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SEA AND LAND

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Showing the ice cave from which emerges a sub-glacial river. The peaks in the background are composed of
ice much fissured by the irregularities of the surface over which it is moving.

SEA AND LAND

FEATURES OF COASTS AND OCEANS [VI TH SPECIAL
REFERENCE TO THE LIFE OF MAN

N. S. SHALER

PROFESSOR OF GEOLOGY IN HARVARD UNIVERSITY

ILLUSTRATED

NEW YORK
CHARLES SCRIBNER'S SONS

1S94

Copyright, 1894, by
CHARLES SCRIBXER'S SONS

Press of J. J. Little & Ca
Astor Place, New York

D

PREFACE

The object of this book is to introduce unprofessional
students of nature to certain interesting phenomena of the
sea-shore and of the depths of the ocean. In no other
fields are large and important truths which are distinctly
related to human interests so readily to be traced ; yet the
treatises which deal with these matters are few in number,
and generally of a recondite character.

The aim of the writer in preparing the essays which are

* here presented has been to separate from the great body

E of technical knowledee concerninsf shores and seas those

features which have value for the reason that they may

g, serve to enlarge the reader's conception as to the methods

i of nature. As commonly observed, or as learned from text-

5 books, these truths appear to be fragmentary and lead to

": no extended notions as to the workings of the earth's

i machinery : thus the student is not led to form those con-

i ceptions which it is most important that he should gain.

I In part the matter presented in the following pages has

- been printed in Scribner's Magazine. That especially relating

' to harbors, which is contained in the three last chapters, is

mainly extracted from a report on the Geological Mistory

of Harbors, which was printed in the Thirteenth Annual

Report of the Director of the United States Geological

Survey. The author and publisher are alike indebted to

that Survey for permission to use the text and the plates

which appear in this part of the book.

431733 N- ^"^^ s-

CONTENTS

SEA AND LAND

PACE

How Energy Comes to and Acts upon the Earth's Surface. — The Work of Water on
the Coasts. — Facts to be Noted on a Coast-Line. — Land constantly Wearing
away and Sea-Floor Receiving Sediments. — Slight Effect of Sea on Rocky Shore.
— Effect of Shore Currents. — Trap-Dykes. — The Great York.shire Wave-Terrace. —
Sea-Caves. — Frost and Ice. — Organic Life. — Elevated and Submerged Beaches. . i

SEA-BEACHES

Various Divisions of Shore-Line. — Symmetry of Sea-Beaches. — Action of Surf. — Rate
of Wear of Detritus. — Action of Coast Currents. — Sand Dunes. — Pocket-Beaches.
— Action of Sea-Weeds. — Straight Beaches. — Continental Shelf. — Action of Tides
and Waves. — Variations in Level of Shores. — Formation of Lagoons. — Marine
Marshes : their Agricultural Value. — Endurance of Sand : Effect in Protecting
the Continents 3S

THE DEPTHS OF THE SEA

Modern Interest in the Deep .Sea: Conditions of Inquiry. — Shape of Ocean-Floors:
Absence of Mountains and Valleys. — Coral Reefs. — Continental Shelf. — Perma-
nence of Continents. — Plants and Animals of the Sea. — Conditions of Marine
Life : Absence of Seasonal Changes. — Marine Communities. — Abysmal Life. —
Detrital Accumulations. — Fate of Sunken Ships

ICEBERGS

Effect of E.Kpansion of Water in Freezing. — Classes of Ice-Fields. — Origin of Ice-
Floes. — Migrations of Ice-Floes.— Origin of Icebergs.— The Greenland Glacier.
— Annual Product of Icebergs ; their Voyages ; their Effect on the Ocean ; the
Order of their Movements ; their Decay ; iheir General Influence on Climate. —
Transportation of Rock Debris by Icebergs.— Effect of Ice on Shores.— Iceberg
"Work in Former Geological Periods. — Dangers to Ships from Colli>ion with
Icebergs ^ ' 5

X CONTENTS

HARBORS AND CIVILIZATION

PACK

First Condition of Ships. — Oii(;in of Maritime Habit ; Relation of Habit to Form of
Shore ; Effect on National Progress. — Condition of North America as regards
Harbors. — Requirements of a Good Port. — Classiiication of Harbors. — Delta Har-
bors.— Valley Harbors : How Dependent on Changes of Level. — Fiord Harbors :
The Conditions of their Formation; Value as Ports. — Mountain Range Harbors. —
Morninal Harbors I53

THE FORMATION AND PRESERVATION OF HARBORS

Lao-oon Harbors ; their Origin and History. — Effect of Wind-blown Sands. — Sand-Spit
Harbors. — Effect of Water-borne Sands. — Crater Harbors. — Coral-Reef Harbors ;
Division into Two Classes ; Ways in which constructed. — Preservation and
Destruction of Harbors ; Ways in which they Act ; Tidal Action ; Changes of
Level ; Accumulation of Sediments ; Invasion of Marine Waste. — Relative Im-
portance of Damaging Agencies in Lake and Sea Harbors. — Effect of Pocket-
Beaches ^^7

TIDAL CURRENTS AND ORGANIC LIFE IN HARBORS

Effects of Tides on Harbors : Organization of Tidal Streams ; Effect of Tidal Bars. —
Action of Organic Life in Harbors ; Classes of Work done.— Effect of Marine
Plants ; Flowering Species ; Sea-Weeds. — Growth of Marine Marshes : their Rela-
tion to Tidal Currents; their Value for Tillage, — Tropical Marine Marshes. —
Effect of Mangroves on these Areas. — Effects of Organic Life,xm FJarbor-s : Work
done by Mollusks ; by the Common Oyster ; Comparison of Northern and Southern
Marine Marshes ; Work done by other Animal Species. — Synopsis 223

LIST OF ILLUSTRATIONS

FULL-PAGE ILLUSTRATIONS

View of the Extremity of a Greenland Glacier, . . Frontispiece

Facing Page

Point Finnin, California, '-

General View of Dunes 3°

View at the End of a Glacier, showing an Iceberg just ready to

Separate '-^

View of a Lar(;e Berg ^3^

Jupiter Inlet, Florida, ^94

A Barrier Beach, '9^

A Hook Spit Harbor '9^

A Wall Beach

ILLUSTRATIONS IN THE TEXT

iS

Shakespeare Cliff, near Dover. England,
Tantallon Castle and Bass Rock,
Natural Bridge. Santa Cruz, California.
Yesnabie Castle, Orkney,
Barra Head, Outer Hebrides, .

lO

iS

20

xii ILLUSTRATIONS IN THE TEXT

PAGE

Seashore View, Zl

The Ovens. Mount Desert, Maine 37

The Isles of ihk Cyclops, near Catania, Sicily 39

Eastern Side oe Cape Ann, Massachusetts, 45

Carmel Beach California, 49

Eastern Shore ok Cape Ann 53

Heavy Surges on Beach Shore, ........ 58

Moderate Suroes seen along their Crests, 67

Sketch showing the Arrangement for Dredging in the Deep Sea, . 77
Diagram showing the Position of a Deep-sea Dredge as the Line is

I'au) Out from the Stern of the Ship, 79

Suggestions concerning Submarine Volcanoes, Coral Reefs, and

\'OLCANic Islands. 85

Living Crinoid 9°

Calyx, Arms, and a Part of the Stem of a Metacrinus— one of

the Ska Liuks, 9'

Antennarius 9^

Figure ok a Free Polyp Community, related 10 the Sea Fans, . 98
Figure ok a sponge, such as Inhabits the Deeper I'arts ok the

Sea 99

A ('.ROUP OK Fishes of Peculiar Form, such as Inhabit Moderate

Depths in the Sea, loi

Sternop'iyx Diaphana 102

A Member ok the Genus Scopelus, 104

Globi<;erina, 106

tomopteris, 107

Suggestions as to the History of a Sunken Ship 109

View on the Coast of Greenland .118

View ok the End of a Glacier at the Head of a Greenland Fiord, 125

ILLUSTRATIONS IN TJIIi TEXT xiii

PAf.H

View at the Mouth of a Greenland Fiord, i2.(

View of a Part of the Coast of Greenland, 141

View showing Large Berg with Ice Arch 14^)

Edgartown Harbor, Martha's Vineyard, 184

Tidal Deltas at Ocracoke and Hatteras Inlets 197

Volcanic Harbor 202

Diagrammatic Section through a Growing Marine Marsh, . . 233
Plum Island Marshes near Newburyport, Massachusetts, , , 236
Dyke and Marshes, Green Harbor River, Marshfield, Massa-
chusetts, 239

SEA AND LAND

How Energy Conies to and Acts upon the Earth's Surface.— The Work of Water on the
Coasts.— Facts to be Noted on a Coast-Line. — Land constantly Wearing away and
Sea-floor Receiving Sediments.— Slight Effect of Sea on Rocky Shore.— Effect of Shore
Currents. — Trap-Dykes.— The Great Yorkshire Wave-Terrace.- Sea-Caves.— Frost and
Ice. — Organic Life. — Elevated and Submerged Beaches.

Ox the greater part of the earth's surface men may dwell
unconscious of the fact that the earth is a laboratory which
is day by day accomplishing constructive work — work which
in the process of the years and ages brings about revolutions
in the forms of land and sea as well as in the nature of their
climates, and thus alters all the conditions of life. Those
who live near active volcanoes, or in lands which are fre-
quently shaken by earthquakes, now and then have evidence
brought to their attention which shows that this globe is a
w^ork-shop wherein much is done ; but in most lands the
order of nature is so quiet, and its processes so familiar, that
the whole appears merely commonplace. It is otherwise,
however, w^ith those wdio dwell in the peculiar realm where
the ereat reservoir of the waters comes in contact with the
land : on the ocean's shore the processes of change are so
marked, man's combat with them so continued, that all mar-
iners, and even those w^ho reside near the sea, acquire a far
more vivid impression of the earth's activities.

The beo-inner in treolocrv should at the outset of his

-,2 ;.'•;'. • ::..:••••.•.• SEA AND LAXD

studies endeavor to acquire certain general notions as to the
\va)' in which energy comes to, and acts upon, the surface of
the earth. He may well begin his steps towards this under-
standing by noting the fact that all the movements which
take place on the land and in the sea, from the storms to
the pulsations of his own heart, represent the action of forces
which oricrinate in the sun. From that orreat master of the
solar system there goes forth such a tide of energy in the
form of light and heat, that even the small share which falls
upon this little globe is in quantity vast almost beyond under-
standing. Some conception of it, however, may be obtained
in the following manner by a simple experiment. Let the
observer put in a vessel containing water at a temperature
of 32° Fahr., or just above the freezing point, a pound of ice.
Let the vessel be placed over a fire, so that the time required
to melt the lump of ice may be noted. It is well, indeed, to
have two vessels, each with the same amount of water and
of like temperature, the one wdth all the ice it wnll l^oat, and
the other without any frozen water. It will be easy to note
in this trial that a great amount of heat is taken up, or, as
the jjhrase is, rendered latent, in melting even a small cpiantity
of ice. But in a single day there comes from the sun to
the earth enough energy in the form of heat to melt about
8,000 cubic miles of ice, or enough to cover the area of the
State of Massachusetts to the depth of, say, 5,000 feet. It
is Avell to remember that the amount of heat which comes
forth from the interior of the earth in the same period prob-
ably does not exceed the (quantity required to melt somewhere
about 100 cubic miles of frozen water.

When it comes to the surface of the earth, a considerable
amount of the solar heat goes quickly away again, by radia-

METHODS OF STUDY fXG THE SHORE 3

tion, into the celestial spaces. It all in the end tintls its way
back to that cold realm, but before it leaves the atmosphere
it does work of varied kinds; converting^ water into vapor, it
lifts the material into the air, whence it descends in the form
of rain or snow, each in their way capable, if they fall upon
the land, of doing a great deal in the way of geological deeds
before their water is returned to the sea. By setting the air
in motion and thus creating the wind, the solar heat gives
rise to the waves which may roll over the deep, gathering
energy as they gain in height, until, arrested at the shore,
they apply their stored force to the work which is done along
the coast line. Not only should this large view be enter-
tained at the outset of the student's inquiries, but it should be
again and again taken into mind, in order that his thoughts
may not altogether be lost in details, but that they may seize
upon these large truths.

All those who would find an easy way to a conception of
the most important facts of geologic science should take uj:*
their inquiry on the coast-line : if they understand the pro-
cesses which are there in operation — they are indeed easily
understood — they will gain a clue to some of the most impor-
tant truths of geology. The portion of the earth's machin-
ery that may there be seen in operation, or may be readily
inferred from that which is visible, is of the utmost impor-
tance in the development of this sphere. It is only necessary
clearly to see what is going on upon this part of the land and
ocean, and then to conceive the conditions arising from tlir
accumulation of these effects through the ages of the past, to
bring before the mind that picture of the slow yet majestic
progress of the earth's history which it is the peculiar privi-
lege of the geologist to win from his studies.

4 SEA A AW LAND

In selecting a portion of the slion; for his first lessons In
freolooy the observer will do well to take some care in his
choice ; the field should, if possible, afford cliffs of bed-rocks
of varied hardness, masses of dyke stones, and stretches of
sandy antl pebbh' beaches ; in these conditions he will be able
to note the important differences in the action of the sea aris-
ing from its diverse circumstances of cc:)ntact with the shore.
It is best that the waters should be rich in the life of marine
plants and animals, and the land forested to the margin ; for
the relation of the earth's work to living creatures is likewise
important to his inquiry. Fortunately the shores of this sort
are abundantly provided for the student's use. The eastern
coast of the United States, from the mouth of the Hudson
River to Labrador, the western border of the continent, from
San PVancisco to Bering's Straits, the northern coast of
Britain, from Scarborough on the coast around by the chalk
downs on the south, as well as the northern shores of the
European continent, afford ideal fields for this class of stud-
ies. It is only when the student has become well versed in
the great array of actions which he may observe within a few
miles journey in any of these fields, that he will have occasion
to undertake special journeys to see peculiar aspects of the
coast-line, such as are afforded by the coral reefs of blorida,
or the singular effects produced where active volcanoes build
their cones along the shore or up from the depths of the
ocean. Interesting as these special features are, they are
only incidental elements in marine work, concerning rather
the professional geologist than the amateur.

Arriving on a shore such as we have advised the observer
to select, he is likely to be at first confounded by the multi-
tude of the facts which this line of interacting- land and water

INTERACTION OF SEA AND lAND 5

exhibits. These facts arc, as is the case with all the extended
phenomena of nature, much entangled with each other; all
united in the common features which the earth always pre-
sents to the untrained eye. It is well for the student to

Shakespeare Cliff, near Dover, England

Showing^ the eflfect of heavy waves on rather soft rocks. The steep beach at the base of the cliff is com-
posed of fragments of flint originally scattered through the mass of chalk which forms the headland. la
times of heavy storm the sea enters the slight caves which appear in the lower portion of the precipice.
Recently fallen masses are shown at the extremity of the headland.

remember, as a protection against discouragement, that this
blended aspect of the work which is clone on the earth, is
what appears to every beginner in inciuiry. All science indeed
has come to exist through the patient labors of students who

6 SEA AND LAND

have slowi)' done the work of unravelhnL;- the tangled web of
interlaced actions, some part of which in turn every faithful
observer must with the teacher's aid repeat. It is not to
be expected that each individual seeker for truth shall go
through all the laborious processes of thought which have
made the science which he seeks to acquire ; it is the part
of his guide to show him the road through the wilderness,
to keep him from the blintl paths which lead to no profit ;
but, if he would accjuire the strength which can come from his
personal activit)-, he must patiently tread the way himself.

At the outset this guide may well ask the novice to have
in mind certain large truths of geology which may serve as a
background upon which he may frame the special conceptions
which will come to him from his shore-line studies. He may
be assured that all these general conceptions will be more or
less verified by the w^ork which he is to do. The first of these
concerns the contrast between the essential conditions of the
two orreat divisions of the earth's surface, the land of the con-
tinents and islands, and the water-covered areas of the sea-
floors. All the land above the level of the oceans which is
somewhat unreasonably called clr)-, for it is everywhere flowed
over and leached through by water, is subjected to continual
wearing by the action of the elements. Every rain-drop as it
falls and strikes ground unprotected by vegetation takes aw^ay
a little? of the earth. The streams bear away much — each of
them sends its tribute of mud, sand, or dissolved rocky mat-
ter to the sea ; and the ocean itself, by its unending assault
upon the shores, is wearing away the land along all coasts
save where the coral reefs build effective walls against the
weaves. All this water of rain-drop, spring, or stream, is sent
from the sea throuoh the air for the direct downward attack

CO MP ENS A TING MO I '/■. MENTS 7

on the emerged fields of the cartli ; the battle the oceans
unendingly wage is so set that it assaults the opposing land in
two directions : on the sea face it assails by the surges, and
in the interior by the rain, the flowing water, and the glaciers.
The result is that the lands are constantly wearing away,
while the sea-tloor receives the sediments which the waters
have given to it and builds them into new deposits.

The effect of this action, if it were not qualified b\- other
conditions, would be that in time the dry parts of the earth
would utterly disappear and the seas be in good part filled
with the waste they had won from them ; but there are com-
pensations to this action . the lands are constantK' growing
upward from the action of those forces which elevate moun-
tain-chains, probably also the whole of the vast ridge which
constitutes the body of each continent is also characterized by
a massive upward growth ; at the same time the ocean basins
seem to be ever deepening b)- the downsinking of their floors.
The result of these beautiful compensating movements is,
that although the contest between land and sea is the most
ancient, far extended, and unbroken of all the man\' combats
which make up the life of this sphere, neither side is ever
victorious or is ever likely to prevail. It is Indeed only in
a metaphoric way that it can be called a battle at all. for the
results of the interaction are profitable to the interests of sea
and land alike. On the land the continued wearing has the
most important result, that the soils on which all its organic
life depends are ever renewed b\- the destructive processes of
erosion. If any considerable time went b)- without the old
soils being swept away, the effete earthy matter would be-
come unfit for the nurture of plants, and plant and animal life
alike w^ould fail of support. This waste, in jiart tlissolved in

8 SEA AND LAND

water, nourishes the marine Hfe, and in part in the form of
mud is contributed to the strata which in time are to be Hfted
into the air with the upward growth of the continent from
whence it came. Here as elsewhere modern science has
shown that the strife of this world is only apparent ; the
result, considered in a large way, is always for the profit of
the whole.

