having taken place in the city of Catanzaro, the 
capital of the province of that name. The houses in 
the quarter called San Giuseppe subsided with the 
ground to various depths from two to four feet, but the 
buildings remained uninjured. 

It would be tedious, and our space would not permit 
us, to follow the different authors through their local 
details of landslips produced in minor valleys ; but 
they are highly interesting, as showing to how great 
an extent the power of rivers to widen valleys, and to 
carry away large portions of soil towards the sea, is 
increased where earthquakes are of periodical occur- 
rence. Among other territories, that of Cinquefrondi 


Ch.XV.] NEW-FORMED LAKES—CURRENTS OF MUD. 233 


Was greatly convulsed, various portions of soil being 
Taised or sunk, and innumerable fissures traversing the 
Country in all direction (see Fig. 52.). Along the flanks 
of a small valley in this district there appears to have 
Deen an almost uninterrupted line of landslips. 
Number of new-formed lakes. — Vivenzio states, that 
ear Sitizzano a valley was nearly filled up to a level 
With the high grounds on each side, by the enormous 
Masses detached from the boundary hills, and cast 
down into the course of two streams. By this barrier 
à lake was formed of great depth, about two miles long 
and a mile broad. The same author mentions that, 
Upon the whole, there were fifty lakes occasioned 
during the convulsions: and he assigns localities to all 
OE these. The government surveyors enumerated 215 


akes, but they included in this number many small 
Ponds, 


Currents of mud. — Near S. Lucido, among other 


Fig. 52. 


= 


Landslips near Cinquefrondi, caused by the earthquake of 1783. 


234 EARTHQUAKE IN CALABRIA, 1783. [Book II 


places, the soil is described as having been “ dis- 
solved,” so that large torrents of mud inundated all 
the low grounds, like lava. Just emerging from this 
mud, the tops only of trees and of the ruins of farm- 
houses were seen. Two miles from Laureana, thé 
swampy soil in two ravines became filled with calca- 
reous matter, which oozed out from the ground imm@ 
diately before the first great shock. This mud, rapidly 
accumulating, began, ere long, to roll onward, like # 
flood of lava, into the valley, where the two stream 
uniting, moved forward with increased impetus fro™ 
east to west. It now presented a breadth of 225 feet 
by fifteen in depth, and, before it ceased to mov® 
covered a surface equal in length to an Italian mile 
In its progress it overwhelmed a flock of thirty goat 
and tore up by the roots many olive and mulberry“ 
trees, which floated like ships upon its surface. Whe? 
ah ae == Fig. 53- 


K Eeti 


Circular hollows in the plain of Rosarno, formed by the earthquake of 1783. 


Ch.XV.] FORMATION OF CIRCULAR HOLLOWS. 235 


this calcareous lava had ceased to move, it gradually 

€came dry and hard, during which process the mass 
Was lowered seven feet and a half. It contained 
fragments of earth of a ferruginous colour, and emit- 
ting a sulphureous smell. 

Cones of sand thrown up. — Many of the appearances 
exhibited in the alluvial plains indicate clearly the al- 
ternate rising and sinking of the ground. The first 
effect of the more violent shocks was usually to dry 
Up the rivers, but they immediately afterwards over- 
flowed their banks. Along the alluvial plains, and in 
marshy places, an immense number of cones of sand 
Were thrown up. These appearances Hamilton ex- 
Plains, by supposing that the first movement raised 
the fissured plain from below upwards, so that the 
Tivers and stagnant waters in bogs sank down, or at 
least were not upraised with the soil. But when the 
round returned with violence to its former position, 
the water was thrown up in jets through fissures.* 

Formation of circular hollows.—In the report of the 
Academy, we find that some plains were covered with 
Circular hollows, for the most part about the size of 
Carriage-wheels, but often somewhat larger or smaller. 
When filled with water to within a foot or two of the 
Surface, they appeared like wells; but, in general, they 
Were filled with dry sand, sometimes with a concave 
Surface, and at other times convex. (See Fig. 53.) 
On digging down, they found them to be funnel- 
Shaped, and the moist loose sand in the centre marked 
the tube up which the water spouted. ‘The annexed 
Cut (Fig. 54.) represents a section of one of these in- 
verted cones when the water had disappeared, and 
Nothing but dry micaceous sand remained. 

* Phil. Trans., Vol. lxxiii. p. 180. 


SS Ses P 


SSS 


EARTHQUAKE IN CALABRIA, 1783. [Book I- 


. Section of one of the circular hollows Jormed in the plainof Rosarno. 


Fall of the sea cliffs.— Along the sea-coast of the 
straits of Messina, near the celebrated rock of Scilla 
the fall of huge masses detached from the bold and 
lofty cliffs overwhelmed many villas and gardens. At 
Gian Greco a continuous line of cliff, for a mile i 
length, was thrown down. Great agitation was fre- 
quently observed in the bed of the sea during the 
shocks, and, on those parts of the coast where the 
movement was most violent, all kinds of fish were 
taken in abundance, and with unusual facility. Some 
rare species, as that called Cicirelli, which usually lie 
buried in the sand, were taken on the surface of the 
waters in great quantity. The sea is said to have 
boiled up near Messina, and to have been agitated as 
if by a copious discharge of vapours from its bottom- 

Shore near Scilla inundated. —The Prince of Scilla 
had persuaded a great part of his vassals to betake 
themselves to their fishing-boats for safety, and he 
himself had gone on beard. On the night of the 5th 
of February, when some of the people were sleeping 
in the boats, and others on a level plain slightly ele- 


Ch. Xv] EXCAVATION OF VALLEYS. `- 237: 


vated above the sea, the earth rocked, and suddenly 
à great mass was torn from the contiguous Mount 
aci, and thrown down with a dreadful crash upon the 
Plain, Immediately afterwards, the sea, rising more 
than twenty feet above the level of this low tract, 
Tolled foaming over it, and swept away the multitude. 
It then retreated, but soon rushed back again with 
Steater violence, bringing with it some of the people 
4nd animals it had carried away. At the same time 
“very boat was sunk or dashed against the beach, and 
‘Ome of them were swept far inland. The aged 
tince, with 1430 of his people, was destroyed. 
State of Stromboli and Etna during the shocks, — 
he inhabitants of Pizzo remarked that, on the 5th of 
€bruary, 1783, when the first great shock afflicted 
alabria, the volcano of Stromboli, which is in full 
“lew of that town, and at the distance of about fifty 
tiles, smoked less, and threw up a less quantity of 
‘tflamed matter, than it had done for some years pre- 
viously, On the other hand, the great crater of Etna 
§ said to have given out a considerable quantity of 
Yapour towards the beginning, and Stromboli towards 
ae close, of the commotions. But as no eruption 
àPpened from either of these great vents during the 
Whole earthquake, the sources of the Calabrian con- 
Yulsions, and of the volcanic fires of Etna and Strom- 
oli, appear to be very independent of each other; 
less, indeed, they have the same mutual relation as 
“suvius and the volcanos of the Phlegraan Fields 
"nd Ischia, a violent disturbance in one district serving 
ma Safety-valve to the other, and both never being in 
i activity at once. 
teavation of valleys.—It is impossible for the 
S*0logist to consider attentively the effect of this 


| 


SS EE 


238 EARTHQUAKE IN CALABRIA, 1783. [Book I. 


single earthquake of 1783, and to look forward to the 
alterations in the physical condition of the country t° 
which a continued series of such movements will here- 
after give rise, without perceiving that the formation 
of valleys by running water can never be understood, 
if we consider the question independently of the agency 
of earthquakes. It must not be imagined that rivers 
only begin to act when a country is already elevated 
far above the level of the sea, for their action must 
of necessity be most powerful while land is rising 9 
sinking by successive movements. Whether Calabria 
is now undergoing any considerable change of relative 
level, in regard to the sea, or is, upon the whole; 
nearly stationary, is a question which our observations, 
confined almost entirely to the last half century, ca®- 
not possibly enable us to determine. But we knoW 
that strata, containing species of shells identical with 
those now living in the contiguous parts of the Medi- 
terranean, have been raised in that country, as they 
have in Sicily, to the height of several thousand feet 
Now, those geologists who grant that the present 
course of Nature in the inanimate world has continu 
the same since the existing species of animals were in 
being, will not feel surprise that the Calabrian stream’ 
and rivers have cut out of such comparatively mode? 
strata a great system of valleys, varying in depth fro™ 
' fifty to six hundred feet, and often several miles wide, 
if they consider how numerous must have been the 
earthquakes which lifted those recent marine stra? 
to so prodigious a height. Some speculators, indee® 
who disregard the analogy of existing Nature, 4” 
who are always ready to assume that her forces were 
more energetic in by-gone ages, may dispense with 4 
long series of movements, and suppose that Calabr’? 


Ch. Xy.y EXCAVATION OF VALLEYS. 239 


“tose like an exhalation” from the deep, after the 
manner of Milton’s Pandemonium. But such an 
Ypothesis would deprive them of that. peculiar re- 
Noving force required to form a regular system of 
“ep and wide valleys ; for time, which they are so 
‘willing to assume, is essential to the operation. 
“he must be allowed in the intervals between dis- 
Net convulsions, for running water to clear away the 
"uins caused by landslips, otherwise the fallen masses 
Will serve as buttresses, and prevent the succeeding 
“atthquake from exerting its full power. The sides of 
S valley must be again cut away by the stream, and 
Made to form precipices and overhanging cliffs, before 
© next shock can take effect in the same manner. 
Possibly the direction of the succeeding shock 
Y not coincide with that of the valley, a great ex- 
nt of adjacent country being equally shaken. Still 
will usually happen that no permanent geographical 
ange will be produced except in valleys. In them 
ne will occur landslips from the boundary cliffs, and 
ĉse will frequently divert the stream from its ac- 
Wtomed course, causing the original ravine to become 
th wider and more tortuous in its direction. 
ar a single convulsion of extreme violence should 
Bitate at once an entire hydrographical basin, or if 
“shocks should follow each other too rapidly, the 
"eviously existing valleys would be annihilated, in- 
“tead of being modified and enlarged. Every stream 
ight in that case be compelled to begin its operations 
New, and to shape out new channels, instead of con- 
Ning to deepen and widen those already excavated. 
Ut if the subterranean movements have been inter- 
Mtent sand if sufficient periods have always inter- 
“ned between the severer shocks to allow the drainage 


240 EARTHQUAKE IN CALABRIA, 1783. [Book IË 


of the country to be nearly restored to its original 
state, then are both the kind and degree of force SUP” 
plied by which running water may hollow out valley° 
of any depth or size consistent with the elevation abov’ 
the sea which the districts drained by them may hav 
attained. 

When we read of the drying up and desertion of 
the channels of rivers, the accounts most frequent 
refer to their deflection into some other part of the 
same alluvial plain, perhaps several miles distant 
Under certain circumstances; a change of level maf 
undoubtedly force the water to flow over into sow? 
distinct hydrographical basin; but even then it W 
fall immediately into some othèr system of valley® 
already formed. 

We learn from history that, ever since the first 


Greek colonists settled in Calabria, that region ha 


been subject to devastation by earthquakes; and, fot 


the last century and a half, ten years have seldo” 
elapsed without a shock: but the severer convulsio® 
have not only been separated by intervals of twenty? 
fifty, or one hundred years; but have not affect? 
precisely the same points when they recurred. The 
the earthquake of 1783, although confined ‘with 
the same geographical limits as that of 1638, ap 
not very inferior in violence, visited, according 
Grimaldi, very different districts. The points whet? 
the local intensity of the force is developed being thu 
perpetually varied, more time is allowed, for the 1 
moval of separate mountain masses thrown into rive 
channels by each shock. 
When chasms and deep hollows open at the potto™ 
of valleys, they must often be filled with those spat 


: J 
lavas” before described ; and these must. be extreme) 


Ch. XV.] EXCAVATION OF VALLEYS. 241 


analogous to the enormous ancient deposits of mud 
Which are seen in many countries, as in the basin of 
the Tay, Isla, and North Esk rivers, for example, in 
Scotland — alluvions hundreds of feet thick, which are 
Neither stratified nor laminated like the ordinary sedi- 
Ment which subsides from water. Whenever a land- 
Slip blocks up à river, these currents of mud will be 
arrested, and accumulate to an enormous depth. 

The portion of the Calabrian valleys formed within 
the last three thousand years may be inconsiderable 
in amount, compared to that previously formed, just 
as the lavas which have flowed from Etna since the 
historical era constitute but a small proportion of the 
Whole cone. But as a continued series of such erup- 
tions as man has witnessed would reproduce another 
one like Etna, so a sufficient number of earthquakes 
like that of 1783 would enable torrents and rivers to 
"e-excavate all the Calabrian valleys, if they were 
Now to be entirely obliterated. It must be evident 
that more change is effected in two centuries in the 
Width and depth of the valleys of that region, than in 
Many thousand years in a country as undisturbed by 
farthquakes as Great Britain. For the same reason, 
therefore, that he who desires to comprehend the 
Volcanic phenomena of Central France will repair to 

€suvius, Etna, or Hecla, so they who aspire to ex- 
Plain the mode in which valleys are formed, must 
Visit countries where earthquakes are of frequent 
Occurrence. For we may be assured, that the power 
Which uplifted our more ancient tertiary strata of 
marine origin to more than a thousand feet above the 
evel of the sea, co-operated at some former epoch 
With the force of rivers in the removal of large por- 
tions of rock and soil, just as the elevatory power 

VOL. IL M 


| 
if. 
ia 
ii 


ie 


942 EARTHQUAKE IN CALABRIA, 1783. [Book I 


which has upraised new strata to the height of several 
thousand feet in the south of Italy has caused those 
formations to be already intersected by deep valleys 
and ravines. 

Number of persons who perished during the earth- 
quake. — The number of persons who perished during 
the earthquake in the two Calabrias and Sicily 1S 
estimated by Hamilton at about forty thousand, and 
about twenty thousand more died by epidemics, which 
were caused by insufficient nourishment, exposure 1° 
the atmosphere, and malaria, arising from the neW 
stagnant lakes and pools. 

By far the greater number were buried under thé 
ruins of their houses; but many were burnt tO 
death in the conflagrations which almost invariably 
followed the shocks. These fires raged the more 
violently in some cities, such as Oppido, from the 
immense magazines of oil which were consumed. 

Many persons were engulphed in deep fissures, espe 
cially the peasants, when flying across the open country? 
and their skeletons may perhaps be buried in the earth 
to this day, at the depth of several hundred feet. 

When Dolomieu visited Messina after the shock of 
Feb. 5th, he describes the city as still presenting, 3t 
least at a distance, an imperfect image of its ancient 
splendour. Every house was injured, but the walls 
were standing : the whole population had taken refuge 
in wooden huts in the neighbourhood, and all was soli- 
tude and silence in the streets: it seemed as if the city 
had been desolated by the plague, and the impressi0® 
made upon his feelings was that of melancholy and 
sadness. “ But when I passed over to Calabria, and 
first beheld Polistena, the scene of horror almost de~ 
prived me of my faculties; my mind was filled with 


Ch. XV.) NUMBER OF PERSONS WHO PERISHED. 943 


mingled compassion and terror; nothing had escaped ; 
all was levelled with the dust; not a single house or 
piece of wall remained; on all sides were heaps of 
Stone so destitute of form, that they gave no concep- 
tion of there ever having been a town on the spot. 
The stench of the dead bodies still rose from the 
ruins. I conversed with many persons who had been 
buried for three, four, and even for five days ; I ques- 
tioned them respecting their sensations in so dreadful 
à situation, and they agreed that, of all the physical 
Evils they endured, thirst was the most intolerable ; 
and that their mental agony was increased by the idea 
that they were abandoned by their friends, who might 
have rendered them assistance. ”* 

It is supposed that about a fourth part of the inha- 
itants of Polistena, and of some other towns, were 
buried alive, and might have been saved had there 
€en no want of hands; but in so general a cala- 
mity, where each was occupied with his own misfor- 
tunes, or those of his family, aid could rarely be 
obtained. Neither tears, nor supplications, nor pro- 
Mises of high rewards, were listened to. Many 
acts of self-devotion, prompted by parental and con- 
Jugal tenderness, or by friendship, or the gratitude of 
faithful servants, are recorded ; but individual exertions 
Were, for the most part, ineffectual. It frequently hap- 
Pened, that persons in search of those most dear to 
them could hear their moans,— could recognize their 
Voices, — were certain of the exact spot where they lay 
buried beneath their feet, yet could afford them no 
‘uccour, The piled mass resisted all their strength, 
and rendered their efforts of no avail. 

* Dissertation on the Calabrian Earthquake, &c. translated in 


kerton’s Voyages and Travels, vol. v. 


M 2 


Akh EARTHQUAKE IN CALABRIA, 1783. [Book II. 


At Terranuova, four Augustin monks, who had taken 
refuge in a vaulted sacristy, the arch of which conti- 
nued to support an immense pile of ruins, made their 
cries heard for the space of four days. One only of 
the brethren of the whole convent was saved, and “ of 
what avail was his strength to remove the enormous 
weight of rubbish which had overwhelmed his com- 
panions ?” He heard their voices die away gradually; _ 
and when afterwards their four corpses were disin- 
terred, they were found clasped in each other’s arms: 
Affecting narratives are preserved of mothers saved 
after the fifth, sixth, and even seventh day of their 
interment, when their infants or children had perished 
with hunger. y 

It might have been imagined that the sight of suf- 
ferings such as these would have been sufficient to 
awaken sentiments of humanity and pity in the most 
savage breasts, but nothing could exceed the atrocity 
of conduct and moral depravity displayed by the Cala- 
brian peasants : they abandoned the farms, and flocked 
in great numbers into the towns— not to rescue their 
countrymen from a lingering death, but to plunder. 
They dashed through the streets, fearless of danger, | 
amid tottering walls and clouds of dust, trampling 
beneath their feet the bodies of the wounded and half 
buried, and often stripping them, while yet living, of 
their clothes. * 

Concluding remarks. — But to enter more fully into 
these details would be foreign to the purpose of the 
present work, and several volumes would be required 
to give the reader a just idea of the sufferings which 
the inhabitants of many populous districts have under- 


* Dolomieu, ibid. 


Ch. XV.] CONCLUDING REMARKS. 245 


Sone during the earthquakes of the last 140 years. 
A bare mention of the loss of life — as that fifty or a 
hundred thousand souls perished in one catastrophe — 
conveys to the reader no idea of the extent of misery 
inflicted: we must learn, from the narratives of eye- 
Witnesses, the various forms in which death was en- 
Countered, the numbers who escaped with loss of limbs 
serious bodily injuries, and the multitude who were 
Suddenly reduced to penury and want. It has been 
Often remarked, that the dread of earthquakes is 
Strongest in the minds of those who have experienced 
them most frequently ; whereas, in the case of almost 
€very other danger, familiarity with peril renders men 
intrepid. The reason is obvious — scarcely any part 
of the mischief apprehended in this instance is ima- 
Sinary ; the first shock is often the most destructive ; 
and, as it may occur in the dead of the night, or if 
by day, without giving the least warning of its ap- 
Proach, no forethought can guard against it; and when 
the convulsion has begun, no skill, or courage, or 
Presence of mind, can point out the path of safety. 
During the intervals, of uncertain duration, between 
the more fatal shocks, slight tremors of the soil are 
Not unfrequent ; and as these sometimes precede more 
Violent convulsions, they become a source of anxiety 
and alarm. The terror arising from this cause alone is 
of itself no inconsiderable evil. 

Although sentiments of pure religion are frequently 
twakened by these awful visitations, yet we more 
“ommonly find that an habitual state of fear, a sense 
of helplessness, and a belief in the futility of all human 
exertions, prepare the minds of the vulgar for the in- 
fluence of a demoralizing superstition. 

M 3 


ae 


i} 
j 

| 

i 

| 

t 

| 
iy 
Ai 
i 


246 CONCLUDING REMARKS. [Book IL 


Where earthquakes are frequent, there can neve! 
be perfect security of property under the best govern- 
ment ; industry cannot be assured of reaping the fruits 
of its labour ; and the most daring acts of outrage may 
occasionally be perpetrated with impunity, when the 
arm of the law is paralysed by the general consterna- 
tion. It is hardly necessary to add, that the progress 
of civilization and national wealth must be retarded by 
convulsions which level cities to the ground, destroy 
harbours, render roads impassable, and cause the most 
cultivated valley-plains to be covered with lakes, 0 
the ruins of adjoining hills. 

Those geologists who imagine that, at remote periods 
ere man became a sojourner on earth, the volcani¢ 
agency was more energetic than now, should be care- 
ful to found their opinion on strict geological evidenc® . 
and not permit themselves to be biassed, as they havé 
often been, by a notion, that the disturbing force would 
probably be mitigated for the sake of man. 

I shall endeavour to point out in the sequel, that thé 
general tendency of subterranean movements, whe® 
their effects are considered for a sufficient lapse of 
ages, is eminently beneficial, and that they constitute 
an essential part of that mechanism by which the 
integrity of the habitable surface is preserved, and the 
very existence and perpetuation of dry land secure 
Why the working of this same machinery should bé 
attended with so much evil, is a mystery far beyond 
the reach of our philosophy, and must probably re- 
main so until we are permitted to investigate, not out 
planet alone and its inhabitants, but other parts of the 
moral and material universe with which they may b@ 
connected. Could our survey embrace other worlds 
and the events, not of a few centuries only, but 0 


Ch. XV] = CONCLUDING REMARKS. 247 


periods as indefinite as those with which geology ren- 
ders us familiar, some apparent contradictions might 
be reconciled, and some difficulties would doubtless be 
cleared up. But even then, as our capacities are finite, 


while the scheme of the universe may be infinite, both’ 


in time and space, it is presumptuous to suppose that 
all sources of doubt and perplexity would ever be re- 
moved. On the contrary, they might, perhaps, go on 
augmenting in number ; for it has been justly said, that 
the greater the circle of light, the greater the bound- 
ary of darkness by which it is surrounded. * 


* Sir H. Davy, Consolations in Travel, p. 246. 


meee ae 


CHAPTER XVI. 


EARTHQUAKES OF THE EIGHTEENTH CENTURY — continued. 


Earthquake of Guatimala, 1773 — Java, 1772 — Truncation of 4 
lofty cone — St. Domingo, 1770 — Colombia, 1766 — Lisbon: 
1755 — Shocks felt throughout Europe, Northern Africa, and 
the West Indies — Great wave (p. 254.) — Conception Bay: 
1750— Permanent elevation — Peru, 1746 — Kamtschatka 
1737 — Java, 1699 (p. 259.).— Rivers obstructed by landslips— 
Subsidence in Sicily, 1693 — Moluccas, 1693 — Jamaica, 1692 
— Large tracts engulphed — Portion of Port Royal sunk — 
Amount of change in the last 140 years — Elevation and sub- 
sidence of land in Bay of Baiz (p-267 .) — Evidence of the 
same afforded by the Temple of Serapis. 


In the preceding chapters we have considered a small 
part of those earthquakes only which have occurred 
during the last fifty years, of which accurate and 
authentic descriptions happen to have been recorded: 
We may next proceed to examine some of earlier 
date, respecting which information of geological inte- 
rest has been obtained. 

Mexico, June, 1773. — The town of Guatimala was 
founded, in 1742, on the side of a volcano, in a valley 
about three miles wide, Opening to the South Sea; 
nine years afterwards it was destroyed by an earth- 
quake, and again, in 1773, during an eruption of the 
volcano. The ground on which the town stood gaped 
open in deep fissures, until at length, after five days» 
an abyss opened, and the city, with all its riches, and 


Ch. XVL] EARTHQUAKE IN JAVA, 1772. 249 


eight thousand families, was swallowed up. Every 
vestige of its former existence was entirely obliterated, 
and the spot is now indicated by a frightful desert, 
four leagues distant from the present town. * 

Java, 1772 — Truncation of a lofty cone. — In the 
year 1772, Papandayang, formerly one of the loftiest 
volcanos in the island of Java, was in eruption. Be- 
fore all the inhabitants on the declivities of the moun- 
tain could save themselves by flight, the ground began 
to give way, and a great part of the volcano fell in 
and disappeared. It is estimated that an extent of 
ground of the mountain itself and its immediate envi- 
rons, fifteen miles long and full six broad, was by this 
commotion swallowed up in the bowels of the earth. 
Forty villages were destroyed, some being engulphed 
and some covered by the substances thrown out on this 
occasion, and 2957 of the inhabitants perished. A 
proportionate number of cattle were also killed, and 
most of the plantations of cotton, indigo, and coffee 
in the adjacent districts were buried under the volcanic 
matter. This catastrophe appears to have resembled, 
although on a grander scale, that of the ancient Vesu- 
vius in the year 79. The cone was reduced in height 
from nine thousand to about five thousand feet ; and, as 
vapours’ still escape from the crater on its summit, a 
new cone may one day rise out of the ruins of the 
ancient mountain, as the modern Vesuvius has risen 
from the remains of Somma.t 


* Von Hoff— Dodsley’s Ann. Regist., vol. xvi. p. 149. ` 
es Drs Horsfield, Batav. Trans., vol. vill. p. 26. Dr. H. im- 
forms me that he has seen this truncated mountain: and, though 
he did not ascend it, he has conversed with those who have exa- 
mined it, Raffles’s account (History of Java, vol. i.) is derived 
from Horsfield. 
M 5 


250 EARTHQUAKES IN CAUCASUS, ETC. * [Book If. 


Caucasus, 1772. — About the year 1772, an earth- 
quake convulsed the ground in the province at Beshtau, 
in the Caucasus, so that part of the hill Metshuka 
sunk into an abyss. * 

St. Domingo, 1770. — During a tremendous earth- 
quake which destroyed a great part of St. Domingo; 
innumerable fissures were caused throughout the 
island, from which mephitic vapours emanated and 
produced an epidemic. Hot springs burst forth in 
many places where there had been no water before; 
but after a time they ceased to flow.+ 

Colombia, 1766. — On the 21st of October, 1766; 
the ground was agitated at once at Cumana, at Carac- 
cas, at Maraycabo, and on the banks of the rivers 
Casanare, the Meta, the Orinoco, and the Ventuario. 
These districts were much fissured, and great fallings 
in of the earth took place in the mountain Paurari: 
Trinidad was violently shaken. A small island in the 
Orinoco, near the rock Aravacoto, sunk down and dis- 
appeared.{ At the same time the ground was raised 
in the sea near Cariaco, where the Point Del Gardo 
was enlarged. A rock also rose up in the river 
Guarapica, near the village of Maturin.§ The shocks 
continued in Colombia hourly for fourteen months. 

Hindostan, 1762.— The town of Chittagong, in 
Bengal, was violently shaken by an earthquake, on 
the 2d of April 1762, the earth opening in many 
places, and throwing up water and mud of a sulphu- 


* Pallas’s Travels in Southern Russia. 

+ Essai surl’ Hist. Nat. del’Isle de St. Domingue, Paris, 1776- 

¢ Humboldt’s Personal Narrative, vol. iv. p. 45.; and Saggio 
di Storia Americana, vol. ii. p. 6. 

§ Humboldt, Voy. Relat. Hist., part i, p. 307. ; and part ii. 
p. 23. 


Ch. XVI] EARTHQUAKE OF LISBON, 1755. 951 


reous smell. At a place called Bardavan a large river 
Was dried up; and at Bakar Churak, near the sea, a 
tract of ground sunk down, and 200 people with all 
their cattle were lost. Unfathomable chasms are de- 
scribed as remaining open in many places after the 
shocks, and towns which subsided several cubits were 
Overflowed with water; among others, Deep Gong, 
which was submerged to the depth of seven cubits. 
Two volcanos are said to have opened in the Secta 
Cunda hills. The shock was also felt at Calcutta.* 

Lisbon, 1755. — In no part of the volcanic region of 
southern Europe has so tremendous an earthquake 
occurred in modern times as that which began on the 
lst of November, 1755, at Lisbon. A sound of 
thunder was heard underground, and immediately 
afterwards a violent shock threw down the greater 
part of that city. In the course of about six minutes, 
sixty thousand persons perished. The sea first retired 
and laid the bar dry ; it then rolled in, rising fifty feet 
or more above its ordinary level. The mountains of 
Arrabida, Estrella, Julio, Marvan, and Cintra, being 
some of the largest in Portugal, were impetuously 
shaken, as it were, from their very foundations ; and 
Some of them opened at their summits, which were 
Split and rent in a wonderful manner, huge masses of 
them being thrown down into the subjacent valleys. t 
Flames are related to have issued from these moun- 
tains, which are supposed to have been electric; they 
are also said to have smoked; but vast clouds of dust 
may have given rise to this appearance. 


* Dodsley’s Ann. Regist., 1763. For other particulars, see 
Phil. Trans., vol. liii. 
. + Hist, and Philos. of Earthquakes, p. 317. 
. M 6 


ae EARTHQUAKE OF LISBON, 1755, [Book I. 


Subsidence of the Quay. — The most extraordinary 
circumstance which occurred at Lisbon during the 
catastrophe was the subsidence of a new quay, built 
entirely of marble at an immense expense. A great 
concourse of people had collected there for safety, as 
a spot where they might be beyond the reach of falling 
ruins ; but, suddenly, the quay sank down with all the - 
people on it, and not one of the dead bodies ever 
fioated to the surface. A great number of boats and 
small vessels anchored near it, all full of people, were 
swallowed up, as in a whirlpool.* No fragments of 
these wrecks ever rose again to the surface, and the 
water in the place where the quay had stood is stated, 
in many accounts, to be unfathomable; but White- 
hurst says, he ascertained it to be one hundred 
fathoms.+ 

In this case, we must either suppose that a certain 
tract sank down into a subterranean hollow, which 
would cause a “fault” in-the strata to the depth of 
six hundred feet, or we may infer, as some have done, 
from the entire disappearance of the substances en- 
gulphed, that a chasm opened and closed again. Yet, 
in adopting this latter hypothesis, we must suppose 
that the upper part of the chasm, to the depth of one 
hundred fathoms, remained open. 
_ Area over which the earthquake extended. — The 
great area over which this Lisbon earthquake extended 
is very remarkable. The movement was most violent 
in Spain, Portugal, and the north of Africa; but 
nearly the whole of Europe, and even the West Indies, 


* Rey. C. Davy’s Letters, vol. ii, Letter ii. p. 12., who was at 
Lisbon at the time, and ascertained that the boats and vessels said 


to have been swallowed were missing. 
t On the Formation of the Earth, p. 55. 


x 


Ch. XVI] EARTHQUAKE OF LISBON, 1755. 253 


felt the shock on the same day. A seaport, called St. 
Ubes, about twenty miles south of Lisbon, was en- 
Sulphed. At Algiers and Fez, in Africa, the agitation 
of the earth was equally violent ; and at the distance of 
eight leagues from Morocco, a village with the inha- 
bitants to the number of about eight or ten thousand 
Persons, together with all their cattle, were swallowed 
Up. Soon after the earth closed again over them. 
Shocks felt at sea. — The shock was felt at sea, on 
the deck of a ship to the west of Lisbon, and produced 
Very much the same sensation as on dry land. Off St. 
Lucar, the captain of the ship Nancy felt his vessel so 
Violently shaken, that he thought she had struck the 
Stound ; but, on heaving the lead, found a great depth 
of water. Captain Clark, from Denia, in latitude 
36° 94’ N., between nine and ten in the morning, 
had his ship shaken and strained as if she had struck 
Upon a rock, so that the seams of the deck opened, and 
the compass was overturned in the binnacle. Another 
Ship, forty leagues west of St. Vincent, experienced so 
Violent a concussion, that the men were thrown a foot 
and a half perpendicularly up from the deck. In 
Antigua and Barbadoes, as also in Norway, Sweden, 
Germany, Holland, Corsica, Switzerland, and Italy, 
tremors and slight oscillations of the ground were felt. 
Rate at which the movement travelled.— The agitation 
of lakes, rivers, and springs, in Great Britain, was re- 
markable. At Loch Lomond, in Scotland, for example, 
the water, without the least apparent cause, rose 
against its banks, and then subsided below its usual 
vel. The greatest perpendicular height of this swell 
Was two feet four inches. It is said that the move- 
Ment of this earthquake was undulatory, and that it 
travelled at the rate of twenty miles a minute, its 


$ 
254 EARTHQUAKE OF, LISBON, 1755. {Book II. 


velocity being calculated by the intervals between the 
time when the first shock was felt at Lisbon, and its 
time of occurrence at other distant places. * 

Great wave and retreat of the sea. — A great wavé 
Swept over the coast of Spain, and is said to have pee? 
sixty feet high at Cadiz. At Tangier, in Africa, if 
rose and fell eighteen times on the coast. At Fur 
chal, in Madeira, it rose full fifteen feet perpendicular 
above high-water mark, although the tide, which ebbs 
and flows there seven feet, was then at half ebb. 
Besides entering the city, and committing great havoc: 
it overflowed other seaports in the island. At Kin- 
sale, in Ireland, a body of water rushed into the har 
bour, whirled round several vessels, and poured int? 
the market-place. 

It was before stated that thé sea first retired at 
Lisbon ; and this retreat of the ocean from the shore 
at the commencement of an earthquake and its subse 
quent return in a violent wave, is a common occu! 
rence. In order to account for the phenomenon 
Michell imagined a subsidence at the bottom of thé 
sea, from the giving way of the roof of some cavity 
in consequence of a vacuum produced by the con- 
densation of steam. Such condensation, he observes 
might be the first effect of the introduction of a large 
body of water into fissures and cavities already filled 
with steam, before there has been sufficient time for 
the heat of the incandescent lava to turn so large 4 
supply of water into steam, which being soon accom- 
plished causes a greater explosion. 

Another proposed explanation is, the sudden rise of 


* Michell on the Cause and Phenomena of Earthquakes, Phil. 
Trans., vol. li. p, 566. 1760. 


Ch. XVI] ST. DOMINGO, 1751. 255 


the land, which would cause the sea to abandon imme- 
diately the ancient line of coast; and if the shore, 
after being thus heaved up, should fall again to its 
Original level, the ocean would return. This theory, 
however, will not account for the facts observed during 
the Lisbon earthquake ; for the retreat preceded the 
Wave, not only on the coast of Portugal, but also at 
-the island of Madeira, and several other places. If 
the upheaving of the coast of Portugal had caused the 
tetreat, the motion of the waters, when propagated to 
Madeira, would have produced a wave previous to the 
tetreat. Nor could the motion of the waters at Ma- 
deira have been caused by a different local earthquake ; 
for the shock travelled from Lisbon to Madeira in two 
hours, which agrees with the time which it required 
to reach other places equally distant.* 

The following is, perhaps, the most probable solution 
of the problem which has yet been offered : — Suppose 
à portion of the bed of the sea to be suddenly up- 
heaved, the first effect will be to raise over the ele- 
vated part a body of water, the momentum of which 
Will carry it much above the level it will afterwards 
assume, causing a draught or receding of the water 
from the neighbouring coasts, followed immediately 

y the return of the displaced water, which will also 
he impelled by its momentum, much farther and 
higher on the coast than its former level-+ 

St. Domingo, 1751.— On the 15th of September, 
1751, an earthquake began in several of the West 
India Islands ; and on the 21st of November, a violent 
Shock destroyed the capital of St. Domingo, Port au 

rince. Part of the coast, twenty leagues in length, 


* Michell, Phil. Trans., vol. li. p. 614. 
+ Quarterly Review, No. 86: p. 459. 


256 PROOFS OF ELEVATION [Book I} 


sank down, and has ever since formed a bay of the 
sea.* 

Chili, 1750. — On the 24th of May, 1750, the an- 
cient town of Conception, otherwise called Penco, was 
totally destroyed by an earthquake, and the sea rolled 
over it. (See plan of the Bay, Fig. 42. p.186.) The 
ancient port was rendered entirely useless, and the 
inhabitants built another town ten miles from the sea- 
coast, in order to be beyond the reach of similar inun- 
dations. 

Proofs of elevation of twenty-four feet. — During a late 
survey of Conception Bay, Captains Beechey and 
Belcher discovered that the ancient harbour, which 
formerly admitted all large merchant vessels which 
went round the Cape, is now occupied by a reef of 
sandstone, certain points of which project above the 
sea at low water, the greater part being very shallow 
A tract ofa mile and a half in length, where, accord 
ing to the report of the inhabitants, the water was 
formerly four or five fathoms deep, is now a shoal: 
consisting, as our hydrographers found, of hard sand- 
stone, so that it cannot be supposed to have bee? 
formed by recent deposits of the river Biobio, an ar™ 
of which carries down loose micaceous sand into thé 
same side of the bay. Besides, it is a well-know? 
fact that ever since the shock of 1750, no vessels 
have been able to approach within a mile and a bal 
of the ancient port of Penco. (See Map, p. 186.) That 
shock, therefore, uplifted the bed of the sea to thé 
height of twenty-four feet at the least, and, most pro 
bably, the adjoining coast shared in the elevation : fo" 
an enormous bed of shells of the same species as thos? 


* Hist. de l’ Acad. des Sciences. 1752. Paris. 


Ch. XVIL] IN CONCEPTION BAY. 257 


now living in the bay, are seen raised above high-water 
mark along the beach, filled with micaceous sand like. 
that which the Biobio now conveys to the bay. These- 
shells, as well as others, which cover the adjoining » 
hills of mica-schist to the height of from 1000 to 15007 | 
feet, have lately been examined by experienced con- + \ 
= Chologists in London, and identified with those taken ¥ \ 

at the same time in a living state from the bay and its ; J 
neighbourhood.* ; 

Ulloa, therefore, was perfectly correct in his state- 
ment that, at various heights above the sea between 
Talcahuano and Conception, “ mines were found of 
Various sorts of shells used for lime of the very same 
kinds as those found in the adjoining sea.” Among 
them he mentions the great mussel called Choros, and 
two others, which he describes. Some of these, he 
Says, are entire, and others broken ; they occur at the 
bottom of the sea, in four, six, ten, or twelve fathom 
Water, where they adhere to a sea-plant called 
Cochayuyo. ` They are taken in dredges, and have no 
resemblance to those found on the shore or in shallow 
Water ; yet beds of them occur at various heights on 
the hills. “I was the more pleased with the sight,” 
he adds, “as it appeared to me a convincing proof of 
the universality of the deluge, although I am not igno- 
tant that some have attributed their position to other 
Causes; but an unanswerable confutation of their sub- 
terfuge is, that the various sorts of shells which compose 
these strata, both in the plains and mountains, are the 
Very same with those found in the bay.” + Perhaps the 
dilavian theory of this distinguished navigator, the 
ae Captain Belcher has shown me these shells, and the collec- 
tion has been examined by Mr. Broderip. 

t Ulloa’s Voyage to South America, vol. ii, book viii. ch. vi. 


258 EARTHQUAKE IN PERU, 1746. [Book IL 


companion of Condamine, may account for his never 
having recorded even reports of changes in the relative 
level of land and sea on the shores of South America 
He could not, however, have given us a relation of the 
rise of the reef above alluded to; for the destructio® 
of Penco happened a few years after the publication of 
his Voyages. 

