Peay ais Bem: AT E t PRINCIPLES GEOLOGY. VOL. II. Lid a00W WALYD]1 Z l g A 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