With such a broad preliminary survey in mind, the ob-
server may well begin his detailed studies of the shore at
some point where the sea and land meet in a steep rocky cliff
which descends abruptly, there being a depth of one hundred
feet or more next the clifts, from its crest into the sea at its
foot. It is easiest to inspect such a bit of shore at a time
when the ocean is (juite still ; for then it may be approached
in a boat. On the northern coast of the Atlantic, from New
York northward, these rocky faces of the shore are gener-
ally more or less rounded by the action of the moving sheet
of ice which lay upon them during the last glacial period.
We are very likely to find the upper portion of the steep,
that which is above the level where the waves do their work,
still bearing here and there the scratches which so plainly tell
of the ice time. Occasionally, when the water at the base of
the cliff is deep, this glaciated surface, if the rock be firm
set, is preserved even within the belt where the surges im-
pinge upon it. This fact tells us that the sea has under
certain conditions little effect on a shore of this nature.
This is made the clearer by the presence on the surface of
the stone of a mass of marine animals and plants, algae, sea
anemones, etc., which, firmly adhering to the stones, can
resist the blow of the waves. If in times of storm we
creep to the verge of such a cliff we may see the waves

ACTION OF WAVES ON SEA-CLIFFS 9

surging violently against its base, but we observe that tliey do
not strike an effective blow, but merely swash up and down,
as they break against the steep. As we shall shortly see,
their action is impotent as compared to what it is when the
cliffs do not descend into deep water, but have something
like a beach at their base.

The fact is that the ocean weaves, when they beat against
a rock-bound shore where the firm cliffs descend into deep
water, have very little destructive power. When they strike
the shore they ma}' apply a pressure of from one to three
tons per square foot of surface against which they run, but
this can only break away the masses of stone which have been
loosened by the action of frost or the other processes of
decay. On a shore which has recently been overridden by
the glacial ice, the weaker kinds of rock have been pretty gen-
erally worn away, and it is only slowly that they yield to the
sea's assault. Yet, now^ and then masses tumble from the top
of the cliff, so that here and there, even on the steepest shores,
we find where the debris from the precipices has been suffi-
cient to make a beach-like accumulation such as is shown in
the illustration (page 10). As soon as this mass of debris
comes near enough to the surface to be much affected by the
dragging action of the waves as they surge against the steep,
the stones are arranged by the waves so that they assume
more distinctly the beach form. In this state of the shore the
surges are at last able to do their effective work. We may
observe them rolling in from the deep in the lorm of broad
folds of the ocean's surface ; when the advancing margm of
each wave arrives at the shallower water at the outer part
of the inclined plane of debris, the friction of the bottom
opposes the forward movement, and causes the front of the

lO

SEA AND LAND

surf swiftly to rise into the form of a wall ; the upper part of
the mass of the water being- less retarded than that at the
Ijase, shoots violently forward, and near the shore tumbles
over in the manner of the familiar breakers or surf.

When the waves break at the foot of cliffs they then strike
much more effective blows than when they splash against

, "5 VS ----->.-v

them, as they
do when the)'
roll through
deep water to their
base. R u s h i II g
over the shallow
Ijottom in times
of heavy storms,

View showing ttie result of erosion on the shores of a rocky island
the)' hurl the loose of considerable heijjht. The dotted lines indicate the oriKinal

preater extension of the isle. The beach in the foreground is. in
stories, even it tn('\' fact, a rocky shelf, the remnant of the cliff which once extended

much further out to sea.

wcngh a ton or

more, forward aeainst the base of the cliff. The blow
these wave-swayed stones can strike is very great ; it Is some-
times almost as powerful as that which is delivered by a shot
from an ancient battery against a besieged wall. If the stu-
dent will watch the action of the storm-waves upon a coast

Tantalion Castie and Bass Rock

RESULTS OF WAVE-ACTION II

where they have the effect we are describing, he will note
that, both to eyes and ears, the results are very different
from what he observed in the part of the shore where the
cliffs descended into deep water. Against the steep cliffs
there were no combing breakers, and the waves gave forth
only a muffled roar as they struck the steep ; here, however,
they rush up the stony beach in a confused white mass of
commingled water, air, and stones. As the mass strikes the
base of the cliff we hear the roar of the waters, and the keen
ear can detect also the crash of the stones as they strike
against the base of the cliff.

If after the storm has ceased the observer will, at a time
of low tide, visit this strand which he could before see only
from a distance, he will be able to examine the result of the
wave-work. At the base of the cliff where the surofes have
beaten, he will generally find that the rocks have been rudely
cut out by the blows wdiich they have received, so that the
upper part of the steep somewhat overhangs its base ; he may
note where great masses of the stone deprived of support
have slipped away from their bed places, and fallen to the
strand. Some of these have been too large for the waves
to toss about, and they remain as angular fragments some-
w^hat rounded, it may be on the side toward the sea, by the
battering they have received from the pebbles which have been
hurled against them. Other and smaller pieces of the bed-
rocks which have fallen from the overhanging steep have been
worn against the base until they have had their sharp corners
beaten off; yet others have been ground into sj^heres by the
pounding they have received, looking like the stone cannon-
balls which in early times served in siege-guns. Putting
these facts tocrether so that their whole meaning is plain, the

12 SEA AND LAND

student perceives that in a single very great storm the face
of the chff ma)' be worn back to the average distance of some
inches, and that the retreat of the upper part goes on
more steadfastly, but in an inevitable way, as the stones of
the overhanging precipice are loosened by frost and decay.
We can often trace the distance to which the sea has cut
back from tlic j^lace where it was left at the last change in the
level of the land, by the broad rocky shelf leading off to
the edge of the deeper water. Sometimes, as in the coast of
Yorkshire just south of Whitby, this extends as a flat table
of stone at about the level of low tide, to a distance of a mile
or more from the base of the cliffs. On this Yorkshire coast
the cliffs rise in places to the height of six or eight hundred
feet, and are so steep that it is impossible to climb them.
Shipwrecked mariners and persons who have been imprisoned
against their base by the swift rising tide have to be rescued,
if they are saved at all, by means of baskets or ladders
lowered from the summit of the escarpment. A similar,
thouofh less extensive, wave-worn shelf extends alonof the
southern shore of the island of Anticosti, in the Gulf of St.
Lawrence, for the distance of more than one hundred miles.
There as elsewhere ships are apt to strike against the margin
of the wave-shelf and to go to pieces or fall away and sink in
the deep water which borders the ledge. The great distance
to the shore, and the wild tumble of waters which a great
storm produces on the rocky table, make shipwreck in these
conditions peculiarly hopeless for the mariner. Shores of this
nature are always formed where the open sea is bordered by
hard rocks and has remained for a loner creoloofic time at the
same elevation with reference to the assault of the waves.
Where a rocky shore does not exhibit these features we may

^JrT

Point F

MK,,x.^-

The view shows the effect of the sea on a shore composed of stratified rock of moderate hardness which dips
toward the ocean. The harder fragments of the strata forma shingled beach, the fragrments of which in times
of storm are driven against the base of the cliff.

SEA-BENCHES 1 3

be sure that the position of the coast has been recently
changed, that the land has been either lowered or uplifted.

It is a feature deserving attention that these wave-benches
rarely retain on their surfaces any considerable part of the
debris which has been removed from the cliffs : here and
there, scattered over their surfaces, we find bits which have
been fastened in the crevices of the bench, but except where
fresh fragments are supplied by the fall of the masses of rock,
the wide surface is usually as clean as a floor. This feature
is peculiarly well shown on the great Yorkshire wave-terrace,
but is noticeable in all similar structures. It is, in a word,
evident that all the matter torn from the receding clift"s is
in some w-ay removed to a distance from the place where
it falls ; a little consideration and a few observations on the
ground will show us the manner and the measure of its re-
moval. Let us first notice that nearly all the detritus at the
foot of the cliffs is of a pebbly nature ; in general it consists
of quite large stones wdiich have been very much rounded.
It is evident that a large part of the rock which has been
worn from those stones w^as taken away in the form of powder
or sand. We can often, in the case of granite pebbles, see
that the surfaces have been crushed by the blows they have
received. We readily apprehend the fact that in the mill of
the surf at the base of these rocky precipices, the fate of the
rocks is to be ground into a very fine grist, which is easily
borne away to a distance by the strong currents which exist
in times of storm.

If the waves rolled directly in at right angles to the face
of the cliffs, and the wind blew in the same direction, the onh-
current which would exist on the shore would arise from the
reflex of the water and the undertow or current which sets

H SEA AND LAND

out along the bottom of the sea from a beach on to which the
waves are rolHng. These movements of the water can, how-
ever, convey the detritus to only a little distance from the
coast-line. In fact, however, the waves rarely come squarely
down upon the coast, but strike it a little obliquely, and the
wind generally blows in the same direction in which the waves
run. The result is that there is almost always a strong cur-
rent made by the water which the waves heave and that which
the wind blows against the shores, which sets as a river in one
or the oth(;r direction along the coast. Moreover, the tidal
currents, more or less combining with these actions, add to the
stream. Those who are familiar with the shore and have
seen a number of shipwrecks, know that the wreckage and
the bodies of the drowned usually do not come ashore just
abreast of the stranded vessel, but drift in one direction,
often to the distance of miles from the place of the disaster.
Those who have escaped by swimming or floating on spars to
the shore, have had an even more impressive experience with
this swift storm-born river of the coast.

These shore currents are strong enough to sweep away a
part of the detritus formed along the shore ; even materials
as coarse as small pebbles may be carried by it to the deeper
re-entrant angles, where it is accumulated in the beaches
which we are in time to study. The coarser pebbles, which
are too heavy to be borne along by these currents, journey
in the grasp of the waves more slowly, but ever as certainly,
to the beaches. The process by which they travel is this :
Each wave, as it sweej)s up and down the slope next the
cliff, in most cases runs a little obliquely to the face of the
shore, so that with the movement the fragment journeys a
little way from the point where it first became rounded

MARINE INDENTATIONS 15

into a pebble. With each backward mo\e of the rctreatiiT''-
splash it is drawn away from the sea-marg-in, to return with
the next surge. With every successive advance and retreat
it may journey onward for the chstance of a few feet, and
so. wearing at every stroke of the wave, it moves on. A
large part of these rolling- stones wear out before they attain
the greater beaches.

Before we follow the waste from the point where it is
made into pebbles and sand to the part of the shore where
we have characteristic beaches, we must return to the cliff
section to consider many interesting details of the work which
is done there by the waves, tides, and the many other elements
of activity which operate in this singular part of the great
laboratory of nature. All who are familiar with the rock-
bound coasts which are much worn by the waves, have noticed
the fact that the materials are very irregularly eaten away ;
rarely indeed is the escarpment of the cliff anywhere near
a straight line : it is generally deeply indented by sharply
re-entering little bays, and not infrequently presents cavern-
like openings which penetrate a considerable distance into the
clifT. By carefully noticing the conditions exhibited by the
face of the precipice at the level where the waves attack it,
or, if occasion favors, by examining what takes place in times
of storm, we may see how these depressions are formed. At
each of these sea-caves, or other indentations, we generally
find that there is some structural feature which weakens the
rock, so that it is more easily worn out by the waves. Some-
times there are several lines of open joints which part the
rock and enable the surees to lift the frafjments from their
bedding places. Again, where the strata have been turned
on edge, there may be here and there soft beds which yield

1 6 SEA AND LAND

readily to the battering action of the stones which the waves
hurl against them ; or in other cases, the rock may be riven
by dykes and veins, that is, by fissures which have been filled
with la\a, or materials deposited by the action of water.
These deposits may be, indeed most often are, softer than
the stone in which they are laid, and may thus afford weak-
nesses which are searched out by the sea and developed
into rifts and caverns.

As soon as any weak spot on the face of the cliff has
been worked back a little way so that the hard bits of stone
may gather in it, every wave sends these fragments with
energy sufficient to wear the place yet farther back into
the land. The effect of the boundary walls is to keep the
rolling stones in a position to do effective work, and as they
are tossed about by the waves, new bits find their wa)' into
the pocket as fast as old ones are worn out. In this way,
these cutting tools are much better supplied in these recesses
than alone the general face of the cliff, and thus the waves
do more effective work here than elsewhere. As the sea
cuts only for a short distance up on the face of the steep,
the excavation, if the rock be tolerably firm, often has at first
the form of a cavern with a wide portal. As the chamber
widens, this opening commonly becomes unable to support
its roof, which falls into ruins and is ground up by the waves.
The greater part of the permanent caverns which are formed
in this general manner are excavated in trap-dykes. These
sometimes extend back from the sea-face to a distance of
one or two hundred feet or more. Most commonly the floor
of the chamber rises pretty rapidly as we penetrate from the
light of day. In fact, a considerable inclination toward the
water is necessary to keep the mining machinery by which

SHORE CAVES AND ARCHES i;

the excavation is made in good working order; unless the
slope is considerable, the inrushing waves will heap larcre
stones in such (quantities against the inner end of the open-
ing that the surges cannot move the whole mass, and the
bed-rock will be preserved from the blows of the bowlders
which then expend their force on each other.

The result of this steep slope, of the cavern floor is, that
if the sea-cliff be low, the extremity of the cavern finally
attains the surface, and gives the conditions which produce
what in New England is called a '' spouting horn." The
waves, in time of heavy storm, rush up the crevice with a
speed accelerated by the narrowing of the opening in its
inner parts, and send a mass of foam high into the air.
Another condition which produces an interesting group of
spouting caves is found when the cavern has the top of the
portal low, and a considerable space within which has no
communication with the outer air except by the opening into
which the wave sweeps. Rushing into the cavity, the billow
energetically compresses the air until the motion of the water
is arrested ; this air then, expanding, blows the water back-
ward toward the sea, discharging a good part of it like the
smoke from a cannon. This group of caverns is less noted
than the spouting horns, for the reason that, though they
are the more common, it is rarely possible to see them when
the waves are high. It is only when some sharp headland
gives a coign of vantage whence we can look down upon
a long stretch of cliff shore, that these peculiar features of
wave-work can be well observed.

Another group of shore features sufficiently frequent to
deserve notice are the arches and natural bridges. On our
New England shore these features are uncommon, tor the

i8

SEA AND LAND

reason that the rocks on that coast are generally too hard
and too ninch jointed to favor the formation and preserva-
tion of these beautiful structures; but on the shore-lands of
northern Britain and at many points along the Mediterranean
Sea, these singular rock forms abound. A stone soft enough
to be easil)- assailed by tlie waves, yet coherent enough to

^^--fWv '•'♦ly't'.t

W' ■» ' '-' . >■,'
■ ■■■I '>jf|

Natural Bridge, Santa Cruz, California

Remnant of a sea cave ; the inland portion of the arch has fallen in. and the space has been widened by
the waves which roll in beneath ihe bridge. The horizontal strata are of limestone, and are thus easily
dissolved by the waves. The material is much jointed, and so the pebbles on the beach are very small.

hold together where the joints or natural lines of weakness
run in several directions, affords the best conditions for this
kind of marine sculpture.

In the ways above described the sea. searching out the
paths of least resistance, will often produce very beautiful
effects, simulating the noblest results of architecture. On

SJfORE OBELISKS 1 9

the Atlantic coast the best of this chiss of hardy i)roduct of
sea and rocl<; are found in the Gulf of St. Lawrence. •' La
Roche Percee," or the pierced rock, a steep-faced isle near
the mouth of Gaspe Harbor, is perhaps the noblest arch of
the eastern American coast. IVhiny beautiful fantastic arches
and natural tunnels, thouij^h never of a;reat size, are found
along the shores where coral reefs have been lifted a little
way above the sea and exposed to the cutting action of the
waves and the solvent work of the streams which flow frnm
the land. A very beautiful small example of these coral reef
islands is found on the western shore of the northern part
of Biscayne Bay, Fla., where a little river escapes froni the
Everglades through the elevated barrier reef beneath a rock
arch.

Vet another picturesque group of shore structures, suffi-
ciently common to have received a name in the vernacular,
are the steep detached masses of stone known as pulpit rocks.
This name is commonly given to any pinnacled stones parted
from the land by a space of water no wider than could have
been bridged by the voice of a sturdy old-fashioned pound-
text, and which afford a good place for the imagined preacher.
On other shores these islets are often so high that the
conditions would not admit of the term pulpit rock : in such
cases the isolated mass usually receives some other name with
clerical associations. The memories of monks and friars arc
often thus preserved. At only one place on our American
shore do I know of an)- of those natural monuments which
have been associated with the religious orders ; this is the
Old Friar, on the northwestern shore of the beautiful island
of Campobello, a bit of British ground which forms the sea-
ward wall of Eastport Harbor, Me. Even where the pleas-

SEA AND LAND

anter religious analogies do not appear in the names of these
striking pictures of the rocky shores, the solemn spirit of the
seafaring people who have given them their designations,
seems to lead them to choose the appellations from the

"-^eSag^i,

Yesnabie Castle, Orkney

The view shows a p"'>d specimen of a pinnacled rock which has been separated from the cliff by the
long-continued action of waves and ice. It should be noted that all the debris of the rock between the
pinnacle and the shore has been broken up and carried away. The main cliflf as well as the detached mass
shows distinct joints, and also beddinj; planes. The latter exhibit in a remarkable manner the phenomena
of cross bedding. This shows that they were formed upon or near an ancient shoreline.

Other side of their faitli. The Devil and his realm come in
for more than a fair share of the titles l)y wliicli these notable
points are designated. His Majesty's thumb, nose, and other
conspicuous bodily parts, are all commemorated. These men
of the sea appear to have found in their association with it

FULPrr ROCKS 2 1

more solemnizincr influences than come to their brethren of
the inland countr\- who dwell amid milder conditions.

The circumstances which lead to the formation of these
curious detachments of rock from the parent cliff are sub-
stantially as follows : The shore precipice being rent by
numerous crevices or joints, it here and there happens that
these lines of weakness lie in such positions that they in-
tersect each other as the excavation is pushed into the land.
Working, as we have seen the waves do, more efificienti}' in
these recesses than on the smooth cliffs, the intervening mass
of the steep does not recede so rapidl)-, and so is left as an
outlying fragment around which the sea washes at low tide.
The observer will note that in general these pulpit rocks
have a prow-like projection turned toward the shore. This
shape is due to the fact that the joints or other lines along
which the waves work, intersect each other so as to form
the wedge-shaped block which in time becomes detached.
One of the most ordinary causes of the peculiar wearing
which we have to note here arises from the crossing of
dykes, or fissures filled with hardened lava, which, like that
thrown out by volcanoes, was once molten. These dyke-
stones are often composed of very fissured rock which the
waves easily disrupt and bear away : it often happens indeed
that the material resembles a mass of billets of wood heaped
closely together, as in the case of the Giant's Causeway of
northern Ireland. When frost acts with vigor, as it does
along most of the shores where the pulpit-rock structure
occurs, its effect is greath' to aid the surges in rending away
these dyke-stones, while it may have very little influence on
the more compact parts of the cliff.