If we duly consider these facts, so recently brought 
to light, as well as the elevations before mentioned of 
the coast of Chili in 1822 and 1835, we shall be less 
sceptical than Raspe, in regard to an event for which 
Hooke had cited Purchas’s Travels. In that passage 1t 
was stated, that “a certain sea-coast in a province 0 
South America, called Chili, was, during a violent 
earthquake, propelled upwards with such force and ve“ 
locity, that some ships on the sea were grounded in it 
and the sea receded to a distanee.” Raspe, being 
himself of opinion that all the continents had been up“ 
raised gradually by earthquakes from the sea, admitted 
that the circumstance was not impossible; but hé 
complains that Purchas had interpolated the account 
of the earthquake (which happened, probably, at thé 
close of the seventeenth century) into Da Costa’ 
History of the West Indies.* 

Peru, 1746.— Peru was visited, on the 28th of Oc- 
tober, 1746, by an earthquake, which is declared t0 
have been more tremendous and extensive than eve? 
that of Lisbon in 1755. In the first twenty-four hours; 
two hundred shocks were experienced. The ocea! 
twice retired and returned impetuously upon the land: 
Lima was destroyed, and part of the coast near Callao 
was converted into a bay; four other harbours, among 


* De Novis Insulis, p. 120. 1753. 


Ch. XVI] EARTHQUAKE IN JAVA, 1699. 259 


which were Cavalla and Guanape, shared the same fate. 
There were twenty-three ships and vessels, great 
and small, in the harbour of Callao, of which nine- 
teen were sunk; and the other four, among which 
was a frigate called St. Fermin, were carried by the 
force of the waves to a great distance up the country. 
The number of the inhabitants in this city amounted 
to four thousand. Two hundred only escaped, twenty- 
two of whom were saved on a small fragment of the 
fort of Vera Cruz, which remained as the only me- 
Morial of the site of the town after this dreadful 
inundation. ; 

A volcano in Lucanas burst forth the same night, 
and such quantities of water descended from the cone 
that the whole country was overflowed; and in the 
Mountain near Patao, called Conversiones de Caxa- 
Marquilla, three other volcanos burst out, and frightful 
torrents of water swept down their sides.* 

Kamitschatha, 1737, &c. — There are records of 
earthquakes in Kamtschatka and the Kurile Isles, in 
1737,—in Martinique, in 1727, — Iceland, 1725, — 
Teneriffe, 1706, — during which the shape of the 
ground both above and beneath the level of the sea was 
greatly changed. ; 

Java, 1699. — On the 5th of January, 1699, a ter- 
rible earthquake visited Java, and no less than 208 
Considerable shocks were reckoned. -Many houses 
in Batavia were overturned, and the flame and noise of 
a volcanic eruption were seen and heard in that city, 
Which were afterwards found to proceed from Mount 
Salak +, a volcano six days’ journey distant. Next 
Morning the Batavian river, which has its rise from 


+ Ulloa’s Voyage, vol. ii. book vii. chap. vii. 
+ Misspelt Sales in Hooke’s Account. 


260 EARTHQUAKE IN JAVA, 1699, = [Book II. 


that “mountain, became very high and muddy, and 
brought down abundance of bushes and trees, half 
burnt. The channel of the river being stopped. up, 
the water overflowed the country round the gardens 
about the town, and some of the streets, so that fishes 
lay dead in them. All the*fish in the river, except 
the carps, were killed by the mud and turbid water: 
A great number of drowned buffaloes, tigers, rhi- 
noceroses, deer, apes, and other wild beasts, were 
brought down by the current ; and, “ notwithstand- 
Ing,” observes one of the writers, “ that a crocodile is 
amphibious, several of them were found dead among 
the rest.” * 

It is stated, that seven hills bounding the river sank 
down, by which is merely meant, as by similar expres- 
sions in the description of the Calabrian earthquakes, 
seven great landslips. These hills, descending some 
from one side of the valley and some from the other, 
filled the channel, and the waters then finding their 
way under the mass, flowed out thick and muddy: 
The Tangaran river was also dammed up by nine hills, 
and in its channel were large quantities of drift trees: 
Seven of its tributaries also are said to have been 
“ covered up with earth.” A high tract of forest land, 
between the two great rivers before mentioned, is de- 
scribed as having been changed into an open countrys 
destitute of trees, the surface being spread over with a 
fine red clay. This part of the account may, perhaps 
merely refer to the sliding down of woody tracts into 
the valleys, as happened to so many extensive vine- 
yards and olive grounds in Calabria, in 1783, The 
close packing of large trees in the Batavian river is 


* Hooke’s Posthumous Works, p. 437. 1705. 


Ch. XVI] QUITO, 1698.—SICILY, 1693. — MOLUCCAS, 1693. 261 


represented as very remarkable, and it attests in a 
Striking manner the destruction of soil bordering the 
Valleys which had been caused by floods and land- 
Slips.* 

Quito, 1698.— In Quito, on the 19th of July, 1698, 
during an earthquake, a great part of the crater and 
Summit of the volcano Carguairazo fell in, and a stream 
of water and mud issued from the broken sides of the 
hill. + 

Sicily, 1693. — Shocks of earthquakes spread over 
all Sicily in 1693, and on the 11th of January the city 
of Catania and forty-nine other places were levelled to © 
the ground, and about one hundred thousand people 
Killed. The bottom of the sea, says Vicentino Bona- 
jutus, sank down considerably, both in ports, inclosed 
bays, and open parts of the coast, and water bubbled 
Up along the shores. Numerous long fissures of various 
breadths were caused, which threw out sulphureous 
Water; and one of them, in the plain of Catania (the 
delta of the Simeto), at the distance of four miles from 
the sea, sent forth water as salt as the sea. The stone 
buildings of a street in the city of Noto, for the length 
of half a mile, sank into the ground, and remained 
hanging on one side. In another street, an opening 
arge enough to swallow a man and horse appeared. 

Moluccas, 1693. — The small isle of Sorea, which 
Consists of one great volcano, was in eruption in the 
Year 1693. Different parts of the cone fell, one after 
the other, into a deep crater, until almost half the 
Space of the island was converted into a fiery lake. 

Ost of the inhabitants fled to Banda; but great pieces 


* Phil. Trans. 1700. + Humboldt, Atl. Pit., p. 106. 
+ Phil. Trans. 1693-4. 


262 EARTHQUAKE IN JAMAICA, 1692. [Book IJ. 


of the mountain continued to fall down, so that the 
lake of lava became wider ; and finally the whole popu- 
lation was compelled to emigrate. It is stated that 
in proportion as the burning lake increased in size, thé 
earthquakes were less vehement.* 

Jamacia, 1692.—In the year 1692, the island of 
Jamaica was visited by a violent earthquake ; the 
ground swelled and heaved like a rolling sea, and w35 
traversed by numerous cracks, two or three hundred 
of which were often seen at a time opening and the? 
closing rapidly again. Many people were swallowed 
up in these rents; some the earth caught by the 
middle, and squeezed to death; the heads of othe 
only appeared above ground; and some were first 
engulphed, and then cast up again with great quanti 
ties of water. Such was the devastation, that even 4! 
Port Royal, then the capital, where more houses af? 
said to have been left standing than in the whole islan 
beside, three quarters of the buildings, together with 
the ground they stood on, sank down with their inh@ 
bitants entirely under water. 

Subsidence in the harbour.— The large store-hous® 
on the harbour side subsided, so as to be twenty-fou” 
thirty-six, and forty-eight feet under water ; yet many 
of them appear to have remained standing, for it 
stated that, after the earthquake, the mast-heads ° 
several ships wrecked in the harbour, together with 
the chimney-tops of houses, were just seen projecting 
above the waves. A tract of land round the tow” 
about a thousand acres in extent, sank down in les 
than one minute, during the first shock, and the $€? 
immediately rolled in. The Swan frigate, which w35 


* Phil. Trans. 1693. 


Ch. XVI] EARTHQUAKE IN JAMAICA, 1692. 263 


repairing in the wharf, was driven over the tops of 
Many buildings, and then thrown upon one of the roofs, 
through which it broke. The breadth of one of the 
Streets is said to have been doubled by the earthquake. 

According to Mr. De la Beche, the part of Port 
Royal described as having sunk was built upon newly 
formed land, consisting of sand in which piles had been 
driven ; and the settlement of this loose sand, charged 
With the weight of heavy houses, may have given 
rise to the subsidences alluded to.* There can be no 
doubt that a waving motion of the earth, accompanied 
by an inroad of the sea, might affect loose sand, while 
Solid rock might remain unmoved ; but, after atten- 
tively considering the original documents, and con- 
Yersing with persons who, ninety years after, saw some 
of the submerged houses, I am inclined to believe that 
there were various and unequal subsidences of the 
land at Port Royal, independently of any sliding and 
Undermining of the sands. 

At several thousand places in Jamaica, the earth is 
telated to have opened. On the north of the island, 
Several plantations, with their inhabitants, were swal- 
Owed up, and a lake appeared in their place, covering 
above a thousand acres, which afterwards dried up, 
faving nothing but sand and gravel, without the least 
Sign that there had ever been a house ora tree there. 

veral tenements at Yallowes were buried under land- 
Slips ; and one plantation was removed half a mile 
Tom its place, the crops continuing to grow upon it 
Uninjured. Between Spanish Town and Sixteen-mile 
Yalk, the high and perpendicular cliffs bounding the 
“er fell in, stopped the passage of the river, and 


* Manual of Geol., p. 133, second edition. 


264 CHANGES CAUSED BY EARTHQUAKES. [Book II. 


flooded the latter place for nine days, so that the 
people “concluded it had been sunk as Port Royal 
was.” But the flood at iength subsided, for the rivet 
had found some new passage at a great distance. 
Mountains shattered. — The Blue and other of the 
highest mountains are declared to have been strangely 
torn and rent. They appeared shattered, and half- 
naked, no longer affording a fine green prospect, 3 
before, but stripped of their woods and natural verdure 
- The rivers on these mountains first ceased to flow fo! 
about twenty-four hours, and then brought down int 
the sea, at Port Royal and other places, several hu 
dred thousand tons of timber, which looked like float 
ing islands on the ocean. The trees were in general 
barked, most of their branches having been torn off 2 
the descent. It is particularly remarked in this, as in 
the narratives of so many earthquakes, that fish wer? 
taken in great numbers on the coast during the shocks 
The correspondents of Sir Hans Sloane, who collecte 
with care the accounts of eye-witnesses of the cata 
strophe, refer constantly to swbstdences, and some sup 
posed the whole of Jamaica to have sunk down.* 
Reflections on the amount of change in the last 0M 
hundred and forty years.—I have now only enum 
rated the earthquakes of the last 140 years, respecting 
which facts illustrative of geological inquiries are °” 
record. Even if my limits permitted, it would be ? 
tedious and unprofitable task to examine all the obscu"® 
and ambiguous narratives of similar events of earlie 
epochs ; although, if the places were now examine 
by geologists well practised in the art of interpreting 
the monuments of physical changes, many events 


* Phil. Trans. 1694. 


Ch. XVI.] DEFICIENCY OF HISTORICAL RECORDS. ` 265 


which have happened within the historical era might 
Still be determined with precision. It: must not be 
imagined that, in the above sketch of the occur- 
Tences of a short period, I have given an account of 
all, or even the greater part, of the mutations which 
the earth has undergone by the agency of subter- 
ranean movements. Thus, for example, the earth- 
quake of Aleppo, in the present century, and of Syria, 
in the middle of the eighteenth, would doubtless 
have afforded numerous phenomena, of great geolo- 
gical importance, had those catastrophes been described 
by scientific observers. The shocks in Syria, in 1759, 
Were protracted for three months, throughout a space 
of ten thousand square leagues ; an area compared to 
Which that of the Calabrian earthquake of 1783 was 
insignificant. Accon, Saphat, Balbeck, Damascus, 
Sidon, Tripoli, and many other places, were almost 
entirely levelled to the ground. Many thousands of 
the inhabitants perished in each ; and, in the valley of 
Balbeck ‘alone, twenty thousand men are said to have 
been victims to the convulsion. In the absence of 
Scientific accounts, it would be as irrelevant to our 
Present. purpose to enter into a detailed account of 
Such calamities, as to follow the track of an invading 
army, to enumerate the cities burnt or rased to the 
round, and reckon the number of individuals who 
Perished by famine or the sword. 

Deficiency of historical records. —If such, then, be 
the amount of ascertained changes in the last 140 
Years, notwithstanding the extreme deficiency of our 
Tecords during that brief period, how important must 
We presume the physical revolutions to have been in 
the course of thirty or forty centuries, during which 
‘Some countries habitually convulsed by earthquakes 

VOL. IL N 


966 DEFICIENCY OF HISTORICAL RECORDS. [Book H- 


have been peopled by civilized nations! Towns er 
gulphed during one earthquake may, by repeated 
shocks, have sunk to enormous depths beneath the 
surface, while the ruins remain as imperishable 3$ 
the hardest rocks in which they are enclosed. Build- 
ings and cities, submerged, for a time, beneath seas 
or lakes, and covered with sedimentary deposits, must 
in some places, have been re-elevated to considerable 
heights above the level of the ocean. The signs ° 
these events have, probably, been rendered visible bY 
subsequent mutations, as by the encroachments of thé 
sea upon the coast, by deep excavations made by to! 
rents and rivers, by the opening of new ravines, a” 

chasms, and other effects of natural agents, so activ? 
in districts agitated by subterranean movements. 

If it be asked why, if such wonderful monument 
exist, so few have hitherto been brought to light, W? 
reply — because they have not been searched for. Jo 
order to rescue from oblivion the memorials of form® 
occurrences, the inquirer must know what he may 
reasonably expect to discover ; and under what pec!” 
liar local circumstances. He must be acquainted with 
the action and effect of physical causes, in order @ 
recognize, explain, and describe correctly the pheno” 

‘mena when they present themselves. 

The best known of the great volcanic regions; 
which the boundaries were sketched in the ninth chap” 
ter, is that which includes Southern Europe, Northe!? 
Africa, and Central Asia; yet nearly the whole, eve? 
of this region, must be laid down in a geological map? 

` as “Terra Incognita.” Even Calabria may be rega! de 
as unexplored, as also Spain, Portugal, the Barbary 
States, the Ionian Isles, the Morea, Asia Minor, cy F 
prus, Syria, and the countries between the Casp!a” 


of 


Ch. XVI] CHANGES IN THE BAY OF BAIE. 267 


and Black Seas. We are, in truth, beginning to ob- 
tain some insight into one small spot of that great 
zone of volcanic disturbance, the district around 
Naples; a tract by no means remarkable for the vio- 
lence of the earthquakes which have convulsed it. 

If, in this part of Campania, we are enabled to 
establish, that considerable changes in the relative 
level of land and sea have taken place since the Chris- 
tian era, it is all that we could have expected ; and it 
ig to recent antiquarian and geological research, not 
to history, that we are principally indebted for the 
information. I shall now proceed to lay before the 
reader some of the results of modern investigations 
in the Bay of Baie and the adjoining coast. 


PROOFS OF ELEVATION AND SUBSIDENCE IN THE 
BAY OF BAIZ. 


Temple of Jupiter Serapis. — This celebrated monu- 
ment of antiquity affords, in itself alone, unequivocal 


Monte Fig. 55. 


Barbaro. 


BY 1 Stadium. 2 


Temple. off icre’s patirailiee m 
Serapis. ilia. nl FARR p ji D 


7 LL: Zi opp Z 
Puzauali{ LL 


Ground plan of the coast of the Bay of Baie, in the environs of Puxxtoli. 


nQ 


268 NEW DEPOSIT UPRAISED NEAR PUZZUOLI. [Book Il. 


evidence that the relative level of land and sea has 
changed twice at Puzzuoli since the Christian era; 
and each movement, both of elevation and subsidence, 
has exceeded twenty feet. Before examining these 
proofs, I may observe, that a geological examinatio?® 
of the coast of the Bay of Baiz, both on the north 
and south of Puzzuoli, establishes, in the most satis- 
factory manner, an elevation, at no remote period, of 
more than twenty feet, and, at one point, of moré 
than thirty feet; and the evidence of this chang? 
would have been complete, even if the temple had, t? 
this day, remained undiscovered. 

Coast south of Puzzuoli.—If we coast along thé 
shore from Naples to Puzzuoli, we find, on approaeb- 
ing the latter place, that the lofty and precipitous 
cliffs. of indurated tuff, resembling that of- whic! 
Naples is built, retire slightly from the sea; and 
that a low level tract of fertile land, of a very 
different aspect, intervenes between the present 
sea-beach, and what was evidently the ancient line 
of coast. 

The inland cliff may be seen opposite the small 
island of Nisida, about two miles and a half south-east 
of Puzzuoli*, where, at the height of thirty-two feet 
above the level of the sea, Mr. Babbage observed a” 
ancient mark, such as might have been worn by the 
waves; and, upon further examination, discovered 
that, along that line, the face of the perpendiculat 
rock, consisting of very hard tuff, was covered with 
barnacles (Balanus sulcatus, Lamk.), and drilled by 
boring testacea. Some of the hollows of the Litho- 
domi contained the shells ; while others were filled wit 


* See Map, Pl. IV. Fig. 2. 


Ch. XVI] TEMPLE OF JUPITER SERAPIS. 269 


the valves of a species of Arca.* Nearer to Puzzuoli, 
the inland cliff is eighty feet high, and as perpendicular 
as if it was still undermined by the waves. At its 


Fig. 56. 


i 
l 


a, Antiquities on hill S.E. of Puzzuoli. 
b. Ancient cliff now inland. 
c. Terrace composed of recent submarine deposit. 


hase, a new deposit, constituting the fertile tract above 
alluded to, attains a height of about twenty feet above 
the sea; and, since it is composed of regular sedi- 
mentary deposits, containing marine shells, its position 
Proves that, subsequently to its formation, there has 
been a change of more than twenty feet in the relative 
level of land and sea. i 

The sea encroaches on these new incoherent strata ; 
and as the soil is valuable, a wall has been built for its 
Protection : but when I visited the spot in 1828, the 
Waves had swept away part of this rampart, and ex- 
Posed to view a regular series of strata of tuff, more or 
less argillaceous, alternating with beds of pumice and 
lapilli, and containing great abundance of marine shells, 
of Species now common on this coast, and amongst 


_ * Mr. Babbage examined this spot in company with Mr, Head, 
m June, 1828, and has shown me numerous specimens of the 
Shells collected here, and in the Temple of Serapis. 


N 3 


270 NEW DEPOSIT UPRAISED NEAR PUZZUOLI. [Book IL 


them Cardium rusticum, Ostrea edulis, Donax trun- 
culus (Lamk.), and others. The strata vary from 
about a foot to a foot and a half in thickness, and one 
of them contains abundantly remains of works of art, 
tiles, squares of mosaic pavement of different colours, 
and small sculptured ornaments, perfectly uninjured- 
Intermixed with these I collected some teeth of the 
pig and ox. These fragments of building occur below 
as well as above strata containing marine shells. Puz- 
zuoli itself stands chiefly on a promontory of the older 
tufaceous formation, which cuts off the new deposit, 
although I detected a small patch of the latter in a 
garden under the town. 

From the town the ruins of a mole, called Caligula’s 
Bridge, run out into the sea. This mole consists of @ 
number of piers and arches; and Mr. Babbage found, 
on the sixth pier, perforations of lithodomi four feet 
above the level of the sea; and near the termination 
of the mole, on the last pier but one, marks of the 
same ten feet above the level of the sea, together with 
great numbers of balani and flustra. 

Coast north of Puzzuoli.— If we then pass to the 
north of Puzzuoli, and examine the coast between that 
town and Monte Nuovo, we find a repetition of ana- 
ogous phenomena. The sloping sides of Monte Bar- 
baro slant down within a short distance of the coast» 
and terminate in an inland cliff of moderate elevation: 
to which the geologist perceives at once that the seê 
must, at some former period, have extended. Betweer 
this cliff and the sea is a low plain or terrace, called 
La Starza, corresponding to that before described 0? 
the south-east of the town; and as the sea encroaches 
rapidly, fresh sections of the. strata may readily be 
obtained, of which the annexed is an example. 


Ch 
XVL] _ TEMPLE OF JUPITER SERAPIS. 


a. Remains of Cicero’s villa, N. side of Puzzuoli,* 
b. Ancient cliff now inland. 

c. Terrace composed of recent submarine deposits. 
d. Temple of Serapis. 


Section on the shore north of the town of Puz- 
zuoli: — 


; Ft. In. 
1. Vegetable soil . ` : PTO 


. Horizontal beds of pumice and scoriæ, with 
broken fragments of unrolled bricks, bones 
of animals, and marine shells - ` 
Beds of lapilli, containing abundance of ma- 
rine shells, principally Cardium rusticum, 
Donax trunculus, Lam., Ostrea edulis, Tri- 
ton cutaceum, Lam., and Buccinum serra- 
tum, Brocchi, the beds varying in thickness 


from one to eighteen inches . . 10 
. Argillaceous tuff, containing bricks and frag- 
ments of buildings not rounded by attrition 1 


The thickness of many of these beds varies greatly 
as we trace them along the shore, and sometimes the 
Whole group rises to a greater height than at the point 
above described. The surface of the tract which they 


* The spot here indicated on the summit of the cliff, is that 
from which Hamilton’s view, plate 26., Campi Phlegrai, is taken, 
and on which, he observes, Cicero’s villa, called the Academia, 
anciently stood. 


N 4 


272 NEW DEPOSIT UPRAISED NEAR PUZZUOLI. [Book II. 


compose appears to slope gently upwards towards the 
base of the old cliffs. 

Now, if these appearances presented themselves on 
the eastern or southern coast of England, a geologist 
would naturally endeavour to seek an explanation in 
some local depression of high-water mark, in conse- 
quence of a change in the set of the tides and cur- 
rents : for towns have been built, like ancient Brighton, 
on sandy tracts intervening between the old cliff and 
the sea, and, in some cases, they have been finally 
swept away by the return of the ocean. On the other 
hand, the inland cliff at Lowestoffe, in Suffolk, remains, 
as was before stated, at some distance from the shore, 
and the low green tract called the Ness may be com- 
pared to the low flat called La Starza, near Puzzuoli.* 
But there are scarce any tides in the Mediterranean ; 
and, to suppose that sea to have sunk generally from 
twenty to twenty-five feet since the shores of Cam- 
pania were covered with sumptuous buildings, is an 
hypothesis obviously untenable. The observations; 
indeed, made during modern surveys on the moles and 
cothons (docks) constructed by the ancients in various 
ports of the Mediterranean, have proved that there 
has been no sensible variation of level in that sea 
during the last two thousand years.+ 

Thus we arrive, without the aid of the celebrated 
temple, at the conclusion, that the recent marine de- 
posit at Puzzuoli was upraised in modern times above 
the level of the sea, and that not only this change of 
position, but the accumulation of the modern strata 
was posterior to the destruction of many edifices, of 


* See Vol. I. p. 410. 
+ Or the anthority of Captain W. H. Smyth, R.N. 


Ch. XVI] TEMPLE OF JUPITER SERAPIS. 273 


which they contain the imbedded remains. If we now 
€xamine the evidence afforded by the temple itself, 
it appears; from the most authentic accounts, that the 
three pillars now standing erect continued, down to 
the middle of the last century, half buried in the new 
Marine strata before described. The upper part of 
the columns, being concealed by bushes, had not at- 
tracted, until the year 1749, the notice of antiquaries ; 
but, when the soil was removed in 1750, they were 
Seen to forra part of the remains of a splendid edifice, 
the pavement of which was still preserved, and upon 
it lay a number of columns of African breccia and of 
granite. The original plan of the building could be 
traced distinctly; it was of a quadrangular form, seventy 
feet in diameter, and the roof had been supported by 
forty-six noble columns, twenty-four of granite, and 
the rest of marble. The large court was surrounded 
by apartments, supposed to have been used as bathing- 
rooms; for a thermal spring, still used for medicinal 
Purposes, issues now just behind the building, and the 
Water, it is said, of this spring was conveyed by marble 
ducts into the chambers. 

Many antiquaries have entered into elaborate dis- 
Cussions as to the deity to which this edifice was con- 
Secrated ; but Signor Carelli, who has written the last 
able treatise on the subject*, endeavours to show that 
all the religious edifices of Greece were of a form 
essentially different ; that the building, therefore, could 
never have been a temple; that it corresponded to the 
Public bathing-rooms at many of our watering-places ; 
and, lastly, that if it had been a temple, it could not 
have been dedicated to Serapis, the worship of the 


* Dissertazione sulla Sagra Architettura degli Antichi. 


N 5 


274 PERFORATION OF THE COLUMNS. [Book I1 


Egyptian god being strictly prohibited, at the time 
when this edifice was in use, by the senate of Rome- 
Perforation of the columns by Lithodomous shells. — 
It is not for the geologist to offer an opinion on these 
topics; and I shall, therefore, designate this valuable 
relic of antiquity by its generally received name, and 
proceed to consider the memorials of physical changes 
inscribed on the three standing columns in most legi- 
ble characters by the hand of Nature. (See Frontis- 
piece, Vol.I.*) These pillars, which have been carved 
each out of a single block of marble, are forty-two feet 
in height. An horizontal fissure nearly intersects one 
of the columns; the other two are entire. They are 
all slightly out of the perpendicular, inclining some- 
what to the south-west, that is, towards the sea. + 
Their surface is smooth and uninjured to the height 
of about twelve feet above their pedestals. Above this 
is a zone, about nine feet in height, where the marble 
has been pierced by a species of marine perforating 
bivalve — Lithodomus, Cuv.t The holes of these 
_ animals are pear-shaped, the external opening being 
minute, and gradually increasing downwards. At the 
bottom of the cavities, many shells are still found: 
notwithstanding the great numbers that have bee? 


* This view of the present state of the temple has been reduced 
from that of the Canonico Andrea de Jorio, Ricerche sul Tempio 
di Serapide, in Puzzuoli. Napoli, 1820. 

t This appears from the measurement of Captain Basil Hall, 
R.N., Proceedings of Geol. Soc., No. 38. p. 114. The fact. 
of the three standing columns having been each formed out of 4 
Single stone, was first pointed out to me by Mr. James Hall, 
and is important, as helping to explain why they were not 
shaken down. 


ł Modiola lithophaga, Lam. Mytilus lithophagus, Linn. 


Ch XVI] TEMPLE OF JUPITER SERAPIS. 275 


taken out by visitors; in many the valves of a species 
ofarca, an animal which conceals itself in small hol- 
lows, occur. The perforations are so considerable in 
depth and size, that they manifest a long-continued 
abode of the lithodomi in the columns; for, as the 
inhabitant grows older and increases in size, it bores a 
large cavity, to correspond with the increasing mag- 
nitude of its shell. We must, consequently, infer a 
long-continued immersion of the pillars in sea-water, 
at a time when the lower part was covered up and 
protected by strata of tuff and the rubbish of build- 
ings; the highest part, at the same time, projecting 
above the waters, and being consequently weathered, 
but not materially injured. 

On the pavement of the temple lie some columns 
of marble, which are perforated in the same manner in 
certain parts; one, for example, to the length of eight 
feet, while, for the length of four feet, it is uninjured. 
Several of these broken columns are eaten into, not 
only on the exterior, but on the cross fracture, and, on 
some of them, other marine animals have fixed them- 
selves.* All the granite pillars are untouched by 
lithodomi. The platform of the temple, which is not 
perfectly even, is at present about one foot below high- 
water mark (for there are small tides in the Bay of 
Naples); and the sea, which is only one hundred feet 
distant, soaks through the intervening soil. The upper 
part of the perforations, then, are at least twenty-three 
feet above high-water mark; and it is clear, that the 
` columns must have continued for a long time in an 


* Serpula contortuplicata, Linn., and Vermilia triquetra, Lam. 
These species, as well as the Lithodomus, are now inhabitants of 
the neighbouring sea. 


N 6 


276 TEMPLE OF JUPITER SERAPIS. [Book II. 


erect position, immersed in salt water. After remain- 
ing for many years submerged, they must have been 
upraised to the height of about twenty-three feet above 
the level of the sea. 

Temples and Roman roads under water. — So far the 
information derived from the temple corroborates that 
before obtained from the new strata in the plain of 
La Starza, and proves nothing more. But, as the tem- 
ple could not have been built originally at the bottom 
of the sea, it must have first sunk down below the 
waves, and afterwards have been elevated. Of such 
subsidences there are numerous independent proofs 
in the Bay of Bais. Not far from the shore, to the 
north-west of the Temple of Serapis, are the ruins of 
a Temple of Neptune, and a Temple of the Nymphs, 
now under water. The columns of the former edifice 
stand erect in five feet water, their upper portions just 
rising to the surface of the sea. The pedestals are 
doubtless buried in the mud; so that if this part of the 
bottom of the bay should hereafter be elevated, the 
exhumation of this temple might take place after the 
manner of that of Serapis. Both these buildings pro- 
bably participated in the movement which raised the 
Starza; but, either they were deeper under water than 
the Temple of Serapis, or they were not raised up 
again to so great a height. There are also two Roman 
roads under water in the bay, one reaching from Puz- 
zuoli towards the Lucrine Lake, which may still be 
seen, and the other near the Castle of Baiæ. The an- 
cient mole, too, of Puzzuoli, before alluded to, has the 
water up to a considerable height of the arches; 
whereas Brieslak justly observes, it is next to certain 
that the piers must formerly have reached the surface 


Ch. XVI] ROMAN ROADS UNDER WATER. Dah 


before the springing of the arches*; so that, although 
the phenomena before described prove that this mole 
has been uplifted ten feet above the level at which it 
Once stood, it is still evident that it has not yet been 
restored to its original position. 

A modern writer also reminds us, that these effects 
are not so local as some would have us believe ; for on 
the opposite side of the Bay of Naples, on the Sor- 
tentine coast, which, as well as Puzzuoli, is subject to 
earthquakes, a road, with some fragments of Roman 
buildings, is covered to some depth by the sea. In 
_ the island of Capri, also, which is situated some way 
at sea, in the opening of the Bay of Naples, one of 
the palaces of Tiberius is now covered with water.+ 
They who have attentively considered the effects of 
earthquakes, before enumerated, as having occurred 
during the last 140 years, will not feel astonished at 
these signs of alternate elevation and depression of 
the bed of the sea and the adjoining coast during the 
Course of eighteen centuries; but, on the contrary, 
they will be very much astonished if future researches 
fail to bring to light similar indications of change in 
almost all regions of volcanic disturbances. 

That buildings should have been submerged, and 
afterwards upheaved, without bemg entirely reduced 
toa heap of ruins, will appear no anomaly, when we 
recollect that, in the year 1819, when the delta of the 


* Voy. dans la Campanie, tome ii. p. 162. 

+ Mr. Forbes, Physical Notices of the Bay of Naples. Ed. 
Journ. of Sci., No. II., new. series, p- 280. October 1829. 
When I visited Puzzuoli, and arrived at the above conclusions, I 
knew nothing of Mr. Forbes’s observations, which I first saw on 
My return to England the year following. 


aaeanoa aa 


978 TEMPLE OF JUPITER SERAPIS, { [Book II 


Indus sank down, the houses within the fort of Sindreé 
subsided beneath the waves, without being over- 
thrown. In like manner, in the year 1692, the build- 
ings around the harbour of Port Royal, in Jamaica, 
descended suddenly to the depth of between thirty 
and fifty feet under the sea without falling, Even o” 
small portions of land transported to a distance of 4 
mile, down a declivity, tenements, like those neat 
Mileto, in Calabria, were carried entire. At Val 
paraiso buildings were left standing, when their found- 
ations, together with a long. tract of the Chilian coasts 
were permanently upraised to the height of several 
feet in 1822. It is true that, in the year 1750, when 
the bottom of the sea in the harbour of Penco was 
suddenly uplifted to the extraordinary elevation of 
twenty-four feet above its former level, the buildings 
of that town were thrown down; but we might still 
suppose that a great portion of them would have 
escaped, had the walls been supported on the exterio? 
and interior with a deposit, like that which surrounded 
and filled to the height of ten or twelve feet thé 
Temple of Serapis at Puzzuoli. 

Periods when the Temple of Serapis sank and rose.— 
The next subject of inquiry is the era when these 
remarkable changes took place in the Bay of Baie 
It appears that, in the Atrium of the Temple of Se- 
rapis, inscriptions were found in which Septimius 


‘Severus and Marcus Aurelius record their labours 12 


adorning it with precious marbles.* We may, there 
fore, conclude, that it existed at least down to the 
third century of our era in its original position; and 1 
may have been built at the close of the second cen- 


* Brieslak, Voy. dans la Campanie, tom. ii. p. 167. 


Ch. XVI] DATE OF ITS RE-ELEVATION. 279 


tury. On the other hand, we have evidence that the 
Marine deposit forming the flat land, called La Starza, 
Was still covered by the sea in the year 1530, or just 
eight years anterior to the tremendous explosion of 
Monte Nuovo. Mr. Forbes has lately pointed out 
the distinct testimony of an old Italian writer, Lof- 
fr edo, in confirmation of this important point.* Writing 
in 1580, Loffredo declares that, fifty years previously, 
the sea washed the base of the hills which rise from 
the flat land before alluded to; and at that time he 
expressly tells us, that a person might have fished from 
the site of those ruins which are now called the Sta- 
dium. (See Fig. 55.) Hence it follows, that the 
subsidence of the ground happened at some period 
between the third century, when the temple was still 
standing, and the beginning of the sixteenth century, 
when its site was still submerged. 

Now, in this interval the only two events which are 
recorded in the imperfect annals of the dark ages are, 
the eruption of the Solfatara in 1198, and an earth- 
quake in 1488, by which Puzzuoli was ruined. It is 
at least highly probable, that earthquakes, which pre- 
ceded the eruption of the Solfatara, which is very 
‘near the temple (See Fig. 55.) caused a subsidence, 
and the pumice and other matters ejected from that 
Volcano might have fallen in heavy showers into the 
sea, and would thus immediately have covered up the 
lower part of the columns, and preserved them from 
the action of the sea and from lithodomous perfor- 
ations. The waves might afterwards have thrown 
down many pillars, and formed strata of broken frag- 
ments of buildings, intermixed with volcanic ejections, 


* Ed, Journ. of Science, new series, No. II. p. 281. . 


280 TEMPLE OF JUPITER SERAPIS. [Book Jl. 


and thus have caused those strata, containing works of 
art and shells, which extend for several miles along the 
coast. Mr. Babbage, after carefully examining several 
incrustations of carbonate of lime, such as the waters 
of the hot spring might have deposited, adhering to 
the walls and columns of the temple at different 
heights, as also the distinct marks of ancient lines 
of water level, visible below the zone of lithophagous 
perforations, has come to the conclusion, and, I think, 
proved, that the subsidence of the building was not 
sudden, or at one period only, but gradual, and by 
successive movements.* 

As to the re-elevation of the depressed tract, that 
may also have occurred at different periods, since earth- 
quakes are not unfrequent in this country. Jorio cites 
two authentic documents in illustration of this point. 
The first, dated Oct. 1503, is a deed, written in 
Italian, by which Ferdinand and Isabella grant to the 
University of Puzzuoli a portion of land, “ where the 
sea is drying up” (Che va seccando el mare); the 
second, a document in Latin, dated May 23. 1511, or 
nearly eight years after, by which Ferdinand grants to 
the city a certain territory around Puzzuoli, where the 
ground zs dried up from the sea (desiccatum ). + 

It is perfectly evident, however, from Loffredo’s 
statement, that the principal elevation of the low 
tract called La Starza took place after the year 1530, 
and some time before the year 1580; and from this 
alone we might have suspected that the change hap- 
pened in the year 1538, when Monte Nuovo was 
formed. But, fortunately, we are not left in the 
slightest doubt that such was the date of this re- 

* Proceedings of Geol. Soc., No. 36. March 1834. 
+ Sul Tempio di Serap. chap. viii. 


Ch. XVII DATE OF ITS RE-ELEVATION. 281 


markable event. Sir William Hamilton has given us 
two original letters describing the eruption of 1538, 
the first of which, by Falconi, dated 1538, contains 
the following passages.* “It is now two years since 
there have been frequent earthquakes at Puzzuoli, 
Naples, and the neighbouring parts. On the day and 
in the night before the eruption (of Monte Nuovo), 
above twenty shocks, great and small, were felt. The 
ruption began on the 29th of September, 1538. It 
Was on a Sunday, about one o'clock in the night, when 
flames of fire were seen between the hot baths and 
Tripergola. In a short time the fire increased to 
Such a degree, that it burst open the earth in this 
Place, and threw up so great a quantity of ashes and 
Pumice stones, mixed with water, as covered the 
Whole country. The next morning (after the form- 
ation of Monte Nuovo) the poor inhabitants of Puz- 
Zuoli quitted their habitations in terror, covered with 
the muddy and black shower which continued the 
Whole day in that country —flying from death, but with 
death painted in their countenances. Some with their 
Children in their arms, some with sacks full of their 
goods ; others leading an ass, loaded with their fright- 
ened family, towards Naples ; others carrying quanti- 
ties of birds of various sorts, that had fallen dead at 
the beginning of the eruption; others, again, with fish 
Which they had found, and which were to be met with 
in plenty on the shore, the sea having left them dry 
Jor a considerable time. I accompanied Signor Mora- 
Maldo to behold the wonderful effects of the eruption. 
The sea had retired on the side of Baize, abandoning 
@ considerable tract, and the shore appeared almost 
€ntirely dry, from the quantity of ashes and broken 


* Campi Phlegræi, p. 70. 


282 ERUPTION OF MONTE NUOVO. [Book 1. 


pumice ‘stones thrown up by the eruption. I saw 
two springs in the newly discovered ruins + one before 
the house that was the queen’s, of hot and salt 
water,” &c. 

So far Falconi; the other account is by Pietro 
Giacomo di Toledo, which begins thus : —« It is now 
two years since this province of Campagna has been 
afflicted with earthquakes, the country about Puzzuoli 
much more so than any other parts: but the 27th and 
the 28th of the month of September last, the earth- 
quakes did not cease day or night in the town of Puz- - 
zuoli : that plain which lies between Lake Avernus, 
the Monte Barbaro, and the sea, was raised a little, 
and many cracks were made in it, from some of which 
issued water ; at the same time the sea immediately 
adjoining the plain dried up about two hundred paces, 
so that the fish were left on the sand a prey to the 
inhabitants of Puzzuoli. At last, on the 29th of the 
same month, about two o’clock in the night, the earth 
opened,” &c. Now, both these accounts, written im- 
mediately after the birth of Monte Nuovo, agree in 
expressly stating that the sea retired, and one men“ 
tions that its bottom was upraised. To this elevation 
we have already seen that Hooke, writing at the close 
of the seventeenth century, alludes as to a well-know? 
fact.* The preposterous theories, therefore, that 
have been advanced in order to dispense with the 
elevation of the land, in the face of all this historical 
and physical evidence, are not entitled to a serious 
refutation. 