The action of freezinof and of frozen water along all cliff

2 2 SEA AiYD LAND

shores in high hititudes is very great. In such regions, in-
deed, the coast hne has a very cHfferent aspect from what it
has in latitudes where water always remains tluid. In the
act of freezing, water expands about one-ninth of its mass.
Thus on our northern shores, when the tide recedes for a
considerable distance from the cliffs, the water exposed in

Showinf; the action of tlie sea on massive but somewhat jointed rock, the base of which lies at no great
depth beneath the surface of the sea. The effect of dykes is shown in the deep recesses in the middle
distance. A large fragment which has fallen from the undermined cliff is seen in the foreground.

the crevices often congeals to the distance; of some inches
from the face of the rock. Expanding in the opening, it
produces an effect like the wedges which the quarryman uses
in his art. I{\ery cranny is sought out by the fluid ; many
fissures which are not evident to the eye are thus forced
open, and so the fragments of the stone which the greater

ACTION OF FROST AND JCE 23

storms have rent from the chfl are hrouL^ht to a size where
the lesser waves can toss them about. In this wa\- the
frosted shores are able to present steeper cliffs than those
which are not thus affected, and when all the work has to be
done by the action of the waves with such sliL;ht assistance
as the slow chemical decay of the rocks may afford.

While the expanding- action of the frost is doubtless most
efficient in wearing back tlie face of rock-clifTs, the effect of
the ice which gathers along the shore is probably of vet
more importance. In all times of comparative calm, when
the temperature is low enough rapidly to freeze the water
next the shore, the ice gathers in extensive fields and often
becomes heaped up by the drifting of these areas until it
has a thickness of ten feet or more. When the tide is low
the stones become fixed in the mass, and by the current,
when in this position, are driven as rasping engines against
the base of the cliff. In this way the ice-imprisoned stones
continue the work which the w'inds have begun, and accom-
plish a great deal of abrasion. The most important in-
fluence of the ice-fields, however, is to clear awa\' from the
shore the excess of detritus which the waves may have accu-
mulated there. The reader may often observe points where
this mass of stones is so great that the waves are fended
from the cliff which they are assailing, except where the
tide lifts the surface of the sea to its greatest height. Thus
it may be, for a few hours in the twenty-four, tiiey may
strike against the base of the ocean cliff. A single heavy
and enduring frost ma\- so ImucI this detritus into the ice-
field that the tide, aided by a strong wind from oft the
shore, can drift it all away to be dropped on the bottom of
the deep sea possibly miles froni the coast-line. Nearly all

24 SEA AND LAND

the rocky shore of tlic Athmtic coast, that is as far south
as New \'ork. beyond whicli point to the southward there
are no hard rocks facing the sea, is kept, by this ])ecuHar
action of tlie ice-floes, in good sliape to be assaulted by
the surges. ,

The reahu of nature exhibits a conflict of marvellously
related operations ; scarce any of her agents are able to act
with perfect freedom ; we therefore may not be surprised to
hnd that the work of frost and ice is much qualified by other
actions. We note among these conflicting conditions the
effect of the coast-line sea-weeds on the effect of frost. From
a point a little below high tide to the border of deep water
the rocky shore is usually covered with a dense growth ot
these lowl)- plants. The growth is generally so thick that we
cannot discern an\- part of the rock. When tiie tide has a
great rise and fall, as in the part of the coast al)Out the east-
ern coast of Maine and New Brunswick, a journey along the
shore at low water will give the student one of the most start-
ling impressions which his studies can afford him. The steep
cliffs are hung with a sombre arras of funereal hue made up of
those pendant fronds w^hich cover the rocks to a depth of a
foot or more. Observing these plants when they are floating
in the water, we perceive tliat the)' are buoyed up l)y numer-
ous air-bladders w liich develop in their tangled leaf-like foli-
age. These air-bladders, as well as the air entangled in the
mass of the matted stems which cover the rock, serve in a
measure to keep out th(; frost when the shore is bared at the
retreat of the tiele. 1 he coating acts as an e.xcellent non-
conductor, and by it our shores in high latitudes are in a
large measure protected from the destruction produced by
the expansion of freezing water in the rock crevices.

EFFECTS OF ANIMAL LIFE

25

In a somewhat similar, but, on the whole, less effective
way, protection against frost action is afforded bv the coatincr
of animal life whicli abounds on the rocks of the sea-shore.
The barnacles are the commonest of these dwellers of the
surges which have by various contrivances managed to with-
stand the rude blow of the waves and win a profitable place
amid this field of dangers ; but the numerous shells termed
limpets, and a host of other delicate but exquisitely adjusted
creatures, maintain a foothold there. The fact is that the
fiercely contending waters of a rocky coast-line afford a sin-^u-
larly favorable place for animals to find footl. Every stroke
of the waves rends away bits of sea-weed from the rocks, and
grinds the fragments into bits which may be seized on by the
expectant mouths. The winds drift vast quantities of organic
matter from the deeper sea, which receives like treatment
from the mill of the surf. The result is that the water next
the shore is a rich soup or broth capable of nourishing a vast
amount of animal life. On sandy coasts there is no foothold
for such creatures ; if they were placed there the first wave
would cast them into the mill ; but on the firm-set rocks they
can, by various most ingenious devices, manage to make avail
of this chance for subsistence. One may judge how well-
spread is this table of the shore by taking a glass of water
from the turmoil of the surf : we see that it is crowded with
the debris of animals and plants, all of which is good nutri-
tion for these marine creatures.

To win security against the waves, and thus to be able 10
get safety and feed at this richly furnished board, the shore
animals have for ages been most assiduoush' contriving ways
of securing themselves to the rock. Thus the barnacles,
whose remote ancestors were free-swimmincr creatures some-

2 6 SEA AND LAND

what like the shrinii)s. hcoan by adhering by their head-parts
to lloatiiiL; timber or rocks not much exposed to the waves,
and i^radiially, by one change after another, all apparently
clesignetl to the one end, have come to a nearly perfect recon-
ciliation with the conditions which surround them. Idieir
original forni is no longer recognizable, for they are now
cased in a cone formed of stony plates, and only these parts
fairl\- ancliored to the rock on which they rest. Their net-
like fringe of arms can, whenever for a moment the sea is still,
sweep the water about them ; and when the surge is about to
strike, withdrawing in their shells, which by their shape part
the; wax'e, they arc perfectly protected. So, too, the limpets
have converted the ordinary snail-like shell into a stout buck-
ler, which, when lifted as the w^ave withdraws, admits the sea-
water with its nutriment. As the water closes down on it the
edge of the shield comes upon the surface of the rock, and is
held there b\' the strong muscle which forms a large part of
the animal's body. Animals and plants pay with infinite toil
and pains for their chance to secure food in places where they
arc; fairly protected against organic enemies. The surf line
is by its conditions the best provisioned part of the sea ; it is
free from creatures which can prey upon its inhabitants ; and
to gain a place there, it is w^ortli while for any creature to
make many sacrifices.

While the effect of this organic lift:, l)oth animal and
vecretable, is mainlv protective, b\- fendinir off the frost, and
to a certain extent diminishing chemical decay, there are
certain animals which themselves assail the rocks and, in a
measure, hast(;n their destruction. A whole group of shell-
fish related to our common mytilus, the sea-mussels of the
vernacular, are known as lithodomes or rock-house makers.

RATE OF WEARING OE COASTS 27

They, in some way not yet well known, hut probiil.'K- hy the
rasping action of their shells, cut out little chambers in soft
rock which sometimes attain a depth of several inches.
Where these creatures are numc-rous they hone\coml) the
stone and make it so frail that the waves can break it up.
Certain of our echini, or sea-urchins, have in yet greater
measure this ability to bore into the rocks : they can by the
movement of their frail-looking spines tunnel downward in
materials as hard as orranite ; as their bodies are larger than
the lithodomi, they bore much greater holes. These cham-
bers are often as much as two inches in diameter with a
depth of a foot or more, and afford one of the most remark-
able evidences of the effort which organic forms make to avail
themselves of the profit which the shore conditions afford.
So far as has been observed, this habit of rock-boring on the
part of the sea-urchins is not known among our American
species, though it is common among their kindred ox\ the
shores of Europe.

Hitherto we have been considering the action of the ocean
waves and currents on shores where the harder kinds of rock
meet the sea. Although this is the commoner condition of
the coast in its cliff-bordered sections, there are many steeps
formed by the frailer rocks, such as are afforded by the glacial
deposits of northern countries or the incoherent strata of the
newer geological formations, when the bits of such beds have
not been bound together in the firm way in which we find
them in most old deposits. Along the coast of the Atlantic,
from the mouth of the Hudson to Greenland, particularh" in
the southern portion of this shoreland. are hundreds of miles
of steeps where the sea beats directly against these yielding
materials ; operating on these clifTs the sea-waves dc^ not have

2 8 SEA AND LAXD

much difficulty in breaking down the strata ; at every stroke
they give way along the face of the cliff, and the frail over-
hanging mass quickly drops down to the shore. There are
of course no sea-caverns, no penetrating chasms, or other
irref'ularitics which indicate the slow and difficult siege of the
sea against the stony walls of the hard-rock shores. Such
coast-lines are usually straight and present little that is pictur-
esque, except when, as at Gay Head, Mass., and at Alum Bay,
in the Isle of Wight, tlie soft strata are of varied colors and
perhaps tilted and folded in complicated ways ; in such cases
the cliffs ma)- have a marvellous beauty of hue to redeem
their lack of variety in contour.

The only difficulty the waves have in making a rapid con-
quest of these soft cliffs arises from the task of clearing the
waste accumulation of debris which comes to them from the
yielding rock, k^xccpt where the beds contain large numbers
of great bowlders, as is often the case with glacial deposits,
there is no such resistance; as arises from the need of grinding
up the rock into bits which the currents can carry away, for
it comes to the waves in a comminuted form. The burthen
of this work of destruction falls upon the currents, and the
speed with which the cliff is worn away depends upon their
abilit)' to remove the fallen material from the point where the
waves have delivered it to the sea. It is rare indeed that
these currents can in their work keep pace with that of the
waves : in large measure this debris remains just to the sea-
ward of the shore-line, and is only slowly removed to a short
distance, to the neighboring beaches or to the deeper parts
of the water: in this position next the shore, it so far shallows
the water that all the greater waves break at a distance from
the face of the cliff, and only the lighter splash waves attain

EFFECTS OF MARINE CURRENTS 29

its base. Gradually the undertow of the breaker dra<''s the
debris to seaward, and the varying- currents produced by
the tides and storms remove it from the j)recipitous shores
to the pocket beaches, where, as we shall see hereafter, it is
ground to povv'der. The result of these causes is one of the
many beautiful adjustments of activities which the study of the
shore brings to our attention. The waves excavate only what
the currents can take away ; if at any time the\' cut out more
debris than is removed, their energy is diminished by the
shoaling of the water next the shelf ; if the currents clear
away more of the waste, the surges are for a time free to
act and deliver more sand and g^ravel to the sea. Thus the
processes of excavation and of carriage become accurately
balanced with each other.

It is on these soft-rock shores, where strong currents oper-
ate, that we find the swiftest conquests of the sea over the'
land. On the hard-rock cliffs the erosion rarely forces the
cliffs inward at a o-reater average rate than a fraction of an
inch a year, while on gravelly or sandy shores the rate often
exceeds a yard per annum. Thus, on the coast of Cape Cod,
near Chatham, the shore is retreatino- into the land at the rate
of at least a foot each year. On the southern shore of Martha's
Vineyard, the recession of cliffs which are about one hundred
feet high, has been, on an average of forty years, about three
feet, and on the southern face of Nantucket, near Surfside,
the retreat of the escarpment has been as much as six feet,
in a single year. Although composed of somewhat harder
materials, the island of Heligoland, in the north of German}-,
near the mouth of the Elbe, exhibits a similarly rapid process
of destruction ; though within the historic period it was a
tolerably extensive land, it has shrunk before the surges of the

30 SEA AND LAND

sea until it has an area of only one or two square miles; it
seems doomed to complete (;ffaccment within another century.
So, too, the Goodwin Sands, now only a dangerous shoal at the
eastern end of the English Channel, probably was in the early
Christian centuries an island of soft rock which the sea wore
away until its waves closed o\-er the; place where; it had been.
If the . historic period of North America were as great as
that of Europe, we should doubtless have many instances of
such vanished lands. As it is, we can see that many capes
and isles on the northeastern shore of this continent are
impending on destruction. No Man's Land, a lonely island
of glacial drift on the Massachusetts shore, south of Martha's
Vineyard, is rapidly wasting before the attack of the stormy
sea to which it is exposed ; it seems likely that in less than a
century this shred of land will have disappeared. The same
is the case with Sable Island, near the entrance to the Gulf
of St. Lawrence, where the remnant of a mass of debris left
1)\- the last glacial period, probabl)- a portion of a frontal
moraine, is raj^idly giN'ing way before the waves and currents
which are carrying its sands to the neighboring deep sea. In
fact, all such islands are liable to very rapid destruction, for
the reason that the waves find less difficulty in removing the
debris than they do on the continental shores. Around an
island of inconsiderable size the debris is readily borne away
b\- the strong currents, and is quickl)- cast into deep water,
so that it does not, for any considerable time, obstruct the
work of the waves. On the long cf)ntinental strands, how-
ever, the waste from yielding cliffs does not so easily escape
from the shore ; the greater part of it is forced to creep
along the coastdine until it passes from the district of cliffs,
and finds its way into the pocket beaches.

ACTION OF TJfE TIDES 3 1

Before leaving the zone of the coast where the sea is work-
ino- the ch'ff backward into kind, we must not fail to consider
the action of the tides on such a shore. \W; have already
noted some incidental effects of these singular movements
of the ocean waters ; we must now^ look upon their larger
manifestations, and consider how they affect the processes of
the shore. As is w^ell known to the reader, the tidal move-
ment is due to the attraction of the sun and moon ujjon the
mass of the earth ; in fact, every star in space pulls upon
the earth ; but the moon, because of its nearness, and the sun.
because of its magnitude, and as compared to the fixed stars
its relative propinquity to our sphere, pull with enough (energy
to raise the sea above its prevailing level. The attractions of
these bodies tend to divert the wdiole mass of the earth, and if
it were completely fluid in its depths, as geologists once sup-
posed, the sea and the land would alike rise in a low tidal
wave, and we should perhaps notice no movement of the
oceans. Because of certain features in this drawing action
of sun and moon, there are two tides corresponding to each of
the attracting bodies. If the earth were uniformly covered
by a very deep ocean, one of these tides would be approxi-
mately under the sun or satellite, and the other on the
opposite side of the earth. Owing, however, to the irregular
form of the lands, these tidal weaves have to chase around the
earth, rushing up the narrow spaces between the lands, and so
fall behind their due jilace. Moreover, because the solar and
lunar tides are sometimes in the same place and sometimes
far apart from each other, these two waves now and then con-
join their volume and again oppose each other. The result
is that the tides, though they have a certain regularity, are,
as regards their rise and fall, rather irregular phenomena.

32 SEA AXD LAND

l-urthcrmore, they are more or less affected by the action
of the wind ; a heavy storm bU)wing off the shore will cause
the tide to retreat farther and advance less far than when the
wind is l)lo\viniX violently toward the coast. These varying
conditions much affect the action of the tidal waves on most
coast-lines.

The form of every coast to which the tides find access very
greatly affects the way in which they operate upon it. In the
open sea the rise and fall of the tide is slight, probably
not exceeding a foot or fifteen inches. If the shores of the
continents were straight shore walls parallel to each other,
with the sea very deep at their bases, the tidal swing would
l)e no o-reater than it is in the middle of the great Southern
Ocean ; but, as we know, the coast abounds in re-entrant and
salient angles, deep bays, and strong promontories, and in this
complication of paths which they open to the waters the tide
is curiously affected. Wherever an ocean or bay opens a
wide mouth to the entering tide and narrows its shores at the
head of the re-entrant, the swift-running broad wave moving
inward, usually at the rate of several hundred miles an hour,
is compressed in the narrowing channel and forced to rise to
a greater height than in the open sea. Thus in the North
Atlantic, the shores of which converge toward the North
Pole, the tide rolling up from the southern sea is constrained
to rise to several times the height it had in the more open
water. So, too, wdien a bay is more broad-mouthed and
tapers to a sharp head, as is the case in the Bay of Fundy or
the mouth of the Severn, the tidal wave is yet further con-
strained and forced up, it may be, to an elevation of fifty feet
or more above tlie lowest level of the sea. Every considerable
variation in the form of the shore has its effect upon the rise

VARIED EFFECTS OF TIDES

IZ

of the tide. Thus in passing north from Cape Florida to
the St. Lawrence, the well-trained student of the tides would
be able to determine in a general way the shape of the shore
by the rise and fall of the sea.

It is easy to conceive how the energy of the tidal currents

^^:^.

Seashore View

Showing the position of the mantle of sea-weed which protects the rocks from the action of frost and. in
a measure, from the assaults of the waves. Note that the smaller fragments which may be tossed about
are destitute of the covering. The lower portion of the stone in the foreground against which the boy is
leaning shows the scouring action of the waves which they effect by means of the sand which they impel

depends, in the most intimate way, upon the altitude the
wave attains in tlie diurnal movement. When, as on
the coast of Florida, the rise and fall is probabl}- not on the
average much more than one foot, we may have but feeble
movements created by the tidal swing ; in the region about
the Bay of Fundy, where the rise is fifty feet or more,

34 SEA AND LAND

the streams have a swiftness and energy comparable to those
exhibited by the greater cataracts. The capacity of the tidal
currents, like that of all streams, their power to scour and
convey sediments, depends immediately on the speed with
which they move. When, as on the eastern coast of Maine,
they often flow at the rate of six or eight miles an hour,
a speed nowhere attained by the waters of the Mississippi,
they strip all the shores on which they impinge of all their
fine detritus which may have accumulated there, and thus
expose the rock to the effective action of the waves.

For the reason that these tidal currents are most energetic
when they are confined as in a wedge-shaped bay, they exert
their maximum influence not on the open coast, but in the
recesses of the shore. The waves of the ocean tend to force
the detritus the)- have torn from the exposed part of the
shore into every neighboring bay, thus in time destroying
all the inlets and bringing the shore to a uniformity of
outline; but where the sun and moon pull the waters about
and send them whirling into the bays and harbors, the cur-
rents which are thereby produced scour out the sand, clay,
and pebbles which the waves have imported into these
recesses and remove them again into the o\iQ.\'\ sea.

Along every continental shore, and often far into the
interior of these great land masses, we may discern indications
that the work which we now observe to be going on upon
the coast-line has at various times been effected at levels
far above the present plane of action. These ancient sea
margins, as they are termed, have been noted by observers
since the early part of this century. It is only, however,
within the last fifty years that geologists have begun to
attend to this class of phenomena. A careful study of such

OLD SEA MARGINS 35

indications of ocean work at higher level is, indeed, about
the last distinct step in geological inquiry.

At many points 'where the elevation of the land has
recently occurred, as it often has in some slight measure
since the beginning of recorded history, it is very easy to
note the traces indicating the recent presence of the sea.
There is the cliff, against which the waves broke, often with
its accompanying caves, and chasms, and the beach slope
frequently retains the semblance of its original character.
But even in these monuments of sea-action, which may not
be older than the Pyramids, the student observes that the
change-bringing forces have often worked with such efficiency
as in good part to destroy, or at least to confuse, the evidence.
A talus has generally formed at the foot of the steep, whicli,
with the falling in of the cavern roofs and the chasm
sides, has greatly modified the form of the strata. At the
same time, the streams cutting through the beach line, have
washed the friable materials to and fro so that the original
regularity of the feature has been in good part lost. Observ-
ing this rapid destruction of the marine monuments which are
so conspicuously in evidence along the existing shore line, the
student is prepared to find the indices of higher, and, therefore,
more ancient shores become progressively and rapid]\- less
clear as he ascends above the existing coast line. His antici-
pations will be more than realized, for he will find that the
task of tracing sea margins of considerable elevation is one of
surprising difficulties. He has, in fact, to trust rather to bits
of evidence than to a massive presentation of the truth. He
will not find the old borders of the land marked as he might
expect them to be, by long straight benches, but rather by
fragments of the ancient shelves with here and there, perhaps,

36 SEA AND LAND

a ruined cave or chasm, or a few rolled pebbles, which have
been covered, and thus protected from cleca)'. b)- the talus of
angular fragments, which weathering action has drawn down
the cliffs. Here and there he may tind his evidence reduced
to that which is afforded by the existence of solitary steeps,
which were evidently islands in the open sea. Thus, on the
Piedmont IMain, to the east of the I^lue Ridge in Virginia and
ihe Carolinas, there are occasional detached elevations, rising
as hills or mountains from the level country, the origin of
which, on account of the steep faces of these elevations and
the nature of the accumulations at their base, we have to
believe to have been due to the fact that the\' were, in no
very ancient da)', islands lying off a shore which lay to the
westward. It may be noted in passing, that such detached
islands are often saved from destruction by the fact that the
waves and currents keep their bases free of pebbles and thus
remove the agents which, as we have seen, serve to batter
the bases of the cliffs.

It is easy to see that the effacement of the ancient
indications of marine work depends upon the constant down-
wearing of the land, which is brought about by the agency
of sub-aerial decay, by the action of frost, and by the move-
ments of water in streams or glaciers. Although the amount
of this down-wearing is variable, it probably amounts to an
average of a foot in from three to six thousand years, so that
in a million years, not a long term in the geological sense, the
lantl surface descends some hundrc^d feet, or enough to take
away all the indices of an ordinary shore life. The fact that
such an escarpment hatl an original bold relief, would be
likely to cause the process of decay along its line to be much
accelerated. We, therefore, cannot expect this kind of record

JOINT WORK OF AIR AND SEA 2<J

of the land outlines of ancient days to be traceable in the
remote past.

There is, however, a way in which sea shores, even those
of very ancient times, may be preserved and revealed to our
time. This occurs, where, in place of the land rising- in the
continental oscillations, it sinks, so that the shore line becomes
submerged. In this case, when the indices of the submerged
shore are not destroyed as they pass through the mill of the
surf, they may be buried beneath stratified deposits, which
may accumulate to any thickness. When the region is again
elevated and the rocks brought above sea level, erosion may
disclose to us the marks of an old shore line preserved in an
excellent shape for ready determination.

It is well for tlie student to associate in his understanding
the joint work of marine and atmospheric agents in wearing
away the land. He will thus see, in his mind's eye, the two
great agents of degradation in their cooperative work, and he
will be prepared to interpret some of the most interesting
features which the continents exhibit.

^.r::^JS

The Cvens Mount Desert, Maine

431753

SEA-BEACHES

Various Divisions of Shore-Line. — Synimeiry of Sea-Beaches. — Action of Surf. — Rate of
Wear of Detritus. — Action of Coast Currents. — Sand Dunes. — rociiet-Beaches. —
Action of Sea-Weeds. — Straight Beaches. — Continental Shelf. — Action of Tides and
Waves. — Variations in Level of Shores. — Formation of Lagoons. — Mfinne Marshes :
Their Agricultural Value. — Endurance of Sand : Effect in Protecting the Continents.

There arc two great divisions of the shore-line which
even the cursory observer quickly learns to recognize ; these
are the cliffs and the beaches. In the cliff section he easily
perceives that the sea is gaining" on the land. The condi-
tions under which the ocean extends its empire afford, as we
have already seen, a beautiful subject for inquiry. We have
now to turn to the parts of the coast where the sea spends
its energies, not on rocky steeps, but on the softer — yet really
more resisting— barriers of sand. Below the frowning walls,
formed where the suro;es are effectivelv assallinof the land,
w^e find generally a wide slope where the breakers are con-
tinually at work grintling the stone they have rent from the
cliff into small ])its. Usually, however, this incline is made
up of large, 1)Owlder-like masses, w^ith a few small pebbles
and a little sand packed into their interstices. We readily
see that the greater part of the Unv, stuff into which the v/aste
from the cliff is ground journeys with the currents, which the
storms and tides produce, to some point where it is built into
sand or pebble beaches. In this migration the pebbles move
along next the shore, in the shallow water where the waves

DIVISIONS OF SIIORE-IINE

39

and currents are strongest, while the sand often travels in
the deeper water at some distance from the shore-line. They
both commonly arrive in the end at some characteristic beach
where they enter on another chapter in their singular history.
In beginning our study of beaches, it will be well to
choose some part of the shore where the cliff district has an

f

The Isles of the Cyclops, near Catania, Sicily

Showing the extremity ot a lava stream much carved by the sea. The bowlders in the foreground and
middle distance constitute a natural sand factory.

irregular front, exposing bold headlands to the free assault
of the waves, while near by there are embayed recesses into
which the detritus, in the form of pebbles, can be impounded,
like the balls in the pockets of the old-fashioned billiard table.
An ideal e.xhibition of these conditions is given in the illus-
trations of this chapter. It will be seen that the waves and

40 :SEA AND LAND

shore currents necessarily import the larger part of the debris
they rend from the promontories into the recesses of these
bays. Places where a study of the results of these conditions
mav be made can be lound along almost any mile of -shore,
from Xew York city to (Greenland, where liard rocks face
the sea. It is rare, indeed, on ever)' clifi shore that we have
to search for as much as five miles along- the coast without
finding one of these pocketdjeaches, whereto the rocky mat-
ter from the neighboring precipices swifth' j()urne\s to
undergo the last stage of its destruction.

To the naturalist's eye the most striking feature of the
pebble beaches is the symmetry of their form. This is so
characteristic that every one, however little trained in the
methods of interrogating nature, is sure to observe it, pro-
vided he follows the path whicli leads 1dm from the rude
clift shore to these more gracious outlines of the beaches.
On die steeps, where the sea is eating into the land, all the
outlines are ragged ; the scenery has the hard, irregular qual-
ity wliich belongs to all fields where the destructive influences
of nature; prepond(;rate o\er the forces which build up or
renew. On the; true beaches the gentle and harmonious
curves attest the constructive order of the actions. They
have the peculiar grace which marks all things which grow,
their form is truly vital. We note the delicate finish of the
curve of the line of contact between the water and the land,
and the equrd symmetr\' of that which extends from deep
water to the crest whereon stands the sea-wall and perhaps
the attendant dunes. However much the e)-e and the mind
may for a time enjoy the stern scenery of a rockdj>ound coast,
we turn with abiding satisfaction to the quiet beauty of these
more perfectly organized shores. They are like calm weather

SYMMETRY OF SEA-BEACHES 4 1

after a storm, which, however well we may enjoy the tempest,
is the more grateful to our senses. We may visit the rude
scenes of the besieged clifTs with the grim pleasure with
which one may behold a battle-field, but that is not the
place where one would dwell if he seeks harmonies and
the peace which comes with them. If one would al)ide by the
sea, it is better to seek a home by the beaches.

At first sight even the most beautiful beach is likely to
seem, to those who are uneducated in the study of the shore,
to be rather monotonous and devoid of interesting features.
The smooth outlines of the scene suggest in themselves a
simplicity in the conditions which, we shall hnd, does not
exist. In fact, these even shores present a greater array of
actions, and afford the student a larger field of profitable
inquiry, than he has found in the apparently more varied
rock coast. It is because all the conditions of the eeoloeic
lite which lead to their growth and maintenance are per-
fectly adjusted to each other, that the w^ell-organized beaches
appear so simple. They are like the living forms of animals
and plants, where the shapely exterior hides the complicated
anatomy and the marvellously delicate adjustment of varying
and interesting functions, so that the creature seems to need
no explanation. This is not a vain analogy, for, as we quickly
see when we make a detailed study of any beach, it is in
many ways a highly organized structure.

The best way to begin the study of these portions of the
strand is to select some small and pebbly pocket-beach near
a cliff section whence comes a plentiful supply of debris worn
from the bed-rocks by the action of the waves. At the horn
or extremity of the beach, next these cliffs, we may often
find bowlders roughly rounded by the rude mill of the surf

42 SEA AND LAND

to the spherical form, and of g'rcat size ; they are sometimes
two or tliree feet in chameter. We can, in times of heavy
storm, see that the surges roll these masses over and against
each other, and we note their constant wearing as they jour-
ney onward, not only in the sound of their clashing, but also
in the steady diminution in their size as they go farther away
from their place of origin. Near the points of the crescent
shore these rolling stones are more exposed to the action of
the waves than they are as they slowly creep down into the
curved bay, so that, notwithstanding their weight, they are
o-round against each other and consequently diminished in
bulk. As we follow them toward the centre of the crescent,
we observe that they constantly become smaller, until, a mile
or two away from the point where they escape from the cliff
section, they may be no larger than billiard-balls. If the
beach be very extended, the central portion of its front may
be composed of fine sand, the pebbles having been ground
to dust in the powerful attrition of the waves. We thus
arrive at the first and most important point in the history of
these pocket-beaches, and see that they are mills which serve
to grind up the rocky matter torn from the cliffs, and that
they bring it to the finely divided state in which it can easily
be taken by the marine currents to great distances. We
must now proceed to see the details of this admirable mechan-
ism of the rock-grinding mill.

When the ocean is in its ordinary summer state of still-
ness, with only the light pulsation which sends a few times a
minute a little breaker against the beach, we find that only
the sand and smaller pebbles are stirred by the motion of the
water; but now and then, even in this peaceful time of the
year, storms send in more powerful surges. These may come

ACTION OF THE SURF 43

from a wind which blows directly upon the shore, or from
some storm in the open sea so far away that the ground-swell
alone attests its passage over the waters. These waves may
roll upon the beach with a height of from five to ten feet,
and at the rate of from four to six strokes a minute, each
blow applying to the shore-line in a mile of its length energy
which is to be measured by thousands of horse-power. These
surges break or overturn, not at the very shore-line, but at a
distance from the dry sands determined b}' their altitude and
the shape of the beach. On ordinary fronts of sand they
tumble into surf-waves, a hundred yards or more from the
point where we may stand dry-shod, and on many parts of
the coast they break at a mile or more from the water-line.
Within the outer line of surf the waves gather again and
again to form lesser breakers, so that there is a wide belt of
tumbling water extending, it may be, for hundreds of miles
along the coast.

Next the shore this turmoil of the sea is marked by fierce
splashings arising from the overturning waves ; the water
rushes up and down the steeper slope of the inner part of
the beach, sweeping the coarse sand and pebbles before it in
each movement, it may be for sixty feet or more. If the
pebbles are abundant, we can easily hear the dull, grating
sound arising from the friction of the stones against each
other as they are driven to and fro. Standing with bared
feet in this splash, we easil)- note the fact that it is not only
the surface of the beach which is moved, but the mass, to the
depth of perhaps a foot or more, partakes of the movement
which the surging waters impress upon it. The stones are
orround against each other, and the sand amono- them pulver-
ized as if between mill-stones. The result is that at each

44 SEA AXn LAXD

swaying of the mass a considerable amount of rocky matter
is made into fine mud. whicii is free to drift away in the whirl-
in;^ waters. W'c may often see that the sea-water is per-
ceptibly muddied by this action for a considerable distance
from the shore, a wide frinq^e of the sea attesting by its tur-
bidity'tlie work of this mill. If the student be an expert surf-
bather, he may venture beyond the shore belt to the point
where the waves topple over in the breakers. There he will
discover another mode of action of the waves, which differs
in many regards from that brought about by the swayings
against the shore. When the wave topples over, the upper
part of its mass falls down, it may be from the height of ten
feet, upon the bottom, on which it strikes with great energy.
If this floor of the sea be tine sand, the effect of the blow
is slight, and the particles are little disturbed, being trodden
to a Arm mass by the long-continued tramping of the surges.
If, however, the bottom be composed of pebbles, with their
faces made slippery from the water or the gelatinous ooze of
the sea-floor, they fly about when the falling wave strikes
them, giving forth a hoarse roar from their friction against
each other. Sometimes we may observe how these swift-
moving stones striking against a flrm-set bowlder skij) into
the air like a ball froni a bowler's hand. So we see that
there are two kinds of rock-grinding done on the beach — that
which is accomplished next the land by the swinging move-
ment of the waves and that which is effected by the breakers.
The rate at which the pebbles are reduced to sand and
mud by these processes of the beach varies, of course, with
the hardness of the materials and the energy with which the
waves assail them. We may judge the speed of this work
not only by the rapid reduction in the size of the pebbles as

RATE OF WEARIXG OF JJJ/j j<j j L .-^

45

they pursue their devious way down the coast, but bv many
other even more instructive examples of this work. It not
infrequently happens that vessels loaded with brick, coal, iron
ores, and other hard substances are cast away on the exposed
beaches of the Atlantic Ocean, and their cargoes delivered to
the shore waves. In a few months we find the waste scat-

Eastern Side of Cape Ann, Massacnuseits

Bowlder beach of the rudest type, showing large stones plucked from the neighboring coas-.
beaten against each other when heavy surges roll against the shore.

tered, it may be for miles, in the direction in which the
materials of the beach are moving. In some cases hard-burned
brick or anthracite coal will journey on a sand beach for a
distance of five miles before the bits are entirely worn out,
and they may endure for a year before they are quite ground
to dust. If the shore be pebbly and well exposed to the sea,
all the fragments, save those which find protection in some

46 SEA AND LAND

sheltered place, will commonly be destroyed within a mile of
the point where they were first exposed to the surf action.
On the eastern face of Cape Ann, where exceedingly hard
fragments of granite — the waste rock from the quarries —
have been cast into the sea, it requires several years for a
frae-ment the size of a nail-keir to be rounded into the sphe-
roidal form so characteristic of marine erosion. Slow as this
wearing may seem, we must remember that, measured against
the geologic ages, it is indeed exceedingly swift.

It will readily be seen that a portion of the beach, that
which is above the limit of the sea except in times of high
tide and great storms, rises more steeply than the portion
which is below the sweep of the water; in fact, the line from
the shallow water to the crest of the beach is like one-half
of a catenary curve, or the shape in which a chain or rope
hanfi-s when it is suspended between two elevated points.
Such a curve is, as we easily recall, nearly Hat in the middle
and rises steeply near the support. This shapely form is due
to the action of the waves, which continually thrust or heave
the sand and gra\-cl against the shore. The effect of this
urgence is modified by the continued reflux of the waves ; in
their backward movement they carr>- away the greater part
of what the)- have brought in. In a short time an equation
is determined between the incoming and outgoing of the
detritus, and so the sea-shores of all the world establish the
same rate of slope for like conditions. In times of storm
the slope may. for a little while, be brought to a greater
declivity, but the weaves, moderating in violence, proceed to
drag away a part of the detritus and soon restore the
declivity to its normal condition.

When a storm has blown obliquely upon the shore, so that

ACTION OF COAST CURRENTS 47

it has produced a stroni^r current in one direction, the heacli
in its u[)per parts will rapidly waste away, but a change of
current will quickly restore the usual outline. On some
coasts, however, there is a steady current in one direction,
so that the beach would quickly disappear were it not for the
constant accession of sands which march down the coast or
are brought in from the deeper sea. Thus on the southern
coast of the United States from Cape Hatteras to Cape
Florida, particularly along the shore of the Florida peninsula,
the sands are journeying toward the south under the influ-
ence of the prevailing current, which sets in that direction on
the landward side of the Gulf Stream. From Cape Canav-
eral toward the coral-reef section of this shore, the coast
current is so strong that the beach is much scoured away,
and has a slope which is often fifteen degrees of declivity
between high and low tide mark. The unhappy footman
who has to toil along this desert strip of sand finds it almost
impossible to make a day's journey of twenty miles without
exhaustion. The orrains of ever-shiftino- sand are so inco-
herent that the foot sinks deep into the mass, and the unequal
position of the feet racks the walker in a painful way. I
remember a walk of sixty miles along this shore, from Bis-
cayne Bay to Jupiter Inlet, as among the most trying incidents
in my field experience. The extended sand shores differ in
certain Important ways from the smaller pocket-beaches, which
still deserve our attention. Along the water-washed portion
of these strands we find that the beach suddenly changes its
character. Below the level of high tide it is exceedingly
shapely; all of its contours are very regular, and present little
else than a gentle, uniform slope toward the waves which
give it form. Where the waves do not act. the contours at

48 SEA AND LAND

once become riKle, and, when first and imperfectly seen,
apparently shapeless.

We commonly find on pebbly beaches a rude wall of
water-worn stones, rising", it may be, ten feet or more above
hii^di tide. This wall sweeps around the crescent of the true
beach, fojlowinj^; its course from one end to the other, looking
often like an artificial rampart. Now and then it is deeply
breached or sometimes for a considerable distance swept away.
The oriein of this beach-wall is simple : in times of unusually
heavy storms blowinc^ directly upon the coast, especially when
they fall in the season of the hiohest tides, the waves tres-
pass upon the upper part of the shore and fling a great
(luantity of pebbles before their swift-moving front ; wdien
the on-rushing surge conveys these pebbles beyond the sea-
ward face of the beach to the crest of its wall, they fall upon
the more level summit, and the retreating waters cannot drag
them back into the sea. When the ocean is in its stormiest
condition, the pebbles may be tossed over the crest of the
embankment and fall down its landward slope. If the seas
struck the shore in a uniform manner, this wall would have
a perfectly regular height ; but now and then, in great tem-
pests, there comes a vast wave, which has gathered unto itself
the strength of several breakers, and which may assail a part
of the sea-wall with such fur\', that it breaks it away and
sends the debris into a steej), delta-like fan out upon the low-
land Ixhind the elevation. Subsequent waves, which may be
of less volume, pour through and deepen the breach, so that
the wall acquires its crenellated or battlemented aspect. The
open structure of the pebbly mass allows the swash of the
wave to penetrate downward and escape slowly to the sea,
so that the retiring water is diminished in volume, and its

ORIGIN OF SAND DUNES

49

ability to drag the stones backward down the slope is less
than its forward thrusting power ; thus the pebbl)' sea-walls
are much steeper-faced than those of sand.