Encroachments of the sea in the Bay of Baia. —The 


* Vol i peel, 


Ch. xvij TEMPLE OF JUPITER SERAPIS. 283 


flat land, when first upraised, must have been more 
extensive than now, for the sea encroaches somewhat 
‘apidly, both to the north and south-east of Puzzuoli. 
The coast has, of late years, given way more than a 
foot in a twelvemonth ; and I was assured, by fisher- 
men in the bay, that it has lost ground near Puzzuoli, 
to the extent of thirty feet, within their memory. It 
is, probable, this gradual encroachment, which has led 
many authors to imagine that the level of the sea is 
Slowly rising in the Bay of Baiz ; an opinion by no 
Means warranted by such circumstances. In the 
Course of time, the whole of the low land will, perhaps, 
be carried away, unless some earthquake shall remodify 
the surface of the country, before the waves reach the 
ancient coast-line ; but the removal of this narrow 
tract will by no means restore the country to its for- 
Mer state, for the old tufaceous hills, and the inter- 
Stratified current of trachytic lava which has flowed 
from the Solfatara, must have participated in the 
Movement of 1538 ; and these will remain upraised, 
even though the sea may regain its ancient limits. 

In 1828, excavations were made below the marble 
pavement of the Temple of Serapis, and another costly 
Pavement of mosaic was found, at the depth of five 
feet or more below the other. The existence of these 
two pavements, at different levels, seems clearly to 
imply some subsidence previously to all the changes 
already alluded to, which had rendered it necessary to 
Construct a new floor at a higher level. But to these 
and other circumstances bearing on the history of the 
Temple antecedently to the revolutions already ex- 
Plained, I shall not refer at present, trusting that 
future investigations will set them in a clearer light. 


284, PERMANENCE OF THE OCEAN’S LEVEL. [Book i. 


Permanence of ‘the ocean's level.—In concluding 
this subject, I may observe, that the interminable con- 
troversies to which the phenomena of the Bay of Baié 
gave rise, have Sprung from an extreme reluctance t0 
admit that the land, rather than the sea, is subject 
alternately to rise and fall. Had it been assumed that 
the level of the ocean was invariable, on the ground 
that no fluctuations have as yet been clearly esta- 
blished, and that, on the other hand, the continents are 
inconstant in their level, as has been demonstrated by 
the most unequivocal proofs again and again, from the 
time of Strabo to our own times, the appearances of 
the Temple at Puzzuoli could never have been re- 
garded as enigmatical. Even if contemporary ac- 
counts had not distinctly attested the upraising of 
the coast, this explanation should have been proposed 
in the first instance as the most natural, instead of 
being now adopted unwillingly when all others have 
failed. 

To the Strong prejudices still existing in regard t0 
the mobility of the land, we may attribute the rarity 
of such discoveries as have been recently brought t0 
light in the Bay of Baia and the Bay of Conception 
A false theory, it is well known, may render us blind 
to facts which are opposed to our prepossessions, oF 
may conceal from us their true import when we behold 
them. But it is time that the geologist should, i 
some degree, overcome those first and natural im- 
pressions which induced the poets of old to select the 
rock as the emblem of firmness—the sea as the image 
of inconstancy. Our modern poet, in a more philo- 
Sophical spirit, saw in the sea “ The image of Eternity, — 
and has finely contrasted the fleeting existence of the 


Ch.XVI] PERMANENCE OF THE OCEAN’S LEVEL. 285 


Successive empires which have flourished and fallen on 
the borders of the ocean with its own unchanged 
Stability. 


Their decay 
Has dried up realms to deserts : — not so thou, 
Unchangeable, save to thy wild waves’ play : 
Time writes no wrinkle on thine azure brow ; 
Such as creation’s dawn beheld, thou rollest now. 
Cupe Haroxp, Canto iy. 


CHAPTER XVII. 


ELEVATION AND SUBSIDENCE OF LAND WITHOUT 
EARTHQUAKES, 


Changes in the relative level of land and sea in regions not vol- 
canic — Opinion of Celsius that the waters of the Baltic Set 
and Northern Ocean were sinking — Objections raised to m 
opinion — Proofs of the stability of the sea-level in the Balti 
— Playfair’s hypothesis that the land was rising in Swede? 
— Opinion of Von Buch (p. 292.) — Marks cut on the rocks— 
Survey of these in 1820—Facility of detecting slight alteratio”? 
in level:of sea on coast of Sweden — Shores of the ocean 4/5? 
rising — Area upheaved (p. 298.) — Shelly deposits of Udde- 
valla — Of Stockholm, containing fossil shells characteristic ° 
the Baltic— Whether subsidence in Sweden — Fishing-bY 
buried under marine strata (p. 303.) — Sinking of land 2 
Greenland — Bearing of these facts on geological phenome”? 


We have now considered the phenomena of volcano’ 
and earthquakes according to the division of the sub“ 
ject before proposed (p. 40), and have next to tut” 
our attention to those slow and insensible changes ” 
the relative level of land and sea which take place m 
countries remote from volcanos, and where no violent 
earthquakes have occurred within the period of huma? 
observation. Early in the last century the Swedis? 
naturalist, Celsius, expressed his opinion that the 
waters, both of the Baltic and Northern Ocean, were 
gradually subsiding. From numerous observations Þe 
inferred, that the rate of depression was about forty 


Ch. XVIL] GRADUAL RISE OF LAND IN SWEDEN. | 287 


Swedish inches in a century.* In support of this po- 
Sition, he alleged that there weremany rocksbothon the 
Shores of the Baltic and the ocean known to have been 
Once sunken reefs, and dangerous to navigators, but 
Which were in his time above water—that the waters 
of the Gulf of Bothnia had been gradually converted 
‘Into land, several ancient ports having been changed 
Into inland cities, small islands joined to the continent, 
andold fishing grounds deserted as being tooshallow, or 
entirely dried up. Celsius also maintained, that the 
evidence of the change rested not only on modern ob- 
Servations, but on the authority of the ancient geogra- 
Phers, who had stated that Scandinavia was formerly 
an island. This island, he argued, must in the course 
of centuries by the gradual retreat of the sea have 
become connected with the continent ; an event which 
he supposed to have happened after the time of Pliny, 
and before the ninth century of our era. 

To this argument it was objected that the ancients 
Were so ignorant of the geography of the most northern 
Parts of Europe, that their authority was entitled to no 
Weight; and that their representation of Scandinavia 
as an island, might with more propriety be adduced 
to prove the scantiness of their information, than to 
Confirm so bold an hypothesis. It was also remarked, 
that if the land which connected Scandinavia with the 
Main continent was laid dry between the time of 
Pliny and the ninth century, to the extent to which 
it is known to have risen above the sea at the latter pe- 
riod, the rate of depression could not have been uniform, 


* The Swedish measure scarcely differs from ours; the foot 
being divided into twelve inches, and being less than ours by 
three eighths of an inch only. 


288 © GRADUAL RISE [Book I 


as was pretended ; for it ought to have fallen much more 
rapidly between the ninth and eighteenth centuries- 
Many of the proofs relied on by Celsius and his 
followers were immediately controverted by sever 
philosophers, who saw clearly that a fall of the sea 1” 
any one region could not take place without a gene! 
sinking of the waters over the whole globe; they 
denied that this was the fact, or that the depressio” 
was universal, even in the Baltic. In proof of th? 
stability of the level of that sea, they appealed t° 
the position of the island of Saltholm, not far fro 
Copenhagen. This island is so low that, in autum? 
and winter, it is permanently overflowed; and it ! 
only dry in summer, when it serves for pasturi®é 
cattle. It appears from documents of the year 1280, 
that Saltholm was then also in the same state, 22° 
exactly on a level with the mean height of the s€% 


instead of having been about twenty, feet unde 
water, as it ought to have been, according to th® 


computation of Celsius. Several towns, also, on the 

- shores of the Baltic, as Lubeck, Wismar, Rostocks 
Stralsund, and others, after six and even eight hundre 
years, are as little elevated above the sea as at the 
era of their foundation, being now close to the waters 
edge. ‘The lowest part of Dantzic was no high@ 
than the mean level of the sea in the year 1000; 4? 

after eight centuries its relative position remains exact ly 
the same. * 

Several of the examples of the gain of land 
shallowing of the sea pointed out by Celsius, 
afterwards by Linnzus, who embraced the same 
opinions, were ascribed by others to the deposition ° 


and 
an 


z r 
* For a full account of the Celsian controversy, we may refe 
our readers to Von Hoff, Geschichte, &c. vol. i. p. 439. 


- Ch, XVII] OF LAND IN SWEDEN. 289 . 


Sediment at points where rivers entered; and, un- 
doubtedly, Celsius had not sufficiently distinguished 
between changes due to these causes, and such as 
would arise if the waters of the ocean itself were 
diminishing. Many large rivers descending from a 
Mountainous country, at the head of the Gulf of 
Bothnia, enter the sea charged with sand, mud, and 
pebbles, and it was said that in these places the low 
land had advanced rapidly, especially near Torneo. 
At Piteo also, half a mile had been gained in forty- 
five years ; at Luleo*, no less than a mile in twenty- 
eight years ; facts which might all be admitted con- 
Sistently with the assumption that the level of the 
Baltic has remained unchanged, like that of the 
Adriatic, during a period when the plains of the Po 
and the Adige have greatly extended their area. 

It was also alleged that certain insular rocks, once 
entirely covered with water, had at length protruded 
themselves above the waves, and grown, in the course 
of a century and a half, to be eight feet high. The 
following attempt was made to explain away this phe- 
nomenon : —In the Baltic, large erratic blocks, as well 
as sand and smaller stones which lie on shoals, are 
liable every year to be frozen into the ice, where the 
Sea freezes to the depth of five or six feet. On the 
melting of the snow in spring, when the sea rises about 
half a fathom, numerous ice-islands float away, bearing 
Up these rocky fragments so as to convey them to a 
distance; and if they are driven by the waves upon 
Shoals, they may convert them into islands by deposit- 


* Piteo, Luleo,’and Obo are spelt, in many English maps, 
Pitea, Lulea, Abo; but the a is not sounded in the Swedish. 
diphthong ao OF a. 

VOL. IL 0 


Ch. XVIL] RISE OF LAND IN SWEDEN. 291 


ing the blocks ; if stranded upon low islands, they may ; 
Considerably augment their height. 

Browallius, also, and some other Swedish naturalists, 
affirmed that some islands were lower than formerly ; 
and that, by reference to this kind of evidence, there 
Was equally good reason for contending that the level 
of the Baltic was gradually rising. They also added 
another curious proof of the permanency of the water- 
level, at some points at least, for many centuries. On 
the Finland coast were some large pines, growing close 
to the water's edge; these were cut down, and, by 
Counting the concentric rings of annual growth, as seen 
in a transverse section of the trunk, it was demonstrated 
that they had stood there for four hundred years. 
Now, according to the Celsian hypothesis, the sea had 
‘unk about fifteen feet during that period, in which 
ĉase the germination and early growth of these pines 
Must have been, for many seasons, below the level of 
the water. In like manner it was asserted, that the 
ower walls of many ancient castles, such as those of 
Sonderburg and Abo, reached then to the water’s 
®dge, and must, therefore, according to the theory of 
Celsius, have been originally constructed below the 
evel of the sea. 

In reply to this last argument, Colonel Hallstrom, a 

Wedish engineer, well acquainted with the Finland 
“oast, assured me, that the base of the walls of the 
“astle of Abo is now ten feet above the water, so that 

€te may have been a considerable rise of the land at 
at point since the building was erected. 
Playfair, in his “ Illustrations of the Huttonian 
Theory,” in 1802, admitted the sufficiency of the proofs 
adduced by Celsius, but attributed the change of level 
° the movement of the land, rather than to a diminu- 
o 2 


992 GRADUAL RISE [Book IL 


tion of the waters. He observed, “that in order tO 
depress or elevate the absolute level of the sea, by 2 
given quantity, in any one place, we must depress of 
elevate it by the same quantity over the whole surface 
of the earth; whereas no such necessity exists with 
respect to the elevation or depression of the land.’* 
The hypothesis of the rising of the land, he adds, 
« agrees well with the Huttonian theory, which holds 
that our continents are subject to be acted upon by the 
expansive forces of the mineral regions ; that by thes? 
forces they have been actually raised up, and are sus- 
tained by them in their present situation.”+ 

In the year 1807, Von Buch, after returning from @ 
tour in Scandinavia, announced his conviction, “ that 
the whole country, from Frederickshall in Sweden © 
Abo in Finland, and perhaps as far as St. Petersburg! | 
was slowly and insensibly rising.” He also suggesté 
“that Sweden may rise more than Norway, and thé 
northern more than the southern part.” } He was Je 
to these conclusions principally by information ob- 
tained from the inhabitants, and pilots, and in part by 
the occurrence of marine shells of recent specie® 
which he had found at several points on the coast ° 
Norway above the level of the sea. He also mentions 
the marks set on the rocks. Von Buch, therefore, has 
the merit of being the first geologist who, after a p°% 
sonal examination of the evidence, declared in favo 
of the rise of land in Scandinavia. 

The attention excited by this subject in the early 
part of the last century, induced many philosophe* 
in Sweden to endeavour to determine, by accurate 
observations, whether the standard level of the Balti 

* Sect. $93. + Sect. 398. 
+ Transl. of his Travels, p. 387. 


Ch. XVIL] OF LAND IN SWEDEN. 293 


was really subject to periodical variations; and under 
their direction, lines or grooves, indicating the ordinary 
level of the water on a calm day, together with the 
date of the year, were chiselled out upon the rocks. 
In 1890-21, all the marks made before those years 
were examined by the officers of the pilotage establish- 
ment of Sweden; and in their report to the Royal 
Academy of Stockholm they declared, that on com- 
paring the level of the sea at the time of their 
observations with that indicated by the ancient marks, 
they found that the Baltic was lower relatively to the 
land in certain places, but the amount of change 
during equal periods of time had not been every where 
the same. During their survey, they cut new marks 
for the guidance of future observers, several of which 
Thad an opportunity of examining fourteen years after 
(in the summer of 1834), and in that interval the land 
appeared to me to have risen at certain places north of 
Stockholm four or five inches. I also convinced my- 
self, during my visit to Sweden, after conversing with 
many civil engineers, pilots, and fishermen, and after 
examining some of the ancient marks, that the evi- 
dence formerly adduced in favour of the change of 
level, both on the coasts of Sweden and Finland, was 
full and satisfactory.* The alteration of level evidently 
diminishes as we proceed from the northern parts of 
the Gulf of Bothnia towards the south, being: slight 
around Stockholm, and not in the least degree per- 
ceptible in Scania, the southernmost province of 


* In former editions I expressed many doubts as to the validity 
of the proofs of a gradual rise of land in Sweden. A detailed 
Statement of the observations which I made in 1834, and which 
led me to change my opinion, will be found in the Philosophical 
Transactions for 1835, part i. 


o3 


TTS eerie os ESAn — a ~ — A = 


294 GRADUAL RISE [Book If. 


Sweden. Some writers have indeed represented the 
rate of depression of the waters at Stockholm as very 
considerable, because certain houses in that city which 
are built on piles have sunk down within the memory 
of persons still living, so as to be out of the perpen- 
dicular ; and this in consequence of the tops of the 
piles giving way, and decaying, owing toa fall of the 
waters which has exposed them to be alternately wet 
and dry. The houses alluded to are situated on the 
borders of Lake Maeler, a large lake, the outlet of 
which joins the Baltic in the middle of Stockholm. 
This lake is certainly lower than formerly ; but the 
principal cause of the change is not the elevation of the 
land, but the removal of two old bridges built on piles, 
which formerly obstructed the discharge of the fresh- 
water into the sea. Another cause is the opening, in 


the year 1819, of a new canal at Sddertelje, a place 


south of Stockholm, by means of which a new line of 
communication was formed between Lake Maeler and 
the Baltic.* 

It will naturally be asked, whether the mean level of 
a sea like the Baltic can ever be determined so exactly 
as to perit us to appreciate a variation of level 
amounting only to one or two feet. In reply, I may 
observe, that, except near the Cattegat, there are no 
tides in the Baltic ; and it is only when particular 
winds have prevailed for several days in succession, OF 
at certain seasons when there -has been an unusually 
abundant influx of river water, or when these causes 
have combined, that this sea is made to rise two oF 
three feet above its standard level. The fluctuations 


* See Professor Johnston’s Paper, Ed. New Phil. Journ.» 
No. 29., July 1833 ; and my remarks, Phil. Trans., 1835, p. 12- 


Ch. XVIL] ` OF LAND IN SWEDEN. 295 


due to these causes are nearly the same from year to 
year ; so that the pilots and fishermen believe, and 
apparently with reason, that they can mark a deviation, 
even of a few inches, from the ordinary or mean height 
of the waters. . 

There are, moreover, peculiarities in the configur- 
ation of the shores of Norway and Sweden, which 
facilitate, in a remarkable degree, the appreciation of 
slight changes in the relative level of land and water. 
It has often been said, that there are two coasts, an 
inner and an outer one ; the inner being the shore of 
the mainland; the outer one, a fringe of countless 
tocky islands of all dimensions, called the skär (shar). 
Boats and small vessels make their coasting voyages 
within this skär; for here they may sail in smooth 
water, even when the sea without is strongly agitated. 
But the navigation is very intricate, and the pilot must 
Possess a perfect acquaintance with the breadth and 
depth of every narrow channel, and the position of 
innumerable sunken rocks. If on such a coast the 
land rises one or two feet in the course of half a cen- 
tury, the minute topography of the skär is entirely 
altered. To a stranger, indeed, who revisits it after 
an interval of many years, its general aspect remains 
the same; but the inhabitant finds that he can no 
longer penetrate with his boat through channels where 
he formerly passed ; and he can tell of countless other 
changes in the height and breadth of isolated rocks, 
now exposed, but once only seen through the clear 
water. > 

The rocks of gneiss, mica-schist, and quartz, are 
usually very hard on this coast, slow to, decompose, 
and, when protected from the breakers, remaining for 
ages unaltered in their form. Hence it is easy to 

o4 


296 GRADUAL’ RISE [Book IL 


mark the stages of their progressive emergence by the 
aid of natural and artificial marks imprinted on them: 
Besides the summits of fixed rocks, there are numerous 
erratic blocks of vast size strewed over the shoals and 
islands in the skär, which have been probably drifted 
by ice in the manner before suggested.* All these 
are observed to have increased in height and dimen- 
sions within the last half century. Some, which were 
formerly known as dangerous sunken rocks, are noW 
only hidden when the water is highest. On their first 
appearance, they usually presenta smooth, bare, rounded 
protuberance, a few feet or yards in diameter ; and @ 
single sea-gull often appropriates to itself this resting- 
place, resorting there to devour its prey. Similar 
points, in the mean time, have grown to long reefs, 
and are constantly whitened by a multitude of sea 
fowl ; while others have been changed from a reef, 
annually submerged, to a small islet, on which a few 
lichens, a fir-seedling, and a few blades of grass, attest 
that the shoal has at length been fairly changed into 
dry land. Thousands of wooded islands around shoW 
the greater alterations which time can work. In the 
course of centuries also, the spaces intervening betwee? 
the existing islands may be laid dry, and become grassy 
plains encircled by heights well clothed with lofty firs. 
This last step of the process, by which long fiords and 
narrow channels, once separating wooded islands, are 
deserted by the sea, has been exemplified within the 
memory of living witnesses on several parts of the coast 

Had the apparent fall of the waters been observed 
in the Baltic only, we might have endeavoured t° 
explain the phenomenon by local causes affecting that 


* See p. 289. ; also Vol. I. p. 271. 


Ch. XVIL] OF LAND IN SWEDEN. 297 


Sea alone. For instance, the channel by which the 
Baltic discharges its surplus waters into the Atlantic, 
Night be supposed to have been gradually widened 
and deepened by the waves and currents, in which 
Case a fall of the water, like that before alluded to in 
Lake Maeler, might have occurred. But the lowering 
of level would in that case have been uniform and 
Universal, and the waters could not have sunk at 
Torneo, while they retained their former level at 
Copenhagen. Such an explanation is also untenable 
on other grounds; for it is a fact, as Celsius long 
ago affirmed, that the alteration of level extends to 
the western shores of Sweden, bordering the ocean. 
The signs of elevation observed between Uddevalla 
and Gothenburg are as well established as those on 
the shores of the Bothnian Gulf. Among the places 
Where they may be studied, are the islands of Mar- 
Strand and Gulholmen, the last-mentioned locality 
being one of those particularly pointed out by Celsius. 

The inhabitants there and elsewhere affirm, that the 
tate of the sinking of the sea (or elevation of land) 
Varies in different and adjoining districts, being greatest 
at points where the coast is low. But in this they 
are deceived ; for they measure the amount of rise by 
the area gained, which is most considerable where the 
and descends with agentle slope into the sea. In the 
Same manner, some advocates of the Celsian theory 
formerly appealed to the increase of lands near the 
Mouths of rivers, not sufficiently adverting to the fact, 
that if the bed of the sea is rising, the change will 
always be most sensible where the bottom has been 
Previously rendered shallow ; whereas, at a distance 
tom these points, where the scarped granitic cliffs 
Plunge at once into deep water, a much greater amount 

0 5 


298 As GRADUAL RISE [Book 1. 


of elevation is necessary to produce an equally con- 
spicuous change. 

; As to the area in northern Europe which is subject 
to this slow upheaving- movement, we have not as ye 
/sufficient data for estimating it correctly. It seems 
| probable, however, that it reaches from Gothenburg t° 
(’ Torneo, and from thence to the North Cape, the rate 
of elevation increasing always as we proceed farthe" 
northwards. The two extremities of this line ar 
more than a thousand geographical miles distant fro™ 
each other; and as both terminate in the ocean, W® 
know not how much farther the motion may be pro 
longed under water. As to the breadth of the trach 
its limits are equally uncertain, though it evidently 
extends across the widest parts of the Gulf of Both- 
nia, and may probably stretch far into the interio" 
both of Sweden and Finland. Now, if the elevatio” 
continue, a larger part of the Gulf of Bothnia will Pe 
turned into land, as also more of the ocean off th® 
west coast of Sweden between Gothenburg and Udde- 
valla ; and, on the other hand, if the change has pee? 
going on for thousands of years at the rate of sever 
feet in a century, large tracts of what is now land mus 
have been submarine at periods comparatively mode™ 
It is natural therefore to inquire whether there 2° 
any signs of the recent sojourn of the sea on district 
now inland? The answer is most satisfactory. 
Near Uddevalla and the neighbouring coastland, we f” 
upraised deposits of shells belonging to species sU¢ 
as now live in the ocean; while on the opposite % 
eastern side of Sweden, near Stockholm, Gefle, 2” 
other places bordering the Bothnian Gulf, there "© 
analogous beds containing shells of species characte- 
istic of the Baltic. 


Ch. XVIL] . OF LAND IN SWEDEN. ' 299 


Von Buch announced, in 1807, that he had discovered 
in Norway and at Uddevalla in Sweden, beds of shells of 
existing species, at considerable heights above the sea. 
Since that time, other naturalists have confirmed his 
observation ; and, according to Ström, deposits occur at 
an elevation of more than 400 feet above the sea in 
the northern part of Norway. M. Alex. Brongniart, 
when he visited Uddevalla, ascertained that one of the 
Principal masses of shells, that of Capellbacken, is 
raised more than 200 feet above the sea, resting on rocks 
of gneiss, all the species being identical with those now 
inhabiting the contiguous ocean. The same naturalist 
also stated that on examining with care the surface of 
the gneiss, immediately above the ancient shelly de- 
posit, he found barnacles (balani) adhering to the 
tocks, showing that the sea had remained there for a 
long time. I was fortunate enough to be able to verify 
this observation by finding, in the summer of 1834, at 
Kured, about two miles north of Uddevalla, and at the 
height of more than 100 feet above the sea, a surface of 
gneiss newly laid open by the partial removal of a mass 
of shells used largely in the district for making lime and 
repairing the roads. So firmly did these barnacles 
adhere to the gneiss that I broke off portions of the 
rock with the shells attached. The face of the gneiss 
was also encrusted with small zoophytes (Cellepora ? 
Lam.), but had these or the barnacles been exposed in 
the atmosphere ever since the elevation of the rocks 
above the sea, they would probably have decomposed 
and been obliterated. 

The town of Uddevalla stands at the head of a 
Narrow creek overhung by steep and barren rocks of 
gneiss, of which all the adjacent country is composed, 
€xcept in the low grounds and bottoms of valleys, 

0 6 


300 GRADUAL RISE [Book 1I. 


where strata of sand, clay, and marl frequently hide 
the fundamental rocks. To these newer and horizontal’ 
deposits the fossil shells above mentioned belong, and 
similar marine remains are found at various heights 
above the sea on the opposite island of Orust. The 
extreme distance from the sea to which such fossils 
extend is as yet unknown, but they have been already 
found. at Trollhattan in digging the canal there, and 
still farther inland on the northern borders of Lake 
Wener fifty miles from the sea, at an elevation of 200 
feet, near Lake Rogvarpen. | 

To pass to the Baltic: I observed near its shores at 
Sodertelje, sixteen miles S. W. of Stockholm, strata of 
sand, clay, and marl, more than 100 feet high, and 
containing shells of species now inhabiting the Both- 
nian Gulf. These consist partly of marine and partly 
of freshwater species; but they are few in number 
the brackishness of the water appearing to be very 
unfavourable to the development of testacea. The 
most abundant species are the common cockle, and the 
common mussel and periwinkle of our shores ( Cardium 
edule, Mytilus edulis, and Littorina littorea), together 
with a small tellina (7. Baltica), and a few minute 
univalves allied to Paludina ulva. These live in the 
same waters as a Lymneus, a Neritina (N. fluviatilis)» 
and some other freshwater shells. 

But the marine mollusks of the Baltic above men- 
tioned, although very numerous in individuals, are 
dwarfish in size, scarcely ever attaining a third of the 
average dimensions which they acquire in the saltet 
waters of the ocean. By this character alone a ge0- 
logist would generally be able to recognize an as- 
semblage of Baltic fossils as distinguished from those 
derived from a deposit in the ocean. The absence also 


‘Ch, XVIL] OF LAND IN SWEDEN. ' 301 


of oysters, barnacles, whelks, scallops, limpets (ostrea, 
balanus, buccinum, pecten, patella), and many other 
forms abounding alike in the sea near Uddevalla, and in 
the fossiliferous deposits of modern date on that coast, 
Supplies an additional negative character of the greatest 
value, distinguishing assemblages of Baltic from those of 
oceanic shells. Now the strata containing Baltic shells 
are found in many localities near Stockholm, Upsala, 
and Gefle, and will probably be discovered every where 
around the borders of the Bothnian Gulf; for I have 
Seen similar remains brought from Finland, in marl 
resembling that found near Stockholm. The utmost 
distance to which these deposits have yet been traced 
inland, is on the southern shores of Lake Maeler, at a 
place seventy miles from the sea.* 

As no accurate observations on the rise of the 
Swedish coast refer to periods’ more remote than a 
Century and a half from the present time, and. as 
traditional information, and that derived from ancient 
buildings on the coast, do not enable the antiquary to 
trace back any monuments of change for more than 
five or six centuries, we cannot declare whether the 
tate of the upheaving force is uniform during very 
long periods. - In those districts where the fossil shells 
are found at the height of more than 200 feet above 
the ocean, as at Uddevalla, Orust, and Lake Rogvarpen, 
the present rate of rise seems less than four feet in a 
Century. Even at that rate it would have required , 
five thousand years to lift up those deposits. But as 
the movement is now very different in different places, 
it may also have varied much in intensity at different 
Periods. 

Whether any of the land in Norway is now rising 


* Phil. Trans., 1835, part i. 


j 
| 
i ip 
f, f fF 
Ef ip 
ga 
EER 
i ji 
1 i it 
Bea) 
} j 
y ii i | 
A id, 
E | 
| ip i 
q li 
' f 
kf 
p | | 
| ay 
mas 
i f i) 
nt ie 
EEEN, 
ai 
ea 
| 


302 ~ GRADUAL RISE ’ [Book II. 


must be determined by future investigations, Marine 
fossil shells, of recent species, have been collected 
from inland places near Drontheim; but Mr. Everest; 
in his “Travels through Norway,” informs us that 
the small island of Munkholm, which is an insu- 
lated rock in the harbour of Drontheim, affords con- 
clusive evidence of the land having in that region 
remained stationary for the last eight centuries. The 
area of this isle does not exceed that of a small village, 
and by an official survey, its highest point has bee? 
determined to be twenty-three feet above the mea? 
high water mark, that is, the mean between neap and 
spring tides. Now, a monastery was founded there by 
Canute the Great, a. D. 1028, and thirty-three years 
before that time it was in use as a common place of 
execution. According to the assumed average rate of © 
rise in Sweden (about forty inches in a century), we 
should be obliged to suppose that this island had bee? 
three feet eight inches below high-water mark when it 
was originally chosen as the site of the monastery. 
But we have not only to learn whether the motion 
proceeds always at the same rate, but also whether it 
has been uniformly in one direction. The level of the 
land may oscillate; and for centuries there may be 4 
depression, and afterwards a re-elevation, of the same 
district. This idea is rendered the more probable by 
the proofs lately brought to light by two Danish inves- 
tigators, Dr. Pingel and Captain Graah, of the sinking 
down of part of the west coast of Greenland, for a space 
of more than 600 miles from north to south. The obser’ 
ations alluded to were made by Captain Graah during ê 
survey of Greenland in 1823-24; and afterwards 
1828-29; those by Dr. Pingel were made in 1830- 
32. It appears from various signs and traditions» 


Ch. XVIL] OF LAND IN SWEDEN. 303- 


that the coast has been subsiding for the last four cen- 
turies from the Firth called Igalliko in lat. 60° 43’. N. 
to Disco Bay, extending to nearly the 69th degree of 
north latitude. Ancient buildings on low rocky islands 
and on the shore of the mainland have been gradually 
submerged, and experience has taught the aboriginal 
Greenlander never to build his hut near the water’s 
edge. In one case, the Moravian settlers have been 
obliged more than once to move inland the poles upon 
which their large boats were set, and the old poles still 
remain beneath the water as silent witnesses of the, 
change.* 

Some phenomena in the neighbourhood of Stock- | 
holm, appear to me only explicable on the supposition 
of the alternate rising and sinking of the ground since 
the country was inhabited by man. In digging a canal, 
in 1819, at Sodertelje, about sixteen miles to the 
south of Stockholm, to unite Lake Maeler with the 
Baltic, marine strata, containing fossil shells of Baltic 
species, were passed through. At a depth of about 
sixty feet, they came down upon what seems to have 
been a buried fishing-hut, constructed of wood, in a 
state of decomposition, which soon crumbled away on 
exposure to the air. The lowest part, however, which 
had stood on a level with the sea, was in a more 
perfect state of preservation. On the floor of this hut 
was a rude fireplace, consisting of a ring of stones, 
and within this were cinders and charred wood. On 
the outside lay boughs of the fir, cut as with an axe, 
with the leaves or needles still attached. It seems 
impossible to explain the position of this buried hut, 
Without imagining, as in the case of the Temple 


* See Proceedings of Geol. Soc., No. 42. p. 208. I also con- 
versed with Dr. Pingel on the subject at Copenhagen in 1834, 


304 GRADUAL RISE [Book H. 


of Serapis (see p. 267.), first, a subsidence to the 
depth of more than sixty feet, then a re-elevation. 
During the period of submergence, the hut must have 
become covered over with gravel and shelly marl, 
under which not only the hut, but several vessels also 
were found, of a very antique form, and having their 
timbers fastened together by wooden pegs instead of 
nails.* 

The probable cause of these movements, whether of 
elevation or depression, will be more appropriately 
discussed in the following chapters, when the origin 
of subterranean heat is considered. But I may re- 
mark here, that the rise of Scandinavia has naturally 
been regarded as a very singular and scarcely credible 
phenomenon, because no region on the globe has been 
more free within the times of authentic history from 
violent earthquakes. In common, indeed, with our 
own island, and with almost every spot on the globe, 
some movements have been, at different periods, ex- 
perienced, both in Norway and Sweden. But some of 
these, as for example during the Lisbon earthquake in 
1755, may have been mere vibrations of the earth’s 
crust prolonged from a great distance. Others, how- 
ever, have been sufficiently local to indicate a source 
of disturbance. immediately under the country itself. 
Notwithstanding these shocks Scandinavia has, upon 
the whole, been as tranquil in modern times, and as 
free from subterranean convulsions, as any region of 
equal extent on the globe. There is also another 
circumstance which has made the change of level in 
Sweden appear anomalous, and has for a long time 
caused the proofs of the fact to be received with 
reluctance. Volcanic action, as we have seen, is 


* See the paper before referred to, Phil. Trans, 1835, pt. i. 


Ch. XVIL] OF LAND IN SWEDEN. 1 305 


Usually intermittent: and the variations of level to 
Which it has given rise have taken place by starts, not 
by a prolonged and insensible movement similar to 
that experienced in Sweden. 

Yet, when we are once assured of the reality of the 
gradual rise of a large region, it enables us to account 
for many geological appearances otherwise very difficult 
of explanation. There are large continental tracts and 
high table lands where the strata are nearly horizontal, 
bearing no marks of having been thrown up by violent 
Convulsions, ndt by a series of movements, such as 
those which occur in the Andes, and cause the earth to 

be rent open, and raised or depressed from time to 


time, while large masses are engulphed in subterranean 
Cavities. The result of a series of such earthquakes | 
Might be to produce in a great lapse of ages a country) \ 
of shattered, inclined, and perhaps vertical strata. But, || 


a movement like that of Scandinavia would cause the | (| 
bed of the sea, and all the strata recently formed in it, | b7 
to be upheaved so gradually, that it would merely \) 
Seem as if the ocean had formerly stood, at a higher || 
level, and had slowly and tranquilly sunk down into À 
its present bed. 

The fact also of a very gradual and insensible ele- 
Vation of land may explain many geological monu- 
Ments of denudation, on a grand scale. If, for ex- 
ample, instead of the hard granitic rocks of Norway 
and Sweden, a large part of the bed of the Atlantic, 
Consisting chiefly of soft strata, should rise up, century 
after century, at the rate of about half an inch, or an 
mch, in a year, how easily might oceanic currents, 
Such as those described in the sixth chapter, sweep 
away the thin film of matter thus brought up annually 
Within the sphere of aqueous denudation! The tract, 


306 GRADUAL RISE OF LAND IN SWEDEN. | [Book Il 


when it finally emerged, might present table lands and 
ridges of horizontal strata, with intervening valleys and 
vast plains, where originally, and during its perio 
of submergence, the surface was level and nearly 
uniform. 

These speculations relate to superficial changes. 
but others must be continually in progress in the sub- 
terranean regions. The foundations of the country) 
thus gradually uplifted in Sweden, must be under- 
going important modifications. Whether we ascribe 
these to the expansion of solid mattef by continually 
increasing heat, or to the liquefaction of rock, or t0 
the crystallization of a dense fluid, or the accumulation 
of pent-up gases, in whatever conjectures we indulges 
we can never doubt for a moment, that at some ur“ 
known depth the structure of the globe is in our ow? 
times becoming changed from day to day, throughout 
a space probably more than a thousand miles in length, 
and several hundred in breadth. 


CHAPTER XVIII. 


CAUSES OF EARTHQUAKES AND VOLCANOS. 


Intimate connexion between the causes of volcanos and earth- 


quakes— Supposed original state of fusion of the planet — 
Universal fluidity not proved by spheroidal figure of the earth 
— Heat in mines increasing with the depth (p. 313.) — Objec- 
tions to the supposed intense heat of a central fluid — Whether 
chemical changes may produce volcanic heat (p. 320.) — Cur- 
rents of electricity circulating in the earth’s crust — Theory of 
an unoxidated metallic nucleus (p. $26.) —The metallic oxides 
When heated may be deoxidated by hydrogen. 


` 


Ir will hardly be questioned, after the description be- 
fore given of the phenomena of earthquakes and vol- 
Canos, that both of these agents have, to a certain 
extent, a common origin; and I may now, therefore, 
Proceed to inquire into their probable causes. But 
first, it may be well to recapitulate some of those 
Points of relation and analogy which lead naturally 
to the conclusion, that they spring from a common 
Source. ts 

The regions convulsed by violent earthquakes in- 
clude within them the site of all the active volcanos. | 

arthquakes, sometimes local, sometimes extending i 
Over vast areas, often precede volcanic eruptions. 'The' 
Subterranean movement and the eruption return again 
“nd again, at irregular intervals of time, and with 
Unequal degrees of force, to the same spots. The 


Dm a 


F: 
A EEN Wi 
és a 


308 ORIGIN OF THE SPHEROIDAL [Book 1! 


action of either may continue for a few hours, or for 
several consecutive years. Paroxysmal convulsions 
are usually followed, in both cases, by long periods 
of tranquillity. Thermal and mineral springs aré 
abundant in countries of earthquakes and active vol- 
canos. Lastly, hot springs situated in districts con 
siderably distant from volcanic vents have been 0b- 
served to have their temperature suddenly raised, and 
the volume of their water augmented, by subterranea? 
movements. 

All these appearances are evidently more or les’ 
connected with the passage of heat from the interio" 

_ of the earth to the surface; and where there are activ® 

volcanos, there must exist, at some unknown depth 
below, enormous masses of matter intensely heated 
and, in many instances, in a constant state of fusio 
We have first, then, to inquire, whence is this he 
derived ? 

It has long been a favourite conjecture, that thé 
whole of our planet was originally in a state of igneo™® 
fusion, and that the central parts still retain a great 
portion of their primitive heat. Some have imagined 
with the late Sir W. Herschel, that the elementary mate 
ter of the earth may have been first in a gaseous stat 
resembling those nebule which we behold in the he% 
vens, and which are of dimensions so vast, that some 
of them would fill the orbits of the remotest planets 
of our system. It is conjectured that such aérifor™ 
matter (for in many cases the nebulous appearanc® 
cannot be referred to clusters of very distant stars)» 
if concentrated, might form solid spheres; and othe! 
have imagined that the evolution of heat, attendant 0” 
condensation, might retain the materials of the new 
globes in a state of igneous fusion. 


Ch. XVIIL] FORM OF THE EARTH. 309 


Without dwelling on such speculations, which can 
only have a distant bearing on geology, we may con- 
Sider how far the spheroidal form of the earth affords 
Sufficient ground for presuming that its primitive con- 
dition was one of universal fluidity. The discussion 
of this question would be superfluous, were the doctrine 
of original fluidity less popular; for it may well be 
asked, why the globe should be supposed to have had. 
a pristine shape diferent from the present one? — 
why the terrestrial materials, when first called into 
existence, or assembled together in one place, should 
Not have been subject to rotation, so as to assume at 
once that form which alone could retain their several 
Parts in a state of equilibrium ? 