The wave-made embankments on the sandy beaches differ
in their form and in the conditions of their construction
from those which arc made up of pebbles. The sand,

Carmel Beach, California

Showing extensive sand-flat with slight dunes above the water level. The foreground also shows traces
of blown sand partly imprisoned by herbage.

owing to the fineness of its grains, is easily blown about by
the wind. When the tide retires, a broad expanse of this
material is left for some hours exposed to the sun. The sur-
face dries, and the gales from the sea sweep the particles up
the slope until they arrive at the crest-wall ; here they are
often caught in the tangle of beach grasses, and other plants
4

=>0 SEA AND LAND

which flourish in arenaceous soils, and in the close-set leaves
and stems, and are protected from the currents of air.
Where the movement of sand is most rapid, it may bury
these plants out of si^ht, but most of them are tolerant of
this submersion and cjuickly grow upward and make a new
entanglement for the nioving grains. In this manner the
crest of the beach grows upward in an irregular manner,
its crown bearing a range of hummocky sand-hills which
often rise fifty feet or more above their base, and in
favorable situations may attain a height of two hundred
feet.

The dunes, as they are termed, are less abundant on the
l^eaches of the Atlantic coast than in many other parts of
the seaboard, for the reason that the prevailing winds of that
region are froni the west ; and the sand swept up from the
sea-marein is, to a crreat extent, carried back h\ the off-shore
winds ; even the scanty dunes of our shore w^ould hardly
exist were it not for the fact that the vegetation on the land
side of the elevations is generally quite luxuriant and holds
the sand which has been brought to its protection from the
shore. The most characteristic dunes of our sea-coast are
found where there is a stretch of shore which, by some irregu-
larity of the coast, is exposed to the sweep of the western
winds. Thus the seaward extremity of Cape Cod is largely
made up of windd^lown sands. So, too, the long stretch of
shore tending to the southeastward from Portsmouth, N. H.,
to the mouth of the Annisquam tidal river in Massachusetts,
yields to the northwest winds a good deal of sand, which
is carried down to the great dunes of the Essex district on
the mainland. "The Banks" of North Carolina, fifteen to
twenty-five miles distant from the mainland enclosing the

^r:»_ " 7T Jftiii

^!

■^h

i^y- , i

^ i.

%

MOVEMENTS OE SAND DUNES 51

waters of Pamlico Sound, afford another excclicnt example
of such dunes.

In this country the greatest dune districts are found about
the southern end of Lake Michigan, where an abundance of
sand of glacial origin is swept upon the shores in times of
storm, and is borne away by the w^inds. Ikit if the student
of these features would find them at their best he should visit
the dunes of eastern England or those about the head of the
Bay of Biscay, where these masses of sand not only grow to
a great height, but frequently separate themselves from the
shore and slowly march as moving hills to great distances
inland. Thus in Britain one of these dunes in the last cen-
tury invaded the village of Eccles, and buried the dw^ellings
and the parish church so that even the top of the spire was
hidden. After a number of years the summit of the church
began to reappear on the leeward side of the hill, and in time
the remote descendants of the dispossessed people ma)- be
restored to their heritage. In the Biscayan lands the incur-
sions of the sand have proved so menacing to the fertile
fields of that country that the government has expended large
sums of money in order to root the invading dunes to their
places. The spectacle of these wandering masses of the fri-
able portions of the earth's crust shows us how^ great is the
effect of the plants in restraining the action of the winds.
Where, as in the great deserts, the soil is too arid to main-
tain vegetation, the finely divided portions of the rock, which
the plants convert into soil, are at the mercy of the air, and
are set upon endless marches, which often alter the neigh-
boring fertile districts to the state of the Sahara.

The way in which these hills of sand march is ver\- simple.
On the windward side the hill is scoured away by the blasts.

52 SEA AND LAND

which are the stron^;er because of the exposed position of
the slope. The sand whirls over the crest and falls into the
lea, where it is caught and fixed by the vegetation so that the
less powerful winds which assail it on that side cannot stir it
from its position. This process repeated may advance the
dune into the interior at the rate of several feet a year. For
a time it receives constant accretions of material from the
neighboring shore ; but as it departs from the coast these
contributions become less in quantity ; generally another dune
forms behind the first of the train, and absorbs all the sand
which is blown from the beach. As the moving mass passes
into the interior it usually becomes ever more and more
coated by vegetation, for the reason that it comes into a
region where a greater variety of plants can dwell than upon
the shore-lands ; moreover the sand becomes decayed, tends
to cement into a firmer shape, and provides more nutrition
for the growth of vegetation. Thus in time the dune is
brouirht into the state of an immovable hill, becomes orass
or forest clad, and only rarely and to the trained eye reveals
its curious origin.

On the small islands which frequently border the shores
of the great lands in the manner in which they are distributed
alono" the northern coast of the United States, beaches are
rare. Only here and there do we find points where the softer
character of the shore materials has permitted the sea to
form an indentation into wliich the waste from the neighbor-
ing shores is driven by the waves, and there retained until
the movement impressed on the fragments by the surges has
ground them to powder, which the undertow and other cur-
rents can carry out to sea. The result is, that the greater
part of the waste from island shores is likely to be carried

NAl^URE OF POCKET-BEACHES

53

across the intervening shallow sea to the niari^in of the main-
land. On the more extended coasts of such mainlands, these
indentations which catch the waste of the shores, and which
we may for convenience term pocket-beaches, are, wherever
the rocks are of varied hardness, of very common occurrence.

Eastern Shore of Cape Ann
Showing small re-entrant with pocket-beach. Thatcher's Island in the distance.

Along the rocky shore of New England they are to be num-
bered by the thousand.

If, after studying the phenomena exhibited by any charac-
teristic pocket-beach, the student will compare the forms of
a number of them, he will see that the> — while agreeing in
all the general features which we have already considered —
differ much in certain important details of lorni. The most
strikine variation is in the measure of the incurve which

54 SEA AND LAND

they present to the sea. Most commonly they are crescentic
in their outhne, hke the slenderest sickle of the new moon,
but they vary from this deeply re-entrant form through all
the stages in which we ma)' trace the filling of the lunar cup
until there is scarce a perceptible hollow left. When the
beach is newly formed it is always much curved ; if it has lost
this shape we can easily note the fact that it is b)' the pro-
gressive heaping up of the pebbles or sand in the central part
of the bay. If the supply of debris which is imported into
the beach is greater than the wave action which there takes
place can reduce to fine dust to be carried away by the
currents, then the basin fills and the shore line becomes
straighten If the waves at any time grind up more detritus
than is supplied to them, the shore is worn backward into the
land, and the beach may, if the process continue long enough,
utterly disappear. There is, however, as is the case in so
many natural forces, a beautiful |)rinciple of compensation
by which the several actions counterbalance or check each
other. Thus, when a beach is ill supplied with detritus, and
its curve becomes deeper, the waves which roll into it have
a longer journey over the shallow bottoni, are diminished in
energy, and are less effective in their work. On the other
hand, when the beach advances on the sea for any consider-
able distance the waves encounter less friction over the shal-
lows and o[>eratc with far more power. In this manner the
ill-fed beaches soon arrange their form so as to grind up less
rocky matter, and those which are gorged with pebbles con-
simie it more rapidly.

There are many other noteworthy features in the pebbly
beaches, only a few of which can be considered in this essay,
for they are matters of detail, and, however interesting, have

ACTION OF SEA-WEEDS 55

little bearini^ on the large problems we have to consider.
We have already remarked the fact that the supply of these
mills in which pebbles are ground to mud comes in the main
from the neighboring cliffs. On the north Atlantic coast,
and generally in all glaciated districts, a large part of these
pebbles are from points where the sea is assailing the easily
worn deposits of bowlders which were so plentifully accumu-
lated in the ice-time. Besides these waste materials on the
land, there is a large amount of the same kind of rubbish on
the floor of the sea, and much of it finds its way to the shore
in the following described manner : All along these shores
sea-weeds abound ; from the level of mean tide down to a
few fathoms' depth the rock-weed thrives, and in deeper
water, even to near one hundred fathoms of sea, the great
laminaria. or "devil's apron," grows wherever it can find
secure foothold. Sometimes these plants attach themselves
by their root-like bases — which are not in fact roots, for they
serve only for support — to shells which lie prone or are fixed
upon the bottom. More commonly they adhere to a pebble
left on the sea-floor by the melting glacial sheet, or drifted
out in the "pan-ice" which in winter forms along the sea-
margins.

All these sea-weeds have floats which hold them upright
in the water, and as they increase in size, they pull on their
bases with constantly augmenting force. As the waves roll
over them they increase the tugging action, until linali}-, in
some time of storm, the plant lifts the stone from its bed
and floats it in the water, buoyed up by the vesicles of air
contained in its fronds. The plant and the uptorn stone are
together borne in by the heave of the sea onto the shore.
Coming into the breakers, the weed is c^uickly beaten to

56 SEA AND LAND

pieces, and the pebble enters the mill where so many of its
fellows have met their fate. The close observer after a storm
may find any number of these bowlders along a pebbly shore
which still show a trace of the sea-weeds which bore them
to the coast. Wading out to near the breakers, he can often
see these sea-weeds with their attached pebbles — sometimes
as large as a man's head — poised in the wave the moment
when it rises for the overturning which makes the surf. On
a (quarter of a mile of the Marblchead beach I have estimated
that as much as ten tons of these seaweed-borne pebbles
cam.: ashore in a single storm. Many of the beaches, which
are so inadequately provided with pebbles from the neighbor-
in^ shores" where the waves are attacking/ the firm land that
they could not be maintained from that source alone, are
sufficiently fed by the means of supply afforded through the
action of marine |)lants.'^*

It follows, from what has been above said, that the move-
ment of coastal detritus is easily accomplished on straight
beaches, such as are characteristic of the southern portion of
the United States, but is very limited in amount on the rock-
bordered shores. Thus, while on the coast of Maine wave-
w^orn pebbles are rarely carried for a distance of more than a

* On the parts of the shore where the land has I)een extensively occupied by
summer residents, the owners have in many cases protected the coast trom erosion
by embankments and sea-walls, thus diminishing the amount of dclwis which was
formerly contributed to the pocket-beaches. In these artificial conditions the
beaches often wear out, and the sea begins to assail the part of the coast which was
once well protected. In sucli cases the only way in which the erosion can effec-
tively be corrected is by carting each year to the beach a sufficient quantity of
large bowlders to give employment to the waves and prevent their encroachment
upon the shore. The larger these bowlders, the better ; for if they are of small size
they will be tossed about by slight storms and rapidly wear out, while masses
weighing half a ton will be stirred only by the more tumultuous seas.

SERRATED BEACHES 57

mile, we find at Cape Florida old and rounded grains of
sand, worn out by a journey which they have made from
hundreds of miles to the northward.

The studious observer of the shore must often have
noticed that when the section between high and low water
mark is composed of pebbles, as is the case with nearly all
the pocket-beaches, the bits of stone are generally arranged
in successive ridges, the crests of which lie at right angles
with the shore and rise perhaps a foot above the general
plane of the beach, the intermediate bays having a breadth
of a score or more feet. Where these ridges and furrows
are well developed, the whole shore-line may have a curious
scalloped aspect. The origin of these peculiar structures is
not easily accounted for ; to attain the explanation we should
note certain evident facts concerning them. In the first place
they are extremely impermanent. By placing a mark in the
centre of one of the elevations, we easily find that they
change their position with almost every storm. Sometimes,
indeed, when the currents which move along the shore are
very strong, they may entirely disappear, to be rebuilt in a
few hours in another time of high waves. If we smooth
them away with a shovel, we may see them reconstructed
before our eyes.

The way in which these pebbles are brought into this
order seems to be as follows, viz.: The crests of the billows
which form the breakers do not tumble down at the same
moment along any extended line. A glance at them shows
us that at every few feet of their length the surge falls to the
beach at a different instant. Hence the swash-wave, which
slips up the beach, has an extremely irregular front ; it
ascends not as a straight line, but in separate broad tongues

58

SEA AND LAND

of water which are impelled by the extremely varied currents
which the irregular falling of the surf and the inequalities of
the bottom bring about. If the beach is smooth when these
tongues of water begin to sweep up its slope, they at once
carve out shallow, indistinct grooves. The very front of the

Heavy Surges on Beach Shore

Showing succes-ive lines of advancing breakers and the process of retreat of a surge which has broken
upon the shore. The parallel lines on the strand represent the swash swiftly flowing down the slope,
dragging the sands and pebbles with it.

swash-flow makes the beginnina- of an indentation, and each
successive movement extends the depression. In the middle
of the re-entrant the current is strongest, because it has
the freest play ; in the rellux movement it scours out the
debris which on the sides is left untouched ; and, indeed.

EFFECT OF POCKET-BEACHES ON JJAKJIORS 59

the sides receive a certain amount of material wliich the
current brought with it, Ijut which the retiring water, shpping
between the pebbles, cannot take away. In this manner the
little bays grow, cutting deeper into the beach at their heads
and extending their horns farther out, until these projections
come to the point where the inner lines of breakers beat them
down. Each of these small divisions of the shore accumula-
tions is in effect of itself a small beach, but it is peculiar in
the fact that it is the product of the swash and not of the
breakers.

The numerous pocket-beaches of our cliff shores have
a very important influence on the history of the harbors, on
which man's relation to the sea so immediately depends.
Owing to the migration of the sand and pebbles along the
shore, the greater part of this debris would soon find its way
into the inlets which afford shelter for ships, and would shal-
low the anchorage grounds, or entirely efface them, were it
not that the material is caught and imprisoned in the pockets
and there ground into .mud, which may be carried away by
the current to the open sea. Wherever we observe a shore
which by its v^'earing produces much detritus, we are sure to
find a number of these beach-mills whereon the bits of rock
are ground to powder. From them little pebbly waste
escapes seaward, as is shown by the fact that, though in all
o-eoloo-ical aees the sea has been at work upon vast stretches
of shore-line, it is rare, indeed, that we find in the rocks any
of the characteristically ovoidal pebbles which have been
shaped by the waves. Even to the cursory eye the beach
pebbles have distinct peculiarities which separate them from
all other similar fragments. They are always spheroids, that
is, they closely approach the globular form, while those which

6o SEA AND LAND

are formed, as most pebbles are — by glacial action — are much
more irregular in shape, generally being many-sided with the
anMes somewhat rounded. Even the pebbles made by the
torrents of elevated countries differ in character from those
produced by wave or ice action.

The student who would make a study of sea-beaches, a
task to which the would-be geologist may well give a long
summer vacation, cannot do better than to resort to eastern
Massachusetts, planning his work so that he may travel on
foot froni Newburyport to Wood's lloll. In this journey,
which, with the detours required by the fretted character of
the coast-line, will extend to about three hundred miles, he
will fmd fairly good types of all the coastal conditions pre-
sented by the Atlantic shore-line south of Greenland and
north of Florida. It is true that he will not have very good
specimens of fiords, nor of the superb marshes which are
offered by the savannas of the Georgia coast, but such feat-
ures as straight beaches will be well shown about the Ipswich
River, excellent dune phenomena may be found in Essex and
about Provincetown, pocket-beaches abound on Cape Ann and
along the shores of Boston Harbor, and Cape Cod exhibits at
Provincetown and elsewhere beautiful examples of hooked
spits. Marine marshes are beautifully shown behind Plum
Island lieach and Revere Beach, while the improved area of
the same nature in Marshfield shows the steps by which such
areas may be won to agriculture, and something of the profit
which may be thus attained. At other points on Cape Cod
the conversion of the marshes into cranberry bog exhibits an
interesting type of agriculture, one w^hich is peculiar to this
country.

As we pass from the northern portion of the Atlantic

ORIGIN OF CONTINUOUS BEACHES 6 1

shore of North America to the southward, the pocket-beaches
increase in chmcnsions, and contain more sand. Going
toward the tropics, this famihar clement of the sea border
becomes constantly more and more abundant, until l)e\ond
Cape Cod the hard rocks are rarely visible, and the pebbles,
if they occur, are altogether from the glacial waste, either
that which is excavated from the shore or that brought in by
the sea-weed. From New York to Florida, and thence to the
Rio Grande, there are no firm materials from whicli pebbles
can be made. We pass from the northern type of pebbly
pocket-beaches to the straight sand-coasts of the south by a
somewhat gradual transition. The accumulations of detritus
become more extensive, here and there the horns of the
re-entrant bays no longer project far enough into the sea to
contain the large amount of material which finds its way into
the depression ; so a portion of the matter flows out and
streams down the shore to the next bay ; this in turn is more
completely filled, and finally we come to the conditions of
continuous beaches.

The change in character of the shore which is brought
about by the passage from the cliff- and pocket- to the con-
tinuous beach, is caused by the alteration in the geological
conditions of the continent in the district in which the shore-
line is laid. The hard rocks of the high north, because of
their resistance to the action of the waves, yield but slowly to
the sea. The water next the shore is deep, and the bottom
either of firm stone, close-set pebbles, or dense clay ; all these
conditions are opposed to the formation of sandy shores.
Although the pebbly beaches grind up a great deal of rocky
matter, they convert the greater part of it to fine material
which forms clay. In the region south of New York, and

62 SEA AND LAND

generally in the regions neighboring to the tropics, the beds
assailed by the sea are of more friable nature than those of
high latitudes, and yield vast (juantities of sand, which are dis-
tributed far and wide over a rather shallow sea-Hoor. The
greater part of the vast accumulations of sand along our
southern coasts come to the shore from the bottom of the
neighboring shallow sea. The way in which this sand w^orks
in against the coast can easily be understood through a
knowledge of the processes which are brought into action by
the movements of the sea-waves over the shallow continental
shelf. First, as to this continental shelf or fringe of shallows
which skirts the ocean shores.