Let us, however, concede that the statical figure 
may be a modification of some other pre-existing form, 
and suppose the globe to have been at first a perfect 
and quiescent sphere, covered with an uniform ocean 
— what would happen when it was made to turn 
round on its axis with its present velocity? “ A cen- 
trifugal force,” says Sir J. Herschel, “would in that 
case be generated, whose general tendency would be 
to urge the water at every point of the surface to recede 
from the avis. A rotation might indeed be conceived 
so swift as to flirt the whole ocean from the surface, 
like water from a mop. But this would require a far 
greater velocity than what we now speak of. In the 
case supposed, the weight of the water would still keep 
it on the earth; and the tendency to recede from the 
axis could only be satisfied, therefore, by the water 
leaving the poles, and flowing towards the equator; 
there heaping itself up in a ridge, and being retained 
in opposition to its weight or natural tendency towards 
the centre by the pressure thus caused. This, how- 


310 ORIGIN OF THE SPHEROIDAL [Book II. 


ever, could not take place without laying dry the polar 
regions, so that protuberant land would appear at the 
poles, and a zone of ocean be disposed around the 
equator. This would be the first or immediate effect: 
Let us now see what would afterwards happen if 
things were allowed to take their natural course. 

“ The sea is constantly beating on the land, grinding 
it down, and scattering its worn-off particles and frag- 
ments, in the state of sand and pebbles, over its bed. 
Geological facts afford abundant proof that the exist- 
ing continents have all of them undergone this process, 
even more than once, and been entirely torn in frag- 
ments, or reduced to powder, and submerged and 
reconstructed. Land, in this view of the subject, loses 
its attribute of fixity. As a mass it might hold to- 
gether in opposition to forces which the water freely 
obeys ; but in its state of successive or simultaneous 
‘degradation, when disseminated through the water, in 
the state of sand or mud, it is subject to all the impulses 
of that fluid. In the lapse of time, then, the protu- 
berant land would be destroyed, and spread over the 
bottom of the ocean, filling up the lower parts, and 
tending continually to re-model the surface of the 
solid nucleus, in correspondence with the Jorm of equi- 
librium. Thus after a sufficient lapse of time, in the 
case of an earth in rotation the polar protuberances 
would gradually be cut down and disappear, being 
transferred to the equator (as being then the deepest 
sea), till the earth would assume by degrees the form 
we observe it to have—that of a flattened or oblate 
ellipsoid. 

“ We are far from meaning here to trace the process 
by which the earth really assumed its actual form; all 
we intend is to show that this is the form to which, 


Ch. XVIIL] FORM OF THE EARTH. sli 


Under a condition of a rotation on its axis, it must 
tend, and which it would attain even if originally and 
(s0 to speak) perversely constituted otherwise.” * 

In this passage, the author has contemplated the} 7 
Superficial effects of aqueous causes only ; he righe | | 


l | 


| | Power; and if the volcanic action should extend to f 
| 8reat depths, so as to melt, one after another, different || 
Parts of the earth, the whole interior might at length | 
be remodelled under the influence of similar changes, | 
| due to causes which may all be operating at this mo- 
| \ ment/ The statical figure, therefore, of the terrestrial 
spheroid (of which the longest diameter exceeds the 
Shortest by about twenty-five miles), may have been 
the result of gradual and even of existing causes, 
and not of a primitive, universal, and simultaneous 
fluidity. 
Experiments made with the pendulum, and observ- 
ations on the manner in which the earth attracts the 
moon, have shewn that our planet is not an empty 
Sphere, but that it must rather increase in density 
from the surface towards the centre ; and it has also 
been inferred that the equatorial protuberance is con- 
tinued inwards, that is to say, that layers of equal 
density are arranged elliptically, and symmetrically, 
from the exterior to the centre. The inequalities, 
Owever, in the moon’s motion, on which this opinion 
Ig founded, are so extremely slight, that it can be 
Tegarded as little more than a probable conjecture. 
The mean density of the earth has been computed 


* Herschel’s Astronomy, chap, iii. 


819 DENSITY OF THE EARTH. [Book I. 


by Laplace to be about 54, or more than five times 
that of water. Now the specific gravity of many of 
our rocks is from 2} to 3, and the greater part of the 
metals range between that density and 21. Hence 
some have imagined that the terrestrial nucleus may 
be metallic—that it may correspond, for example; 
with the specific gravity of iron, which is about 7: 
But here a curious question arises in regard to thé 
form which materials, whether fluid or solid, might 
assume, if subjected to the enormous pressure which 
must obtain at the earth’s centre. Water, if it com, 
tinued to decrease in volume according to the rat? 
of compressibility deduced from experiment, wou! 
have its density doubled at the depth of ninety-thre® 
miles, and be as heavy as mercury at the depth of 362 
miles. Dr. Young computed that, at the earth’s cent! 
steel would be compressed into one fourth, and ston? 
into one eighth of its bulk.* It is more than probabl® 
however, that after a certain degree of condensatio™ 
the compressibility of bodies may be governed by law’ 
altogether different from those which we can put t° 
the test of experiment ; but the limit is still undete? 
mined, and the subject is involved in such obscurity 
that we cannot wonder at the variety of notions which 
have been entertained respecting the nature and c0? 
ditions of the central nucleus. Some have conceive 
it to be fluid, others solid ; some have imagined it a 
have a cavernous structure, and have even endea- 
voured to confirm this opinion by appealing to observe 
irregularities in the vibrations of the pendulum in ceF 
tain countries. 


* Young’s Lectures, and Mrs. Somerville’s Connexion of the 
Physical Sciences, p. 90. 


Ch, XVIIL] THEORY OF CENTRAL HEAT. 313 


Central Heat. — The hypothesis of internal fluidity 
calls for the more attentive consideration, as it has 
been found that the heat in mines augments in propor- 
tion as we descend. Observations have been made, 
` not only on the temperature of the air in mines, but 
on that of the rocks, and on the water issuing from 
them. The mean rate of increase, calculated from 
results obtained in six of the deepest coal mines in 
Durham and Northumberland, is 1° Fahr. for a descent 
of forty-four English feet.* A series of observations, 
made in several of the principal lead and silver mines 
in Saxony, gave 1° Fahr. for every sixty-five feet. In 
this case, the bulb of the thermometer was introduced 
into cavities purposely cut in the solid rock at depths 
varying from two hundred to above nine hundred feet. 
But in other mines of the same country, it was neces- 
Sary to descend thrice as far for each degree of tem- 
perature.+ 

-A thermometer was fixed in the rock of the Dolcoath 
mine, in Cornwall, by Mr. Fox, at the great depth of 
1380 feet, and frequently observed during eighteen 
months ; the mean temperature was 68° Fahr., that of 
the surface being 50°, which gives 1° for every 
Seventy-five feet. 

Kupffer, after an extensive comparison of the re- 
Sults in different countries, makes the increase 1° F, 
for about every thirty-seven English feet; and Cor- 
dier considers that it would not be overstated at 1° 
Cent. for every twenty-five metres, or about 1° F, for 
every forty-five feet. § 


* Ed. Journal of Sci., April 1832. 

+ Cordier, Mém. de l’Instit., tom. vii. 

ł Pog. Ann. tom. xv. p. 159. 

§ Cordier, Mém. de I’Instit. tom. vii. 
VOL, II. P 


314 THEORY OF CENTRAL [Book II. 


Some writers have endeavoured to refer these phe- 
nomena (which, however discordant as to the ratio of 
increasing heat, appear all to point one way), to the 
condensation of air constantly descending from the 
surface into the mines. For the air under pressure 
would give out latent heat, on the same principle as it 
becomes colder when rarified in the higher regions of 
the atmosphere. But, besides that the quantity of 
heat is greater than could be supposed to flow from 
this source, the argument has been answered in @ 
satisfactory manner by Mr. Fox, who has shown, that 
in the mines of Cornwall the ascending have generally 
a higher temperature than the descending aérial cur- 
rents. The difference between them was found tO 
vary from 9° to 17° F.: a proof, that instead of im- 
parting heat, these currents actually carry off a large 
quantity from the mines.* 

If we adopt M. Cordier’s estimate of 1° F. for every 
45 feet of depth as the mean result, and assume, with 
the advocates of central fluidity, that the increasing 
temperature is continued downwards, we should reach 
the ordinary boiling point of water at about two miles 
below the surface, and at the depth of about twenty- 
four miles should arrive at the melting point of iron, 4 
heat sufficient to fuse almost every known substance. 
The temperature of melted iron was estimated at 
21,000° F., by Wedgwood; but his pyrometer gives, 
as is now demonstrated, very erroneous results. It 
has been ascertained by Professor Daniell, that the 
point of fusion is 2786° F.} 


* Phil. Mag. and Ann., Feb. 1830. 
+ The heat was measured in Wedgwood’s pyrometer by the 
contraction of pure clay, which is reduced in volume when heated, 


Ch, XVIIL] HEAT AND FLUIDITY. ee 


By adopting the least correct of these two results 
the melting point of our ordinary rocks would be far- 
ther removed from the surface ; but this difference 
does not affect the probability of the theory now under 
Consideration. According to Mr. Daniell’s scale, we 
ought to encounter the internal melted matter before 
Penetrating through a thickness represented by that of 
the outer circular line in the annexed diagram (Fig. 59.); 
Whereas, if the other scale be correct, we should meet 
With it at some point between the two circles; the space 
between them, together with the lines themselves, re- 
Presenting a crust of two hundred miles in depth. In 
Cither case, we must be prepared to maintain, that a 
temperature many times greater than that sufficient to 
Melt the most refractory substances known to us, is 
Sustained at the centre of the globe; while a compa- 
‘atively thin crust, resting upon the fluid, remains 
Umelted; or is even, according to M. Cordier, in- 
“teasing in thickness, by the continual addition of new 
Internal layers solidified during the process of refri- 
eration. 

The mathematical calculations of Fourier, on the 
Passage of heat through conducting bodies, have been 


first by the loss if its water of combination, and afterwards on 
€ application of more intense heat, by incipient vitrification. 
he expansion of platina is the test employed by Mr. Daniell, in 
is Pyrometer, and this has been found to yield uniform and con- 
Sistent results, such as are in perfect harmony with conclusions 
rawn from various other independent sources. ‘The instrument 
for which the author received the Rumford Medal from the Royal 
ciety in 1833, is described in the Phil, Trans, 1830, part iie, 
and 1831, part ii. 
P 2 


THEORY OF CENTRAL 


Fig. 59. 


pesenis, 
ath 


Section of the earth in which the breadth of the outer boundary line rep 
a thickness of 25 miles ; the space between the circles including the brea 
the lines, 200 miles. 

since appealed to in support of these views ; for he has 

shown that it is compatible with theory that the pt 

sent temperature of the surface might coexist wit 
an intense heat, at a certain depth below. But bis 

reasoning seems to be confined to the conduction ° 

heat through solid bodies; and the conditions of the 

problem are wholly altered when we reason about p 

fluid nucleus, as we must do, if it be assumed that 

the heat augments from the surface to the intero" 
according to the rate observed in mines. For whe? 
the heat of the lower portion of a fluid is increased, ? 
circulation begins throughout the mass, by the asce” 


Ch. XVIIL] ~ HEAT AND FLUIDITY. 317 


of hotter, and the descent of colder currents. And 
this circulation, which is quite distinct from the mode 
in which heat is propagated through solid bodies, must 
evidently occur in the supposed central ocean, if the 
laws of fluids and of heat are the same there as upon 
the surface. 

In Mr. Daniell’s recent experiments for obtaining a 
measure of the heat of bodies, at their point of fusion, 
he invariably found that it was impossible to raise the 
heat of a large crucible of melted iron, gold, or silver, 
asingle degree beyond the melting point, so long as_ 
a bar of the respective metals was kept immersed. in 
the fluid portions. So in regard to other substances, 
however great the quantities fused, their temperature 
could not be raised while any solid pieces immersed 
in them remained unmelted ; every accession of heat 
‘being instantly absorbed during their liquefaction. 
These results are, in fact, no more than the extension 
of a principle previously established, that so long as a 
fragment of ice remains in water, we cannot raise the 
temperature of the water above 32° F. 

If, then, the heat of the earth’s centre amount to 
450,000° F., as M. Cordier deems highly probable, 
that is to say; about twenty times the heat of melted 
iron, even according to Wedgwood’s scale, and up- 
wards of 160 times according to the improved pyro- 
meter, it is clear that the upper parts of the fluid 
mass could not long have a temperature only just ` 
sufficient to melt rocks. There must be a continual 
tendency towards a uniform heat ; and until this were 
accomplished, by the interchange of portions of fluid 
of different densities, the surface could not begin to 
consolidate. Nor, on the hypothesis of primitive 
fluidity, can we conceive any crust to have been 

Pro 


318 THEORY OF CENTRAL [Book If. 


formed until the whole planet had cooled down to about 
the temperature.of incipient fusion. 

It cannot be objected that hydrostatic pressure 
would prevent a tendency to equalization of temper- 
ature ; for, as far as observations have yet been made, 
it is found that the waters of deep lakes and seas are 
governed by the same laws as a shallow pool; and no 
experiments indicate that solids resist fusion under 
high pressure. The arguments, indeed, now con- 
troverted, always proceed on the admission that the 
internal nucleus is in a state of fusion. 

It may be said that we may stand upon the hardened 
surface of a lava current while it is still in motion,— 
nay, may descend into the crater of Vesuvius after an 
eruption, and stand on the scoriz while every crevice 
shows that the rock is red-hot two or three feet below 
_ us; and at a somewhat greater depth, all is, perhaps, 
in a state of fusion. May not, then, a much more 
intense heat be expected at the depth of several 
hundred yards, or miles? . The answer is, —that, until 
a great quantity of heat has been given off, either by 
the emission of lava, or in a latent form by the evolu- 
tion of steam and gas, the melted matter continues to 
boil in the crater of a volcano. But ebullition ceases 
when there is no longer a sufficient supply of heat 
from below, and then a crust of lava may form on the 
top, and showers of scoriz may then descend upon the 
surface, and remain unmelted. If the internal heat 
be raised again, ebullition will recommence, and soon 
fuse the superficial crust. So in the case of the moving 
current, we may. safely assume that no part of the 
liquid beneath the hardened surface is much above the 
temperature sufficient to retain it in a state of fluidity- 

It may assist us in forming a clearer view of the 


Ch, XVIIL] HEAT AND FLUIDITY. 319 


doctrine now controverted, if we consider what would 
happen were a globe of homogeneous composition 
placed under circumstances analogous, in regard to the 
distribution of heat, to those above stated. If the 
whole planet, for example, were composed of water 
covered with a spheroidal crust of ice fifty miles thick, 
and with an interior ocean having a central heat about 
two hundred times that of the melting point of ice, or 
6400° F. ; and if, between the surface and the centre, 
there was every intermediate degree of temperature 
between that of melting ice and that of the central 
nucleus;——could such a state of things last for a 
moment ? If it must be conceded, in this case, that 
the whole spheroid would be instantly in a state of 
violent ebullition, that the ice (instead of being 
strengthened annually by new internal layers) would 
soon melt, and form part of an atmosphere of steam— 
on what principle can it be maintained that analogous 
effects would not follow, in regard to the earth, under 
the conditions assumed in the theory of central heat ? 
M. Cordier admits that there must be tides in the 
internal melted ocean; but their effect, he says, has 
become feeble, although originally, when the fluidity — 
of the globe was perfect, the rise and fall of these 
ancient land tides could not have been less than from 
thirteen to sixteen feet. Now granting, fora moment, 
that these tides have become so feeble as to be incapa- 
ble of lifting up every six hours the fissured shell of 
the earth, may we not ask whether, during eruptions, 
jets of lava ought not to be thrown up from the craters 
of volcanos, when the tides rise ? — and whether the 
same phenomena would not be conspicuous in Strom- 
boli, where there is always lava boiling in the crater ? 
Ought not the fluid, if connected with the interior 
P 4 


320 HEAT PRODUCED BY [Bcok If. 


ocean, to disappear entirely on the ebbing of its 
tides ? 

Whether chemical changes may produce volcanic heat. 
— Having now explained the reasons which have in- 
duced me to question the hypothesis of central heat as 
the primary Source of volcanic action, it remains to 
consider what has been termed the chemical theory ° 
of volcanos. It is well known that many, perhaps all, 
of the substances of which the earth is composed are 
continually undergoing chemical changes. To what 
depth these processes may be continued downwards 
must, in a great degree, be matter of conjecture; but 
there is no reason' to suspect that, if we could descend 
to a great distance from the surface, we should find 
elementary substances differing essentially from those 
with which we are acquainted. 

Playfair has, indeed, attempted to deduce, from an 
observation of Pallas, that we can, by the aid of geo- 
logy, see, as it were, into the interior as far as thirty 
miles or more ; for Pallas had described, in the penin- 
sula of Tauris, a series of parallel strata as regular as 
the leaves of a book, inclined at an angle of 45° to the 
horizon, and exposed in a continuous section eighty- 
six English miles long. The height of the range of 
hills composed of these strata does not exceed twelve 
hundred feet; but if we measure. the thickness of the 
stratified mass by a line perpendicular to its strati- 
fication, the height of the uppermost bed above the 
undermost must have been originally more than sixty 
miles; and, even allowing, says Playfair, that the strata 
had shifted during their elevation, we may stil] suppose 
a thickness of thirty miles. But, if a deception to-the 
extent of one half is allowed for, on the score of shift- 
ing, it may well be asked why the same cause might 


Ch. XVIIL] CHEMICAL CHANGES. 321 


not have produced a much greater amount of error ? 
I shall point out, in another place, that, besides the 
probability of a shifting of the beds during elevation, 
there may also have been an original deviation from 
horizontality in the strata, which might cause them to 
assume the appearance of having been deposited in an 
Ocean many leagues in depth, when, in fact, they may 
have been accumulated in a sea only a few hundred 
fathoms deep.* 

Nevertheless, since we discover in mountain chains 
strata thousands of feet thick, which must have been 
formed at the bottom of the sea, but are now raised to 
the height of three or four miles above it, we may 
fairly speculate on the probability of rocks, such as are 
now on the surface, existing at the depth of several 
leagues below. pds 

We may next recall to mind that all the solid, fluid, 
and gaseous bodies which enter into the composition 
of the earth, consist of a very small number of ele- 
mentary substances variously combined: the total 
number of elements at present known is less than 
sixty ; and not half of these enter into the composition 
of the more abundant inorganic productions. 

Some portions of the compounds above alluded to 
are daily resolved into their elements; and these, on 
being set free, are always passing into new combin- 
ations. These processes are by no means confined to 
the surface, and are almost always accompanied by the 
evolution of heat, which is intense in proportion to the 
rapidity of the combinations. At the same time, there 
is a development of electricity. 

It is well known that mixtures of sulphur and iron, 
sunk in the ground, and exposed to moisture, give out 


* Book iv. chap. xii. 
pe 


PS 


322 HEAT PRODUCED BY [Book 1. 


sufficient heat to pass gradually into a state of com- 
bustion, and to set fire to any bodies that are near: 
The following experiment was first made by Lemery :— 
Let a large quantity of clean iron filings be mixed with 
a still larger proportion of sulphur, and as much wate! 
as is necessary to make them into a firm paste. Let 
the mixture be then buried in the earth, and the soil 
pressed down firmly upon it. In a few hours it will 
grow warm, and swell so as to raise the ground ; sul- 
phureous vapours will make their way through the 
crevices, and sometimes flames appear. There is 
rarely an explosion ; but, when this happens, the fire is 
vivid, and, if the quantity of materials is considerable, 
the heat and fire both continue for a long time.* 

The spontaneous combustion of beds of bituminous 
shale, and of refuse coal thrown out of mines, is also 
generally due to the decomposition of pyrites; and it 
is the contact of water, not of air, which brings about 
the change. A smouldering heat results from the 
various new combinations, which immediately take 
place when the sulphur and other substances are set 
free. Similar effects are often produced in mines where 
no coaly matter is present, where substances capable of 
being decomposed by water are heaped together. 

On what principle heat is generated, when two of 
more bodies having a strong affinity for each other 
unite suddenly, is wholly unexplained ; but it is a sin- 
gular fact that, while chemical combination causes 
heat, the disunion of elements does not produce the 
opposite effect, or a corresponding degree of cold. It 
may be said that decomposition is usually brought 
about by the combination of one or more of the ele- 


* Daubeny’s Volcanos, p. 356. 


Ch. XVIIL] CHEMICAL CHANGES. 323 


ments with a new substance, and this concomitant 
agency might be supposed to neutralize or counter- 
balance any frigorific effects which might otherwise be 
sensible. . But this explanation is, in many cases, 
wholly inapplicable ; as, for example, when the voltaic 
pile is used for decomposition, or in the more striking 
instance of the well-known detonating pow der,e 


/@ iodine of nitrogen, which explodes with violence in 


the open air, the instant it is touched by a cold sub- 
stance. The two elements into which this binary 
compound is resolved fly off in a gaseous form, and 
do not unite with any other body, the iodine rising in 
a purple vapour, while the nitrogen may be collected 
separately. Yet sudden as is the process by which 
their union is broken, we find that heat and light, 
instead of cold, are generated. 

Electricity a source of volcanic heat.— It has already 
beenstated, that chemical changes develope electricity; 
which, in its turn, becomes a powerful disturbing 
cause. As a chemical agent, says Davy, its silent 
and slow operation in the economy of nature is much 
more important than its grand and impressive ope- 
ration in lightning and thunder. It may be considered, 
not only as directly producing an infinite variety of 
changes, but as influencing almost all which take place ; 
it would seem, indeed, that chemical attraction itself 
is only a peculiar form of the exhibition of electrical 
attraction.* 

Now that it has been demonstrated that magnetism 
and electricity are always associated, and are perhaps 
only different conditions of the same power, the phe- 
nomena of terrestrial magnetism have become of no 


* Consolations in Travel, p. 271. 


P 6 


I 


324 ELECTRICITY A SOURCE [Book 13. 


ordinary interest to the geologist. Soon after the first 
great discoveries of Oersted in electro-magnetism, 
Ampere suggested that all the phenomena of the mag- 
netic needle might be explained by supposing currents 
of electricity to circulate constantly in the shell of the 
globe in directions parallel to the magnetic equator- 
This theory has acquired additional consistency the 
farther we have advanced in science ; and according to 
the experiments of Mr. Fox, on the electro-magnetic 
properties of metallifercus veins, some trace of electric 
currents seems to have been detected in the interior 
of the earth.* 

Some philosophers ascribe these currents to the 
chemical action going on in the superficial parts of 
the globe to which air and water have the readiest 
access ; while others refer them, in part at least, to 
thermo-electricity excited by the solar rays on the 
surface of the earth during its rotation; successive 
parts of the land and sea being exposed to the influ- 
ence of the sun, and then cooled again in the night. 
That this idea is not a mere speculation, is proved by 
the correspondence of the diurnal variations of the 
magnet with the apparent motion of the sun ; and by 
the greater amount of variation in summer than in 
winter, and during the day than in the night. M. de 
la Rive, although conceding that such minor variations 
of the needle may be due to thermo-electricity, con- 
tends that the general phenomena of terrestrial mag- 
netism must be attributed to currents far more intense ; 
which, though liable to secular fluctuations, act with 
much greater constancy and regularity than the causes 
which produce the diurnal variations.t| The remark 


* Phil, Trans. 1830, p. 399. 
t Biblioth, Univers., 1833, Electricité. 


Ch. XVIIL] OF VOLCANIC HEAT, 325 


Seems just; yet it is difficult to assign limits to the 
accumulated influence even of a very feeble force con- 
Stantly acting on the whole surface of the earth. This 
Subject, however, must evidently remain obscure, until 
we become acquainted with the causes which give a 
determinate direction to the supposed electric currents. 
Already the experiments of Faraday on the rotation 
of magnets have led him to speculate on the manner 
in which the earth, when once it had become mag- 
netic, might produce electric currents within itself, in 
Consequence of its diurnal rotation. * 

Before leaving the consideration of thermo-elec- 
tricity, I may remark, that it may be generated by 
great inequalities of temperature, arising from a partial 
distribution of volcanic heat. Wherever, for example, 
Masses of rock occur of great horizontal extent, and of 
Considerable depth, which are, at one point in a state 
of fusion (as beneath some active volcano) ; at another, 
red hot; and at a third, comparatively cold — strong 
thermo-electric action may be excited. 

Some, perhaps, may object, that this is reasoning 
in a circle; first to introduce electricity as one of the 
primary catises of volcanic heat, and then to derive 
the same heat from thermo-electric currents. But 
there must, in truth, be much reciprocal action between 
the agents now under consideration ; and it is very 
dificult to decide which should be regarded as the 
prime mover, or to see where the train of changes, 
Once begun, would terminate. 

In the ordinary operations of nature, it is in the 
atmosphere alone that we observe the action of elec- 
tricity; and it is probable that a moment never passes 


* Phil. Trans., 1832, p. 176.; also pp. 172, 173, &c. 


326 THEORY OF AN [Book H. 


without a flash of lightning striking some part of the 
earth. ‘The electric fluid shatters rocks, and instan- 
taneously melts substances which are commonly re- 
garded as infusible. The air is supposed to derive 4 
great part of this eletricity directly from the earth * ; 
and M. Necker seems to have succeeded in establish- 
ing that there is a connection between the direction 
of the curves of equal magnetic intensity and the strike 
of the principal mountain chains.t Some, also, at- 
tribute the electricity of the air to the evaporation of 
sea-water by the sun: for it can be shown, by experi- 
ment, that the conversion of salt water into vapour is 
accompanied by the excitement of electricity ; and the 
process alluded to takes place on so vast a scale, —the 
measure of the quantity of evaporation being the con- 
stant flow of all the rivers of the earth, exclusive of 
the rain which falls directly into the ocean, — that @ 
feeble action of this kind may become very powerful 
by accumulation. 

During volcanic eruptions, vivid lightnings are almost 
invariably seen in the clouds of vapour which ascend 
from the crater ; and, as there are always one or moré 
eruptions going on in some part of the globe, we are 
here presented with another perpetual source of de- 
rangement. How far subterranean electric currents 
may possess the decomposing power of the voltaic 
pile is a question for those alone who are farthest 
advanced in the career of discovery in a rapidly pro- 
gressive science; but such a power would at once 
supply us with a never-failing source of chemical 
action, from which volcanic heat might be derived. 

Theory of an unoxidated metallic nucleus. — Whe? 

* Faraday, Phil. Trans., 1832, p. 177. 
t Bibliot. Univers., tom. xliii; p. 166. 


Ch. XVII] UNOXIDATED METALLIC NUCLEUS. 397 


Sir H. Davy first discovered the metallic bases of the 
earths and alkalies, he threw out the idea that those 
metals might abound in an unoxidized state in the 
subterranean regions to which water must occasionally 
penetrate. Whenever this happened, gaseous matter 
would be set free, the metals would combine with the 
oxygen of the water, and sufficient heat might be 
evolved to melt the surrounding rocks. This hypothesis 
Was at first very favourably received both by the 
chemist and the geologist; for silica, alumina, lime, 
soda, and oxide of iron,—substances of which lavas 
are principally composed, — would all result from the 
contact of the inflammable metals alluded to with 
water. But whence this abundant store of unsatu- 
rated metals in the interior? It was asumed that, in 
the beginning of things, the nucleus of the earth was 
mainly composed of inflammable metals, and that 
oxidation went on with intense energy at first ; till, at 
length, when a superficial crust of oxides had been 
formed, the chemical action became more and more 
languid. A 

It must be confessed, that this assumption was not 
less arbitrary than that first suggested by Leibnitz, of 
an original igneous fluid; for a particular mineral con- 
dition of a primitive solid nucleus is, to say the least, 
as bold a speculation as a newly created mass of in- 
candescent matter. It would, perhaps, be more philo- 
Sophical to begin by inquiring, whether any existing 
causes may have the power of deoxidating the earthy 
and alkaline compounds formed from time to time by 
the action of water upon the metallic bases; so that 
the previous state of things might, under favourable 
Circumstances, be restored, a permanent chemical ac- 
tion sustained, and a continual circle of operation kept 


298 RECAPITULATION, [Book IL 


up. It has been suggested to me, by Mr. Daniell, 
that we have, in hydrogen, precisely such a deoxidat- 
ing agent as would be required. It is well known to 
chemists, that the metallization of the most difficultly 
reduced oxides may be effected by hydrogen brought 
into contact with them at a red heat; and it is more 
than probable that the production of potassium itself, 
in the common gun-barrel process, is due to the power 
of nascent hydrogen derived from the water which the 
hydrated oxide contains. According to the recent 
experiments, also, of Faraday, it would appear that 
every case of metallic reduction by voltaic agency; 
from saline solutions, in which water is present, is due 
to the secondary action of hydrogen upon the oxide; 
both of these being determined to the negative pole, 
and then reacting upon one another. 

It has never been disputed that intense heat might 
be produced by the occasional contact of water with 
the metallic bases; and it is quite certain that, during 
the process of saturation, vast volumes of hydroge? 
must be evolved. The hydrogen, thus generated, might 
permeate the crust of the earth in different directions: 
and be stored up for ages in fissures and caverns, 
sometimes in a liquid form, under the necessary pres 
sure. Whenever, at any subsequent period, in con- 
sequence of the changes effected by earthquakes in the 
shell of the earth, this gas happened to come in contact 
with metallic oxides at a high temperature, the reduc- 
tion of these oxides would be the necessary result. 

Recapitulation.—In the next chapter I shall inquire 
more particularly into the manner in which the phe- 
nomena of earthquakes and volcanos accord with the 
hypothesis of a continued generation of heat by che- 
mical action. But, first, it may be desirable to reca- 


Ch. XVIIL] RECAPITULATION. 329 


Pitulate, in a few words, the conclusions already 
obtained. 

lst. The primary causes of the volcano and the 
farthquake are, to a great extent, the same, and must 
be connected with the passage of heat from the in- 
terior to the surface. 

2dly. This heat has been referred, by many, to a 
Supposed state of igneous fusion of the central parts of 
the planet when it was first created, of which a part 
Still remains in the interior, but is always diminishing 
in intensity. 

3dly. The spheroidal figure of the earth, adduced 
in support of this theory, does not of necessity imply 
a universal and simultaneous fluidity in the begin- 
ing; for supposing the original figure of our planet 
ad been strictly spherical — which, however, is a 
Statuitous assumption, resting on no established ana- 
logy — still the statical figure must have been assumed, 
if sufficient time be allowed, by the gradual operation 
of the centrifugal force, acting on the materials brought 
Successively within its action by aqueous and igneous 
Causes. 

4thly. It appears, from experiment, that the heat 
in mines increases progressively with their depth; and 
if the ratio of increase be continued uniformly from 
the surface to the interior, the whole globe, with the 
exception of a small external shell, must be fluid, and 
the central parts must have a temperature many times 
higher than that of melted iron. 

Sthly. But the theory adopted by M. Cordier and 
Others, which maintains the actual existence of such 
4 State of things, seems wholly inconsistent with the 
aws which regulate the circulation of heat through 
fluid bodies, For, if the central heat were as intense 


330 RECAPITULATION. [Book I 


as is represented, there must be a circulation of cur- 
rents, tending to equalize ' the temperature of the 
‘ resulting fluid, and the solid crust itself would be 
melted, 

6thly. Instead of an original central seats we may» 
perhaps, refer the heat of the interior to chemical 
changes constantly going on in the earth’s crust; fo! 
the general effect of chemical combination is thé 
evolution of heat and electricity, which, in their tur? 
become sources of new chemical changes. 

ithly. The existence of currents of electricity in the 
shell of the earth has been deduced from the pheno 
mena of terrestrial magnetism ; from the connection 
between the diurnal variations of the magnet and the 
apparent motion of the sun; from observations on thé 
electro-magnetic properties of metalliferous veins ; and; 
lastly, ftom atmospheric electricity, which is continually 
passing between the air and the earth. 

Sthly. Subterranean electric currents may exert 4 
slow decomposing power like that of the voltaic pile 
and thus become a constant source of chemical action 
and, consequently, of volcanic heat. 

9thly. It has been suggested, that the metals of thé 
earths and alkalies may exist in an unoxidized state ® 
the subterranean regions, and that the occasional cod’ 
tact of water with these metals must produce intens? 
heat. The hydrogen, evolved during the process of 
saturation, may, on coming afterwards in contact with 
the heated metallic oxides, reduce them again t0 
metals ; and this circle of action may be one of th? 
principal means by which internal heat, and the st# 
bility of the volcanic energy, are preserved. 


CHAPTER XIX. 


CAUSES OF EARTHQUAKES AND VOLCANOS — continued. 


Heat of the interior of the earth— Causes of earthquakes — 
Expansive power of condensed gases — How land may be per- 
manently elevated — Expansion of rocks by heat (p. 339. )—Sub- 
sidence of land— Volcanic eruptions — Geysers of Iceland — 
Whether decomposition of water a source of volcanic heat — 
Almost all volcanos near the sea (p. 347. )— Many subterranean 
changes now unseen; therefore many geological phenomena 
obscure — Average annual number of earthquakes — Ele- 
vatory movements alone not opposed to the levelling force of 
running water — The sinking in of the earth’s crust must ex- 
ceed the forcing out of the same by earthquakes (p. 355.) — 
Whether earthquakes have diminished in energy — Conserva- 
tive influence of volcanic action. 


Wuen we reflect that the largest mountains are but 
insignificant protuberances upon the surface of the 
earth, and that these mountains are nevertheless com- 
Posed of different parts which have been formed in 
Succession, we may well feel surprise that the central 
fluidity of the planet should have been called in to 
account for volcanic phenomena. To suppose the 
€ntiré globe to be in a state of igneous fusion, with the 
€xception of a solid shell, not more than from thirty 
to one hundred miles thick, and to imagine that the 
Central heat of this fluid spheriod exceeds by more 
than two hundred times that of liquid lava, is to intro- 
duce a force altogether disproportionate to the effects 
Which it is required to explain. 


= ae 


SSS ea 
a ia F we 

Te ee SS — ha 
ee ——— a i 


302 VOLCANIC PHENOMENA. [Book IE 


The ordinary repose of the surface implies, on the 
contrary, an inertness in the internal mass which is 
truly wonderful. When we consider the combustible 
nature of the elements of the earth, so far as they are 
known to us, —the facility with which their compounds 
may be decomposed, and made to enter into new com- 
binations, — the quantity of heat which they evolve 
during these processes ; when we recollect the expan 
sive power of steam, and that water itself is composed 
of two gases which, by their union, produce intens¢ 
heat ; when we call to mind the number of explosive 
and detonating compounds which have been already. 
discovered, we may be allowed to share the astonish- 
ment of Pliny, that a single day should pass without 
a general conflagration : — “ Excedit profectd omnia 
miracula, ullum diem fuisse quo non cuncta confla- 
grarent.” * 

The signs of internal heat observable on the surface 
of the earth do not necessarily indicate the permanent 
existence of subterranean heated masses, whether fluid 
or solid, by any means so vast as our continents aD 
seas ; yet how insignificant would these appear if dis 
tributed through an external shell of the globe one 0 
two hundred miles in depth! The principal facts in pro? 
of the accumulation of heat below the surface may be 
summed up in a few words. Several volcanos are col 
stantly in eruption, as Stromboli and Nicaragua? 
others are known to have been active for periods 0 
60, or even 150 years, as those of Sangay in Quito» 
Popocatepetl in Mexico, and the volcano of the Isle 0 
Bourbon. Many craters emit hot vapours in the intet- 
vals between eruptions, and solfataras evolve inces- 


* Hist. Mundi, lib. ii. c. 107. 


| Ch. XIX.] ` VOLCANIC PHENOMENA. 


y 


Centre of the Earth. 


eii =— 


———— uu 


334 VOLCANIC PHENOMENA. [Book I. 


santly the same gases as volcanos. Steam of high 
temperature has continued for more than twenty cen- 
turies to issue from the “ stufas,” as the Italians call 
them, — thermal springs abound not only in regions of 
earthquakes, but are found in almost all countries; 
however distant from active vents; and, lastly, the 
temperature in the mines of various parts of the world 
is found to increase in proportion as we descend. 

It is probably to this unceasing discharge of subter- 
ranean heat that we owe the general tranquillity of 
the globe; and the occasional convulsions which occu! 
may arise from the temporary stoppage of the chan- 
nels by 'which heat is transmitted to the surface; fot 
the passage of caloric from below upwards may be 
compared to the descent of water from the continents 
to the sea; and as a partial interruption of the drain- 
age of a country causes a flood, so any obstruction t0 
the discharge of volcanic heat may give rise to an earth- 
quake or eruption. 

The annexed diagram may convey some idea of 
the proportion which our continents and the ocea! 
bear to the radius of the earth.* If all the land were 
about as high as the Himalaya mountains, and the 
ocean every where as deep as the Pacific, the whole of 
both might be contained within a space expressed by 
the thickness of the line a b; and masses of nearly 
equal volume might be placed in the space marked by 
the line ¢ d, in the interior. Seas of lava, therefore, 
of the size of the Mediterranean, or even of thé 
Atlantic, would be as nothing if distributed through 
such an outer shell of the globe as is represented by 


* Reduced, by permission, from a figure in plate 40. of Mr. 
De la Beche’s Geological Sections and Views. 


Ch. XIX.] CAUSES OF EARTHQUAKES. 335 


the shaded portion of the figurea bcd. If through- 
Out that space we imagine electro-chemical causes to 
be continually in operation, even of very feeble power, 
they might give rise to heat which, if accumulated at 
Certain points, might melt or render red-hot entire 
Mountains, or sustain the temperature of stufas and 
hot springs for ages. 

Causes of earthquakes — wave-like motion. —I shall 
Now proceed to examine the manner in which the heat 
of the interior may give rise to earthquakes; and shall 
then pass on to the probable causes of eruptions. ` One 
of the most common phenomena attending subterra- 
Nean movements, is the undulatory motion of the 
8tound. And this, says Michell, will seem less extra- 
ordinary, if we call to mind the extreme elasticity of 
the earth, and the compressibility of even the most 
Solid materials. Large districts, he suggests, may 
Test on fluid lava; and, when this is disturbed, its 
Motions may be propagated through the incumbent 
rocks. He also adds the following ingenious specu- 
lation :— «As a small quantity of vapour almost in- 
‘tantly generated at some considerable depth below 
the surface of the earth will produce a vibratory motion, 
So a very large quantity (whether it be generated 
almost instantly, or in any small portion of time) will 
Produce a wave-like motion. The manner in which 
this wave-like motion will be propagated may, in some 
Measure, be represented by the following experiment : 
T Suppose a large cloth, or carpet (spread upon a floor), 
to be raised at one edge, and then suddenly brought 

Own again to the floor; the air under ie being by 

18 means propelled, will pass along, tll it escapes at 
the Opposite side, raising the cloth in a wave all the 
Way as it goes. In like manner, a large quantity of 


P a =n 
Se aT Te SSeS SS P a Ereann 


` 


336 CAUSES OF EARTHQUAKES, [Book 1. 


vapour may be conceived to raise the earth in a wave 
as it passes along between the strata, which it may 
easily separate in a horizontal direction, there being 
little or no cohesion between one stratum and another 
The part of the earth that is first raised, being bent 
from its natural form, will endeavour to restore itse! 
by its elasticity ; and the parts next to it being to havé 
their weight supported by the vapour, which will 
insinuate itself under them, will be raised in the! 
turn, till it either finds some vent, or is again cop 
densed by the cold into water, and by that means pre 
vented from proceeding any farther.”* 

To this hypothesis of Michell it has been objected 
with some reason, that the wave-like movements ° 
the surface of the land during earthquakes, thoug? 
violent, are on a very minute scale; as appears fro 
the account of tall trees touching the ground with 
their tops, and then resuming their erect position, the 
sea-sickness experienced by spectators, and other ph® 
nomena, clearly indicating that the radius of e2¢ 
superficial curvature is very small. On the oth 
hand, the sudden fracture, it is said, of solid strat 
might produce a vibratory jar; which, being prop% 
gated in undulations through a mass of rock seve! 
thousand feet thick, would give rise to superfici! 
waves, even though the subjacent crust of the globe 
were entirely solid, and not reposing either on fluid * 
gaseous matter. t : 

The facility with which all the particles of a solid 
mass can be made to vibrate, may be illustrated, s4Y* 


* On the Cause and Phenomena of Earthquakes, Phil. Trans 
vol. li. sect, 58. 1760. 
t Quarterly Review, No, Ixxxvi. p. 463. 


Ch. XIX] CAUSES OF EARTHQUAKES. 337 


Gay Lussac, by many familiar examples. If we apply 

the ear to one end of a long wooden beam, and listen 
attentively when the other end is struck by a pin’s 
head, we hear the shock distinctly ; which shows that 
every fibre throughout the whole length has been 
Made to vibrate. The rattling of carriages on the 
pavement shakes the largest edifices ; and in the quar- 
ries underneath some quarters in Paris, it is found that 
the movement is communicated through a consider- 
able thickness of rock.* 

The rending and upheaving of continental masses 
are operations which are not difficult to explain, when 
“We are once convinced that heat, of sufficient power 
hot only to melt, but to reduce to a gaseous form a 
reat variety of substances, is accumulated in certain 
Parts of the interior. We see that elastic fluids are 
Capable of projecting solid masses to immense heights 
in the air; and the volcano of Cotopaxi has been 
known to throw out, to the distance of eight or nine 
miles, a mass of rock about one hundred cubic yards 
In yolume. When we observe these aériform fluids 
Tushing out from particular vents for months, or even 
Years, continuously, what power may we not expect 
them to exert in other places, where they happen to 
be confined under an enormous weight of rock? 

Liquid gases.— The experiments of Faraday and 
Others have shown, within the last twelve years, that 
Many of the gases, including all those which are most 
Copiously disengaged from volcanic vents, as the car- 
bonic, sulphurous, and muriatic acids, may be con- 
densed into liquids by pressure. At temperatures of 
from 30° to 50° F., the pressure required for this pur- 
Pose varies from fifteen to fifty atmospheres; and this 

* Ann, de Ch, et de Ph., tom. xxii. p. 428, 

VOL, II. Q 


238 LIQUID GASES. [Book 11. 


amount of pressure we may regard as very insigni- 
ficant in the operations of nature. A column of Vesu- 
vian lava that would reach from the lip of the crater t0 
the level of the sea, must be equal to about three hun- 
dred atmospheres; so that, at depths which may be 
termed moderate in the interior of the crust of the 
earth, the gases may be condensed into liquids, eve? 
at very high temperatures. The method employed t0 
reduce some of these gases to a liquid state is, t0 
confine the materials, from the mutual action of which 
they are evolved, in tubes hermetically sealed, so that 
the accumulated pressure of the vapour, as it rises 
and expands, may force some part of it to assume the 
liquid state. A similar process may, and indeed must 
frequently take place in subterranean caverns and 
fissures, or even in the pores and cells of many rocks: 
by which means, a much greater store of expansiv? 
power may be packed into a small space than could 
happen if these vapours had not the property of be 
coming liquid. For, although the gas occupies mu¢ 
less room in a liquid state, yet it exerts exactly th® 
same pressure upon the sides of the containing cavity 
as if it remained in the form of vapour. 

If a tube, whether of glass or other materials, filled 
with condensed gas, have its temperature slightly 
raised, it will often burst; for a slight increment ° 
heat causes the elasticity of the gas to increase ” 
a very high ratio. We have only to suppose certai” 
rocks permeated by these liquid gases (as porous 
strata are sometimes filled with water), to have the? 
temperature raised some hundred degrees, and we 
obtain a power capable of lifting superincumbe™ 
masses of almost any conceivable thickness : while, 
if the depth at which the gas is confined be great 


Ch. XIX.] CAUSES OF ELEVATION. 339 


there is no reason to suppose that any other appear- 
ances would be witnessed by the inhabitants of the 
Surface than vibratory movements and rents, from 
Which no vapour might escape. In making their way 
through fissures a very few miles only in length, or in 
forcing a passage through soft yielding strata, the 
Vapours may be cooled and absorbed by water. For 
Water has a strong affinity to several of the gases ; and 
will absorb large quantities, with a very slight increase 
of volume. In this manner, the heat or the volume of 
Springs may be augmented, and their mineral proper- 
ties made to vary. 

Permanent elevation and subsidence. —It is easy to 
Conceive that the shattered rocks may assume an 
arched form during a convulsion, so that the country 
above may remain permanently upheaved. In other 
Cases gas may drive before it masses of liquid lava, 
Which may thus be injected into newly opened fissures. 
The gas having then obtained more room, by the 
forcing up of the incumbent rocks, may remain at rest; 
While the lava congealing in the rents, may afford a 
Solid foundation for the newly raised district. 

Experiments have recently been made in America, 
by Colonel Totten, to ascertain the ratio according to 
Which some of the stones commonly used in archi- 
tecture expand with given increments of heat.* It 
Was found impossible, in a country where the annual 
Variation of temperature was more than 90° F., to make 
à coping of stones, five feet in length, in which the 
joints should fit so tightly as not to admit water between 
the stone and the cement; the annual contraction and 


* Silliman’s American Journ., vol. xxii. p. 136. The appli- 
Cation of these results to the theory of earthquakes, was first 
“Uggested to me by Mr. Babbage. 

Q 2 


Se 


340 CAUSES OF ELEVATION. {Book I. 


expansion of the stones causing, at the junctions, small 
crevices, the width of which varied with the nature of 
the rock. It was ascertained that fine-grained granite 
expanded with 1° F. at the rate of -000004825 ; white 
crystalline marble -000005668; and red sandstone 
"000009532, or about twice as much as granite. 

Now, according to this law of expansion, a mass 
of sandstone, a mile in thickness, which should havé 
its temperature raised 200° F., would lift a super- 
imposed layer of rock to the height of ten feet above 
its former level. But, suppose a part of the earth's 
crust, one hundred miles in thickness and equally 
expansible, to have its temperature raised 600° oF 
800°, this might produce an elevation of betwee? 
two and three thousand feet. The cooling of the same 
mass might afterwards cause the overlying rocks t0 
sink down again and resume their original position. 
By such agency we might explain the gradual rise 0 
Scandinavia or the subsidence of Greenland, if this 
last phenomenon should also be established as a fact 
on further inquiry. 

It is also possible that as the clay in Wedgwood's 
pyrometer contracts, by giving off its water, and the® 
by incipient vitrification; so, large masses of argil- 
laceous strata in the earth’s interior may shrink, whe? 
subjected to heat and chemical changes, and allow the 
incumbent rocks to subside gradually. It may fre- 
quently happen that fissures of great extent may be 
formed in rocks simply by the unequal expansion ofa 
continuous mass, heated in one part, while in anothet 
it remains at a comparatively low temperature. The 
sudden subsidence of land may also be occasioned by 
subterranean caverns giving way, when gases are COP” 
densed, or when they escape through newly-forme 


Ch. XIX.] CAUSES OF ERUPTIONS. 341 


crevices. The subtraction, moreover, of matter from 
Certain parts of the interior, by the flowing of lava, 
and of mineral springs, must, in the course of ages, 
Cause vacuities below, so that the undermined surface 
May at length fall in. 

Cause of volcanic eruptions. — The most probable 
causes of a volcanic outburst at the surface have been 
ina great degree anticipated in the preceding specu- 
lations on the liquefaction of rocks and the generation 
of gases. When a minute hole is bored in a tube filled 
With gas condensed into a liquid, the whole becomes 
instantly aériform, or, as some writers have expressed 
it, “flashes into vapour,” and often bursts the tube. 
Such an experiment may represent the mode in which 
gaseous matter may rush through a rent in the rocks, 
and continue to escape for days or weeks through a 
small orifice, with an explosive power sufficient to 
reduce every substance which opposes its passage into 
small fragments, or even dust. Lava may be propelled 
upwards at the same time, and ejected in the form of 
scoria. In some places, where the fluid lava lies in a 
Space intervening between a fissure, communicating 
with the surface, and a cavern in which a considerable 
body of vapour has been formed, there will be an 
efflux of lava, followed by the escape of gas. Eruptions 
often commence and close with the discharge of va- 
pour: and, when this is the case, the next outburst 
may be expected to take place by the same vent, for 
the concluding evolution of elastic fluids will keep 
Open the duct, and leave it unobstructed. 

The breaking out of lava from the side or base 
of a lofty cone, rather than from the summit, may be 
attributed to the hydrostatic pressure to which the 
flanks of the mountain are exposed, when the column 

Q3 


342 GEYSERS OF ICELAND. [Book II. 


of lava has risen to a great height. If, before it has 
reached the top, there should happen to be a stoppage 
of the main duct, the upward pressure of the ascend- 
ing column of gas and lava may be sufficient to burst 
a lateral opening. 

Geysers of Iceland. — As aqueous vapour constitutes 
the most abundant of the aériform products of vol- 
canos in eruption, it may be well to consider atten- 
tively a case in which steam is exclusively the moving 
power — that of the Geysers of Iceland. These inter- 
mittent hot springs occur in a district situated in the 
south-western division of Iceland, where nearly one 
hundred of them are said to break out within a circle 
of two miles. They rise through a thick current of 
lava, which may perhaps have flowed from Mount 
Hecla, the summit of that volcano being seen from 
the spot at the distance of more than thirty miles. 
In this district, the rushing of water is sometimes 
heard in chasms beneath the surface ; for here, as on 
Etna, rivers flow in subterranean channels through the 
porous and cavernous lavas. It has more than once 
happened, after earthquakes, that some of the boiling 
fountains have increased or diminished in violence and 
volume, or entirely ceased, or that new ones have 
made their appearance—changes which may be ex- 
plained by the opening of new rents and the closing 
of pre-existing fissures. It has often been reported that 
the powers of the Geysers are, upon the whole, on the 
decline; but the description given by Mr. Barrow, Jun. 
of the eruptions in 1834, agrees very closely with that 
of Sir J. Banks, written more than 60 years before.* 

Few of the Geysers play longer than five or six 


* See Barrow’s visit to Iceland, ch. vi. 1834. 


Ch, XIX.] GEYSERS OF ICELAND. . 343 


minutes at a time, and the intervals between their 
eruptions are for the most part very irregular. The 
great Geyser rises out of a spacious basin at the 
summit of a circular mound composed of siliceous 
incrustations deposited from the spray of its waters. 
The diameter of this basin, in one direction, is fifty-six 
feet, and forty-six in another. 


In the centre is a pipe seventy-eight feet in perpen- 
dicular depth, and from eight to ten feet in diameter, 
but gradually widening, as it rises into the basin. 
The inside of the basin is whitish, consisting of a sili- 
ceous crust, and perfectly smooth, as are likewise two 
small channels on the sides of the mound, down which 
the water escapes when the bow] is filled to the margin, 
The circular basin is sometimes empty, as represented 


* Reduced from a sketch given by W. J. Hooker, M. D., in 
his Tour in Iceland, vol. i. p. 149. 


Q 4 


344 GEYSERS OF ICELAND. [Book tt. 


in the above sketch; but is usually filled with beauti- 

fully transparent water in a state of ebullition, During 
the rise of the boiling water in the pipe, especially 
when the ebullition is most violent, and when the 
water is thrown up in jets, subterranean noises are 
heard, like the distant firing of cannon, and the earth 
is slightly shaken. The sound then increases and the 
motion becomes more violent, till at length a column 
of water is thrown up, with loud explosions, to the 
height of one or two hundred feet. After playing 
for a time like an artificial fountain, and giving off 
great clouds of vapour, the pipe or tube is emptied; 
and a column of steam rushing up with amazing force 
and a thundering noise, terminates the eruption. 

If stones are thrown into the crater, they are in- 
stantly ejected; and such is the explosive force, that 
very hard rocks are sometimes shivered by it into 
small pieces. Henderson found that by throwing a 
great quantity of large stones into the pipe of Strockr, 
one of the Geysers, he could bring on an eruption in 
a few minutes.* The fragments of stone, as well as 
the boiling water, were thrown in that case to a much 
greater height than usual. After the water had been 
ejected, a column of steam continued to rush up with 
a deafening roar for nearly an hour; but the Geyser, 
as if exhausted by this effort, did not send out a fresh 
eruption when its usual interval of rest had elapsed. 

Among the different theories proposed to account 
for these phenomena, I shall first mention one sug- 
gested by Sir J. Herschel. An imitation of these jets, 

he Says, may be produced on a small scale, by heating 
ted hot the stem of a tobacco pipe, filling the bowl 
with water, and so inclining the pipe as to let the 


* Journal of a Residence in Iceland, p. 74. 


Ch XIX.] GEYSERS OF ICELAND. 345 


water run through the stem. Its escape, instead of 
taking place in a continued stream, is then performed 
by a succession of violent explosions, at first of steam 
alone, then of water mixed with steam; and, as the 
pipe cools, almost wholly of water. At every such 
paroxysmal escape of the water a portion is driven 
back, accompanied with steam, into the bowl. The 
intervals between the explosions depend on the heat, 
length, and inclination of the pipe ; their continuance, 
on its thickness and conducting power. * The appli- 
cation of this experiment to the Geysers merely re- 
quires that a subterranean stream, flowing through 
the pores and crevices of lava, should suddenly reach 
a fissure, in which the rock is red hot, or nearly so. 
Steam would immediately be formed, which, rushing 
up the fissure, might force up water along with it to 
the surface, while, at the same time, part of the 
steam might drive back the water of the supply for a 
certain distance towards its source. And when, after 
the space of some minutes, the steam was all condensed, 
the water would return, and a repetition of the phe- 
nomena take place. 

There is, however, another mode of explaining the 
action of the Geyser perhaps more probable than that 
above described. Suppose water percolating from the 
surface of the earth to penetrate into the subterranean 
cavity AD by the fissures FF, while, at the same 
time, steam, at an extremely high temperature, such 
as is commonly given out from the rents of lava cur- 
rents during congelation, emanates from the fissures 
C. A portion of the steam is at first condensed into 
water, while the temperature of the water is raised 


* MS. read to Geol. Soc. of London, Feb. 29. 1832. 
a 5 


346 GEYSERS OF ICELAND. [Book IL 


by the latent heat thus evolved, till, at last, the lower 
part of the cavity is filled with boiling water and the 
upper with steam under high pressure. The expansive 
force of the steam becomes, at length, so great, that 
the water is forced up the fissure or pipe E B, and 
runs over the rim of the basin. When the pressure 
is thus diminished, the steam in the upper part of the 
, cavity A expands, until all the water D is driven into 
the pipe: and when this happens, the steam, being 
the lighter of the two fluids, rushes up through the 


water with great velocity. If the pipe be choked up 
artificially, even for a few minutes, a great increase of 
heat must take place ; for it is prevented from escaping 


* From Sir George Mackenzie’s Iceland. 


Ch. XIX.) CAUSES OF VOLCANOS. ` 347 


in a latent form in steam; so that the water is made 
to boil more violently, and this brings on an eruption. 

If we suppose that large subterranean cavities exist 
at the depth of some miles below the surface of the 
earth, in which melted lava accumulates, and that 
water penetrates into these, the steam thus generated 
may press upon lava and force it up the duct of a 
volcano, in’ the same manner as a column of water is 
driven up the pipe of a Geyser. 

Agency of water in volcanos. — No theory seems at 
first more improbable, than that which represents 
water as affording an inexhaustible supply of fuel to 
the volcanic fires ; yet, if subterraneous heat be derived 
from chemical action, as before hinted, and if electric 
currents in the crust of the earth may exert a slow de- 
composing power, the hypothesis is far from visionary. 

It is a fact that must never be overlooked, when we 
are speculating on the probable causes of volcanos, 
that, while a great number are entirely submarine, the 
remainder are for the most part in islands or maritime 
tracts. There area few exceptions, but some of these, 
as Dr. Daubeny observes, are near inland salt lakes, 
as in Central Tartary; while others form part of a 
train of volcanos the extremities of which are near 
the sea. Thus Jorullo, in Mexico, though itself not 
less than forty leagues from the nearest ocean, appears 
to be connected with the volcano of Tuxtla on the one 
hand, and that of Colima on the other ; the first bor- 
dering on the Atlantic, the latter on the Pacific Ocean. 
This communication is rendered more probable by the 
parallelism that exists between these and several inter- 


mediate volcanic hills. * 


* See Daubeny’s remarks — “ Volcanos,” p. 368. 


Qa 6 


348 DECOMPOSITION OF WATER [Book Il. . 


Sir H. Davy supposes that, when the sea is distant, 
as in the case of some of the South American volcanos, 
they may still be supplied with water from subter- 
ranean lakes; since, according to Humboldt, large 
quantities of fish are often thrown out during erup- 
tions.* 

It has been already stated, that the gases exhaled 
from volcanos, together with steam, are such as would 
result from the decomposition of salt water, and the 
fumes which escape from the Vesuvian lava have been 
observed to deposit common salt.+ The emission of 
free muriatic acid gas in great quantities favours the 
theory of the decomposition of the salt contained in 
sea water; but M. Boussingault did not meet with 
this gas in his late examination of the elastic fluids 
evolved from the volcanos of equatorial America. He 
informs us, that the same are given out by all the 
different vents, namely, aqueous vapour, in very large 
quantity, carbonic acid gas, sulphurous acid gas, and 
sometimes fumes of sulphur. The same naturalist 
found by analysis, that all the thermal waters of the 
Cordilleras were charged with sulphuretted hydrogen 
gas. : 

M. Gay Lussac, while he avows his opinion that the 
decomposition of water contributes largely to volcanic 
action, calls attention, nevertheless, to the fact, that 
hydrogen has not been detected in a separate form 
among the gaseous products of volcanos; nor can it, 
he says, be present; for, in that case, it would be 
inflamed in the air by the red-hot stones thrown out 
during an eruption. Dr. Davy, also, in his account 


* Phil. Trans., 1828, p. 250. 
+ Davy, Phil. Trans., 1828, p. 244. 
ł Ann. de Chim. et de Phys., tom. lii. p. 181. 


Ch. XIX. A SOURCE OF VOLCANIC HEAT. 349 


of Graham Island, says, “I watched when the light- 
ning was most vivid, and the eruption of the greatest 
degree of violence, to see if there was any inflamma- 
tion occasioned by this natural electric spark — any 
indication of the presence of inflammable gas ; but in 
vain.” * ; 

May not the hydrogen, Gay Lussac inquires, be 
Combined with chlorine, and produce, muriatic acid ? 
for this gas has been observed to be evolved from 
Vesuvius —-and the chlorine may have been derived 
from sea salt; which was, in fact, extracted by simple 
washing from the Vesuvian lava of 1822, in the pro- 
Portion of nine per cent. But it was answered, that 
Sir H. Davy’s experiments had shown, that hydrogen 
is not combustible when mixed with muriatic acid 
gas; so that if muriatic gas was evolved in large 
quantities, the hydrogen might be present without 
inflammation. + 

M. Gay Lussac, in the memoir just alluded to, ex- 
presses doubt as to the presence of sulphurous acid; 
but the abundant disengagement of this gas during 
eruptions is now ascertained: and thus all difficulty 
in regard to the absence of hydrogen in an inflammable 
State is removed. For, as Dr. Daubeny supposes, the 
hydrogen of decomposed water may unite with sulphur 
to form sulphuretted hydrogen gas, and this gas will 
then be mingled with the sulphurous acid as it rises 
to the crater. It is shown by experiment, that these 
gases mutually decompose each other when mixed 
where steam is present ; part of the hydrogen of the 
one immediately uniting with the oxygen of the other, 


* Phil. Trans., 1832, p. 240. 
+ Ann. de Chim. et de Phys., tom. xxu. 
+ Quart. Journ. of Science, 1823, pe 132. note by editor. 


350 DECOMPOSITION OF WATER. [Book T. 


to form water, while the excess of sulphurous acid alone 
escapes into the atmosphere. Sulphur is at the same 
time precipitated. 

This explanation is sufficient, but it may be asked, 
whether the flame of hydrogen would be visible during 
an eruption ; as that gas, when inflamed in a pure state, 
burns with a very faint blue flame, which even in thé 
night could hardly be perceptible by the side of red- 
hot and incandescent cinders. Its immediate conver- 
sion into water when inflamed in the atmosphere, might 
also account for its not appearing in a separate form. 

When treating of springs and overflowing wells, 1 
have stated that porous rocks are percolated by fresh 
water to great depths, and that sea-water probably 
penetrates in the same manner through the rocks which 
form the bed of the ocean. But, besides this universal 
circulation in regions not far from the surface, it must 
be supposed that, wherever earthquakes prevail, much 
larger bodies of water will be forced by the pressure 
of the ocean into fissures at greater depths, or swal- 
lowed up in chasms; in the same manner as, on the 
land, towns, houses, cattle, and trees are sometime’ 
engulphed. It will be remembered, that these chasms 
often close again after houses have fallen into them > 
and, for the same reason, when water has penetrated 
to a mass of melted lava, the steam into which it 15 
converted may often rush out at a different aperture 
from that by which the water entered. The frequent 
explosions caused by the generation of steam in thé 
neighbourhood of the sea or of deep lakes, may shatte? 
the solid crust of the earth, and allow the free escap? 
of gases and lava which, but for this cause, might 
never have reached the surface, and might only havé 
given rise to earthquakes. 


Ch. XIX] A SOURCE OF VOLCANIC HEAT. 351 


Dr. Daubeny has suggested that water containing 
atmospheric air may descend from the surface of the 
earth to the volcanic foci, and that the same process of 
combustion by which water is decomposed may de- 
prive such subterranean air of its oxygen. In this 
manner we might explain the great quantities of nitro- 
gen evolved from volcanic vents, and thermal waters, 
and the fact that air disengaged from the earth in 
volcanic regions is either wholly or in part deprived of 
its oxygen. 

Sir H. Davy, in his memoir on the “ Phenomena of 
Volcanos,” remarks, that there was every reason to 
suppose in Vesuvius the existence of a descending cur- 
rent of air; and he imagined that subterranean cavities 
which threw out large volumes of steam during the 
eruption, might afterwards, in the quiet state of the 
volcano, become filled with atmospheric air.* The 
presence of ammoniacal salts in volcanic emanations, 
and of ammonia in lava, favours greatly, says Dr. Dau- 
beny, the notion of air as well as water being deox- 
idated in the interior of the earth. + 

Such phenomena admit of a ready explanation on 
the principles of the chemical theory of volcanos, con- 
sidered in the last chapter; but are left unexplained 
by thé hypothesis of the gradual contraction of an 
external crust upon a fluid nucleus. 

Importance of attending to the unseen volcanic phe- 
nomena.——1n concluding these remarks on the causes 
of volcanos and earthquakes, I may observe, that spe- 
culations and conjectures on this obscure subject 


* Phil. Trans. 1828. 

ł Ammonia is composed of hydrogen and nitrogen: or the 
elements of air without its oxygen. See Daubeny, Encyc, Metrop., 
Part 40. 


352 SUBTERRANEAN CHANGES, [Book II. 


should be encouraged ; because a great step is gained, 
if geologists are rendered more conscious of the changes 
in the earth’s crust now going on out of sight, and 
under circumstances widely different from any which 
can ever come within the sphere of human observ- 
ation. In estimating the effects of existing causes, We 
are too apt to confine our views to operations such as 
we actually see in progress upon the habitable surfaces 
regardless of those which must be going on at various 
depths below. But when we examine the geological 
structure of the earth, we behold the results of former 
processes both subterranean and superficial; and re- 
cognize at once the exact agreement of many of the 
superficial class with the effects of known causes. To 
what agency, then, ought we to refer the phenomena 
which still remain unexplained ? Surely not to imagi- 
nary forces, which may by possibility have prevailed 
in the infancy of the planet ; but rather to the unseen 
portion of that machinery which is still at work. Let 
it be supposed that a person has made such progress 
in a foreign language— German, for example — that, 
in perusing the works of living authors, he understands 
the meaning of about two thirds of what he reads. If 
on taking up a book written two or three centuries 
ago, he finds that he is able to interpret about as much 
of that also, he might naturally conclude that the lan- 
guage had remained the same, or nearly the same, 
during the intervening time. Would he have apy 
doubt respecting this identity, from being unable to 
comprehend all that is written in the older volume? 
or would he not, on the contrary, think it unreasonable; 
while he remains ignorant of a great part of the living 
language, to expect to interpret every thing in the 
ancient book ? . 


— mea 
mons PERG ne Soe eee Te = 
wea vars RRR RR ES 


Ch. XIX.] DRY LAND, HOW PRESERVED. 353 


The balance of dry land, how preserved. — In the 
present state of our knowledge, we cannot pretend to 
estimate the average number of earthquakes which 
may happen in the course of a single year. As the 
area of the ocean is nearly three times that of the 
land, it is probable that about three submarine earth- 
quakes may occur for one exclusively continental: and 
when we consider the great frequency of slight move- 
ments in certain districts, we can hardly suppose that 
a day ever passes without one or more shocks being 
experienced in some part of the globe. We have also 
seen that in Sweden, and other countries, changes in 
the relative level of sea and land may take place 
without commotion, and these perhaps produce the 
most important geographical and geological changes ; 
for the position of land may be altered to a greater 
amount by an elevation or depression of one inch over 
a vast area, than by the sinking of a more limited tract, 
such as the forest of Aripao, to the depth of many 
fathoms at once.* i 

It must be evident, from the historical details above 
given, that the force of subterranean movement, 
whether intermittent or continuous, whether with or 
without disturbance, does not operate at random, 
but is developed in certain regions only; and although 
the alterations produced during the time required 
for the occurrence of a few volcanic eruptions may be 
inconsiderable, we can hardly doubt that, during the 
ages necessary for the formation of large volcanic 
Cones, composed of thousands of lava currents, shoals 
might be converted into lofty mountains, and low lands 


mto deep seas. 


* See p. 208. 


354 BALANCE OF DRY LAND [Book 1. 


In a former chapter, I have stated that aqueous and 
igneous agents may be regarded as antagonist forces’ 
the aqueous labouring incessantly to reduce the in- 
equalities of the earth’s surface to a level, while the 
igneous are equally active in renewing the unevenness 
of the surface.* By some geologists it has bee? 
thought that the levelling power of running water was 
opposed rather to the elevating force of earthquakes 
than to their action generally. This opinion is, however 
untenable ; for the sinking down of the bed of the ocea” 
is one of the means by which the gradual submersio? 
of land is prevented. The depth of the sea cannot be 
increased at any one point without a universal fall of 

the waters, nor can any partial deposition of sediment 
occur without the. displacement of a quantity of wate! 
of equal volume, which will raise the sea, though in a? 
imperceptible degree, even to the antipodes. The 
preservation, therefore, of the dry land may sometimes 
be effected by the subsidence of part of the earth’s 
crust (that part, namely, which is covered by the 
ocean), and in like manner an upheaving movement 
must often tend to destroy land; for if it render the 
bed of the sea more shallow, it will displace a certai? 
quantity of water, and thus tend to submerge low tracts: 

Astronomers having proved that there has been 1° 
change in the diameter of the earth during the last 
two thousand years, we may assume it as probable, 
that the dimensions of the planet remain uniform-T 
If, then, we inquire in what manner the force of earth- 
quakes must be regulated, in order to restore perpe“ 
tually the inequalities of the surface which the level- 
ling power of water tends to efface, it will be found, 


* Book ii. chap. i. + Vol. i. p. 222. 


Ch, XIX.] HOW PRESERVED BY EARTHQUAKES. 355 


that the amount of depression must exceed that of 
elevation. It would be otherwise if the action of vol- 
canos and mineral springs were suspended ; for then 
the forcing outwards of the earth’s envelope ought 
to be no more than equal to its sinking in. 

To understand this proposition more clearly, it 
must be borne in mind, that the deposits of rivers and 
currents probably add as much to the height of lands 
which are rising, as they take from those which have 
risen. Suppose a large river to bring down sediment 
to a part of the ocean two thousand feet deep, and 
that the depth of this part is gradually reduced by the 
accumulation of sediment till only a shoal remains, 
covered by water at high tides; if now an upheaving 
force should uplift this shoal to the height of 2000 feet, 
the result would be a mountain 2000 feet high. But 
had the movement raised the same part of the bottom 
of the sea before the sediment of the river had filled 
it up; then, instead of changing a shoal into a mountain 
2000 feet high, it would only have converted a deep sea 
into a shoal. 

It appears, then, that the operations of the earth- 
quake are often such as to cause the levelling power 
of water to counteract itself; and, although the idea 
may appear paradoxical, we may be sure, wherever we 
find hills and mountains composed of stratified de- 
Posits, that such inequalities of the surface would have 
had no existence if water, at some former period, had 
not been labouring to reduce the earth’s surface to one 
level. 

But, besides the transfer of matter by running water 
from the continents to the ocean, there is a constant 
transportation from below upwards, by mineral springs 
and volcanic vents. As mountain masses are, in the 


356 SUBSIDENCE IN EXCESS, [Book II. 


course of ages, created by the pouring forth of suc- 
cessive streams of lava, so stratified rocks, of great 
extent, originate from the deposition of carbonate of 
lime, and other mineral ingredients, with which springs 
are impregnated. The surface of the land, and por- 
tions of the bottom of the sea, being thus raised, the 
external accessions due to these operations would 
cause the dimensions of the planet to enlarge con- 
tinually, if the amount of depression of the earth’s 
crust were no more than equal to the elevation. In 
order, therefore, that the mean diameter of the earth 
should remain uniform, and the unevenness of the sur- 
face be preserved, it is necessary that the amount of 
subsidence should be in excess. And such a predo- 
minance of depression is far from improbable, on me- 
chanical principles, since every upheaving movement 
must be expected either to produce caverns in the 
mass below, or to cause some diminution of its density- 
Vacuities must, also, arise from the subtraction of the 
matter poured out from volcanos and mineral springs: 
and the foundations having been thus weakened, the 
earth’s crust, shaken and rent by reiterated convul- 
sions, must, in the course of time, fall in. 

If we embrace these views, important geological 
consequences will follow; since, if there be, upon the 
whole, more subsidence than elevation, the average 
depth to which former surfaces have sunk beneath 
their original level must exceed the height which an- 
cient marine strata have attained above the sea. If 
for example, marine strata, about the age of our chalk 
and green-sand, have been lifted up in Europe to a? 
extreme height of more than eleven thousand feet, and 
a mean elevation of some hundreds, we may conclude 
that certain parts of the surface, which existed whe? 


Ch. XIX] ACTION OF EARTHQUAKES. 357 


those strata were deposited, have sunk to an extreme 
depth of more than eleven thousand feet below their 
original level, and to a mean depth of more than a few 
hundreds. 

In regard to faults, also, we must infer, according to 
the hypothesis now proposed, that a greater number 
have arisen from the sinking down than from the ele- 
vation of rocks. 

Mr. Conybeare; and some other writers, have con- 
tended, that the upheaving force of earthquakes was 
more energetic during remote geological epochs, and 
that it has since been gradually on the decline*; while 
M. Elie de Beaumont, on the contrary, maintains, that 
the most tremendous of known convulsions belong to 
times comparatively modern. But in order to com- 
pare the relative amount of change produced, at dif- 
ferent periods, by any given cause, we must obtain 
some standard for the measurement of time at both 
the periods compared. 

I have shown that, during the last two thousand 
years, considerable tracts of land have been upheaved 
above, or depressed below their former level} Now, 
they who contend that a greater or less amount of 
change was formerly accomplished in an equal number 
of years, must first explain the mode in which they mea- 

‘sure the time referred to; for they cannot, in geology, 
avail themselves of the annual revolutions of our planet 
in its orbit. If they assume that the power of volcanos 
to emit lava, and of running water to transport sedi- 
ment from one part of the globe to the other, has 


* Phil. Mag., No. 48. Dec. 1830, p. 402. 
+ Ann. des Sci. Nat., 1829; — Phil. Mag., No. 58. Oct. 1831. 
f See Chapters vi. vii. viii. and ix. 


358 ACTION OF EARTHQUAKES. [Book II 


remained uniform from the earliest periods; they may 
then atempt to compare the effects of subterranean 
movements in ancient and modern times by reference 
to one common standard; and to show that, during 
the time required for the production of a certain num- 
ber of lava currents, or of so many cubic yards of sedi- 
ment, the elevation and depression of the earth’s crust 
were once much greater than they are now. Or, if 
they premise that the progressive rate of change of 
species in the animal and vegetable kingdoms had been 
always uniform, they may then endeavour to prove the 
diminished energy of earthquakes, by showing that, in 
relation to the periods connected with the changes of 
organic species, earthquakes had become comparatively 
feeble. 

But those who contend for the reduced activity of 
natural agents, have not attempted to support this line 
of argument ; nor does our scanty acquaintance, both 
with the animate and inanimate world, warrant such 
generalizations. That it would be most premature, in 
the present state of natural history, to reason on the 
comparative rate of fluctuation in the species of organic 
beings in ancient and modern times, or at any two 
geological periods, will be more fully demonstrated, 
when I come, in the next book, to consider the inti- 
mate connexion between geology and the study of 
the present condition of the animal and vegetable 
kingdoms. 

To conclude: it seems to be rendered probable, by 
the views above explained, that the constant repair of 
the land, and the subserviency of our planet to the 
support of terrestrial as well as aquatic species, are 
secured by the elevating and depressing power 0 
causes acting in the interior of the earth; which, al- 


Ch. XIX] ACTION OF EARTHQUAKES. 359 


though so often the source of death and terror to the 
inhabitants of the globe—visiting, in succession, every 
zone, and filling the earth with monuments of ruin and 
disorder — are, nevertheless, the agents of a conserv- 
ative principle above all others essential to the stability 
of the system. 


BOOK III. 


CHAPTER I. 


CHANGES OF THE ORGANIC WORLD NOW IN PROGRESS. 


Division of the subject — Examination of the question, Whether 
species have a real existence in nature? — Importance of this 
question in geology— Sketch of Lamarck’s arguments in 
favour of the transmutation of species, and his conjectures 
respecting the origin of existing animals and plants (p. 363.)— 
His theory of the transformation of the orang outang int? 
the human species. 


Tue last book was occupied with the consideration 
of the changes brought about on the earth’s surface, 
within the period of human observation, by inorganic 
agents; such, for example, as rivers, marine currents, 
volcanos, and earthquakes. But there is another class 
of phenomena relating to the organic world, which havé 
an equal claim on our attention, if we desire to obtain 
possession of all the preparatory knowledge respecting 
the existing course of nature, which may be available 
in the interpretation of geological monuments. It ap- 
peared, from our preliminary sketch of the progress of 
the science, that the most lively interest was excited 
among its earlier cultivators, by the discovery of the 
remains of animals and plants in the interior of moun- 
tains frequently remote from the sea. Much contro- 
_ versy arose respecting the nature of these remains, the 
causes which may have brought them into so singular 


Ch. L] ' CONSTANCY OF SPECIES. ' i 361 


a position, and the want of a specific agreement be- 
tween them and known animals and plants. To qualify 
Ourselves to form just views on these curious ques- 
tions, we must first study the present condition of the 
animate creation on the globe.: 

This branch of our inquiry naturally divides itself 
into two parts: first, we may examine the vicissitudes 
to which species are subject ; secondly, the processes 
by which certain individuals of these species occasion- 
ally become fossil. The first of these divisions will 
lead us, among other topics, to inquire, first, whether 
Species have a real and permanent existence in nature? 
or whether they are capable, as some naturalists pre- 
tend, of being indefinitely modified in the course of a 
long series of generations? Secondly, whether, if 
Species have a real existence, the individuals com- 
Posing them have been derived originally from many 
Similar stocks, or each from one only, the descendants 
of which have spread themselves gradually from a 
Particular point over the habitable lands and waters? 
Thirdly, how far the duration of each species of animal 
and plant is limited by its dependence on certain fluc- 
tuating and temporary conditions in the state of the 
animate and inanimate world? Fourthly, whether 
there be proofs of the successive extermination of 
Species in the ordinary course of nature, and whether 
there be any reason for conjecturing that new animals 
and plants are created from time to time, to supply 
their place? 

Whether species have a real existence in nature.— 
Before we can advance a step in our proposed inquiry, 
We must be able to define precisely the meaning which 
We attach to the term species. This is even more 

VOL. II. R 


naasa rt 
as ae z 


362 WHETHER SPECIES HAVE [Book IIl; 


necessary in geology than in the ordinary studies of the 
naturalist; for they who deny that such a thing as & 
species exists, concede nevertheless that a botanist oF 
zoologist may reason as if the specific character were 
constant, because they confine their observations to & 
brief period of time. Just as the geographer, in con- 
structing his maps from century to century, may 
proceed as if the apparent places of the fixed stars 
remained absolutely the same, and as if no alteration 
were brought about by the precession of the equinoxes; 
so, it is said, in the organic world, the stability of 4 
species may be taken as absolute, if we do not extend 
our views beyond the narrow period of human history> 
but let a sufficient number of centuries elapse, to allow 
of important revolutions in climate, physical geo- 
graphy, and other circumstances, and the characters 
say they, of the descendants of common parents may 
deviate indefinitely from their original type. 

Now, if these doctrines be tenable, we are at once 
presented with a principle of incessant change in the 
organic world; and no degree of dissimilarity in the 
plants and animals which may formerly have existed, 
and are found fossil, would entitle us to conclude that 
they may not have been the prototypes and proge; 
nitors of the species now living. Accordingly M. 


“Geoffroy St. Hilaire has declared his opinion, that 


there has been an uninterrupted succession in the 
animal kingdom, effected by means of generation, from 
the earliest ages of the world up to the present day’ 
and that the ancient animals whose remains have bee? 
preserved in the strata, however different, may neve!” 
theless have been the ancestors of those now in being: 
This notion is not very generally received, but we até 
hot warranted in assuming the contrary, without fully 


Ch. L] A REAL EXISTENCE IN NATURE. : 863 


explaining the data and reasoning by which it may be 
refuted. 