If the reader will take the admirable general charts of the
Atlantic shore and neighboring sea which have been prepared
by the United States Coast Survey, he will find, on examin-
ing the soundings of the district from the St. Lawrence to
Florida, that the water very gradually deepens from the sea-
margin for a varying distance, amounting in places to as
much as one hundred miles, declining generally at the rate of
onh' four to six feet in a mile, for a distance from the shore,
and then plunging down steeply to the abysmal depths of the
sea. On the coast of Europe there is a similar shelf, and
researches in otlier parts of the ocean seem to indicate that
this broad platform is a common feature of the continental
margins, being present along all parts of the great lands
which ha\e long been elevated above the se;i and thus much
exposed to the action of the tides and waves. This shelf is
doubtless in the main composed of the waste from the neigh-
boring land which has been taken to sea by the rivers, or con-
tributed by the sea-waves to the ocean bottom. These con-
tributions of sediment have been borne to their places mainly

ACTION OF THE TIDES ON SAND BEACHES 6

J

by the action of the tidal currents, which are the principal
agents serving to distribute sediments next the shores. The
action of the tide is in brief as follows : In tlie profounder
depths of the ocean, say where it is three miles deep, the
water in a tidal swing moves to and fro for only a few hun-
dred feet of distance twice each day. This rate of movement
is so slow that it does not disturb the finest mud. As the
tidal wave moves in toward the shallower parts of the ocean-
floor, the swing of the sea increases with every stage in the
decrease of the depth, until on the higher part of the conti-
nental shelf the current which it creates becomes strong
enough to move the grains of sand to and fro with each
oscillation which the heavenly bodies communicate to the
water. In the shoals next the shore the movement is often
strong enough to roll even the pebbles about.

In order to conceive the effects of this tidal movement,
the student should imagine a billiard-table slightly tilted at
one end, and a number of balls pushed with the same amount
of force up and down the slope. He will easily understand
that the balls will, when thus pushed up and down the table
with equal impetus in each direction, gradually work toward
its lower end, and this for the reason that the force of gravita-
tion acts ever to diminish their upward movement and to
increase their downward journey. The seaward slope of the
continental shelf may then in the mind's eye be given the
place of the billiard-table, the grains of sand that of the balls,
and in lieu of the force applied by the hand we have the alter-
nating push of the tide. There, age by age, the swinging of
the water in the tidal flow and ebb, each movement acting
with equal force, gradualh', with the daily journe)'s, works the
particles of sand from the shore where they are formed, out

64 SEA AND LAND

\\\\.o tlic deeper water, where the currents can no longer stir
them, and where they may be bound to the bottom by the
organic ooze or shme which aljounds on tlie ocean-floor. In
this manner, by tlie endless i)rocession of tide-borne sand, the
greater part of tlie continental shelves are formed.

The work of the tides in conveying the sediments from
the shore out toward the margin of these great submerged
sand-i)lains, is directly and often effectively opposed by the
movement of the sea-waves. These surges, like the incon-
ceivably wider tidal oscillations, have little effect upon the
bottom of the ocean in its deeper parts. If the abysmal sea-
floor were inhabited by a race of philosophical fishes, and
they were provided with the most accurate appliances for
obser\ation which have been invented by men of science, they
would hardly be able to detect the effect of the waves, how-
ever high, when they rolled over the surface three miles above
the ocean-floor ; at most they would find the water lifted a
fraction of an inch as the wave advanced, and lowered by the
same amount as it passed by. The trifling currents thus
induced would not disturb the finest mud upon the bottom ;
but if the imagined aquatic observers carried their studies to
higher levels of the sea-floor, they would find an ever-increas-
ing dragging action produced by the waves upon the base of
the ocean. When they came to the shallows of the conti-
nental shelf, they would perceive that the water under each
successive wave swung toward the shore with sufficient energy,
where; the surges were high, to drag the sand up the declivity.
The less the dei)th of the w^ater, the stronger this movement
would be, and next the beach, where the water was not more
than fifty feet deep, the action would be strong enough to
urge coarse sand or even fine pebbles to the margin wdiere

ACTION OF MARINE CURRENTS 65

the breakers would commit it to the strand. The result is
that the waves, which are only powerful when they run toward
the shore, oppose the work of the tides, and tend to return
to the margin of the continent the fine detritus which the tides
labor to carry away.

While these two irregular classes of marine movements of
tides and waves are contending with the grains of sand and
mud, the ocean currents in their continuous, though slow,
pace share in determining the fate of the wandering bits of
stony matter. Almost all parts of the shallow water near the
shore are the seat of these oceanic rivers, which flow with tol-
erable steadiness in one direction. In their currents, which
generally flow at right angles with, the run of the tides and
waves, the particles of sand and mud are given a decided set
in one direction. Thus on the eastern coast of North America
there is a prevailing, though variable, southerly current which
skirts near the shore over the surface of the continental
shelf, and to a certain extent operates to convey all the sandy
matter from the northern part of the continent to the southern
part of its shallow waters next the coast. It is now contribut-
ing to the growth of the vast submerged sand-plains which
extend from Cape Cod to Cape Florida, and in past geologi-
cal ages has doubtless helped to bring to their place the exten-
sive deposits of sand and clay once a part of the continental
shelf but now uplifted into the dry land of the Southern
States. We may recognize the fact that these lowlands were
originally portions of the continental shelf, by their gently
undulating surface, which is exactly like that of the neighbor-
ing sea-floors, by the nature of the fossils in their beds, as
well as by other indications of a more recondite nature. In
fact, the greater part of the surface of the continents was

66 SEA AND LAND

doubtless orij^inally formed as shore-shelves near the old
lands, then elevated above the sea, folded into mountains,
and worn into hills, until we can no longer, or with difticulty,
recoL^nize their original aspect.

If the relative level of the sea and land remained stead-
fast for a considerable geologic time, the detritus of a conti-
nental shelf would, und(;r the unceasing action of the tides,
and despite the perturbing effect of the waves in occasional
storms, grow steadfastly to the seaward ; but all our study of
the relations of sea and land tends to convince us that they
are peculiarly unstable. It seems likely that nowhere in the
world is the sea-margin at exactly the same height in any two
successive centuries. In general this variation is so slowly
brought about that in the brief moment of time for which we
have any account, in the case of the longest-known shores, we
do not have evidence of it, and the sea-level is said to be per-
manent. Again, it is sufficiently rapid to be observable in the
duration of a single human life. Thus on the coast of New
Jersey there is a tolerably rapid subsidence of the land, which
is sinking at the rate of near two feet in a century. Along
the shores from Eastport, southward, there have been many
ups and downs of the shore since the glacial period ; within
a range- of from a few score to a few hundred feet, the last
\-ariations appear generally to have lowered the shore in the
re'Mons south of New Brunswick. In those rei^ions where the
lat(M- movements of the coast-line have been of an uprising
nature, the effect is to brincf a ijreat deal of sand, which had
been in too deep water for the waves to afYect the particles,
within the power of the surges. In these cases the coast-line
becomes inundated with sand swept in from the sea.

It is characteristic of the typical sandy shores, that their

INSTABILITY OF SAND-BEACHES

67

materials are apt to be in a state of continued instability;
their sands are generally moving- with considerable speed in
the direction in which they are borne by the shore currents.
The march of the sands along the shore continues until they

,-*~S«K^

■.4mt^<'

Moderate Surges seen along their Crests

"^ .V '-.• r on.

The shore is in its nature alluvial, and the most approved method of protection by means of sea-wall,
together with spur breakwaters, is shown. The object of these breakwaters is to keep the sand and
pebbles from working along the beach under the influence of the waves and currents.

have attained the extremity of the coast, or found their far-
ther progress obstructed by some strong ocean current which
sweeps the incoherent matter away into the depths. Thus
along the Atlantic shore from Cape Hatteras to Cape Florida

68 SEA AND LAND

the sands are constantU- and rather rai)idly moving to the
southward. At the last-named cape the coral reefs carry the
shore out to the edge of the northward-flowing Gulf Stream,
which speedily conveys a great part of the mobile waste into
the deep valley between the Bahama Islands and the margin
of the continent. Where these coast-moving sands abound the
beaches usually lie upon the seaward face of long, low, sandy
islands separated from the shore by lagoons. These sand-bar
islands are a very conspicuous feature along all the shore
from Portsmouth, N. H., to Cape Florida, and again along
the Gulf of Mexico from the western coast of Florida to the
mouth of the Rio Grande. This peculiar type of beaches
appears to be originated under the following diverse condi-
tions : Whenever by an elevation of the shore-line a new
beach-line is to be formed farther out to sea than that which
previously existed, the construction is begun, not at the very
water's ^A^o., but at a distance out from the shore at the
depth where the storm-waves break, in perhaps twenty feet
of water. When the w^ave topples over in the surf, all the
sand which it has swept forward from the seaward falls down,
and each successive wave adds to the supply, until the mass
reaches to the top of the water and forms a new bar. Upon
this elevation the storms Ijiiild yet more sand, grasses take
root, and low dunes are formed. As the waves bring in not
only sand but much shelly matter and the bones of fishes, the
deposit may make tolerably fertile land, such as is found on
the long beach islands which border the great lagoon known
as Indian River in eastern Florida. In other cases, where
the sea-shore slowly sinks, similar islands may be formed in
a rather different way. If the continental land is low, as it is
next the sea in all the Southern States in this country, the

INWARD MOVEMENT OF OUTLYING BEACHES 69

beach-wall may in time be built to a considerably greater
height than the land upon which it formed. If the land
sinks down, the waves and winds may constantly add to the
height of this growing beach, so that its crown is kept well
above the surface of the water, while the interior land, having
no such means of adding to its mass, slowly subsides below
the level of the sea.

These outlying beaches, especially wdierc they are swept
by strong, coastwise-running currents, are apt to work rapidly
in toward the land. Thus on the southern shore of the island
of Martha's Vineyard, where an extensive series of lagoons is
shut out from the open water by a low sand barrier, the coast
current constantly cuts away the sand next the shore and con-
veys it to the eastward until it is discharged around the end
of the island to form the great promontory of Cape Pogue.
This leads to the deepening of the water next the shore so
that the waves have very free access to It. In times of great
storms the swash from the surf sweeps clear over the beach,
and in its movement conveys a great quantity of sand from
its outer to its inner wall. In this manner a beach moves
inward in much the same way as a sand-dune, rolling over and
over itself in its forward- motion. On the southern coast of
Martha's Vineyard the inward march of the beach is now at
the rate of about three feet per annum. It is now probably
near a thousand feet from the place it occupied when the
land was first seen by the whites.

These barrier-beaches, arising, as we have seen they may,
from either the uprising or the downsinking of the continent,
are extremely common features of the ocean coasts ; probably
near one-fourth of the continental shores are fringed by them.
They are of much interest to man, not only because they

70 SEA AND LAND

afford numerous harbors, but for the reason that they lead to
the production of certain i^roups of marine marshes, which
niay be readily converted into \ery rich arable land. Some
of the most fertile of the dyked lands of Holland were origi-
nally of this nature ; and on the eastern shore of the United
States there is awaiting the thrift which shall win it to agricul-
ture an area far greater than that occupied by all the Nether-
lands. These marshes, the products of the sea-beaches, afford
such promise of good harvests in the generations to come, that
we ma)- devote a portion of this chapter on the history of the
shore to a brief account of their curious [phenomena.

As soon as a space of tidal waters is protected by a bar-
rier-beach from the incursions of the sea-waves, its bottom is
occupied by various si)ecies of marine plants, of which the
well-known eel-grass is the most common. These form.s make
a network in which the currents of the tides, or those of the
rivers which may discharge into the embayed area from the
land, are deadened and lay down such sediments as they may
be bearing. A host of animals dwell in this vegetation, and
contribute to the deposits which rapidly shallow the water.
When by these accumulations the surface is brought to the
level of low^ tide, several kinds of. true grasses and other
fiovvering plants, as well as certain sea-weeds, continue the
construction of the sedimentary deposit until the surface is
brought to a level a little below high-tide mark. This growth
of the higher tidal marshes usually begins next the shore,
while that of the eel-grass tlats, which never rise above the
retreating tide, may take place anyw^here in the basin where
the currents are not strong enough to sw^eep the plants away.
Starting at the shore the grassed marshes extend gradually
outward until they leave only narrow channels for the en-

ORIGIN OF MARINE-MARSHES /I

trance and exit of the tidal currents, as for the escape of
the land waters. In this manner bays originally of many
square miles in extent appear as grassed plains, except for a
few hours at high tide, when they have a foot or two of water
on their surfaces. Thus the great marine marshes which have
grown in the quiet waters land-locked by Plum Island, near
Newburyport, Mass., have an area of about sixteen thousand
acres, and there are many others in New England which
exceed a thousand acres in area. Between New York and
Portland, Me., a careful study has shown that there are
over three hundred thousand acres of these lands, all of
which are reclaimable and will make exceedingly fertile
fields.

In the region south of New York, in New Jersey, Dela-
ware, Maryland, Virginia, and the Carolinas, there are other
and far more extensive marshes of the same general nature.
It seems probable that ultimately not far from two million
acres, or over three thousand square miles, of excellent land
will be won from these fringes of the sea to agriculture, and
this with a relatively slight expense for the necessary engi-
neering work. With more costlv contrivances the area to be
won to the best uses of men may be brought to more than
three times this amount. There are, in other words, the agri-
cultural possibilities of a Holland in these inundated lands
awaiting the time when the increased population of this coun-
try shall make it necessary to utilize these naturally produc-
tive areas.

The process of subjugating these fields where the tidal
rise and fall exceeds four or five feet is simple. The beach
which protects the embayment from the sea usually consti-
tutes a most effective dyke against the ocean waters. There

72 SEA AND LAND

is ofeneralh' a sinsfle breach in this wall throucrh which the tide
gains ingress, and through which the lantl waters pass into
the sea. If the outflowing streams of fresh water are small,
as is generally the case, it is only necessary to place a dam at
this exit, provided with gates which open at low tide to allow
the fresh water to escape, and close as soon as the tide begins
to flow in. In this way the surface of the soil once over-
flowed at each tide is kept permanently from three to six
feet above the level of the water in the river channel. It
requires some time and care to take out the saline matter
froni the marsh, but within a few years the soil will produce
luxuriant and varied crops. Its fertility is greater than that
of the prairies, and from its depth and the variety of its
natural constituents it seems almost inexhaustible. An
excellent example of the possibilities of this interesting means
of winning land from the sea is afforded by the Green Harbor
lands of Marshfield, Mass., where a district of about fifteen
hundred acres was freed from the sea by a dam costing a few
thousand dollars.

Where the tidal fall and rise is less than five feet, it is
difficult to secure the necessar}' dryness for tillage by any
automatic system of drainage. In these districts recourse
will probably have to be had to pumping by means of wind-
mills, a method of drainage which has been found effective
and economical in the low countries about the mouth of the
Rhine.

Before we close this imperfect story of the sea-beaches we
may well note the comnion fact that the sand of which the
bulk of their masses is composed is vastly more durable than
the seemingly more resisting pebbles. As we have seen,
pebbles wear out rapidly. Scarcely any, even the hardest,

PROTECTIVE EFFECT OF SAND-BEACHES 7Z

can stand a year of steady thrashin^^ on the shore, but these
sands endure for ages. The reasons for this are simple. In
the first phice, each grain of sand is an admirable illustration
of the principle of the survival of the fittest. If it be not
perfectly coherent and very hard, it will not be carried far
before its weakness is found out and it is broken into mud
on the pebble-beaches, where it is generally made and borne
away by the sea to the deeper water. Then, because of their
smallness, the grains lie with so little interspaces between
them that they hold the water next their faces by capillary
attraction. When a wave strikes the shore the grains of sand
are pounded together, but they do not touch each other. If
we press on the wet sand with the foot we see that the mass
whitens as the pressure is applied and a part of the intersti-
tial water is poured out : take the foot away, and the water
returns to the crevices between the grains. Only dry sand
will rub, grain against grain, and give the audible sound
which when it is sharp and clear is called singing. No
beach will thus creak or sing beneath the feet when it is
wet.

This curious endurance of rocky matter, in its comminuted
form, to the erosive force of the sea, makes the sand the
natural protector of the land against the fierce assaults of
the sea. If sand were easily pulverized, if it were readily
floated away, if it had, indeed, any other than its actual
assemblage of properties, it is doubtful if the lands could
have made good their place in the contest with the ocean.
These doughty little champions have certainly kept for our
use empires which but for their good work would long ago
have vanished beneath the waves. Thus a process which
begins with swift wasting of the land on the exposed cliffs of

-&

74 SEA AND LAND

the sea, and is continued in the wearing of the pebble
beaches, ends in the protective work of the sand beaches.
So it is with nearly all the processes of nature ; however
destructive the work may seem to be in its inception, the
end, if we can but see it, is ever creative.

THE DEPTHS OF THE SEA

Modern Interest in the Deep Sea : Conditions of Inquiry. — Shape of Ocean-floors :
Absence of Mountains and Valleys. — Coral Reefs. — Continental Shelf. — Permanence of
Continents. — Plants and Animals of the Sea. — Conditions of Marine Life : Absence
of Seasonal Changes. — Marine Communities. — Abysmal Life. — Detrital Accumulations.
— Fate of Sunken Ships.

Ever since man began to speculate concerning the unseen
parts of nature, the spaces of the sea have shared with the
vaster reahiis of the encircHnor heavens the manifold excur-
sions of the imagination. The poet and the philosopher,
whose paths upon the land most often lie far apart, have
alike sousfht to tread over the hidden ocean-floors. For a
time the realms of the sky, because they are more visible than
the submerged realm, were the favorite field for speculation.
The Greeks, by far the most richly endowed in constructive
imagination of any of the ancient peoples, gave little thought
to the regions beneath the sea. The true love of the deep,
and interest in its hidden regions, is a matter of modern
days. The people of northern Europe have felt these
motives more strongly than those of any other lands. 1 he
Scandinavians were the first navigators of our race who
learned the pleasure which comes to those who break into an
unknown sea ; a thousand years ago they dared in frail barks
the fierce tempests of the North Atlantic ; led thereto by no
clearly defined purpose of conquest or propagandism. but

76 SEA AND LAND

inspired, it would seem, b\- tiic pleasure of dangerous cruis-
ing. It is principally among the people who share this
Scandina\ian blood that we hnd that vivid interest in all that
pertains to the ocean which has led to some of the most
fruitful and interesting incjuiries of modern science ; researches
w^hich have created the brancli of learning which is termed
thalasograph.y, or the description of the ocean.