I shall begin by stating as concisely as possible all 
the facts and ingenious arguments by which the theory 
has been supported; and for this purpose I cannot do 
better than offer the reader a rapid sketch of Lamarck’s 
statement of the proofs which he regards as confirm- 
atory of the doctrine, and which he has derived partly 
from the works of his predecessors and in part from 
original investigations. 

His proofs and inferences will be best considered in 
the order in which they appear to have influenced his 
mind, and I shall then point out some of the results to 
which he was led while boldly following out his prin- 
ciples to their legitimate consequences. 

Lamarck’s arguments in favour of the transmutation 
of species. —The name of species, observes Lamarck, 
has been usually applied to “every collection of 
similar individuals produced by other individuals 
like themselves.”* This definition, he admits, is 
correct; because every living individual bears a very 
close resemblance to those from which it springs, 
But this is not all which is usually implied by the term 
species; for the majority of naturalists agree with 
Linnæus in supposing that all the individuals propa- 
gated from one stock have certain distinguishing cha- 
racters in common, which will never vary, and which 
have remained the same since the creation of each 
species. 

In order to shake this opinion, Lamarck enters upon 
the following line of argument: — The more we ad- 


* Phil. Zool. tom., i. p. 54. 
R2 


364 LAMARCK’S THEORY OF THE [Book III. 


vance in the knowledge of the different organized 
bodies which cover the surface of the globe, the more 
our embarrassment increases, to determine what ought 
to be regarded as a species, and still more how to 
limit and distinguish genera. In proportion as our 
collections are enriched, we see almost every void 
filled up, and all our lines of separation effaced; we 
are reduced to arbitrary determinations, and are some- 
times fain to seize upon the slight differences of mere 
varieties, in order to form characters for what we 
choose to call a species; and sometimes we are induced 
to pronounce individuals but slightly differing, and 
which others regard as true species, to be varieties. - 

The greater the abundance of natural objects as- 
sembled together, the more do we discover proofs 
that every thing passes by insensible shades into some- 
thing else: that even the more remarkable differences 
are evanescent, and that nature has, for the most part, 
left us nothing at our disposal for establishing dis- 
tinctions, save trifling, and, in some respects, puerile 
particularities. . 

We find that many genera amongst animals and 
plants are of such an extent, in consequence of the 
number of species referred to them, that the study 
and determination of these last has become almost 
impracticable. When the species are arranged in a 
series, and placed near to each other, with due regard 
to their natural affinities, they each differ in so minute 
a degree from those next adjoining, that they almost 
melt into each other, and are in a manner confounded 
together. If we see isolated species, we may pre- 
sume the absence of some more closely connected, 
and which have not yet been discovered. Already 
are there genera, and even entire orders — nay, whole 


ci 


i i : j 
Ch. L] TRANSMUTATION OF SPECIES. 365 


classes, which present an approximation to the state 
of things here indicated. 

If, when species have been thus placed in a regular 
series, we select one, and then, making a leap over 
several intermediate ones, we take a second, at some 
distance from the first, these two will, on comparison, |` 
be seen to be very dissimilar; and it is in this manner | 
that every naturalist begins to study the objects which 
are at his own door.. He then finds it an easy task to | 
establish generic and specific distinctions; and it is 
only. when his experience is enlarged, and when he 
has made himself master of the intermediate links, 
that his difficulties and ambiguities begin. But while 
we are thus compelled to resort to trifling and minute 
characters in our attempt to separate species, we find 
a striking disparity between individuals which we 
know to have descended from a common stock; and 
these newly acquired peculiarities are regularly trans- 
mitted from one generation to another, constituting 
what are called races. 

From a great number of facts, continues the author, 
we learn that in proportion as the individuals of one of 
our species change their situation, climate, and man- 
ner of living, they change also, by little and little, the 
consistence and proportions of their parts, their form, 
their faculties, and even their organization, in such a 
manner that every thing in them comes at last to par- 
ticipate in the mutations to which they have been ex- 
posed. Even in the same climate, a great difference of 
situation and exposure causes individuals to vary ; but 
if these individuals continue to live and to be repro- 
duced under the same difference of circumstances, 
distinctions are brought about in them which become 
in some degree essential to their existence. In a 

R 3 


266 \ LAMARCK’S THEORY OF THE [Book 12h 


word, at the end of many successive generations, 
these individuals, which originally belonged to another 
species, are transformed into a new and distinct 
species.” 

Thus, for example, if the seeds of a grass, or any 
other plant which grows naturally in a moist meadow, 
be accidentally transported, first to the slope of some 
neighbouring hill, where the soil, although at a greater 
elevation, is damp enough to allow the plant to live; 
and if, after having lived there, and having been 
several times regenerated, it reaches by degrees the 
drier and almost arid soil of a mountain declivity, it 
will then, if it succeeds in growing, and perpetuates 
itself for a series of generations, be so changed that 
botanists who meet with it will regard it as a particular 
species.t The unfavourable climate in this case, de- 
ficiency of nourishment, exposure to the winds, and 
other causes, give rise to a stunted and dwarfish race, 
with some organ more developed than others, and 
having proportions often quite peculiar. 

What nature brings about in a great lapse of time, 
we occasion suddenly by changing the circumstances 
in which a species has been accustomed to live. All 
are aware that vegetables taken from their birth-place, 
and cultivated in gardens, undergo changes which ren- 
der them no longer recognizable as the same plants- 
Many which were naturally hairy become smooth, or 
nearly so; a great number of such as were creepers 
and trailed along the ground, rear their stalks and 
grow erect. Others lose their thorns or asperities ; 
others, again, from the ligneous state which their stem 
possessed in hot climates, where they were indige- 


* Phil. Zool., tom. i. p. 62. + Ibid. 


ch. 1] TRANSMUTATION OF SPECIES. 367 


nous, pass to the herbaceous; and, among them, some 
which were perennials become mere annuals. So well 
do botanists know the effects of such changes of cir- 
cumstances, that they are averse to describe species 
from garden specimens, unless they are sure that they 
have been cultivated for a very short period. 

« Is not the cultivated wheat” (Triticum sativum), 
asks Lamarck, “a vegetable brought by man into the 
state in which we now see it? Let any one tell me in 
what country a similar plant grows wild, unless where it 
has escaped from cultivated fields? Where do we find 
in nature our cabbages, lettuces, and ‘other culinary 
vegetables, in the state in which they appear in our 
gardens? Is it not the same in regard to a great quan- 
tity of animals which domesticity has changed or con- 
siderably modified?” * Our domestic fowls and pigeons 
are unlike any wild birds. Our domestic ducks and 
geese have lost the faculty of raising themselves into 
the higher regions of the air, and crossing extensive 
countries in their flight, like the wild ducks and wild 
geese from which they were originally derived. A 
bird which we breed in a cage cannot, when restored 
to liberty, fly like others of the same species which 
have been always free. This small alteration of cir- 
cumstances, however, has only diminished the power 
of flight, without modifying the form of any part of 
the wings. But when individuals of the same race 
are retained in captivity during a considerable length 
of time, the form even of their parts is gradually 
made to differ, especially if climate, nourishment, and 
other circumstances be also altered. 

The numerous races of dogs which we have pro- 


* Phil. Zool., tom. i. p. 227. 
R 4 


368 CHANGES IN ANIMALS AND PLANTS [Book IIL 


duced by domesticity are nowhere to be found in a 
wild state. In nature we should seek in vain for mas- 
tiffs, harriers, spaniels, greyhounds, and other races, 
between which the differences are sometimes so great 
that they would be readily admitted as specific 
between wild animals; “yet all these have sprung 
originally from a single race, at first approaching very 
near to a wolf, if, indeed, the wolf be not the true 
type which at some period or other was domesticated 
by man.” 

Although important changes in the nature of the 
\places which they inhabit modify the organization of 
animals as well as vegetables; yet the former, says 
‘Lamarck, require more time to complete a consider- 
able degree of transmutation; and, consequently, we 


wt are less sensible of such occurrences. Next to a 


diversity of the medium in which animals or plants 
may live, the circumstances which have most influence 
in modifying their organs are differences in exposure, 
climate, the nature of the soil, and other local parti- 
culars. These circumstances are as varied as are 
the characters of the species, and, like them, pass by 
insensible shades into each other, there being every 
intermediate gradation between the opposite extremes. 
But each locality remains for a very long time the 
same, and is altered so slowly that we can only become 
conscious of the reality of the change by consulting 
geological monuments, by which we learn that the 
order of things which now reigns in each place has 
not always prevailed, and by inference anticipate that 
it will not always continue the same.* 

Every considerable alteration in the local circum- 


* Phil. Zool., tom. i. p. 232. 


Ch. L] CAUSED BY DOMESTICATION. © 369 


stances in which each race of animals exists causes a 
change in their wants, and these new wants excite 
them to new actions and habits. These .actions re- 
quire the more frequent employment of some parts 
before but slightly exercised, and then greater deve- 
lopment follows as a consequence of their more 
frequent use. Other organs no longer in use are im- 
poverished and diminished in size, nay, are sometimes 
entirely annihilated, while in their place new parts 
are insensibly produced for the discharge of new 
functions. * : 

I must here interrupt the author’s argument, by 
observing, that no positive fact is cited to exemplify 
the substitution of some entirely new sense, faculty, or 
organ, in the room of some other suppressed as use- 
less. All the instances adduced go only to prove that 
the dimensions and strength of members and the per- 
fection of certain attributes may, in a long succession 
of generations, be lessened and enfeebled by disuse ; 
or, on the contrary, be matured and augmented by 
active exertion ; just as we know that the power of 
- scent is feeble in the greyhound, while its swiftness of 
pace and its acuteness of sight are remarkable — that 
the harrier and stag-hound, on the contrary, are com- 
paratively slow in their movements, but excel in the 
sense of smelling. 

It was necessary to point out to the reader this im- 
portant chasm in the chain of evidence, because he 
might otherwise imagine that I had merely omitted 
the illustrations for the sake of brevity, but the plain 
truth is, that there were no examples to be found ; and 
when Lamarck talks “ of the efforts of internal senti- 


* Phil. Zool., tom. i. p. 234. 
Ro 


Li 


370 LAMARCK’S THEORY OF THE [Book IIÉ 


ment,” “ the influence of subtle fluids,” and “acts of 
organization,” as causes whereby animals and plants 
may acquire new organs, he substitutes names for’ 


things; and, with a disregard to the strict rules of in- ~- 


duction, resorts to fictions, as ideal as the “ plastic 
virtue,” and other phantoms, of the geologists of the 
middle ages. 

It is evident that, if some well-authenticated facts 
could have been adduced to establish one complete 


pa step in the process of transformation, such as the ap- 


pearance, in individuals descending from a common 
stock, of a sense or organ entirely new, and a complete 
disappearance of some other enjoyed by their progeni- 
tors, time alone might then be supposed sufficient to 
bring about any amount of metamorphosis. The gra- 
tuitous assumption, therefore, of a point so vital to the 
theory of transmutation, was unpardonable on the part 
of its advocate. 

But to proceed with the system : it being assumed 
as an undoubted fact, that a change of external cir- 
cumstances may cause one organ to become entirely 
obsolete, and a new one to be developed, such as never 
before belonged to the species, the following propo- 
sition is announced, which, however staggering and 
absurd it may seem, is logically deduced from the 
assumed premises. It is not the organs, or, in other 
words, the nature and form of the parts of the body of 
an animal, which have given rise to its habits, and its 
particular faculties ; but, on the contrary, its habits, 
its manner of living, and those of its progenitors, have 
in the course of time determined the form of its body, 
the number and condition of its organs, in short, the 
faculties which it enjoys. Thus otters, beavers, water- 
fowl, turtles, and frogs, were not made web-footed in 


is 


ah 


Ch. 1] TRANSMUTATION\,OF SPECIES. 371 


order that they might swim; but their wants having 
attracted them to the water in search of prey, they 
stretched out the toes of their feet to strike the water 
and move rapidly along its surface. By the repeated 
stretching of their toes, the skin which united them at 
the base acquired a habit of extension, until, in the 
course of time, the broad membranes which now con- 
nect their extremities were formed. 

In like manner, the antelope and the gazelle were 
not endowed with light agile forms, in order that they 
might escape by flight from carnivorous animals ; but, 
having been exposed to the danger of being devoured 
by lions, tigers, and other beasts of prey, they were 
compelled to exert themselves in running with great 
celerity ; a habit which, in the course of many gener- 
ations, gave rise to the peculiar slenderness of their 
legs, and the agility and elegance of their forms. 

The camelopard was not gifted with a long flexible 
neck because it was destined to live in the interior of 
Africa, where the soil was arid and devoid ot herbage ; 
but, being reduced by the nature of that country to 
support itself on the foliage of lofty trees, it contracted 
a habit of stretching itself up to reach the high boughs, 
until its fore legs became longer than the hinder, and 
its neck so elongated that it could raise its head to 
the height of twenty feet above the ground. 

Another line of argument is then entered upon, in 
further corroboration of the instability of species. In 
order, it is said, that individuals should perpetuate 
themselves unaltered by generation, those belonging 
to one species ought never to ally themselves to those 
of another ; but such sexual unions do take place, both 
among plants and animals ; and although the offspring 
of such irregular connexions are usually sterile, yet 

R 6 


372 LAMARCK’S THEORY OF THE [Book III 


such is not always the case. Hybrids have some- 
times proved prolific, where the disparity between the 
species was not too great; and by this means alone, 
says Lamarck, varieties may gradually be created by 
near alliances, which would become races, and in the 
course of time would constitute what we term species.* 

But if the soundness of all these arguments and 
inferences be admitted, we are next to inquire, what 
were the original types of form, organization, and 
instinct, from which the diversities of character, as now 
exhibited by animals and plants, have been derived ? 
We know that individuals which are mere varieties of 
the same species would, if their pedigree could be 
traced back far enough, terminate in a single stock; 
so, according to the train of reasoning before described, 
the species of a genus, and even the genera of a great 
family, must have had a common point of departure. 
What, then, was the single stem from which so many 
varieties of form have ramified ? Were there many of 
these, or are we to refer the origin of the whole 
animate creation, as the Egyptian priests did that of 
the universe, to a single egg? 

In the absence of any positive data for framing a 
theory on so obscure a subject, the following consider- 
ations were deemed of importance to guide conjecture. 

In the first place, if we examine the whole series of 
known animals, from one extremity to the other, when 
they are arranged in the order of their natural rela- 
tions, we find that we may pass progressively, or, at 
least, with very few interruptions, from beings of 
more simple to those of a more compound structure ; 
and, in proportion as the complexity of their organ- 


* Phil. Zool. p. 64. 


Ch. L] TRANSMUTATION OF SPECIES. 373 


ization increases, the number and dignity of their 
faculties increase also. Among plants, a similar ap- 
proximation to a graduated scale of being is apparent. 
Secondly, it appears, from geological observations, that 
plants and animals of more simple organization existed 
on the globe before the appearance of those of more 
compound structure, and the latter were successively 
formed at more modern periods : each new race being 
more fully developed than the most perfect of the 
preceding era. 

Of the truth of the last-mentioned geological theory, 
Lamarck seems to have been fully persuaded ; and he 
also shows that he was deeply impressed with a belief 
prevalent amongst the older naturalists, that the 
primeval ocean invested the whole planet long after it 
became the habitation of living beings ; and thus he 
was inclined to assert the priority of the types of ma- 
rine animals to those of the terrestrial, so as to fancy, 
for example, that the testacea of the ocean existed 
first, until some of them, by gradual evolution, were 
improved into those inhabiting the land. 

These speculative views had already been, in a great 
degree, anticipated by Demaillet in his Telliamed, and 
by several modern writers ; so that the tables were 
completely turned on the philosophers of antiquity, 
with whom it was a received maxim, that created 
things were always most perfect when they came first 
from the hands of their Maker; and that there was a 
tendency to progressive deterioration in sublunary 
things when left to themselves — 


—_—_—— omnia fatis 


In pejus ruere, ac retro sublapsa referri. 


So deeply was the faith of the ancient schools of 


374: LAMARCK’S THEORY OF THE [Book IIL 


philosophy imbued with this doctrine, that, to check 
this universal proneness to degeneracy, nothing less 
than the re-intervention of the Deity was thought 
adequate ; and it was held, that thereby the order, 
excellence, and pristine energy of the moral and 
physical world had been repeatedly restored. 

But when the possibility of the indefinite modifi- 
cation of individuals descending from common parents 
was once assumed, as also the geological inference 
respecting the progressive development of organic life, 
it was natural that the ancient dogma should be re- 
jected, or rather reversed, and that the most simple 
and imperfect forms and faculties should be conceived 
to have been the originals whence all others were 
developed. Accordingly, in conformity to these views, 
inert matter was supposed to have been first endowed 
with life; until, in the course of ages, sensation was 
superadded to mere vitality: sight, hearing, and the 
other senses were afterwards acquired ; then instinct 
and the mental faculties ; until, finally, by virtue of the 
tendency of things to progressive improvement, the 
irrational was developed into the rational. 

The reader, however, will immediately perceive 
that when all the higher order of plants and animals 

_ were thus supposed to be comparatively modern, and 
to have been derived in a long series of generations 
from those of more simple conformation, some further 
hypothesis became indispensable, in order to explain 
why, after an indefinite lapse of ages, there were still 
so many beings of the simplest structure. Why have 
the majority of existing creatures remained stationary 
throughout this long succession of epochs, while others 
have made such prodigious advances? Why are there. 
such multitudes of infusoria and polyps, or of conferve 


m ae — k e 
mS y ke £3 


Ch. LJ TRANSMUTATION OF SPECIES. 375 


and other cryptogamic plants? Why, moreover, has 
the process of development acted with such unequal 
and irregular force on those classes of beings which 
have been greatly perfected, so that there are wide 
chasms in the series ; gaps so enormous, that Lamarck 
fairly admits we can never expect to fill them up by 
future discoveries ? 

The following hypothesis was provided to meet these 
objections. Nature, we are told, is not an intelligence, 
nor the Deity ; but a delegated power — a mere instru- 
ment—a piece of mechanism acting by necessity — 
an order of things constituted by the Supreme Being, 
and subject to laws which are the expressions of his 
will. This Nature is obliged to proceed gradually in 
all her operations ; she cannot produce animals and. 
plants of all classes at once, but must always begin by 
the formation of the most simple kinds, and out of 
them-elaborate the more compound, adding to them, 
successively, different systems of organs, and multiply- 
ing more and more their number and energy. 

This Nature is daily engaged in the formation of the 
elementary rudiments of animal and vegetable exist- 
ence, which correspond to what the ancients termed 
spontaneous generation. She is always beginning anew, 
day by day, the work of creation, by forming monads, 
or “rough draughts” (ébauches), which are the only 
living things she gives birth to directly. 

There are distinct primary rudiments of plants and 
animals, and probably of each of the great divisions of 
the animal and vegetable kingdoms.* These are gra- 
dually developed into the higher and more perfect 
classes by the slow but unceasing agency of two 


* Animaux sans Vert. tom. i, p, 56. Introduction. 


876 LAMARCK’S THEORY OF THE | [Book III. 


influential principles : first, the tendency to, progressive 
advancement in organization, accompanied by greater 
dignity in instinct, intelligence, &c.; secondly, che 
Jorce of external circumstances, or of variations in the 
physical condition of the earth, or the mutual relations 
of plants and animals. For, as species spread: them- 
selves gradually over the globe, they are exposed from 
time to time to variations in climate, and to changes 
in the quantity and quality of their food; they meet 
with new plants and animals which assist or retard 
their development, by supplying them with nutriment, 
or destroying their foes. The nature, also, of each 
locality, is in itself fluctuating ; so that, even if the 
relation of other animals and plants were invariable, 
the habits and organization of species would be modi- 
fied by the influence of local revolutions. 

Now, if the first of these principles, the tendency to 
progressive development, were left. to exert itself with 
perfect freedom, it would give rise, says Lamarck, in 
_. the course of ages, to a graduated scale of being, where 
the most insensible transition might be traced from 
the simplest to the most compound structure, from 
the humblest to the most exalted degree of intelli- 
gence. But, in consequence of the perpetual inter- 
ference of the external causes before mentioned, this 
regular order is greatly interfered with, and an approx- 
imation only to such a state of things is exhibited by 
the animate creation, the progress of some races being 
retarded by unfavourable, and that of others accele- 
rated by favourable, combinations of circumstances. 
Hence, all kinds of anomalies interrupt the ‘continuity 
of the plan; and chasms, into which whole genera or 
families might be inserted, are seen to separate the 
nearest existing portions of the series. 


f 


Ch. L] TRANSMUTATION OF SPECIES. 5 a 


Lamarck’s theory of the transformation of the Orang- 
Outang into the human species. — Such is the machinery 
of the Lamarckian system ; but the reader will hardly, 
perhaps, be able to form a perfect conception of so 
complicated a piece of mechanism, unless it is exhibited 
in motion, so that we may see in what manner it can 
work out, under the author’s guidance, all the extra- 
ordinary effects which we behold in the present state 
of the animate creation. I have only space for exhibit- 
ing a small part of the entire process by which a com- 
plete metamorphosis is achieved, and shall, therefore, 
‘omit the mode by which, after a countless succession 
of generations, a small gelatinous body is transformed 
into an oak or an ape; passing on at once to the last 
_ grand step in the progressive scheme, by which the 
orang-outang, having been already evolved out of a 
monad, is made slowly to attain the attributes and 
dignity of man. 

One of the races of quadrumanous animals which 
had reached the highest state of perfection, lost, by 
Constraint of circumstances (concerning the exact na- 
ture of which tradition is unfortunately silent), the 
habit of climbing trees, and of hanging on by grasping ee 
the boughs with their feet as with hands. The indi- 
viduals of this race being obliged, for a long series of 
generations, to use their feet exclusively for walking, 
and ceasing to employ their hands as feet, were trans- 
formed into bimanous animals ; and what before were 
thumbs became mere toes, no separation being required 
when their feet were used solely for walking. Having 
acquired a habit of holding themselves upright, their 
legs and feet assumed, insensibly, a conformation fitted 
to support them in an erect attitude, till at last these 


878 CONVERSION OF THE ORANG-OUTANG [Book IIE 


animals could no longer go on all-fours without much 
inconvenience. 

The Angola orang (Simia troglodytes, Linn.) is the 
most perfect of animals ; much more so than the Indian 
orang (Simia Satyrus), which has been called the 
orang-outang, although both are very inferior to man 
in corporeal powers and intelligence. These ani- 
mals frequently hold themselves upright; but theif 
organization has not yet been sufficiently modified to 
sustain them habitually in this attitude, so that the 
standing posture is very uneasy to them. When the 
Indian orang is compelled to take flight from pressing 
danger, he immediately falls down upon all-fours, show- 
ing clearly that this was the original position of. the 
animal. Even in man, whose organization, in the 
course of a long series of generations, has advanced s0 
much farther, the upright posture is fatiguing, and can 
be supported only for a limited time, and by aid of 
the contraction of many muscles. If the vertebral 
column formed the axis of the human body, and sup- 
ported the head and all the other parts in equilibrium, 
then might the upright position be a state of repose: 
but, as the human head does not articulate in the cen- 
tre of gravity, as the chest, belly, and other parts press 
almost entirely forward with their whole weight, and 
as the vertebral column reposes upon an oblique base, 
a watchful activity is required to prevent the body 
from falling. Children which have large heads and 
prominent bellies can hardly walk at the end even of 
two years; and their frequent tumbles indicate thé 
natural tendency in man to resume the quadrupedal 
state. 

Now, when so much progress had been made by the 
quadrumanous animals before mentioned, that they 


€h. 1.] INTO THE HUMAN SPECIES. 379 


could hold themselves habitually in an erect attitude, 
and were accustomed to a wide range of vision, and 
ceased to use their jaws for fighting and tearing, or for 
clipping herbs for food, their snout became gradually 
shorter, their incisor teeth became vertical, and the 
facial angle grew more open. 

Among other ideas which the natural tendency to 
Perfection engendered, the desire of ruling suggested 
itself, and this race succeeded at length in getting the 
better of the other animals, and made themselves mas- 
ters of all those spots on the surface of the globe 
which best suited them. They drove out the animals 
which approached nearest them in organization and 
intelligence, and which were in a condition to dis- 
pute with them the good things of this world, 
forcing them to take refuge in deserts, woods, and 
wildernesses, where their multiplication was checked, 
and the progressive development of their faculties re- 
` tarded ; while, in the mean time, the dominant race 
spread itself in every direction, and lived in large 
companies, where new wants were successively cre- 
ated, exciting them to industry, and gradually perfect- 
ing their means and faculties. 

In the supremacy and increased intelligence acquired 
by the ruling race, we see an illustration of the natu- 
ral tendency of the organic world to grow more per- 
fect ; and, in their influence in repressing the advance 
of others, an example of one of those disturbing causes 
before enumerated, that force of external circumstances, 
which causes such wide chasms in the regular series 
of animated being. 

When the individuals of the dominant race became 
very numerous, their ideas greatly increased in num- 
ber, and they felt the necessity of communicating them 


380 CONVERSION OF THE ORANG-OUTANG [Book II}. 


to each other, and of augmenting and varying the signs 
proper for the communication of ideas. Meanwhile 
the inferior quadrumanous animals, although most of 
them were gregarious, acquired no new ideas, being 
persecuted and restless in the deserts, and obliged to 
fly and conceal themselves, so that they conceived no 
new wants. Such ideas as they already had remained 
unaltered, and they could dispense with the communi- 
cation of the greater part of these. To make them- 
selves, therefore, understood by their fellows, required 
merely a few movements of the body or limbs — whis- 
tling, and the uttering of certain cries varied by the 
inflexions of the voice. 

On the contrary, the individuals of the ascendant 
race, animated with a desire of interchanging theif 
ideas, which became more and more numerous, were 
prompted to multiply the means of communication; 
and were no longer satisfied with mere pantomimic 
signs, nor even with all the possible inflexions of the 
voice; but-made continual efforts to acquire the power 
of uttering articulate sounds, employing a few at first, 
but afterwards varying and perfecting them according 
to the increase of their wants. The habitual exercise 
of their throat, tongue, and lips, insensibly modified the 
conformation of these organs, until they became fitted 
for the faculty of speech.* 

In effecting this mighty change, “ the exigencies of 
the individuals were the sole agents ; they gave rise to 
efforts, and the organs proper for articulating sounds 
were developed by their habitual employment.” Hence; 
in this peculiar race, the origin of the admirable faculty 
of speech ; hence also the diversity of languages, since 


* Lamarck’s Phil, Zool., tom. i, p. 356. 


Ch. 1.] INTO THE HUMAN SPECIES. ~ 381 


the distance of places where the individuals composing | 
the race established themselves soon favoured the 
Corruption of conventional signs.* 

In conclusion, it may be proper to observe that the 
above sketch of the Lamarckian theory is no exagger- 
ated picture, and those passages which have probably 
€xcited the greatest surprise in the mind of the reader 
are literal translations from the original. 


' * Lamarck’s Phil. Zool., tom. i. p. 357. 


CHAPTER II. 
TRANSMUTATION OF SPECIES — continued. 


Recapitulation of the arguments in favour of the theory of trans 
mutation of species — Their insufficiency — Causes of diffi. 
culty in discriminating species — Some varieties possibly mor? 
distinct than certain individuals of distinct species (p. 388-)— 
Variability in a species consistent with a belief that the limits 
of deviation are fixed — No facts of transmutation authe?” 
ticated — Varieties of the Dog —the Dog and Wolf distin 


species — Mummies of various animals from Egypt identical I” 
character with living individuals (p. 395.) — Seeds and plan 
from the Egyptian tombs — Modifications produced in plas 


by agriculture and gardening. 


Tue theory of the transmutation of species, cons” 
dered in the last chapter, has met with some degree ° 
favour from many naturalists, from their desire to dis” 
pense, as far as possible, with the repeated interventio” 
ofa First Cause, as often as geological monuments attes 

the successive appearance of new races of animals an 

plants, and the extinction of those pre-existing. But 
independently of a predisposition to account, if pow 
sible, for a series of changes in the organic world b 

the regular action of secondary causes, we have see” 
that in truth many perplexing difficulties present the™ 
selves to one who attempts to establish the nature an 

reality of the specific character. And if once thet? 
appears ground of reasonable doubt, in regard to the 


Ch. II] PERMANENCE OF SPECIFIC CHARACTER. 383 


Constancy of species, the amount of transformation 
which they are capable of undergoing may seem to 
resolve itself into a mere question of the quantity of 
time assigned to the past duration of animate exist- 
ence. 

Before entering upon the reasons which may be 
adduced for rejecting Lamarck’s hypothesis, I shall 
recapitulate, in a few words, the phenomena, and the 
whole train of thought, by which I conceive it to have 
been suggested, and which have gained for this and 
analogous theories, both in ancient and modern times, 
a considerable number of votaries. 

In the first place, the various groups into which 
plants and animals may be thrown seem almost inva- 
riably, to a beginner, to be so natural, that he is 
usually convinced at first, as was Linnzeus to the last, 
“that genera are as much founded in nature as the 
Species which compose them.”* When, by examining 
the numerous intermediate gradations, the student 
finds all lines of demarcation to be in most instances 
obliterated, even where they at first appeared most 
distinct, he grows more and more sceptical as to the 
Teal existence of genera, and finally regards them as 
mere arbitrary and artificial signs, invented, like those 
which serve to distinguish the heavenly constellations, 
for the convenience of classification, and having as 
little pretensions to reality. 

Doubts are then engendered in his mind as to 
whether species may not also be equally unreal. The 
Student is probably first struck with the phenomenon, 
that some individuals are made to deviate widely from 


* Genus omne est naturale, in primordio tale creatum, &c, 
Phil. Bot, § 159. See also ibid. § 162, 


384 PERMANENCE OF SPECIFIC CHARACTER. [Book III. 


the ordinary type by the force of peculiar circum- 
stances, and with the still more extraordinary fact, that 
the newly acquired peculiarities are faithfully trans- 
mitted to the offspring. How far, he asks, may such 
variations extend in the course of indefinite periods of 
time, and during great vicissitudes in the physical con- 
dition of the globe? His growing incertitude is at first 
checked by the reflection, that nature has forbidden 
the intermixture of the descendants of distinct original 
stocks, or has, at least, entailed sterility on their off- 
spring, thereby preventing their being confounded 
together; and pointing out that a multitude of distinct 
types must have been created in the beginning, and 
must have remained pure and uncorrupted to this 
day. 

Relying on this general law, he endeavours to solve 
each difficult problem by direct experiment, until he is 
again astounded by the phenomenon of a prolific 
hybrid, and still more by an example of a hybrid per- 
petuating itself throughout several generations in the 
vegetable world. He then feels himself reduced to 
the dilemma of choosing between two alternatives ; 
either to reject the test, or to declare that the tw? 
species, from the union of which the fruitful progeny 

has sprung, were mere varieties. If he prefer the lat- 
ter, he is compelled to question the reality of the dis- - 
tinctness of all other supposed species which differ n0 
more than the parents of such prolific hybrids: for 
although he may not be enabled immediately to pro- 
cure, in all such instances, a fruitful offspring ; yet 
experiments show, that after repeated failures, the 
union of two recognized species may at last, under 
very favourable circumstances, give birth to a fertile 


Ch. IIL] PERMANENCE OF SPECIFIC CHARACTER. 385 


progeny. Such circumstances, therefore, the naturalist 
may conceive to have occurred again and again, in the 
course of a great lapse of ages. 

His first opinions are now fairly unsettled, and every 
Stay at which he has caught has given way one after 
another; he is in danger of falling into any new and 
Visionary doctrine which may be presented to him; for 
he now regards every part of the animate creation as 
void of stability, and in a state of continual flux. In 
this mood he encounters the Geologist, who relates to 
him how there have been endless vicissitudes in the 
Shape and structure of organic beings in former ages — 
how the approach to the present system of things has 
been gradual — that there has been a progressive de- 
velopment of organization subservient to the purposes 
of life, from the most simple to the most complex 
State — that the appearance of man is the last pheno- 
menon in a long succession of events ; and finally, that 
a series of physical revolutions can be traced in the 
inorganic world, coeval and coextensive with those of 
organic nature. . 

These views seem immediately to confirm all his 
preconceived doubts as to the stability of the specific 
character, and he begins to think there may exist an 
inseparable connexion between a series of changes in 
the inanimate world, and the capability of the species 
to be indefinitely modified by the influence of external 
circumstances. Henceforth his speculations know no 
definite bounds; he gives the rein to conjecture, and 
fancies that the outward form, internal structure, in- 
stinctive faculties, nay, that reason itself may have 
been gradually developed from some of the simplest 
States of existence — that all animals, that man himself, 
and the irrational beings, may have had one common 


VOL. IL. S 


re pL 


_ ee 


SE 


—<——== 


386 PERMANENCE OF SPECIFIC CHARACTER. [Book III. 


origin; that all may be parts of one continuous and 
progressive scheme of development, from the most 
imperfect to the more complex ; in fine, he renounces 
his belief in the high genealogy of his species, and 
looks forward, as if in compensation, to the future 
perfectibility of man in his physical, intellectual, and 
moral attributes. 

Let us now proceed to consider what is defective 
in evidence, and what fallacious in reasoning, in the 
grounds of these strange conclusions. Blumenbach 
judiciously observes, that “no general rule can be laid 
down for determining the distinctness of species, as 
there is no particular class of characters which can 
serve as a criterion. In each case we must be guided 
by analogy and probability.” The multitude, in fact, 
and complexity of the proofs to be weighed, is so 
great, that we can only hope to obtain presumptive 
evidence, and we must, therefore, be the more careful 
to derive our general views as much as possible from 
those observations where the chances of deception are 
least. We must be on our guard not to tread in the 
footsteps of the naturalists of the middle ages, who be- 
lieved the doctrine of spontaneous generation to be 
applicable to all those parts of the animal and vegetable 
kingdoms-which they least understood, in direct con- 
tradiction to the analogy of all the parts best known 
to them; and who, when at length they found that 
insects and cryptogamous plants were also propagated 
from eggs or seeds, still persisted in retaining theif 
old prejudices respecting the infusory animalcules and 
other minute beings, the generation of which had not 
then been demonstrated by the microscope to be 80- 
verned by the same laws. 

Lamarck has, indeed, attempted to raise an argument 


Ch, IL] DIFFICULTY OF DISCRIMINATING SPECIES. 387 


in favour of his system, out of the very confusion 
which has arisen in the study of some orders of animals 
and plants, in consequence of the slight shades of dif- 
ference which separate the new Species discovered 
within the last half century. That the embarrassment 
of those who attempt to classify and distinguish the 
new acquisitions, poured in such multitudes into our 
museums, should increase with the augmentation of 
their number, is quite natural; since to obviate this it 
is not enough that our powers of discrimination should 
keep pace with the increase of the objects, but we 
ought to possess greater opportunities of studying each 
animal and plant in all stages of its growth, and to 
know profoundly their history, their habits, and phy- 
siological characters, throughout several generations ; 
for, in proportion as the series of known animals 
grows more complete, none can doubt that there is a 
nearer: approximation to a graduated scale of being ; 
and thus the most closely allied species will be found 
to possess a greater number of characters in common. 

Causes of the difficulty of discriminating species, — 
But, in point of fact, our new acquisitions consist, 
` more and more as we advance, of specimens brought 
from foreign and often very distant and barbarous 
countries. A large proportion have never even been 
seen alive by scientific inquirers. Instead of having 
Specimens of the young, the adult, and the aged indi- 
viduals of each sex, and possessing means of investi- 
gating the anatomical structure, the peculiar habits, 
and instincts of each, what is usually the state of our 
information? A single specimen, perhaps, of a dried 
plant, or a stuffed bird or quadruped; a shell, without 
the soft parts of the animal; an insect in one stage of 
its numerous transformations; — these are the scanty 

s 2 


388 CAUSES OF THE DIFFICULTY [Book III. 


and imperfect data which the naturalist possesses- 
Such information may enable us to separate species 
which stand at a considerable distance from each other; 
put we have no right to expect any thing but difficulty 
and ambiguity, if we attempt, from such imperfect 
opportunities, to obtain distinctive marks for defining 
the characters of species which are closely related. 

If Lamarck could introduce so much certainty and 
precision into the classification of several thousand 
species of recent and fossil shells, notwithstanding 
the extreme remoteness of the organization of these 
animals from the type of those vertebrated species 
which are best known, and in the absence of so many 
of the living inhabitants of shells, we are led to form 
an exalted conception of the degree of exactness to 
which specific distinctions are capable of being carried, 
rather than to call in question their reality. 

When our data are so defective, the most acute 
naturalist must expect to be sometimes at fault, and, 
like the novice, to overlook essential points of differ- 
ence, passing unconsciously from one species to an- 
other, until, like one who is borne along in a current, 
he is astonished, on looking back, at observing that he 
has reached a point so remote from that whence he 
set out. 

It is by no means improbable, that, when the series 
of species of certain genera is very full, they may be 
found to differ less widely from each other than do thé 
mere varieties or races of certain species. If such 4 
fact could be established, it would, undoubtedly, dimi- 
nish the chance of our obtaining certainty in ou? 
results; but it would by no means overthrow ou? 
confidence in the reality of species. 

Some mere varieties possibly more distinct than certain 


Ch. IL] OF DISCRIMINATING SPECIES. 389 


individuals of distinct species. —It is almost necessary, 
indeed, to suppose that varieties will differ in some 
cases more decidedly than some species, if we admit 
that there is a graduated scale of being, and assume 
that the following laws prevail in the economy of the 
animate creation : —first, that the organization of in- 
dividuals is capable of being modified to a limited 
extent by the force of external causes; secondly, that 
these modifications are, to a certain extent, transmis- 
sible to their offspring; thirdly, that there are fixed 
limits, beyond which the descendants from common 
parents can never deviate from a certain type; fourthly, 
that each species springs from one original stock, and 
can never. be permanently confounded by intermixing 
with the progeny of any other stock; fifthly, that each 
species shall endure for a considerable period of time. 
Now, let us assume, for the present, these rules hypo- 
thetically, and see what consequences may naturally 
be expected to result from them. 

We must suppose that when the Author of Nature 
creates an animal or plant, all the possible circum- 
stances in which its descendants are destined to live 
are foreseen, and that an organization is conferred 
upon it which will enable the species to perpetuate 
itself, and survive under all the varying circumstances 
to which it must be inevitably exposed. Now, the 
range of variation of circumstances will differ essen- 
tially in almost every case. Let us take, for example, 
any one of the most influential conditions of existence, 
such as temperature. In some extensive districts 
near the equator, the thermometer might never vary, 
throughout several thousand centuries, for more than 
20° Fahrenheit ; so that if a plant or animal be pro- 
vided with an organization fitting it to endure such a 

s 3 


i 


390 CAUSES OF THE DIFFICULTY [Book Ii 


range, it may continue on the globe for that immense 
period, although every individual might be liable at 
once to be cut off by the least possible excess of heat 
or cold beyond the determinate degree. But if a 
species be placed in one of the temperate zones, and 
lave a constitution conferred on it capable of sup- 
porting a similar range of temperature only, it will 
inevitably perish before a single year has passed away. 

Humboldt has shown that, at Cumana, within the 
tropics, there is a difference of only four degrees 
(Fahr.) between the temperature of the warmest and 
coldest months; whereas at Quebec and Pekin, in the 
temperate zones, the annual variation amounts to 
about 60°. 

The same remark might be applied to any other 
condition, as food, for example: it may be foreseen 
that the supply will be regular throughout indefinite 
periods in one part of the world, and in another very 
precarious and fluctuating both in kind and quantity. 
Different qualifications may be required for enabling 
species to live for a considerable time under circum- 
stances so changeable. If, then, temperature and food 
be among those external causes which, according to 
certain laws of animal and vegetable physiology, 
modify the organization, form, or faculties, of indivi- 
duals, we instantly perceive that the degrees of varia- 
bility from a common standard must differ widely in 
the two cases above supposed ; since there is a neces- 
sity of accommodating a species in one case to a much 
greater latitude of circumstances than in the other. 

If it be a law, for instance, that scanty sustenance 
should check those individuals in their growth which 
are enabled to accommodate themselves to privations 
of this kind, and that a parent, prevented in this 


Ch, 1L] OF DISCRIMINATING SPECIES. - 391 


manner from attaining the size proper to its species, 
should produce a dwarfish offspring, a stunted race 
will arise, as is remarkably exemplified in some varie- 
ties of the horse and dog. The difference of stature 
in some races of dogs, when compared to others, is as 
one to five in linear dimensions, making a difference 
of a hundred-fold in volume.* Now, there is good | 
reason to believe that species in general are by no 


means susceptible of existing under a diversity of cir- | j 


cumstances, which may give rise to such a disparity | | 


in size, and, consequently, there will be a multitude of | | | 


distinct species, of which no two adult individuals can rm 


ever depart so widely from a certain standard of dimen- 
sions as the mere varieties of certain other species — 
the dog, for instance. Now, we have only to suppose 
that what is true of size, may also hold in regard to 
colour and many other attributes; and it will.at once 
follow, that the degree of possible discordance between 
varieties of the same species may, in certain cases, 
exceed the utmost disparity which can arise between 
two individuals of many distinct species. 

The same remarks may hold true in regard to 
instincts; for, if it be foreseen that one species will 
have to encounter a great variety of foes, it may be 
necessary to arm it with great cunning and circum- 
spection, or with courage or other qualities capable of 
developing themselves on certain occasions; such, for 
example, as those migratory instincts which are so 
remarkably exhibited at particular periods, after they 
have remained dormant for many generations. The 
history and habits of one variety of such a species may 
often differ more considerably from some other than 


* Cuvier, Disc, Prélim., p. 128. sixth edition. 
s4 


| 


i 


392 EXTENT OF KNOWN [Book IIF 


those of many distinct species which have no such 
latitude of accommodation to circumstances. 

Extent of known variability in species. — Lamarck 
has somewhat misstated the idea commonly enter- 
tained of a species; for it is not true that naturalists 
in general assume that the organization of an animal 
or plant remains absolutely constant, and that it can 
never vary in any of its parts.* All must be aware 
that circumstances influence the habits, and that the 
habits may alter the state of the parts and organs ; but 
the difference of opinion relates to the extent to which 
these modifications of the habits. and organs of a par- 
ticular species may be carried. 

Now, let us first inquire what positive facts can be 
adduced in the history of known species, to establish 
a great and permanent amount of change in the form, 
structure, or instinct of individuals descending from 
some common stock. The best authenticated examples 
of the extent to which species can be made to vary 
may be looked for in the history of domesticated ani- 
mals and cultivated plants. It usually happens, that 
those species, both of the animal and vegetable king- 
dom, which have the greatest pliability of organization, 
those which are most capable of accommodating them- 
selves to a great variety of new circumstances, are 
most serviceable to man. These only can be carried 
by him into different climates, and can have their pro- 
perties or instincts variously diversified by differences 
of nourishment and habits. If the resources of a 
species be so limited, and its habits and faculties be 
of such a confined and local character, that it can 


* Phil. Zool., tom. i, p. 266. 


Ch, IL] VARIABILITY IN SPECIES. ; 393 


only flourish in a few particular spots, it can rarely be 
of great utility. 

We may consider, therefore, that, in the domestica- 
tion of animals and the cultivation of plants, mankind 
have first selected those species which have the most 
flexible frames and constitutions, and have then been 
engaged for ages in conducting a series of experi- 
ments, with much patience and at great cost, to as- 
certain what may be the greatest possible deviation 
from a common type which can be elicited in these 
extreme cases. 

Varieties of the dog — no transmutation. — The mo- 
difications produced in the different races of dogs 
exhibit the influence of man in the most striking point 


of view. These animals have been transported into 


every climate, and placed in every variety of circum- 


stances; they have been made, as a modern naturalist 
observes, the servant, the companion, the guardian, 
and the intimate friend of man, and the power of a 
superior genius has had a wonderful influence, not only 
on their forms, but on their manners and intelligence.* 
Different races have undergone remarkable changes in 
the quantity and colour of their clothing; the dogs of 
Guinea are almost naked, while those of the arctic 
circle are covered with a warm coat both of hair and 
wool, which enables them to bear the most intense cold 
without inconvenience. There are differences algo of 
another kind no less remarkable, as in size, the length 
of their muzzles, and the convexity of their foreheads. 

But, if we look for some of those essential changes 
which would be required to lend even the semblance 


-* Dureau de la Malle, Ann. des Sci. Nat., tom. xxi, P. 63. 


Sept. 1830. 
8s 5 


394 VARIABILITY IN SPECIES. [Book III. 


of a foundation for the theory of Lamarck, respecting 
the growth of new organs and the gradual obliteration 
of others, we find nothing of the kind. For, in all these 
varieties of the dog, says Cuvier, the relation of the 
bones with each other remains essentially the same; 
the form of the teeth never changes in any perceptible 
degree, except that, in. some individuals, one additional 
false grinder occasionally appears, sometimes on the 
one side, and sometimes on the other.* The greatest 
departure from a common type—and it constitutes the 
maximum of variation as yet known in the animal king- 
dom— is exemplified in those races of dogs which have 
a supernumerary toe on the hind foot with the corre- 
sponding tarsal bones; a variety analogous to one pre- 
sented by six-fingered families of the human race. 
© Lamarck has thrown out as a conjecture, that the 
wolf may have been the original of the dog ; but he has 
adduced no data to bear out such an hypothesis. “The 
wolf,” observes Dr. Prichard, “and the dog differ, not 
only with respect to their habits and instincts, which 
in the brute creation are very uniform within the limits 
of one species; but some differences have also been 
pointed out in their internal organization, particularly 
in the structure of a part of the intestinal canal.{ 
Domestic animals in South America have reverted to 
their original character. — It is well known that the 
horse, the ox, the boar, and other domestic animals, 
which have been introduced into South America, and 
have run wild in many parts, have entirely lost all 
marks of domesticity, and have reverted to the original 
characters of their species. But dogs have also become 
* Disc. Prél., p. 129. sixth edition. + Ibid. 


} Prichard, Phys. Hist. of Mankind, vol. i. p. 96., who cites 
Professor Giildenstadt. 


Ch.11.] MUMMIES IDENTICAL WITH LIVING SPECIES. 395 


wild in Cuba, Hayti, and in all the Caribbean islands. 
In the course of the seventeenth century, they hunted 
in packs from twelve to fifty, or more, in number, and 
fearlessly attacked herds of wild boars and other ani- 
mals. It is natural, therefore, to inquire to what form 
they reverted? Now, they are said by many travellers 
to have resembled very nearly the shepherd’s dog ; 
but it is certain that they were never turned into 
wolves. They were extremely savage, and their 
ravages appear to have been as much dreaded as those 
of wolves ; but when any of their whelps were caught, 
and brought from the woods to the towns, they grew 
up in the most perfect submission to man. 

Mummies of animals in Egyptian tombs identical with 
species still living. — As the advocates of the theory 
of transmutation trust much to the slow and insensible 
changes which time may work, they are accustomed 
to lament the absence of accurate descriptions, and 
figures of particular animals and plants, handed down 
from the earliest periods of history, such as might 
have afforded data for comparing the condition of spe- 
cies,-at two periods considerably remote. But, fortu- 
nately, we are in some measure independent of such 
evidence; for, by a singular accident, the priests of 
Egypt have bequeathed to us, in their cemeteries, 
that information which the museums and works of the 
Greek philosophers have failed to transmit. 

For the careful investigation of these documents, we 
are greatly indebted to the skill and diligence of those 
naturalists who accompanied the French armies during 
their brief occupation. of Egypt: that conquest of four 
years, from which we may date the improvement of 
the modern Egyptians in the arts and sciences, and 
the rapid papens which has been made of late in our 

CS.) 


396 EGYPTIAN MUMMIES IDENTICAL [Book IIT. 


knowledge of the arts and sciences of their remote 
predecessors. Instead of wasting their whole time, as 
so many preceding travellers had done, in exclusively 
collecting human mummies, M. Geoffroy and his asso- 
ciates examined diligently, and sent home great num- 
bers of embalmed bodies of consecrated animals, such 
as the bull, the dog, the cat, the ape, the ichneumon, 
the crocodile, and the ibis. 

To those who have never been accustomed to con- 
nect the facts of Natural History with philosophical 
speculations, who have never raised their conceptions 
of the end and import of such studies beyond the mere 
admiration of isolated and beautiful objects, or the ex- 
ertion of skill in detecting specific differences, it will 
seem incredible that amidst the din of arms, and the 
stirring excitement of political movements, so much 
enthusiasm could have been felt in regard to these 
precious remains. 

In the official report, drawn up by the Professors of 
the Museum at Paris, on the value of these objects, 
there are some eloquent passages, which may appear 
extravagant, unless we reflect how fully these natural- 
ists could appreciate the bearing of the facts thus 
brought to light on the past history of the globe. 

“It seems,” say they, “as if the superstition of the 
ancient Egyptians had been inspired by Nature, with 
a view of transmitting to after ages a monument of her 
history. That extraordinary and whimsical people, by 
embalming with so much care the brutes which were 
the objects of their stupid adoration, have left us, i? 
their sacred grottos, cabinets of zoology almost com- 
plete. The climate has conspired with the art of 
embalming to preserve the bodies from corruption, and 
we can now assure ourselves by our own eyes what 


Ch. IL] WITH SPECIES STILL LIVING. 397 


was the state of a great number of species three thou- 
sand years ago. We can scarcely restrain the trans- 
ports of our imagination, on beholding thus preserved, 
with their minutest bones, with the smallest portions 
of their skin, and in every particular most perfectly 
recognizable, many an animal, which at Thebes or 
Memphis, two or three thousand years ago, had its own 
priests and altars.” * 

Among the Egyptian mummies thus procured were 
not only those of numerous wild quadrupeds, birds, 
and reptiles; but, what was perhaps of still higher 
importance in deciding the great question under dis- 
cussion, there were the mummies of domestic animals, 
among which those above mentioned, the bull, the dog, 
and the cat, were frequent. Now, such was the con- 
formity of the whole of these species to those now 
living, that there was no more difference, says Cuvier, 
between them than between the human mummies and 
the embalmed bodies of men of the present day. Yet 
some of these animals have since that period been 
transported by man to almost every climate, and forced 
to accommodate their habits to the greatest variety of 
circumstances. The cat, for example, has been carried 
over the whole earth, and, within the last three cen. 
turies, has been naturalized in every part of the 

“new world, — from the cold regions of Canada to the 
tropical plains of Guiana; yet it has scarcely under- 
gone any perceptible mutation, and is still the same 
animal which was held sacred by the Egyptians. 

Of the ox, undoubtedly, there are many very distinct 
races: but the bull Apis, which was led in solemn 


* Ann. du Muséum d’ Hist. Nat., tom. i. p. 234, 1802, The 
reporters were MM. Cuvier, Lacépède, and Lamarck, 


Aa F P! 

£4 BS 
$ T ee Ps 
“e PeF g aa 


CHANGES IN PLANTS [Book III. 


processions by the Egyptian priests, did not differ from 
some of those now living. Theblack cattle that have 
run wild in America, where there were many peculi- 
arities in the climate not to be found, perhaps, in any 
part of the old world, and where scarcely a single 
plant on which they fed was of precisely the same 
species, instead of altering their form and habits, 
have actually reverted to the exact likeness of the 
aboriginal wild cattle of Europe. 

In answer to the arguments drawn from the Egyptian 
mummies, Lamarck said that they were identical with 
their living descendants in the same country, because 
the climate and physical geography of the banks of 
the Nile have remained unaltered for the last thirty 
centuries. But why, it may be asked, have other 
individuals of these species retained the same charac- 
ters in so many different quarters of the globe, where 


\ ‘the climate and many other conditions are so varied ? 


Seeds and plants from the Egyptian tombs. — The 
evidence derived from the Egyptian monuments was 
not confined to the animal kingdom ; the fruits, seeds, 
and other portions of twenty different plants, were 
faithfully preserved in the same manner ; and among 
these the common wheat was procured by Delille, from 
closed vessels in. the sepulchres of the kings, the 
grains of which retained not only their form, but even 
their colour; so effectual has proved the process of 
embalming with bitumen in a dry and equable climate. 
No difference could be detected between this wheat 
and that which now grows in the East and elsewhere, 
and similar identifications were made in regard to all 
the other plants. 

Native country of the common wheat. — And here I 
may observe, that there is an obvious answer to La- 


Ch. 11] PRODUCED BY CULTIVATION. 399 


marck’s objection, that the botanist cannot point out 
a country where the common wheat grows wild, unless 
in places where it may have been derived from neigh- 
bouring cultivation.* All naturalists are well aware 
that the geographical distribution of a great number of 
species is extremely limited; that it was to be expected 
that every useful plant should first be cultivated suc- 
cessfully in the country where it was indigenous ; and 
that, probably, every station which it partially occu- 
pied, when growing wild, would be selected by the 
agriculturist as best suited to it when artificially in- 
creased. Palestine has been conjectured, by a late 
writer on the, Cerealia, to have been the original 
habitation of wheat and barley; a supposition which 
appears confirmed by Hebrew and Egyptian traditions, 
and by tracing the migrations of the worship of Ceres, 
as indicative of the migrations of the plant.+ 

If we are to infer that some one of the wild grasses 
has been transformed into the common wheat, and that 
some animal of the genus canis, still unreclaimed, has 
been metamorphosed into the dog, merely because we 
cannot find the domestic dog, or the cultivated wheat, 
in a state of nature, we may be next called upon to 
make similar admissions in regard to the camel; for it 
seems very doubtful whether any race of this species 
of quadruped is now wild. 

Changes in plants produced by cultivation. — But if 
agriculture, it will be said, does not supply examples 
of extraordinary changes of form and organization, the 
horticulturist can, at least, appeal to facts which may 


* Phil. Zool. tom. i. p. 227. 
+ L’Origine et la Patrie des Céréales, &c., Ann. des Sci, Nat., 
tom, ix. p. 61. 


400 VARIETIES IN PLANTS [Book III. 


confound the preceding train of reasoning. The crab 
has been transformed into the apple; the sloe into the 
plum: flowers have changed their colour, and become 
double ; and these new characters can be perpetuated 
by seed: a bitter plant, with wavy sea-green leaves; 
has been taken from the sea-side, where it grew like 
wild charlock ; has been transplanted into the garden, 
lost its saltness, and has been metamorphosed into two 
distinct vegetables, as unlike each other as is each to 
the parent plant — the red cabbage and the cauliflower. 
These, anda multitude of analogous facts, are undoubt- 
edly among the wonders of nature, and attest more 
strongly, perhaps, the extent to which species may be 
modified, than any examples derived from the animal 
kingdom. But in these cases we find that we soon 
reach certain limits, beyond which we are unable to 
cause the individuals descending from the same stock 
to vary; while, on the other hand, it is easy to show 
that these extraordinary varieties could seldom arise; 
and could never be perpetuated in a wild state for 
many generations, under any imaginable combination 
of accidents. They may be regarded as extreme cases; 
brought about by human interference, and not as 
phenomena which indicate a capability of indefinite 
modification in the natural world. 

The propagation of a plant by buds or grafts, and 
by cuttings, is obviously a mode which nature does 
not employ; and this multiplication, as well as that 
produced by roots and layers, seems merely to operate 
as an extension of the life of an individual, and not as 
a reproduction of the species such as happens by seed. 
All plants increased by grafts or layers retain pre- 
cisely the peculiar qualities of the individual to which 
they owe their origin, and, like an individual, they 


Ch. IL] PRODUCED BY HORTICULTURE. ~ 401 


have only a determinate existence; in some cases 
longer, and in others shorter.* It seems now admitted 
by horticulturists, that none of our garden varieties 
of fruit are entitled to be considered strictly perma- 
nent, but that they wear out after a time+; and weare 
thus compelled to resort again to seeds: in which case 
there is so decided a tendency in the seedlings to re- 
vert to the original type, that our utmost skill is some- | 
‘times baffled in attempting to recover the desired | 

variety. 

Varieties of the cabbage. — The different races of 
cabbages afford, as. was admitted, an astonishing ex- 
ample of deviation from a common type; but we can 
scarcely conceive them to have originated, much less 
to have lasted for several generations, without the 
intervention of man. It is only by strong manures 
that these varieties have been obtained, and in poorer 
soils they instantly degenerate. If, therefore, we sup- 
pose in a state of nature the seed of the wild Brassica . 
oleracea to have been wafted from the sea-side to some 
spot enriched by the dung of animals, and to have 
there become a cauliflower, it would soon diffuse its 
seed to some comparatively sterile soils around, and 
the offspring would relapse to the likeness of the 
parent stock. 

But if we go so far as to imagine the soil, in the 
spot first occupied, to be constantly manured by herds 
of wild animals, so as to continue as rich as that of a 
garden, still the variety could not be maintained ; be- 
cause we know that each of these races is prone to 


* Smith’s Introduction to Botany, p. 138. Edit. 1807. 
+ See Mr. Knight’s Observations, Hort. Trans,, vol. ii. p. 160. 


402 VARIETIES IN PLANTS [Book IIL 


'fecundate others, and gardeners are compelled to exert 
‘the utmost diligence to prevent cross-breeds. The 
| intermixture of the pollen of varieties growing in the 
| poorer soil around would soon destroy the peculiar | 
characters of the race which occupied the highly ma- 
nured tract; for, if these accidents so continually 
happen, in spite of our care, among the culinary va- 
rieties, it is easy to see how soon this cause might 
obliterate every marked singularity in a wild state. 

Besides, it is well known that, although the pam- 
pered races which we rear in our gardens for use of 
ornament may often be perpetuated by seed, yet they 
rarely produce seed in such abundance, or so prolific 
in quality, as wild individuals ; so that if the care of 
man were withdrawn, the most fertile variety would 
always, in the end, prevail over the more sterile. 

Similar remarks may be applied to the double flowers, 
which present such strange anomalies to the botanist. 
The ovarium, in such cases, is frequently abortive ; and 
the seeds, when prolific, are generally much fewer than 
where the flowers are single. 

Changes caused by soil. — Some curious experiments; 
recently made on the production of blue instead of 
red flowers in the Hydrangea hortensis, illustrate the 
immediate effect of certain soils on the colours of the 
calyx and petals. In garden-mould or compost, the 
flowers are invariably red ; in some kinds of bog-earth 
they are blue; and the same change is always pr°- 
duced by a particular sort of yellow loam. 

Varieties of the primrose. — Linnæus was of opinio? 
that the primrose, oxlip, cowslip, and polyanthus 
were only varieties of the same species. The majority 
of modern botanists, on the contrary, consider them t° 
be distinct, although some conceived that the oxlip 


Ch. IL] PRODUCED BY HORTICULTURE. 403 


might be a cross between the cowslip and the prim- 
rose. Mr. Herbert has lately recorded the following 
experiment :—“ I raised from the natural seed of one 
umbel of a highly manured red cowslip a primrose, a 
cowslip, oxlips of the usual and other colours, a black 
polyanthus, a hose-in-hose cowslip, and a natural prim- , 
rose bearing its flower on a polyanthus stalk. From 
the seed of that very hose-in-hose cowslip, I have 
since raised a hose-in-hose primrose. I therefore con- 
sider all these to be only local varieties, depending 
- upon soil and situation.” * Professor Henslow, of Cam- 
bridge, has since confirmed this experiment of Mr. 
Herbert; so that we have an example, not only of the 
remarkable varieties which the florist can obtain from 
a common stock, but of the distinctness of analogous 
races found in a wild state.t 

On what particular ingredient, or quality in the 
earth, these changes depend, has not yet been ascer- 
tained.{ But gardeners are well aware that particular 
plants, when placed under the influence of certain cir- 
cumstances, are changed in various ways, according 
to the species; and as often as the experiments are 
repeated, similar results are obtained. The nature of 
these results, however, depends upon the species, and 
they are, therefore, part of the specific character: 
they exhibit the same phenomena again and again, and 
indicate certain fixed and invariable relations between 
the physiological peculiarities of the plant, and the 
influence of certain external agents. They afford no 
ground for questioning the instability of species, but 


* Hort. Trans., vol. iv. p. 19. 
+ Loudon’s Mag. of Nat. Hist., Sept. 1830, vol. iii. p. 408. 
+ Hort. Trans. vol. iii. p. 173. 


404 VARIETIES IN PLANTS. [Book IIÍ. 


rather the contrary: they present us with a class of 
phenomena which, when they are more thoroughly 
understood, may afford some of the best tests for 
identifying species, and proving that the attributes 
originally conferred endure so long as any issue of the 
original stock remains upon the earth. 


« 


CHAPTER III. 


WHETHER SPECIES HAVE A REAL EXISTENCE IN NATURE — 
continued. 


Variability of a species compared to that of an individual — Species 
susceptible of modification may be altered greatly in a short 
time, and in a few generations; after which they remain sta- 
tionary — The animals now subject to man had originally an 
aptitude to domesticity — Acquired peculiarities which become 
hereditary have a close connexion with the habits or instincts of 
the species in a wild state (p- 409.) — Some qualities in certain 
animals have been conferred with a view of their relation to 
man — Wild elephant domesticated in a few years, but its facul- 
ties incapable of further development (p. 417.) 


Variability of a species compared to that of an indivi- 
dual. — I ENDEAVOURED, in the last chapter, to show, 
that a belief in the reality of species is not inconsistent 
with the idea of a considerable degree of variability in 
the specific character. This opinion, indeed, is little 
more than an extension of the idea which we must 
entertain of the identity of an individual, throughout 
the changes which it is capable of undergoing. 

If a quadruped, inhabiting a cold northern latitude, 
and covered with a warm coat of hair or wool, be 
transported to a southern climate, it will often in the 
course of a few years, shed a considerable portion of 
its coat, which it gradually recovers on being again 


£ 


406 EXTENT OF CHANGE IN SPECIES. [Book IU. 


e 
» 


restored to.its native country. Even there the same 
changes are, perhaps, superinduced to a certain extent 
by the return of winter and summer. We know that 
the Alpine hare, (Lepus variabilis, Pal.,) and the 
ermine, or stoat, (Mustela erminea, Linn.,) become 
white during winter, and again obtain their full colour 
during the warmer season ; that the plumage of the 
ptarmigan undergoes a like metamorphosis in colour 
and quantity, and that the change is equally temporary- 
We are aware that, if we reclaim some wild animal, 
and modify its habits and instincts by domestication, 
it may, if it escapes, become in a few years nearly as 
wild and untractable as ever; and if the same indivi- 
dual be again retaken, it may be reduced to its former 
tame state. A plant is placed in a prepared soil, in 
order that the petals of its flowers may multiply, and 
their colour be heightened or changed; if we then 
withhold our care, the flowers of this same individual 
become again single. In these, and innumerable other 
instances, we must suppose that the individual was 
produced with a certain number of qualities ; and, in 
the case of animals, with a variety of instincts, some 
of which may or may not be developed according t0 
circumstances, or which, after having been called 
forth, may again become latent when the exciting 
causes are removed. 

Now, the formation of races seems the necessary 
consequence of such a capability in individuals tO 
vary, if it be a general law that the offspring should 
very closely resemble the parent. But, before we can 
infer that there are no limits to the deviation from a? 
original type which may be brought about in the cours? 
of an indefinite number of generations, we ought tO 
have some proof that, in each successive generation, 


Ch. IIL] EXTENT OF CHANGE IN SPECIES. 407 


individuals may go on acquiring an equal amount of 
new peculiarities, under the influence of equal changes 
of circumstances. The balance of evidence, however, 
inclines most decidedly on the opposite side; for in all 
cases we find that the quantity of divergence dimi- 
nishes from the first in a very rapid ratio. 

Species susceptible of modification may be greatly 
altered in a few generations. — It cannot be objected, 
that it is out of our power to go on varying the circum- 
stances in the same manner as might happen in the 
natural course of events during some great geological 
cycle. For in the first place, where a capacity is given 
to individuals to adapt themselves to new circum. 
stances, it does not generally require a very long 
period for its development ; if, indeed, such were the 
case, it is not easy to see how the modification would 
answer the ends proposed, for all the individuals would 
die before new qualities, habits, or instincts were 
conferred. i 

When we have succeeded in naturalizing some tro. 
pical plant in a temperate climate, nothing prevents 
us from attempting gradually to extend its distribution 
to higher latitudes, or to greater elevations above the 
level of the sea, allowing equal quantities of time, or 
an equal number of generations, for habituating the 
species to successive increments of cold. But every 
husbandman and gardener is aware that such experi- 
ments will fail; and we are more likely to succeed in 
making some plants, in the course of the first two | 
generations, support a considerable degree of difference 
of temperature than a very small difference afterwards, 
though we persevere for many centuries. i 

It is the same if we take any other cause instead of | 


temperature; such as the quality of the food, or the 


4.08 EXTENT OF CHANGE IN SPECIES. [Book III. 


kind of dangers to which an animal is exposed, or the 
soil in which a plant lives. The alteration in habits, 
form, or organization, is often rapid during a short 
period; but when the circumstances are made to vary 
farther, though in ever so slight a degree, all modi- 
fication ceases, and the individual perishes. Thus some 
herbivorous quadrupeds may be made to feed partially 
on fish or flesh ; but even these can never be taught to 
live on some herbs which they reject, and which would 
even poison them, although the same may be very 
nutritious to other species of the same natural order. 
So, when man uses force or stratagem against wild 
animals, the persecuted race soon becomes more cau- 
tious, watchful, and cunning ; new instincts seem often 
to be developed, and to become hereditary in the first 
two or three generations: but let the skill and address 
of man increase, however gradually, no further vari- 
ation can take place, no new qualities are elicited by 
the increasing dangers. [he alteration of the habits 
of the species has reached a point beyond which no 
ulterior modification is possible, however indefinite the 
lapse of ages during which the new circumstances 
operate. Extirpation then follows, rather than such a 
transformation as could alone enable the species to 
perpetuate itself under the new state of things. 
Animals now subject to man had originally an aptitude 
to domesticity.— It has been well observed by M. F. 
Cuvier and M. Dureau de la Malle, that, unless some 
animals had manifested in a wild state an aptitude to 
second the efforts of man, their domestication would 
never have been attempted. If they had all resembled 
the wolf, the fox, and the hyena, the patience of the 
experimentalist would have been exhausted by innu- 
merable failures before he at last succeeded in obtain- 


Ch, I1.] ACQUIRED INSTINCTS HEREDITARY. 409 


ing some imperfect results; so, if the first advantages 
derived from the cultivation of plants had been elicited 
by as tedious and costly a process as that by which we 
now make some slight additional improvement in cer- 
tain races, we should have remained to this day in 
ignorance of the greater number of their useful 
qualities. ; 

Acquired instincts of some animals become heredi- 
tary. — It is undoubtedly true, that many new habits 
and qualities have not only been acquired in recent 
times by certain races of dogs, but have been trans- 
mitted to their offspring. But in these cases it will 
be observed, that the new peculiarities have an inti- 
mate relation to the habits of the animal in a wild 
state, and therefore do not attest any tendency to de- 
parture to an indefinite extent from the original type 
of the species. A race of dogs employed for hunting 
deer in the platform of Santa Fé, in Mexico, affords a 
beautiful illustration of a new hereditary instinct. 
The mode of attack, observes M. Roulin, which they 
employ, consists in seizing the animal by the belly and 
overturning it by a sudden effort, taking advantage of 
the moment when the body of the deer rests only upon 
the fore-legs. The weight of the animal thus thrown 
over is often six times that of its antagonist. The 
dog of pure breed inherits a disposition to this kind 
of chase, and never attacks a deer from before while 
running. Even should the deer, not perceiving him, 
come directly upon him, the dog steps aside and makes 
his assault on the flank; whereas other hunting dogs, 
though of superior strength and general sagacity, 
which are brought from Europe, are destitute of this 
instinct. For want of similar precautions, they are 


VOL. Il. T 


410 ACQUIRED INSTINCTS HEREDITARY, [Book III, 


often killed by the deer on the spot, the vertebre 
of their neck being dislocated by the violence of the 
shock.* ; 

A new instinct has also become hereditary in a mon- 
grel race of dogs employed by the inhabitants of the 
banks of the Magdalena almost exclusively in hunting 
the white-lipped pecari. The address of these dogs 
consists in restraining their ardour, and attaching them- 
selves to no animal in particular, but keeping the whole 
herd in check. Now, among these dogs some are 
found, which, the very first time they are taken to the 
woods, are acquainted with this mode of attack; 
whereas, a dog of another breed starts forward at 
once, is surrounded by the pecari, and, whatever may 
be his strength, is destroyed in a moment. 

Some of our countrymen, engaged of late in con- 
ducting one of the principal mining associations in 
Mexico, that of Real del Monte, carried out with 
them some English greyhounds of the best breed to 
hunt the hares which abound in that country. The 
great platform which is the scene of sport is at an 
elevation of about nine thousand feet above the level 
of the sea, and the mercury in the barometer stands 
habitually at the height of about nineteen inches. 
It was found that the greyhounds could not support 
the fatigues of a long chase in this attenuated at- 
mosphere, and before they could come up with their 
prey, they lay down gasping for breath; but these 
same animals have produced whelps which have 
grown up, and are not in the least degree incom- 
moded by the want of density in the air, but run down 


* M. Roulin, Ann. des Sci. Nat., tom. xvi. p. 16, 1829. 


Ch. IIL] INFLUENCE OF DOMESTICATION. ALL 


the hares with as much ease as the fleetest of their race 
in this country. 

The fixed and deliberate stand of the pointer has 
with propriety been regarded as a mere modification 
of a habit, which may have been useful to a wild race 
accustomed to wind game, and steal upon it by sur- 
prise, first pausing for an instant, in order to spring 
with unerring aim. The faculty of the Retriever, 
however, may justly be regarded as more inexplicable 
and less easily referrible to the instinctive passions of 
the species. M. Majendie, says a French writer in g 
recently published memoir, having learnt that there 
was a race of dogs in England, which stopped and 
brought back game of their own accord, procured 
a pair, and, having obtained a whelp from them, kept it 
constantly under his eyes, until he had an opportunity 
of assuring himself that, without having received any 
instruction, and on the very first day that it was car- 
ried to the chase, it brought back game with as much 
steadiness as dogs which had been schooled into the 
same manceuvre by means of the whip and collar. 

Attributes of animals in their relation to man.— 
Such attainments, as well as the habits and disposi- 
tions which the shepherd’s dog and many others in- 
herit, seem to be of a nature and extent which we can 
hardly explain by supposing them to be modifications 
of instincts necessary for the preservation of the spe- 
cies in a wild state. When such remarkable habits 
appear in races of this species, we may reasonably 
conjecture that they were given with no other view 
than for the use of man and the preservation of the 
dog, which thus obtains protection. 

As a general rule, I fully agree with M. F. Cuvier, 

rt 2 e 


Aaa oe 


AQ _ INSTINCTS. [Book III. 


that, in studying the habits of animals, we must 
attempt, as far as possible, to refer their domestic qua- 
lities to modifications of instincts which are implanted 
in them in a state of nature; and that writer has suc- 
cessfully pointed out, in an admirable essay on the 
domestication of the mammalia, the true origin of 
many dispositions which are vulgarly attributed to 
the influence of education alone.* But we should go 
too far if we did not admit that some of the qualities 
of particular animals and plants may have been given 
solely with a view to the connexion which it was fore- 
seen would exist between them and man—especially 
when we see that connexion to be in many cases so 
intimate, that the greater number, and sometimes all 
the individuals of the species which exist on the earth, 
are in subjection to the human race. 

We can perceive in a multitude of animals, espe- 
cially in some of the parasitic tribes, that certain 
instincts and organs are conferred for the purpose of 
defence or attack against some other species. Now, if 
we are reluctant to suppose the existence of similar 
relations between man and the instincts of many of the 
inferior animals, we adopt an hypothesis no less violent, 
though in the opposite extreme to that which has led 
some to imagine the whole animate and inanimate 
creation to have been made solely for the support, 
gratification, and instruction of mankind. 

Many species, most hostile to our persons or pro- 
perty, multiply, in spite of our efforts to repress them ; 
others, on the contrary, are intentionally augmented 
many hundred-fold in number by our exertions. In 


* Mém. du Mus. d’Hist. Nat. — Jameson, Ed. New Phil. 
Journ,, Nos. 6, 7, 8. 


Ch. IIL] INFLUENCE OF DOMESTICATION. 413 


such instances, we must imagine the relative resources 
of man and of species, friendly or inimical to him, to 
have been prospectively calculated and adjusted. To 
withhold assent to this supposition, would be to refuse 
what we must grant in respect to the economy of 
Nature in every other part of the organic creation; 
for the various species of contemporary plants and 
animals have obviously their relative forces nicely 
balanced, and their respective tastes, passions, and in- 
stincts so contrived, that they are all in perfect har- 
mony with each other. In no other manner could it 
happen that each species, surrounded, as it is, by 
countless dangers, should be enabled to maintain its 
ground for periods of considerable duration. 

The docility of the individuals of some of our do- 
mestic species, extending, as it does, to attainments 
foreign to their natural habits and faculties, may, per- 
haps, have been conferred with a. view to their asso. 
ciation with man. But, lest species should be thereby 
made to vary indefinitely, we find that such habits are 
never transmissible by generation. o 

A pig has been trained to hunt and point game with 
great activity and steadiness*; and other learned in- 
dividuals, of the same species, have been taught to 
spell; but such fortuitous acquirements never become 
hereditary, for they have no relation whatever to the 
exigencies of the animal in a wild state, and cannot, 
therefore, be developments of any instinctive propen- 
sities. 

Influence of domestication.— An animal in domes- 
ticity, says M. F. Cuvier, is not essentially in a differ- 


* In the New Forest, near Ringwood, Hants, by Mr. Toomer 
2 
keeper of Broomy Lodge. I have conversed with witnesses of 


the fact. 
Pd 


414 INFLUENCE OF DOMESTICATION. [Book IL 


ent situation, in regard to the feeling of restraint, from 
one left to itself. It lives in society without constraint, 
because, without doubt, it was a social animal; and it 
conforms itself to the will of man, because it had a 
chief, to which, in a wild state, it would have yielded 
obedience. There is nothing in its new situation that 
is not conformable to its propensities ; it is satisfying 
its wants by submission to a master, and makes no 
sacrifice of its natural inclinations. All the social ani- 
mals, when left to themselves, form herds more or less 
numerous: and all the individuals of the same herd 
know each other, are mutually attached, and will not 
allow a strange individual to join them. In a wild 
state, moreover, they obey some individual, which, by 
its superiority, has become the chief of the herd. Our 
domestic species had, originally, this sociability of dis- 
position ; and no solitary species, however easy it may 
be fo tame it, has yet afforded true domestic races. 
We merely, therefore, develope, to our own advantage, 
propensities which propel the individuals of certain 
species to draw near to their fellows. 

The sheep which we have reared is induced to 
follow us, as it would be led to follow the flock among 
which it was brought up; and, when individuals of 
gregarious species have been accustomed to one 
master, it is he alone whom they acknowledge as their 
chief—he only whom they obey. “ The elephant 
allows himself to be directed only by the carnac whom 
he has adopted; the dog itself, reared in solitude with 
its master, manifests a hostile disposition towards all 
others; and every body knows how dangerous it is to 
be in the midst of a herd of cows, in pasturages that 
are little frequented, when they have not at their head 
the keeper who takes care of them.” 


‘ 


Ch. IL] INFLUENCE OF DOMESTICATION. 415 


« Every thing, therefore, tends to convince us, that 
formerly men were only, with regard to the domestic 
animals, what those who are particularly charged with 
the care of them still are — namely, members of the 
society which these animals form among themselves; 
and that they are only distinguished, in the general 
mass by the authority which they have been enabled 
to assume from their superiority of intellect. Thus, 
every social animal which recognizes man as a member, 
and as the chief of its herd, is a domestic animal. It 
might even be said, that, from the moment when such 
an animal admits man as a member of its society, it is 
domesticated, as man could not enter into such a 
society without becoming the chief of it.” * 

But the ingenious author whose observations I have 
here cited, admits that the obedience which the indi- 
viduals of many domestic species yield indifferently to 
` every person, is without analogy in any state of things 
which could exist previously to their subjugation by 
man. Each troop of wild horses, it is true, has some 
stallion for its chief, who draws after him all the in- 
dividuals of which the herd is composed; but, when 
a domesticated horse has passed from hand to hand, 
and has served several masters, he becomes equally 
docile towards any person, and is subjected to the 
whole human race. It seems fair to presume that the 
capability in the instinct of the horse to be thus 
modified, was given to enable the species to render 
greater services to man; and, perhaps, the facility with 
which many other acquired characters become here- 
ditary in various races of the horse, may be explicable 
only on a like supposition. The amble, for example, 


* Mém. du Mus. d’Hist. Nat. 
T4 


ADS EIE E bee aia dite Ae -un e _ 


AATE TARA 
ae ama eee ae 


416 MODIFICATION OF INSTINCTS [Book IIE 


a pace to which the domestic races in Spanish America 
are exclusively trained, has, in the”Course of several 
generations, become hereditary, and is assumed by all 
the young colts before they are broken in.* 

It seems, also, reasonable to conclude, that the 
power bestowed on the horse, the dog, the ox, the 
sheep, the cat, and many species of domestic fowls, of 
supporting almost every climate, was given expressly 
to enable them to follow man throughout all parts of 
the globe, in order that we might obtain their services, 
and they our protection. If it be objected that the 
elephant, which by the union of strength, intelligence, 
and docility, can render the greatest services to man- 
kind, is incapable of living in any but the warmest 
latitudes, we may observe, that the quantity of vege- 
table food required by this quadruped would render 
its maintenance in the temperate zone too costly, and 
in the arctic impossible. 