The study of the ocean depths is an extremely difficult
incpiiry : we know far more concerning the form of the
moon's surface, though that sphere is a quarter of a million
miles away, than we can ever hope to learn of the shape of
the ocean-floors. There are few instruments as yet devised
which can give us any considerable information as to the
conditions at any great depth below the surface. A century
ago the only apparatus of submarine research was the
plummet, by which the navigator, to learn the position of
shallows, sounded for the depth of at most a few hundred
feet. A little tallow on the bottom of the lead brought up
some fragments of the sea-iloor, and showed whether it was
sandy, muddy, or covered with fragments of shells. A
hundred years ago nothing was known as to the greater
depths of the ocean. The lines to which the sounding leads
were attached were limited in length to about six hundred
feet ; when the bottom was not found with them, the vessel
was said to be "off soundings." The depth beneath her keel
was then left to conjecture. With the modern increase in
curiosity concerning the ocean, the lines were lengthened and
the weights increased, so that some information began to be
obtained as to the deeper parts of the sea. But there were
many and serious difficulties encountered in these explora-
tions. The ropes had to be of considerable size to sustain

CONDITIONS OF INQUIRY

n

the heavy phimmcts, and the friction of these cords on the
water, though not noteworthy in shallows, became very great

Sketch showing the Arrangement for Dredging in the Deep Sea

The dredge is seen in the foregrround. The fringed tassels are intended to entangle objects which rest
upon the bottom. The drum like piece of apparatus is a set of springs intended to prevent the breaking

of the line by sudden strains.

when a mile or more of depth was encountered. In the
abysmal portions it required hours for the weight to drag the
hempen rope to the bottom, and a )'et longer time to litt it

7.8 SEA AND LAND

again to the ship's deck. In very deep water so slow was
the descent of the weight, that it was not easy to tell when
it liad attained the ocean-tloor. Moreover, as the ocean
waters are often pervaded by currents of considerable veloc-
ity which move in various directions, the thick cord in its
downgoing would often tlex, now tliis way and now that,
and thus give very exaggerated records of the depth at any

The most important of these difficulties encountered in
exploring the depth of the sea, have, through the skill of the
American and English explorers of thalassal problems, been
overcome. The lead is no longer hung on a roije, but is
attached to a hue steel wire, which, because of its tenuity
and smootliness, slips easily through tlie water ; the weight is
so arranged that when it strikes the bottom it is at once
detached from the line, which is then easily wound back
to the drum from which it was lowered, while the plummet
itself is left to be entombc;d in the strata forming on the sea-
lloor. Although these very clever inventions, as well as the
com|>licated and beautiful machinery by which tlie miles of
delicate wire may be lowered and hoisted in the rolling sea,
have made it possible for a properh" ecpiipped exploring ship
to determine, in a tolerably accurate manner, the depth of
wat(;r at any point, the information which is gained even by
very numerous soundings, though valuable, is very meagre.
Let us fancy that the atmosphere was as impenetrable to
vision as the depths of the ocean, and that creatures which
dwelt above it should seek to learn the shape of the land by
means of a few thousand soundings disposed in lines here and
there, so as to give what we may term sections, over the
surface of the terra firma. W'e can easily imagine that

LIMJTATIOXS OF KNOWLEDGE OE DEEP SEA 79

the information would be very incomplete. Such a cror<'-e
as the Grand Canon of Colorado would have but a bare
chance to be noted ; a volcanic peak like /Etna, though it
rises two miles above its base, would most likely escape
observation.

If our imagined super-terrestrial beings should limit tlieir
inquiries to the facts developed by the plummet, they would
have but the most general notions as to the form of the sur-
face they were exploring. We can conceive them using the

Diagram showing the Position of a Deep-sea Dredge as the Line is Paid Out from the Stern of ihe Ship

The letters G, G', etc., show the position and effect of the weight which is used to bring the dredge into

the proper attitude.

Other aids in their research which have been devised b\- the
explorers of the deep sea : the dredge, a contrivance like a
scoop, which is dragged over the bottom, so as to collect a
sample of the deposits which arc forming there. A few thou-
sand essays with this instrument would certainly give some
notion as to the nature and variety of the organic forms which
people the surface of this sphere, and are contributing their
bodies to its dust on sea-floor and land. Yet we readily fancy
that these observations would afford but an inadequate basis

8o SEA AND LAND

on whicli to construct a picture of the hidden realm. So, too,
the thermometers which give us the ranges of temperature in
the depths, and the instruments which collect water from the
various levels of the sea, in order tliat it may be subjected to
chemical analysis, though they provide us with valuable infor-
mation, do not give us anything like the accurate data for
determining the climatology of the ocean-Hoors that we have
secured from the land. Similar observations on the land made
by beings in the upper air, even if they were applied only to
the natural wildernesses of the earth, would afford only details
which would require exceeding skill to frame into important
and trustworthy general views. This skill has fortunately
been commanded by the naturalists who have prosecuted the
modern studies concerning the oceans : no department of
modern science has so well united the daring of the man of
action with the i)atient labor of the closet student ; hardly any
other has so profited by the advance in the mechanic arts.
The methods of the students of the deep sea may indeed serve
as a model of the scientihc research which is so characteristic
of our century, for they coml^ine in an admirable way patience
in difficult inquiry with skill in interpretation. The affirmed
results, at least those which are likely to prove interesting to
the general student, are among the most fascinating chapters
in th(' liistory of the earth.

The student who from the familiar studies of the land
surface — studies whicli we are all insensibly making in the
daily experiences of our ordinary lives — comes to the margin
of the sea, is naturally led to the opinion that the ocean-floors
have a form essentially like that of the continental fields.
At the shore he finds the mountains and plains of the land
passing by a gradual decline of the surface below the level of

PERMANENCE OF OCEANS 8 1

the water. The emerged mountain-tops often form a fringe
of islands extendinof some distance from the coast-line, and
the valleys are prolonged as deep bays which penetrate far
into the land. Thus the land and the sea appear to be
blended in a way that very naturally leads to the supposition
that the ocean-t^oor is merely an inundated portion of its
surface, differing from the dry parts only in the absence of
certain minor features, such as river-valleys which are due to
actions peculiar to the land.

Naturalists for a long time adopted this popular view
concernincr the conditions of the sea-bottom. Observing that
the greater part, if not the whole, of the land was made up of
sediments which had been accumulated on the sea-floor, the stu-
dents of this field were led to the idea that sea and land had
often changed places ; no part of the earth for any long period
escaping from the invasions of the ocean. Gradually, with
the advances in knowledge concerning the history of the
earth, these students have been driven to other views. While
they are thus forced to allow that the continents have been
subjected to great alterations of form, a part of their surface
from time to time sinking beneath the sea while other
portions which had long been under water rose above its
surface, they find good evidence that, as a whole, the seas and
lands have not changed places, but that the greater oceans
have been permanent features in the physiography of this
planet. There is doubtless a debatable area .next the shores
of each continent, which is now won to the realm of the land
and now to the domain of the waters, but there remains a
vast field, probably including more than half the oceanic area,
which for a great time, perhaps since organic life has tenanted
this sphere, has been always in the condition of deep sea.

82 SEA AND LAND

Accepting this view as to the tolerable })ermanence of land
and sea with the greater assurance, because it has slowly won
its way to belief over the previous opinions and prejudices of
students, we are prepared to fintl that the conditions of the
ocean-bottom are in man)' regards entirely unlike those of the
land. It is easy to see that the shape of the land is mainly
determined b)' a contest between the down-wearing action of
the water which falls upon its surface as rain or snow, or is
swung against it in tides and waves, and the uprising movement
which lifts the mass of the continent and wrinkles the under-
lying rocks into mountain folds. Rivers and glaciers have
battled with these ascending masses of strata, they have
carved out the valleys and gorges which fret the land in
every direction ; even the plains which appear to feel little of
this erosive action generally owe their horizontal aspect to
the fact that the wearinof assents have done their most effec-
tive work in these areas. We readily perceive that all this
mighty machinery of flowing rivers and beating waves has no
place in the depths of the sea. It is true that the ocean has
great streams upon its surface, some of which, for certain
parts of their courses, move with the speed of the larger
rivers; but these swift currents are superficial things; they
rarely if ever touch the bottom except where they come upon
the shores of continents or islands, but flow upon a base of
deep-lying nearly motionless water. While everywhere upon
the land, e\en in the most arid regions, there are occasional
rains, and for a time the torrents do their appointed work of
wearing away the surface of the earth, the deeper ocean-lloors
are practically always the seat of deposition, that is, they are
receiving contributions of sediment from the rivers of the
land, from the waves and tides of the shores, from the vast

ABSENCE OE MOUNTAINS 8

J

amounts of dust thrown out of volcanoes as well as that
which falls from the celestial spaces. In a word, the land is
characteristically the place where the strata are in the course
of destruction, and the sea-fioor the laboratory where these
materials are separated from the water, partly by gravity and
partly by the growth of organic forms, and built again into
compact rocks.

The result of these differences in conditions is, that while
the land is carved into innumerable vallexs which mark the
process of its destruction, the sea-floor is approximately
level, for that is the shape which the growing deposits
assume as they are accumulated. But there are yet other
influences which serve to give to the sea-floor a uniform
aspect. Chief among these we must reckon the prevailing
absence of true mountains in the fields which are covered
by the ocean waters. Although these vast realms contain
numerous elevations, some of which are of magnificent pro-
portions, it seems tolerably certain that true mountains — that
is, elongated heights produced by the folding of rocks into
rido-es and furrows — do not occur in the abysmal portions
of the ocean.

The evidence of this lack of mountains in the deep seas,
though inferential, is very satisfactory in its nature. We
note that the average depth of the oceans, as determined by
many thousand soundings as well as by the speed with which
the waves caused by earthquakes travel over their basins, is
about fifteen thousand feet, while the portion of the marine
fields where the depth exceeds twenty thousand feet is
extremely limited, and the most profound abyss yet encoun-
tered in sounding is only about twenty-eight thousand feet
below the surface. In the land we find many hundred peaks

84 SEA AND LAND

^vhich exceed fifteen thousand feet in height, and some score
wliich rise twenty thousand feet above the sea level. There
are indeed several considerable areas of mountainous country
where extensive fields attain a greater height than the aver-
age depth of the sea. It is thus at once plain that if moun-
tains developed in the ocean-floor as freely as they do on the
land there would be a great number of them rising above the
plane of the seas, but in fact that there is not a single dis-
tinct mountain peak rising above the water level at any great
distance away from the margins of the continents. All the
numerous islands of the wide oceans are either coral reefs or
the summits of volcanic cones.

It is furthermore evident that if mountains grew upward
from the sea-floor they would attain the surface of the water
without being subjected to the erosion which has robbed the
elevations of the land of a great part of their height. If we
carefully examine any of the great mountainous peaks of the
continents we find that they have been much worn away by
the rivers, torrents, frost, or glaciers, which have always oper-
ated uj)on them ; but mountains growling upon the sea-floor
would be safe from these assaults until they rose above the
surface of the water. We would on this account expect to
find them even more abundant and of loftier forms in the
marine areas than on the parts of the earth's surface which
rise above the sea. We are therefore forced to the conclu-
sion that mountains do not form upon the sea-floor, or if they
develop there they attain no such dimensions as they exhibit
upon the land.

Although the deeper sea-floors probably lack mountains,
they are not without striking reliefs which if they could be
seen would present all the dignity which their height gives to

the

H i m a -
lay as or
Andes: the
difference i s
that these ele-
vations are not
true mountains
but volcanic peaks,
sometimes isolated,
again accumulated
in long narrow ^^

ridges, but all made
up of matter poured out from
craters or through great fis-
sures in the crust. So numer-
ous are these heaped masses
of lava and other ejections
from these vents, that there
is hardly any considerable
area of the oceans where they
do not rise above the surface;
there are indeed thousands
of these volcanic peaks dis-

H' - \.l'-'^'>"'.f"~ '

Suggestions concer

Coral Reefs,

and Volcanic Islands

In the foreground the upward growth and lateral enlarge-
ment of volcanic cones is indicated. The largest of these
. , has been levelled off and occupied by an atoll. Inthedis-

tributecl from pole to pole. tancc a volcano, stlll active, is in a state of slight eruption.

86 SEA AND LAND

Vet it is likely that only a small part of these elevations
attain the surface of the ocean. i^robably the greater part
of them remain buried beneath the sea, and are onh' imper-
fectly perceived when the sounding lead indicates an elevation
of the bottom. Thus on the floor of the North Atlantic there
is apparently a long discontinuous chain of these elevations
extending from the Icelandic oroup of islands southward to
the Azores. If an explorer could view this part of the sea-
bottom he would probably find that the line of craters was as
continuous as that exhibited b)- the volcanoes of the Andes.
In the invisible landscape of the sea-floor, volcanoes play the
part of mountains on the land. It seems indeed clear that
these elevations, due to the action of the earth's interior fires,
are in their way as characteristic of the deeper seas as the
mountains are of the land portion of the continents : the
volcanic field is so essentially marine, that of the hundreds
of vents that have been in activity within the historic period
not one is situated more than three hundred miles from the
marofin of the sea.

Besides the volcanic peaks the sea-bottom in certain parts
of the tropics and in the regions near to the e(|uatorial realm
which are swept over by warm ocean currents is beset with
the sin^rular elevations formed bv coral reefs. Next the
shore these reefs take on the form of long submerged walls,
sometimes many hundred miles in length and only a hundred
feet or so in height. To the eye they would appear as singu-
larly regular and artificial terraces, their crests on an exact
level for a considerable part of their length. Here and there
the wall would present port-like openings through which the
streams of the tides and rivers find entrance and egress. The
reefs of the deeper sea present a very different aspect ; they

ORIGIN OF COR A I REEFS 87

are usually in the form of very lofty cones rising steeply
from the depths of the ocean to the height of a few feet
above the level of the water. On their tops there is gener-
ally a shallow cup-shaped depression of a few score feet in
depth, bounded by the low f]at wall of the living reef of coral
sand which had been formed along the shore. The origin of
these deep atoll sea-reefs is not yet perfectly understood.
Mr. Darwin's explanation, long considered satisfactory but
now brought into doubt, was to the effect that they were
produced wherever a massive coral growth was formed around
the flanks of a slowly down-sinking island, the polyps build-
ing their limestone wall upward as the peak lowered into
the depths of the sea. Dr. John Murray, the well-known
oceanographer, has recently shown that these basin-shaped
reefs may be formed wherever shallows are produced in situa-
tions where they are swept over by a warm marine current.
The upward growth of the coral tends to form a cap upon
the shoal which slowly rises to near the level of low tide.
Attaining this altitude, the central part of the mass begins
to dissolve away, and the process of solution continues until
a basin is formed, while on the outside margin of the reef the
polyp communities continue to grow, and from the debris
which they afford under the beating action of the waves the
ring-like island is formed. Although there may be cases in
which the elaborate hypothesis of Mr. Darwin is applicable,
there can be no doubt that by far the greater part of the
atolls have developed in the manner indicated by Dr.
Murray.

Yet another singular feature in the topograph)- of the
oceans is found in the great shelf-like shallows which usually
border the margins of the continents. These remarkable

88 SEA AND LAND

features are best known alon^' tlie coasts of the North Atlan-
tic, perhaps for the reason that there alone is the form of the
bottom ascertained. In going- from New York to Liverpool,
the traveller for the first hundred miles of his eastward course
passes over a portion of the sea where the water rarely
exceeds five hundred feet in depth ; the bottom slopes grad-
ually toward the central portion of the ocean, at the rate of
about five feet to the mile. There are occasional broad
swales on the nearly level floor, but as a whole it is much
more nearly a plain than an)- similarh' extensive part of the
prairie land of the Mississippi Valley, This gradual descent
toward the deep sea is terminated by an abrupt slope where
the bottom declines at the rate of from ten to one hundred
feet to the mile, from the crest of the submerged plain to
the abysmal depths of the ocean.

Unlike most of the submarine topography it is possible for
us to orct a clear idea as to the "eneral character of this con-
tinental shelf from certain portions of the dry land which
have recently been elevated above the watery envelope.
While it is true that nearly if not quite all parts of the
continents have been formed on the ocean-floor, the greater
portion of the land surface has been so much warped by
mountain building, and made uneven by stream action, that
the original impress of the marine conditions has been
entirely lost. In the southern portion of North America,
from Virginia through the lowlands of the Carolinas, Georgia,
Alabama, Mississippi and a part of Texas and Louisiana, we
have a portion of this shelf, which was formed when the shore
was farther inland and when the area in question was below
the level of the sea, constituting a portion of the continental
deposits such as is now submerged along our shores. Like

PERMANENCE OF CONTINENTS 89

that part of the submarine pkun which is still under water,
this lowland of the southern Atlantic coast-lands is extremely
level with a slight dip toward the ocean depths, and a faintly
undulating surface, the irregularities not usually causing a
difference of altitude in one square mile of more than five or
six feet. Examining into the materials which compose this
emerged portion of the continental shelf, we find that they
consist in large part of detritus which the waves and rivers
have worn away from this land, and conveyed a little w^ay
from the ancient shore, together Avith quantities of fossils
which in their lifetime dreAV their solid parts from the sea-
water. Although nowhere else do we find any other so
perfect and extensive a fragment of the continental shelf
lying above the level of the sea, there is here and there
about the ereat lands evidence that this is the common nature
of these deposits. We may therefore conclude that they are
mainly made up of sediments brought to the sea from the
neighboring hills and plains of the land.

Until within recent times geologists have generally held to
the opinion that the lands and seas had occasionally changed
positions, so that the continental areas were from time to
time lowered into the deep, and the floors of the abysmal
' seas, by a similar alternating movement, lifted into the realm
of the air. The researches of Dr. Murray and others appear
to indicate that this alternation of relations does not occur.
Nowhere on the land have we yet found clear evidence going
to show the existence of any deposits such as are formed in
the abysmal regions of the ocean. The students of the
subject are now coming to believe that, while the continents
have been subjected to frequent oscillations, portions of the
surface of each becoming depressed to a moderate depth

90

SEA AND LAND

beneath the ocean while other parts are extended farther into
the field of waters, these L^reat lands are never deeply sub-
mero-ed, and that correspondingly the abysmal realms are
never converted into dry land. This view finds much sup-
■ port in the fact that each of the continental
areas has a somewhat peculiar assemblage of
life which is evidently continued in unbroken
succession throughout the greater part of the
time which is recorded in the pages of the
great stone book whose leaves are the strata of
the successive formations. As the i)ast is the
index to the future, we may anticipate in the
hereafter of this ancient though still youthful
sphere, that geographers will often have to
reframe the charts of land and sea, but it is
doubtful if they will ever delineate as con-
tinents those portions of the world which are
now in the deeper parts of the ocean.

We have now considered the principal topo-

Showing at the top

the arms which graphic featuTcs of the sea-floors, and have

branch from the ca-
lyx which encloses notecl the fact that they consist mainly of

the body caviiy, and

at the base the root- extcusivo plaiuswith geutlo slopes toward the

like processes whicli

attach it to the bot deep Water extending for some distance from

torn.

the shore, and terminating in steeper slopes
which lead down into deeper water ; broad undulating fields
in tlie bottoms of abysmal depths; volcanic peaks generally
grouped in long ranges ; and lastly the shore walls and steep
cap-topped cones of the coral reefs or isles. We will there-
fore turn our attention ta the organic forms which people
this vast realm — forms so numerous and varied, that we can
only consider their more important aspects, limiting ourselves

Living Crinoid.