Among the changes superinduced by man, none 
appear, at first sight, more remarkable than the perfect 
tameness of certain domestic races. It is well known 
that, at however early an age we obtain possession of 
the young of many unreclaimed races, they will retain, 
throughout life, a considerable timidity and appre- 
hensiveness of danger; whereas, after one or two 
generations, the descendants of the same stock will : 
habitually place the most implicit confidence in man. 
There is good reason, however, to suspect that such 
changes are not without analogy in a state of nature 5 
or, to speak more correctly, in situations where man 
has not interfered. 

Thus, Dr. Richardson informs us, in his able history 


* Dureau de la Malle, Ann. des Sci. Nat., tom. xxi. p. 58- 


Ch. IIL] BY DOMESTICATION. ` ALT 


of the habits of North American animals, that, “in 
the retired parts of the mountains, where the hunters 
had seldom penetrated, there is no difficulty in ap- 
proaching the Rocky Mountain sheep, which there 
exhibit the simplicity of character so remarkable in. the 
domestic species ; but where they have been often fired 
at, they are exceedingly wild, alarm their companions, 
on the approach of danger, by a hissing noise, and 
scale the rocks with a speed and agility that baffles 
pursuit.” * 

It is probable, therefore, that as man, in diffusing 
himself over the globe, has tamed many wild races, so, 
also, he has made many tame races wild. Had someyy—~<> 
of the larger carnivorous beasts, capable of scaling the x 
rocks, made their way into the North American moun- ip 
tains before our hunters, a similar alteration in the). 
instincts of the sheep would doubtless have been! 
brought about. 

Wild elephants domesticated in a few years. —-No 
animal affords a more striking illustration of the prin- 
cipal points which I have been endeavouring to esta- 
blish, than the elephant; for, in the first place, the 
wonderful sagacity with which he accommodates him- 
self to the society of man, and the new habits which 
he contracts, are not the result of time, nor of modi- 
fications produced in the course of many generations. 
These animals will breed in captivity, as is now ascer- 
tained, in opposition to the vulgar opinion of many 
modern naturalists, and in conformity to that of the 
ancients Elian and Columella+: yet it has always 


* Fauna Boreali- Americana, p. 273. 
+ Mr. Corse on the Habits, &c. of the Elephant, Phil. Trans, 
1799. 
TH 


Se 


== 


an 


= 


48 MODIFICATION OF INSTINCTS [Book 111. 


been the custom, as the least expensive mode of ob- 
taining them, to capture wild individuals in the forests, 
usually when full grown ; and, in a few years after they 
are taken — sometimes, it is said, in the space of a few 
months — their education is completed. 

Had the whole species been domesticated from an 
early period in the history of man, like the camel, 
their superior intelligence would, doubtless, have been 
attributed to their long and familiar intercourse with 
the lord of the creation ; but we know that a few years 
is sufficient to bring about this wonderful change of 
habits; and, although the same individual may con- 
tinue to receive tuition for a century afterwards, yet 
it makes no further progress in the general develop- 
ment of its faculties. Were it otherwise, indeed, the 
animal would soon deserve more than the poet's epithet 
of “ half-reasoning.” 

From the authority of our countrymen employed in 
the late Burmese war, it appears, in corroboration of 
older accounts, that, when elephants are required to 
execute extraordinary tasks, they may be made to 
understand that they will receive unusual rewards. 
Some favourite dainty is shown to them, in the hope 
of acquiring which the work is done ; and so perfectly 
does the nature of the contract appear to be under- 
stood, that the breach of it, on the part of the master, 
is often attended with danger. In this case, a power 
has been given to the species to adapt their social 
instincts to new circumstances with surprising rapidity ; 
but the extent of this change is defined by strict and 
arbitrary limits. There is no indication of a tendency 
to continued divergence from certain attributes with 
"which the elephant was originally endued —no ground 


Ch. IL] BY DOMESTICATION. 419 


whatever for anticipating that, in thousands of centu- 
ries, any material alteration could ever be effected: 
All that we can infer from analogy is, that some more 
useful and peculiar races might probably be formed, if 
the experiment were fairly tried; and that some indi- | 
vidual characteristic, now only casual and temporary: © 
might be perpetuated by generation. : 
In all cases, therefore, where the domestic qualities 
‘exist in animals, they seem to require no lengthened 
process for their development; and they appear to 
have been wholly denied to some classes, which, from 
their strength and social disposition, might have ren- 
dered great services to man; as, for example, the 
greater part of the quadrumana. The orang-outang, 
indeed, which, for its resemblance in form to man, 
and apparently for no other good reason, has been 
assumed by Lamarck to be the most perfect of the 
inferior animals, has been tamed by the savages of 
Borneo, and made to climb lofty trees, and to bring 
down the fruit. But he is said to yield to his 
masters an unwilling obedience, and to be held in sub- 
jection only by severe discipline. We know nothing 
of the faculties of this animal which can suggest the 
idea that it rivals the elephant in intelligence ; much 
less any thing which can countenance the dreams of 
those who have fancied that it might have been trans- 
muted into “the dominant race.” One of the baboons 
of Sumatra (Simia carpolegus) appears to be more 
docile, and is frequently trained by the inhabitants to 
ascend trees, for the purpose of gathering cocoa-nuts ; 
a service in which the animal is very expert. He 
selects, says Sir Stamford Raffles, the ripe nuts, with 
great judgment, and pulls no more than he is ordered.* 


* Linn. Trans., vol. xiii. p. 244, 
TG 


eens 


annsan n saii 


420 RECAPITULATION. : “© [Book IIL 


The capuchin and cacajao monkeys are, according to 
Humboldt, taught to ascend trees in the same manner, 
and to throw down fruit on the banks of the lower 
Orinoco. * 

It is for the Lamarckians to explain how it happens 
that those same savages of Borneo have not themselves 
acquired, by dint of longing, for many generations, for 
the power of climbing trees, the elongated arms of the 
orang, or even the prehensile tails of some American 


_monkeys. Instead of being reduced to the necessity 


of subjugating stubborn and untractable brutes, we 
should naturally have anticipated “ that their wants 
would have excited them to efforts, and that continued 
efforts would have given rise to new organs;” or, rather 
to the re-acquisition of organs which, in a manner 
irreconcileable with the principle of the progressive 
system, have grown obsolete in tribes of men which 
have such constant need of them. 

Recapitulation.—It follows, then, from the different 
facts which have been considered in this. chapter, that 
a short period of time is generally sufficient to effect 
nearly the whole change which an alteration of ex- 
ternal circumstances can bring about in the habits of 
a species, and that such capacity of accommodation to 
new circumstances is enjoyed, in very different de- 
grees, by different species. 

Certain qualities appear to be bestowed exclusively 
with a view to the relations which are destined to 
exist between different species and, among others, 
between certain species and man; but these latter are 
always so nearly connected with the original habits 


* Pers, Narr. of Travels to the Equinoctial Regions of the 
New Continent, in the years 1799—1804. 


Ch, IIL] ' RECAPITULATION, ~ 421 


and propensities of each species in a wild state, that 
they imply no indefinite capacity of varying from the 
original type. The acquired habits derived from human 
tuition are rarely transmitted to the offspring; and 
when this happens, it is almost universally the case 
with those merely which have some obvious connexion 
with the attributes of the species when in a state of 
independence. 


CHAPTER IV. 


WHETHER SPECIES HAVE A REAL EXISTENCE IN NATURE— 
continued, 


Phenomena of hybrids — Hunter’s opinions — Mules not strictly 
intermediate between parent species — Hybrid plants — Expe- 
riments of Kolreuter and Wiegmann — Vegetable hybrids pro- 
lific throughout several generations — Why rare in a wild state 
(p. 428.) — De Candolle on hybrid plants — The phenomena 
of hybrids confirm the distinctness of species — Theory of the 
gradation in the intelligence of animals as indicated by the 
facial angle (p. 436.) — Tiedemann on the brain of the foetus in 
mammalia assuming successively the form of the brain of fish, 
reptile, and bird — Bearing of this discovery on the theory of 
progressive development and transmutation (p. 441.) — Reca- 
pitulation. 


Phenomena of hybrids. We have yet to consider 
another class of phenomena, ‘those relating to the pro- 
duction of hybrids, which have been regarded in a 
very different light with reference to their bearing on 
the question of the permanent distinctness of species ; 
some naturalists considering them as affording the 
strongest of all proofs in favour of the reality of 
species; others, on the contrary, appealing to them 
as countenancing the opposite doctrine, that all the 
varieties of organization and instinct now exhibited in 
the animal and vegetable kingdoms may have been 
propagated from a small number of original types. 


Ch. IV. EXPERIMENTS ON HYBRID ANIMALS, TAD 


In regard to the mammifers and birds, it is found 
that no sexual union will take place between races 
which are remote from each other in their habits and 
organization ; and it is only in species that are very 
nearly allied that such unions produce offspring. It 
may be laid down as a general rule, admitting of very 
few exceptions among quadrupeds, that the hybrid 
progeny is sterile; and there seem to be no well-authen- 
ticated examples of the continuance of the mule race 
beyond one generation. The principal number of 
observations and experiments relate to the mixed off- 
spring of the horse and the ass; and in this case it is 
well established that the he-mule can generate, and 
the she-mule produce. Such cases occur in Spain and 
Italy, and much more frequently in the West Indies 
and New Holland; but these mules have never bred 
in cold climates, seldom in warm regions, and still 
more rarely in temperate countries. 

The hybrid offspring of the she-ass and the stallion, 
the ywves of Aristotle, and the hinnus of Pliny, differs 
from the mule, or the offspring of the ass and mare. 
In both cases, says Buffon, these animals retain more 
of the dam than of the sire, not only in the magnitude, 
put in the figure of the body ; whereas, in the form 
of the head, limbs, and tail, they bear a greater re- 
semblance to the sire. The same naturalist infers, 
from various experiments respecting cross-breeds be- 
tween the he-goat and ewe, the dog and she-wolf, the 
goldfinch and canary-bird, that the male transmits 
his sex to the greatest number, and that the prepon- 
derance of males over females exceeds that which 
prevails where the parents are of the same species. 

Hunters opinion. — The celebrated John Hunter 
has observed, that the true distinction of species must 


Saas en: 


ans 


—_ 


ADA EXPERIMENTS ON : [Book III, 


ultimately be gathered from their incapacity of pro- 
pagating with each other, and producing offspring, 
capable of again continuing itself. He was unwilling, 
however, to admit that the horse and the ass were of 
the same species, because some rare instances had been 
adduced of the breeding of mules, although he main- 
tained that the wolf, the dog, and the jackal were all 
of one species; because he had found, by two experi- 
ments, that the dog would breed both with the wolf 
and the jackal ; and that the mule, in each case, would 
breed again with the dog. In these cases, however, 
it may be observed, that there was always one parent 
at least of pure breed, and no proof was obtained that 
a true hybrid race could be perpetuated; a fact of 
which I believe no examples are yet recorded, either in 
regard to mixtures of the horse and ass, or any other 
of the mammalia. 

Should the fact be hereafter ascertained, that two 
mules can propagate their kind, we must still inquire 
whether the offspring may not be regarded in the 
light of a monstrous birth, proceeding from some ac- 
cidental cause, or, rather, to speak more philosophically, 
from some general law not yet understood, but which 
may not be permitted permanently to interfere with 
those laws of generation by which species may, in 
general, be prevented from becoming blended. If, for 
example, we discovered that the progeny of a mule 
race degenerated greatly, in the first generation, in 
force, sagacity, or any attribute necessary for its pre- 
servation in a state of nature, we might infer that, 
like a monster, it is a mere temporary and fortuitous 
variety. Nor does it seem probable that the greater 
number of such monsters could ever occur unless ob- 
tained by art; for, in Hunter’s experiments, stratagem 


Ch. IV.] [HYBRID ANIMALS. ; 425 


or force was, in most instances, employed to bring 
about the irregular connexion.* 

Mules not strictly intermediate between the parent 
species. —It seems rarely to happen that the mule 
offspring is truly intermediate in character between 
the two parents. Thus Hunter mentions that, in his 
experiments, one of the hybrid pups resembled the 
wolf much more than the rest of the litter; and we 
are informed by Wiegmann, that, in a litter lately ob- 
tained in the Royal Menagerie at Berlin, from a 
white pointer and a she-wolf, two of the cubs resem- 
bled the common wolf-dog, but the third was like a 
pointer with hanging ears. 

There is undoubtedly a very close analogy between 
these phenomena and those presented by the inter- 
mixture of distinct races of the same species, both in 
the inferior animals and in man. Dr. Prichard, in his 
« Physical History of Mankind,” cites examples where 
the peculiarities of the parents have been transmitted 
very unequally to the offspring; as where children, 
entirely white, or perfectly black, have sprung from 
the union of the European and the negro. Sometimes 
the colour or other peculiarities of one parent, after 
having failed to show themselves in the immediate 
progeny, reappear in a subsequent generation; as 
where a white child is born of two black parents, 
the grandfather having been a white.t 

The same author judiciously observes that, if dif- 
ferent species mixed their breed, and hybrid races 
were often propagated, the animal world would soon 
present a scene of confusion; its tribes would be 


* Phil. Trans., 1787. Additional Remarks, Phil. Trans., 1789, / 
+ Prichard, vol. i. p. 217. Í 


426 EXPERIMENTS ON [Book III, 


everywhere blended together, and we should perhaps 
find more hybrid creatures than genuine and uncor- 
rupted races. * 

Hybrid plants — Kélreuter’s experiments. — The his- 
tory of the vegetable kingdom has been thought to 
afford more decisive evidence in favour of the theory 
of the formation of new and permanent species from 
hybrid stocks. The first accurate experiments in il- 
lustration of this curious subject appear to have been 
made by Kölreuter, who obtained a hybrid from two 
species of tobacco, Nicotiana rustica and N. paniculata, 
which differ greatly in the shape of their leaves, the 
colour of the corolla, and the height of the stem. 
The stigma of a female plant of N. rustica was im- 
pregnated with the pollen of a male plant of N. pani- 
culata. The seed ripened, and produced a hybrid 
which was intermediate between the two parents, and 
which, like all the hybrids which this botanist brought 
up, had imperfect stamens. He afterwards impreg- 
nated this hybrid with the pollen of W. paniculata, 
and obtained plants which much more resembled the 
last. This he continued through several generations, 
until, by due perseverance, he actually changed the 
Nicotiana rustica into the Nicotiana paniculata. 

The plan of impregnation adopted was the cutting 
off of the anthers of the plant intended for fructification 
before they had shed pollen, and then laying on foreign 
pollen upon the stigma. 

Wiegmann’s experiments.— The same experiment 
has since been repeated with success by Wiegmann, 
who found that he could bring back the hybrids to the 
exact likeness of either parent, by crossing them a 
Sufficient number of times. 


* Prichard, vol. i. p. 97, 


Ch, IV.] HYBRID PLANTS. 427 


The blending of the characters of the parent stocks, 
in many other of Wiegmann’s experiments, was COM- 
plete; the colour and shape of the leaves and flowers, 
and even the scent, being intermediate, as in the off- 
spring of the two species of verbascum. An inter- 
marriage, also, between the common onion and the 
leek (Allium cepa and A. porrum) gave a mule plant, 
which, in the character of its leaves and flowers, ap- 
proached most nearly to the garden onion, but had the 
elongated bulbous root and smell of the leek. 

The same botanist remarks, that vegetable hybrids, 
when not strictly intermediate, more frequently ap- 
proach the female than the male parent species, bué 


they never exhibit characters foreign to both. A recross { | 


with one of the original stocks generally causes the | J 
mule plant to revert towards that stock; but this is 
not always the case, the offspring sometimes continuing 


to exhibit the character of a full hybrid. 
In general, the success attending the production 


and perpetuity of hybrids among plants depends, as 
in the animal kingdom, on the degree of proximity 
between the species intermarried. If their organiz- 
ation be very remote, impregnation never takes place ; 
if somewhat less distant, seeds are formed, but always 
imperfect and sterile. The next degree of relationship 
yields hybrid seedlings, but these are barren ; and it 
is only when the parent species are very nearly allied. 
that the hybrid race may be perpetuated for several 
generations. Even in this case, the best authenticated 
examples seem confined to the crossing of hybrids 
with individuals of pure breed. In none of the ex- 
periments most accurately detailed does it appear that 
both the parents were mules. 

Wiegmann diversified as much as possible his mode 


428 RARITY OF HYBRIDS AMONG [Book IH, 


of bringing about these irregular unions among plants. 
He often sowed parallel rows, near to each other, of 
the species from which he desired to breed ; and, 
instead of mutilating, after Kölreuter’s fashion, the 
plants of one of the parent stocks, he merely washed 
the pollen off their anthers. The branches of the 
plants in each row were then gently bent towards each 
other and intertwined ; so that the wind, and numerous 
insects, as they passed from the flowers of one to those 
of the other species, carried the pollen and produced 
fecundation. 

Vegetable hybrids why rare in a wild state. —The 
same observer saw a good exemplification of the 
manner in which hybrids may be formed in a state of 
nature. Some wallflowers and pinks had been growing 
in a garden, in a dry sunny situation ; and their stigmas 
had been ripened sc as to be moist, and to absorb pollen 
with avidity, although their anthers were not yet de- 
veloped. These stigmas became impregnated by 
pollen blown from some other adjacent plants of the 
same species ; but, had they been of different species, 
and not too remote in their organization, mule races ` 
must have resulted. 

When, indeed, we consider how busily some insects 
have been shown to be engaged in conveying anther- 
dust from flower to flower, especially bees, flower- 
eating beetles, and the like, it seems a most enigmati- 
cal problem how it can happen that promiscuous 
alliances between distinct species are not perpetually 
occurring. 

How continually do we observe the bees diligently 
employed in collecting the red and yellow powder by 
which the stamens of flowers are covered, loading it 
on their hind legs, and carrying it to their hive for the 


Ch. IV.J PLANTS IN A WILD STATE. 4.99 


purpose of feeding their young! In thus providing 
for their own progeny, these insects assist materially 
the process of fructification.* Few persons need be 
reminded that the stamens in certain plants grow on 
different blossoms from the pistils; and, unless the 
summit of the pistil be touched with the fertilizing 
dust, the fruit does not swell, nor the seed arrive at 
maturity. It is by the help of bees, chiefly, that the 
development of the fruit of many such species is se~ 
cured, the powder which they have collected from the 
stamens being unconsciously left by them in visiting 
the pistils. : 

How often, during the heat of a summer's day, do 
we see the males of dicecious plants, such as the yew- 
tree, standing separate from the females, and sending 
off into the air, upon the slightest breath of wind, 
clouds of buoyant pollen! That the zephyr should so 
rarely intervene to fecundate the plants of one species 
with the anther-dust of others, seems almost to realize 
the converse of the miracle believed by the credulous 
herdsmen of the Lusitanian mares — 

Ore omnes verse in Zephyrum, stant rupibus altis, 


Exceptantque leves auras: et sæpe sine ullis 
Conjugiis, vento gravide, mirabile dictu. + 


But, in the first place, it appears that there is a 
natural aversion in plants, as well as in animals, to 
irregular sexual unions; and in most of the successful 
experiments in the animal and vegetable world, some 
violence has been used in order to procure impregna- 
tion. The stigma imbibes, slowly and reluctantly, the 


* See Barton on the Geography of Plants, p. 67. 
+ Georg. lib. iii. 273. 


430 RARITY OF HYBRIDS AMONG [Book III. 


granules of the pollen of another species, even when 
it is abundantly covered with it; and if it happen 
that, during this period, ever so slight a quantity of 
the anther dust of its own species alight upon it, this 
is instantly absorbed, and the effect of- the foreign 
pollen destroyed. Besides, it does not often happen 
that the male and female organs of fructification, in 
different species, arrive at a state of maturity at pre- 
cisely the same time. Even where such synchronism 
does prevail, so that a cross impregnation is effected, 
the chances are very numerous against the establish- 
ment of a hybrid race. 

If we consider the vegetable kingdom generally, it 
must be recollected that even of the seeds which are 
well ripened, a great part are either eaten by insects, 
birds, and other animals, or decay for want of room 
and opportunity to germinate. Unhealthy plants are 
the first which are cut off by causes prejudicial to the 
species, being usually stifled by more vigorous indivi- 
duals of their own kind. If, therefore, the relative 
fecundity or hardiness of hybrids be in the least degree 
inferior, they cannot maintain their footing for many 
generations, even if they were ever produced beyond 
one generation in a wild state. In the universal strug- 
gle for existence, the right of the strongest eventually 
prevails ; and the strength and durability of a race 
depends mainly on its prolificness, in which hybrids 
are acknowledged to be deficient. 

Centaurea hybrida, a plant which never bears seed, 
and is supposed to be produced by the frequent inter- 
mixture of two well-known species of Centaurea, grows 
wild upon a hill near Turin. Ranunculus lacerus, also 
sterile, has been produced accidentally at Grenoble, 


Ch. IV.J PLANTS IN A WILD STATE. 431 


and near Paris, by the union of two Ranunculi; but 
this occurred in gardens.* 

Mr. Herbert's experiments. —'Mr. Herbert, in one 
of his ingenious papers on mule plants, endeavours to 
account for their non-occurrence in a state of nature, 
from the circumstance that all the combinations that 
were likely to occur have already been made many 
centuries ago, and have formed the various species of 
botanists; but in our gardens, he says, whenever 
species, having a certain degree of affinity to each 
other, are transported from different countries, and 
prought for the first time into contact, they give rise 
to hybrid species.t But we have no data, as yet, to 
warrant the conclusion, that a single permanent hybrid. 
race has ever been formed, even in gardens, by the 
intermarriage of two allied species brought from dis- 
tant habitations. Until some fact of this kind is fairly 
established, and a new species, capable of perpetuating 
itself in a state of perfect independence of man, can 
be pointed out, it seems reasonable to call in question 
entirely this hypothetical source of new species. That 
varieties do sometimes spring up from cross breeds, in 
a natural way, can hardly be doubted; but they pro- 
bably die out even more rapidly than races propagated 
by grafts or layers. 

Opinion of De Candolle.— De Candolle, whose 
opinion on a philosophical question of this kind de- 
serves the greatest attention, has observed, in his 
Essay on Botanical Geography, that the varieties of 
plants range themselves under two general heads: 
those produced by external circumstances, and those 
formed by hybridity. After adducing various argu- 


* Hon. and Rev. W. Herbert, Hort. Trans., vol, iv. Pp. 41. 
+ Ibid. 


439, DIFFICULTIES ATTENDING THE [Book III. 


ments to show that neither of these causes can ex- 
plain the permanent diversity of plants indigenous 
in different regions, he says, in regard to the crossing 
of races, “I can perfectly comprehend, without alto- 
gether sharing the opinion, that, where many species 
of the same genera occur near together, hybrid species 
may be formed, and I am aware that the great num- 
ber of species of certain genera which are found in 
particular regions may be explained in this manner; 
but I am unable to conceive how any one can regard 
the same explanation as applicable to species which 
live naturally at great distances. If the three larches, 
for example, now known in the world, lived in the same 
localities, I might then believe that one of them was 
the produce of the crossing of the two others; but I 
never could admit that the Siberian species has been 
produced by the crossing of those of Europe and 
America. I see, then, that there exist, in organized 
beings, permanent differences which cannot be referred 
kio any one of the actual causes of variation, and these 
differences are what constitute species.” * 

Reality of species confirmed by the phenomena of 
hybrids. — The most decisive arguments, perhaps, 
amongst many others, against the probability of the 
derivation of permanent species from cross-breeds, are 
to be drawn from the fact alluded to by De Candolle, 
of species having a close affinity to each other occur- 
‘ring in distinct botanical provinces, or countries in- 
habited by groups of distinct species of indigenous 
plants: for in this case naturalists who are not pre- 
pared to go the whole length of the transmutationists, 
are under the necessity of admitting that, in some 


* Essai Elémentaire, &c., 3me partie. 


Ch. IV.] . PROPAGATION OF HYBRIDS. 433 


cases, species which approach very near to each other - 
in their characters, were so created from their origin ; 
an admission fatal to the idea of its being a general 
law of nature, that a few original types only should be 
formed, and that all intermediate races should spring 
from the intermixture of those stocks. 

This notion, indeed, is wholly at variance with all 
that we know of hybrid generation ; for the phenomena 
entitle us to affirm, that had the types been at first 
somewhat distant, no cross-breeds would ever have been 
produced, much less those prolific races which we now 
recognize as distinct species. 

In regard, moreover, to the permanent propagation 
of hybrid races among animals, insuperable difficulties > 
present themselves, when we endeavour to conceive 
the blending together of the different instincts and 
propensities of two species, so as to insure the pre- 
servation of the intermediate race. The common mule, 
when obtained by human art, may be protected by the 
power of man; but, in a wild state, it would not have 
precisely the same wants either as the horse or the 
ass: and if, in consequence of some difference of this 
kind, if strayed from the herd, it would soon be 
hunted down by beasts of prey, and destroyed. 

If we take some genus of insects, such as the bee, 
we find that each of the numerous species has some 
difference in its habits, its mode of collecting honey, 
or constructing its dwelling, or providing for its young, 
and other particulars. In the case of the common hive- 
bee, the workers are described, by Kirby and Spence, 
as being endowed with no less than thirty distinct 
instincts.* _ So also we find that, amongst a most nu- 


* Intr. to Entom., vol, ii., p, 504. Ed. 1817. 
VOL. IIL. U 


434 HYBRIDS. [Book TIT. 


merous class of spiders, there are nearly as many 
different modes of spinning their webs as there are 
species. When we recollect how complicated are the 
relations of these instincts with co-existing species, 
both of the animal and vegetable kingdoms, it is 
scarcely possible to imagine that a bastard race could 
spring from the union of two of these species, and re- 
tain just so much of the qualities of each parent stock 
as to preserve its ground in spite of the dangers which 
surround it. ; 

We might also ask, if a few generic types alone 
have been created among insects, and the intermediate 
species have proceeded from hybridity, where are 
those original types, combining, as they ought to do, 
the elements of all the instincts which have made their 
appearance in the numerous derivative races? So also 
in regard to animals of all classes, and of plants; if 
species in general are of hybrid origin, where are the 
stocks which combine in themselves the habits, proper- 
ties, and organs, of which all the intervening species 
ought to afford us mere modifications ? 

Recapitulation of the arguments from hybrids. — 1 
shall now conclude this subject by summing up, in a 
few words, the results to which I have been led by the 
consideration of the phenomena of hybrids. It appears, 
that the aversion of individuals of distinct species to 
the sexual union is common to animals and plants ; and 
that it is only when the species approach near to each 
other in their organization and habits, that any off- 
spring are produced from their connexion. Mules are 
of extremely rare occurrence in a state of nature, and 
no examples are yet known of their having procreated 
in a wild state. But it has been proved, that hybrids 
are not universally sterile, provided the parent stocks 


Ch. IV.] HYBRIDS. 435 


have a near affinity to each other, although the con- 
_ tinuation of the mixed race, for several generations, 
appears hitherto to have been obtained only by crossing 
the hybrids with individuals of pure species; an ex- 
periment which by no means bears out the hypothesis 
that a true hybrid race could ever be permanently 
established. : 

Hence we may infer, that aversion to sexual inter- 
course is, in general, a good test of the distinctness 
of original stocks, or of species ; and the procreation of 
hybrids is a proof of the very near affinity of species. 
Perhaps, hereafter, the number of generations for 
which hybrids may be continued, before the race dies 
out (for it seems usually to degenerate rapidly), may 
afford the zoologist and botanist an experimental test 
of the difference in the degree of affinity of allied 
species. 

I may also remark, that if it could have been shown 
that a single permanent species had ever been pro- 
duced by hybridity (of which there is no satisfactory 
proof ), it might certainly have lent some countenance 
to the notions of the ancients respecting the gradual 
deterioration of created things, but none whatever to 
Lamarck’s theory of their progressive perfectibility ; for 
observations have hitherto shown that there is a 
tendency in mule animals and plants to degenerate in 
organization. 

It was before remarked, that the theory of progres- 
sive development arose from an attempt to ingraft 
the doctrines of the transmutationists upon one of the 
most popular generalizations in geology. But modern 
geological researches have almost destroyed every ap- 
pearance of that gradation in the successive groups of ` 

u 2 


436 FACIAL ANGLE. [Book III, 


animate beings, which was supposed to indicate the 
slow progress of the organic world from the more sim- 
ple to the more compound structure. In the more 
modern formations, we find clear indications that the 
highest orders of the terrestrial mammalia were fully 
represented during several successive epochs ; but in 
the monuments which we have hitherto examined of 
more remote eras, in which there are as yet discovered 
few fluviatile, and perhaps no lacustrine formations, 
and, therefore, scarcely any means of obtaining an in- 
sight into the zoology of the continents then existing, 
we have only as yet found one example of a mammi- 
ferous quadruped. ‘The recent origin of man, and the 
absence of all signs of any rational being holding an 
analogous relation to former states of the animate 
world, affords one, and the only reasonable argument, 
in support of the hypothesis of a progressive scheme; 
but none whatever in favour of the fancied evolution 
of one species out of another. 
Theory of the gradation in intellect as shown by the 
facial angle. — When the celebrated anatomist, Camper, 
first attempted to estimate the degrees of sagacity of 
different animals, and of the races of man, by the mea- 
-surement of the facial angle, some speculators were 
bold enough to affirm, that certain simiæ differed as 
little from the more savage races of men, as those do 
from the human race in general; and that a scale 
might be traced from “apes with foreheads villanous 
low” to the African variety of the human species, and 
from that to the European. The facial angle was 
measured by drawing a line from the prominent centre 
of the forehead to the most advanced part of the lower 
jaw-bone, and observing the angle which it made with 
the horizontal line ; and it was affirmed, that there was 


Ch. IV.) FACIAL ANGLE, 437 


a regular series of such angles from birds to the 
mammalia. 

The gradation from the dog to the monkey was said 
to be perfect, and from that again to man. One of 
the ape tribe has a facial angle of 42° ; and another, 
which approximated nearest to man in figure, an angle 
of 50°. To this succeeds (longo sed proximus inter- 
vallo) the head of the African negro, which, as well as 
that of the Kalmuc, forms an angle of 70°; while that 
of the European contains 80°. The Roman painters 
preferred the angle of 95°; and the character of 
beauty and sublimity, so striking in some works of 
Grecian sculpture, as in the head of the Apollo, and 
in the Medusa of Sisocles, is given by an angle which 
amounts to 100°. * i 

A great number of valuable facts and curious ana- 
logies in comparative anatomy were brought to light 
during the investigations which were made by Camper, 
John Hunter, and others, to illustrate this scale of 
organization ; and their facts and generalizations must- 
not be confounded with the fanciful systems which 
White and others deduced from them. t 

That there is some connection between an elevated 
and capacious forehead, in certain races of men, and a 

‘large development of the intellectual faculties, seems 
highly probable ; and that a low facial angle is fre- 
quently accompanied with inferiority of mental powers, 
is certain ; but the attempt to trace a graduated scale 
of intelligence through the different species of animals 
accompanying the modifications of the form. of the 
skull, is a mere visionary speculation. It has been 
found necessary to exaggerate the sagacity of the ape 
x Prichard’s Phys. Hist. of Mankind, vol.i. p. 159. 
+ Ch. White on the Regular Gradation in Man, &c., 1799. 
v 3 


438 DIFFERENT RACES OF MEN. [Book III. 


tribe at the expense of the dog; and strange contra- 
dictions have arisen in the conclusions deduced from 
the structure of the elephant; some anatomists being 
disposed to deny the quadruped the intelligence which 
he really possesses, because they found that the volume 
of his brain was small in comparison to that of the 
other mammalia ; while others were inclined to mag- 
nify extravagantly the superiority of his intellect, be- 
cause the vertical height of his skull is so great when 
compared to its horizontal length. 

Different races of men are all of one species. — It 
would be irrelevant to our subject if we were to enter 
into a further discussion on these topics; because, even 
if a graduated scale of organization and intelligence 
could have been established, it would prove nothing in 
favour of a tendency, in each species, to attain a 
higher state of perfection. I may refer the reader to 
the writings of Blumenbach, Prichard, Lawrence, and 
others, for convincing proofs that the varieties of 
form, colour, and organization of different races of 
men, are perfectly consistent with the generally re- 
ceived opinion, that ali the individuals of the species 
‘have originated from a single pair; and, while they 
exhibit in man as many diversities of a physiological 
nature as appear in any other species, they confirm 
also the opinion of the slight deviation from a common 
standard of which species are capable. 

The power of existing and multiplying in every 
latitude, and in every variety of situation and climate, 
which has enabled the great human family to extend 
itself over the habitable globe, is partly, says Law- 
rence, the result of physical constitution, and partly of 
the mental prerogative of man. Ifhe did not possess 
the most enduring and flexible corporeal frame, his 


Ch. IV.] DISCOVERIES OF TIEDEMANN. 439 


arts would not enable him to be the inhabitant of all 
climates, and to brave the extremes of heat and cold, 
and the other destructive influences of local situation.* 
Yet, notwithstanding this flexibility of bodily frame, 
we find no signs of indefinite departure from a common | 
standard, and the intermarriages of individuals of the | 
most remote varieties are not less fruitful than between j 
those of the same tribe. i 

Tiedemann on the brain of the fætus in vertebrated 
animals. — There is yet another department of ana- 
tomical discovery to which I must allude, because it 
has appeared, to some persons, to afford a distant 
analogy, at least, to that progressive development by 
which some of the inferior species may have been 
gradually perfected into those of more complex organ- 
ization. ‘Tiedemann found, and his discoveries have 
been most fully confirmed and elucidated by M. Serres, 
that the brain of the foetus, in the highest class of 
vertebrated animals, assumes, in succession, forms 
analogous to those which belong to fishes, reptiles, and 
pirds, before it acquires the additions and modifications 
which are peculiar to the mammiferous tribe. So 
that, in the passage from the embryo to the perfect 
mammifer, there is a typical representation, as it 
were, of all those transformations which the primitive 
species are supposed to have undergone, during a long 
series of generations, between the present period and 
the remotest geological era. 

If you examine the brain of the mammalia, says 
M. Serres, at an early stage of uterine life, you per- 
ceive the cerebral hemispheres consolidated, as in fish, 
in two vesicles, isolated one from the other; at a later 


* Lawrence, Lectures on Phys. Zool. and Nat. Hist. of Man, 
p. 192. Ed. 1823, 


440 DISCOVERIES OF TIEDEMANN. [Book ILI. 


period, you see them affect the configuration of the 
cerebral hemispheres of reptiles; still later again, 
they present you with the forms of those of birds; 
finally, they acquire, at the era of birth, and some- 
times later, the permanent forms which the adult 
mammalia present. 

The cerebral hemispheres, then, arrive at the state 
which we observe in the higher animals only by a 
series of successive metamorphoses. If we reduce 
the whole of these evolutions to four periods, we shall 
see, that in the first are born the cerebral lobes of 
fishes; and this takes place homogeneously in all 
classes. The second period will give us the organ- 
ization of reptiles; the third, the brain of birds; and 
the fourth, the complex hemispheres of mammalia. 

If we could develop the different parts of the brain 
of the inferior classes, we should make, in succession, 
a reptile out of a fish, a bird out of a reptile, and a 
mammiferous quadruped out of a bird. If, on the con- 
trary, we could starve this organ in the mammalia, we 
might reduce it successively to the condition of the 
brain of the three inferior classes. 

Nature often presents us with this last phenomenon 
~ jn monsters, but never exhibits the first. Among the 
various deformities which organized beings may ex- 
perience, they never pass the limits of their own 
classes to put on the forms of the class above them. 
Never does a fish elevate itself so as to assume the 
form of the brain of a reptile ; nor does the latter ever 
attain that of birds ; nor the bird that of the mammifer. 
It may happen that a monster may have two heads; 
but the conformation of the brain always remains cir- 
cumscribed narrowly within the limits of its class-* 


* E. R. A. Serres, Anatomie Comparée du Cerveau, illustrated 
by numerous plates, tomei., 1824. 


‘ch. IV.] RECAPITULATION. 44l 


Bearing of these discoveries on the theory of pro- 
gressive development. — It will be observed, that these 
curious phenomena disclose, in a highly interesting 
manner, the unity of plan that runs through the organ- 
ization of the whole series of vertebrated animals; but 
they lend no support whatever to the notion of a gra- 
dual transmutation of one species into another ; least 
of all of the passage, in the course of many generations, 
from an animal of a more simple to one of a more 
complex structure. On the contrary, were it not for 
the sterility imposed on monsters, as well as on hy- 
brids in general, the argument to be derived from 
Tiedemann’s discovery, like that deducible from expe- 
riments respecting hybridity, would be in favour of the 
successive degeneracy, rather than the perfectibility, 
in the course of ages, of certain classes of organic 


beings. 
Recapitulation. — For the reasons, therefore, detailed 


in this and the two preceding chapters, we may draw 
the following inferences in regard to the reality of 
species in nature : — 

Ist. That there is a capacity in all species to ac- 
commodate themselves, to acertain extent, to a change 
of external circumstances, this extent varying greatly, 
according to the species. 
oe: Qdly. When the change of situation which they can 

endure is great, it is usually attended by some modifi- 
cations of the form, colour, size, structure, or other 
particulars ; but the mutations thus superinduced are, 
governed by constant laws, and the capability of so 
varying forms part of the permanent specific cha- 
racter. oe i teak, 
3dly. Some acquired peculiarities of form, structure, 
and instinct, are transmissible to the offspring; but 


449 RECAPITULATION. [Book III. 


these consist of such qualities and attributes only as 
are intimately related to the natural wants and pro- 
pensities of the species. 

Athly. The entire variation from the original type, 
which any given kind of change can produce, may 
usually be effected in a brief period of time, after 
which. no farther deviation can be obtained by con- 
tinuing to alter the circumstances, though ever so 
_ gradually ; indefinite divergence, either in the way of 
-improvement or deterioration, being prevented, and 
‘the least possible excess beyond the defined. limits 
being fatal to the existence of the individual. 

5thly. The intermixture of distinct species is guarded 
against by the aversion of the individuals composing 
them to sexual union, or by the sterility of the mule 
- offspring. It does not appear that true hybrid races 
have ever been perpetuated for several generations, 
even by the assistance of man; for the cases usually 
cited relate to the crossing of mules with individuals 
of pure species, and not to the intermixture of hybrid 
with hybrid. 

6thly. From the above considerations, it appears 
that species have a real existence in nature ; and that 
each was endowed, at the time of its creation, with 
the attributes and organization by which it is now 
distinguished. 


af 
W jt 


END OF THE SECOND VOLUME. 


Lee . 


Lonpon: 
Printed by A. SPOTTISWOODE, 
New-Street-Square. 


ere NSA z | Ce 
Fone pihy T$ 


kd 
f