MARINE PLANTS

91

mh\

in the discursive inquiry to those features which seem to
throw Hg'ht on the general history of hfe. The first matter
to be noted is that now, as in all the past ages of the earth,
the creatures which tenant the sea are in organization much
inferior to those dwelling on the land. This is true, not only
of the organic forms as a whole, but essentially so of every
separate group of animals and plants. Thus in the vegetable
king'dom, the truly marine
species contain no tlower-
incr forms; none which
have devised the function-
ally and structurally sepa-
rated parts of root, stem,
and leaves, or which com-
bine their offices to afford
the well-ordered life of the
familiar vegetation of the
land. Although the sea-
floor is generally covered
by a coating of detritus far
richer in the elements of

A representative of a group which abounded in the
plant crrOWth than the SUr- early geological periods, but which is rare in the seas of

the present time.

face of the land, it does

not serve the lowly marine plants as a soil ; they send no
roots into it ; they take no nourishment from it, but derive
all their sustenance from the water which envelops their
stems and fronds. Although there are many diverse forms
of marine vegetables, the species are generally small and
weak structures; only one group, the J/acrorys//s, is known
to attain any great bulk. This tenant of the Pacific and
Antarctic Oceans has a stem extendimj from the bottom of

Calyx, Arms, and a Part of the Stem of a Metacrlnus — one
of the Sea Lilies

g2 SEA AND LAND

the sea to the crown wliich lloats at the surface of the water,
and llie phmt may have the length of one thousand feet or
more. Remarkaljle as is this structure, it is lowly organized,
and does not deserve to be compared with our more highly
developed land plants, which, in every feature by which we
measure superiority, are far above their kindred of the sea.
Although the deeper parts of the seas lack vegetation, the
shore belt within the depth of a few score feet abounds in
such forms, except, indeed, where the bottom is too sandy to
afford them foothold. In this littoral zone, besides the host
of forms of lowly organization, the ancestors of which have
never been, so far as we know% occupants of the land, there
are many species which have adapted themselves by curious
transformations of structure and habit, so that they have been
able to work down from the dry realni into the sea. Along
the high tide line we tind sundry species which have overcome
the destructive effect which salt water has on the roots of
most land plants. Farther down on the marshes other species
have extended their experience so that they can live, provided
their upper parts are bared at high tide. Yet deeper there
are other forms, such as the eelgrass, which can perform all
their functions and flourish greatly, though they are altogether
within the water. One or two groups of trees, of which the
species of mangrove are the most important, have become
specially modified, so that they may make head against the
sea in embayed waters even where they are miles in width,
gradually extending the margins of the forests over the shal-
lows to the border of the deep waters. In Florida some
hundred thousand acres have thus been won from the sea, and
in the more tropical areas the gain of the land which is thus
brought about is of yet greater importance.

LOW GRADES OF MARINE LIFE 93

Although the animal forms of the deep are proportionall)'
far more diversified, and attain to relatively higher states of
life than the plants of that realm, they are also much inferior
to their relatix'es of the land. Each of the great ty[)es has its
representatives among the marine forms, and certain of them,
as for instance the group of animals commonly known as
radiates, to which the polyps and star-fishes belong, arc, with
some trifling exceptions of species which live in fresh water,
confined to the sea. But all the mammals, birds, and insects,
the groups which contain the intelligent animals, are essen-
tially the creations of the continents ; the few members of the
series which have developed close and permanent relations
with the ocean, such as the whales, penguins, and rare marine
insects, have clearly been derived from characteristic land
forms, which, in the rude struesrle for existence, have been
forced to resort for subsistence to the sea. The greater part
of the higher species avoid the sea, for it is to them a place
of death.

Nothing is clearer than the fact that all our land animals
have been derived from parent stocks which had their origin
in the waters ; it is not so certain as to plants, but it is proba-
ble that they, too, were first nurtured in the sea. In the land
areas these great groups of animal and vegetable organisms
attain their perfection. The articulates and vertebrates are
at their best above the level of the waters, and in them alone
do we find intellectual species. How does it come about that
though the deep has been the cradle of these varied creatures
it has not been the place of their fuller development ? The
answer is plain, and in it we shall lind some most important
teaching. A common view of the action of natural selection
is, that, oriven a full measure cf increase and a fair share of

94 SEA AND LAND

variation, the stru<^gle for existence will brine;' about a stead-
fast gain in the fitness of a form for the duties of life in its
proper station, and that in time almost any measure of ad-
vance may be attained. But the failure of the marine forms to
\\\\\ their way to the organic and intellectual successes of the
hit^her life is suf^cient evidence that time and struijorle. infinite
toil and pain, ceaseless life and death, will not alone enable
species to win the upward way. Many other conditions,
which, in a question-begging manner, we terni the influences
of environment, must ent(;r into the inconceivably complicated
equation which determines the fate of living beings. The
struggle for existence has been as bitter in the seas as upon
the land, it might well be maintained that it is far more intense
in the water than in the animal realm, and it has endured for
a greater time. What, then, is the reason for the lagging
behind of the marine creatures ?

It may well be that this slow advance, or rather, we should
term it, this wide-spread failure of the aquatic life in all that
regards elevation in structure and function, is due to many
different causes ; but there is one cause which may, of itself,
perhaps, in large part, account for the tardy evolution of the
inhabitants of the sea. This is the imperfect nature of the
breathing process which is inevitable in all truly aquatic
animals. Marine animals necessarily depend for their process
of respiration on the small amount of air which is dissolved
in the water, a part of which they appropriate by means of
their gills. The result is that in proportion to their size a
gill-bearing animal, at best, has perhaj^s not the tenth part
of the access to oxygen which is enjoyed by the ordinary
land forms. Now, on the amount of this gas which comes in
contact with the blood depends the share of nervous energy

HABITS OF MARINE ANIMALS 95

and muscular power of an animal : the force which propels
their bodies or their brains is as much a matter of combustion
as that which is generated in a steam boiler. This respiratory
process is necessarily slow in all gill-breathers, which take the
air from the exceeding dilution in water where it does not
constitute one-hundredth of the mass, as compared with lung-
breathers where the oxygen can be supplied as rapidly as
needed. There is another condition of the sea which has,
doubtless, much retarded the. advance of its tenants : the
greater part of its life dwells in utter darkness. At one
hundred feet in depth the vertical sun yields only a twilight,
and below one thousand feet it is perpetual night. As a large
part of intellectual life depends upon the knowledge acquired
by sight, we easily perceive that the utter darkness of the
deeper sea is most unfavorable to the development of intelli-
gent beincrs.

With this understanding of the general limitations of
marine life, we are not surprised to find that the animals
of the sea are almost completely lacking in habits of an
intellectual order. Save in a few forms, as, for instance,
the species of tish which weave a rude nest of sea-weed, the\-
make no constructions such as are so commonly produced by
land animals. They rarely emit any sound in the nature of a
sexual call ; they never dwell in organized communities of
a social sort ; the sexes rarely if ever mate, even for a season.
With them life in general has not risen above the plane of
mere existence. The only marine animals which have been
observed to have any distinct marks of intelligence are the
forms which have the habit of resorting to the shore, espe-
cially the seals, which are descended from the land animals
in the kinship of our bears and dogs ; and are. in fact, not

96

SEA AND LAND

properly to be classed as marine animals, at least in their
more essential qualities. There seems to be not sufficient
nervous energy to spare from the ceaseless turmoil of the
combat which goes on among the creatures of the sea, to
afford the basis for intellectual development. All the small
share of force which these animals with their scanty supply of
oxygen can engender goes to the labor of flight and chase ;

Antennarius .

A creature related to our shore goose-fish, but adapted to live in water of moderate depth.

the ceaseless struggle to obtain food or to avoid falling a prey
to their enemies. Although the mental processes of these
creatures of the deep are limited, their physical growth is
marvellously vigorous, and creates an amazing variety of
forms, which are so far hidden below the veil of the waters
that even the eager search of the naturalist has but imper-
fectly disclosed them.

POPULATION OF THE SEA 97

The Immediate conditions of aquatic life differ in many
Important \va}'s from those of the hind. In the hitter realm
the weight of the animal or plant Is not sensibly diminished
by the buoyancy of the air ; the result is that the creatures
have in all cases to dwell mainly on the ground ; even the
most volant of the birds and insects spend the greater part of
their days on the surface of the earth. The result Is that the
quantity of these land forms M'hich can find a place for exist-
ence is determined by the room afforded by a shallow zone
next the soil ; the depth of this stratum Is practically limited
between the bottom of the true soil and the top of the vegeta-
tion which occupies its field ; in other words, the stratum
occupied by organic life on the dry land Is limited In thick-
ness to a few score feet, and in the vast treeless regions is
but a foot or two in vertical extent. In the oceans, however,
because the greater part of the creatures may freely float or
swim In the water, the realm which living things can occupy is
vastly greater. It may extend from the surface downward to
the depth of four miles or more. It is true that the most
inhabited sections are upon or near the bottom, and within a
short distance of the top of the water ; yet the whole of the
deep is open to certain groups of beings, and probably has a
share of occupants. The result is that, to each square mile
of ocean surface, there are usually many times the number of
individual beings which we find in an equal area of the land.
As each of these creatures dies, even If it live out Its terni
of existence, its bodily parts are likely to become the food of
many hungry mouths which are exactly adapted to the task
of bringing its carcass back to the living state. Something of
this same speedy conversion of the dead to the uses of life
is seen upon the land ; but what we see there affords but
7

98

SEA AND LAND

an imperfect image of

^'Vvi*"*'-

Figure of a Free Polyp Comrmunl'ty, re-
lated to the Sea Fans

Each little serration on the leaflets
of the frond-like body is a separate
individual.

the swiftness with which the translation
^roes on in the sea.

The movements of the organic
machinery in the deeper seas, unlike
those of the land, are unaffected by
the process of seasons. In the shal-
low water next the shore the sum-
mer's heat and winter's cold have
some effect upon their tenants. In
winter, at least in high latitudes,
fishes, with rare exceptions, especially
the schooling species, desert the
shores, and many mollusks migrate
into deeper waters ; but in the pro-
founder sea, where neither day nor
night, summer or winter, brings any
pause to the contest of life or any
change in its conditions from age
to age since these abyssal regions
became first tenanted by organisms —
the contest has been without any of
these pauses of the winter sleep,
which on the land is evident, even in
the tropics as well as in high lati-
tudes.

This continuity in the organic
history of marine creatures makes it
possible for a number of singular
communities of animals to develop
in its waters, the like of which are
unknown in the regions which are

ORGANIC COMMUNITIES

99

enveloped by the air. In the hitter reahii all the aninial
species consist of separate individuals which may be associ-
ated in intellectual communities and colonies, such as those of
the bees and ants, or in the herds of the herbivora or the
flocks of birds ; but in no case do we find them united by a
physical bond. It is otherwise in the sea. There, many
groups consist of individuals which are knit together in the
manner of the polyps and sponges; the several animals often

, ,i,„ vij.

Figure of a Sponge, such as Inhabits the Deeper Parts of the Sea

to the number of millions combining their bodies to form vast
organic associations, which may build the monumental struc-
tures of the fringing, or atoll reefs. This structural union in
the life of the marine animals is paralleled on the land in the
plants where many separate buds are associated in a single
bush or tree, but none of the land animals have any such
union of their bodies ; such associations are possible in plants,
even in regions where there is winter cold, because they
become essentially lifeless while the frigid conditions prevail.
It is easy to see that it would be quite impossible for the

lOO SEA AND LAND

more highly organized animal creatures to enter on such
combinations in the open air.

Another peculiarit)- in tlie environment of aquatic animals
depends on the capacity of water for floating substances. All
these forms on the land have to be endowed with the power
of moving that they may seek their food, but in the sea the
water floats the food to many waiting mouths, and the creat-
ures may dwell fixed to thc^ same place on the bottoni from
their birth to their death, waiting patiently for the currents to
bring thcMii their nourishment. All the corals and sponges,
and nearly half the mollusks, obtain their supply of food in
this manner; perhaps one-half of all the marine species trust
to this chance of gathering their aliment from the passing
water.

For a century or more naturalists have known a great
deal concerninir the marine organisms which dwell in the
shallow water next the sliore. They long ago learned the
amazing richness of these littoral forms. The census of
species amounts now to more than one hundred thousand
distinct kinds ; it is, however, of late that tliey have ascer-
tained that the deeper parts of the ocean-floors have also an
abundant and varied ])eopling. Although the study of the
abysmal life of the seas is but just begun, and the knowledge
which has been gained is probably but a small part of that
which will be gathered during the coming years, the results
of the incpiiries, in many ways, are not only most interesting,
but in the highest degree important in shaping our views con-
cerning the origin and history of organic life. These creat-
ures of the abysmal regions of the ocean appear mainly to
have been derived, by a process of variation, from those
which once inhabited the shallower waters next the shore.

CONDITIONS OF DEEP-SEA LIFE

i<:)\.

The greater part of these shore dwellers are exceedingly
intolerant of the enormous pressure of the deeper waters, as
well as of the low temperature and total darkness which exist
there. Certain forms have, however, acquired the ability

A Group of Fishes of Peculiar Form, such as Inhabit M'^derate Depths in the Sea

The bottom form is a flounder, with both eyes on the same side of the head to fit it for lying flat upon
the bottom. The third from the base of the picture is provided with fringed appendages which attract the
attention of its prey, and bring them so near that they may be captured in one leap.

to withstand these peculiar conditions; generation by genera-
tion through the geologic ages they have crept away from
the realms of tierce combat next the shores, to the less con-
tested fields of the open and deeper seas. Through all the

'T02

SEA AND LAND

geologic ages this selection of especially prepared groups
for the singular stations or habits of the ocean depths has
been going on, with the result that those dark and pressure-
burthcned regions are now tenanted by many eminently
peculiar animals, by species which ever surprise the student
who is accustomed to the forms which dwell only near the
shores.

One of the most strikino; features connected with the

animals of the deep
seas, is the frequency
with which we find
there living species
which remind us of
kinds which in former
geologic periods
dwelt in the coastal
districts of the
oceans. It seems
that many of these

A fish of singular form from the open sea, and possibly inhabiting a U C 1 6 U t CreatUreS
the greater depths.

when they no longer
could hold their own against the more highly organized and
developed animals which inhabited the favored stations next
the shores, shrunk away into the deep water, and in that
undesired part of the world found an asylum, where, amid
the changeless environment, they have dwelt for ages, unal-
tered. Thus the vast profounds of the deep have become a
sort of almshouse, whereunto anticjuated species have retired
before the overwhelming pressure which the newer and
higher life ever imposes. From the results of the relatively
trifling explorations which have, as yet, been made, there

Sternoptyx Diaphana

EYES OF DEEP-SEA ANIMALS 1 03

seems good reason to hope that in time we may win from the
deep the nearest living representations of many creatures
which once occupied a large place in the seas, but now have
abandoned the fields of more active combat, which are usu-
ally the seat of the greatest advance.

In the profounder seas the invertebrate life appears to
have a larger share than is secured by the vertebrate, or back-
boned animals ; yet there are a number of fishes known in
these depths, and it seems likely that these tenants of the
deep sea may be numbered by thousands of species. Among
the finned tenants of the deeper parts of the ocean, we find
some startling departures from the types with which we
are familiar in coastal waters. In general shape they differ
little from their kindred which dwell in the sunlit shallows.
The differences are largely in the mechanism of the senses,
especially of the eyes. These organs undergo surprising
variations with reference to the enduring of the darkness of
these deeps. In certain of the species the sight not only
fails, but the visual apparatus entirely disappears ; in others
the eyeballs become very much enlarged and the nervous
apparatus increased ; they are evidently arranged to catch
mere glimpses of light. As it is certain that no trace of sun-
light can ever penetrate through the deep which overlies the
realm where these animals dwell, the adaptation of these eyes
to the needs of difficult vision at first appeared to be a very
inexplicable matter. Some recent discoveries provide us with
what seems to be an adequate explanation of the enigma.
It has been found that certain of the denizens of the deep
sea-floors have phosphorescent parts of their bodies which
serve to crive lieht in the manner in which it is yielded by
the familiar fire-flies and glow-worms. The end secured by

I04

SEA AND LAND

these light-givinc^ parts is probably the attraction of the
sexual mates of the creatures. In the utter darkness of the
ocean this indispensable end could be so well attained in no
other way ; even the fishes appear to have this beautiful pro-
vision for avoiding one of the most serious evils of the dark-
ness in which they are compelled to exist.

It is evident that the fishes with large eyes would also
have a decided advantage in the pursuit of food, for their

keen vision would
enable them to dis-
,,^r3r!^ cern the glimmer
of the phosphor-
escent light for
some distance
through the still,

A Member of the Genus Scopelus cleaT WatPT Thc

Showing the large eyes common in fishes which swim in the depths rl iffinill-\7' nonipc in

of the sea to which the light of the sun does not penetrate. The eyes J

are probably specially adapted to perceiving the phosphorescent glow fl-,/^ rncp> nf tlTnc:F>
of various animals.

fishes which under
the same general conditions of existence in darkness, com-
bined with the same need of food, and of finding their
mates, have not only failed to better their sight, but have
abandoned it altogether. There is, perhaps, no other simple
instance in which we may so well perceive the cardinal diffi-
culty which the extreme selectionist encounters in his effort
to explain all the complications of the organic world by the
single hypothesis of the survival of the fittest. Here are
two groups of like creatures introduced to the conditions of
utter darkness after long ages of experience in the realms
of light ; under circumstances which, so far as we can perceive,
are absolutely identical, the creatures enter upon v»'idely diver-

LIFE OF THE WIDER SEAS 105

gent paths of variation. The lesson we may read in these
facts seems plain ; it is to the effect that environment alone is
not always competent to determine the way followed by a
species in its process of change.

In the sunlit regions of the surface of the open oceans,
even in the under water of the sea, down to the utmost
depths to whicli the light penetrates, we have a zone of
waters in which the variety of form is limited, and the greater
part of them belong to the lower orders of being. From this
part of the sea few fishes have been obtained, for the creatures
are able to dwell only where there is an abundance of food.
In this zone the most interesting forms are the lowly protozoa
wdiose bodies, to the eye, appear as mere bits of translucent
jelly, essentially unorganized, but which secrete shapely shells,
showing that the apparent simplicity which they present to
our eyes is due to our imperfect knowledge of them. Dwell-
ing in myriads in the superficial parts of the sea, these foram-
inifera, as they are termed, sink at death to the bottom, over
which they accumulate a thick coating of minutely divided
limestone powder, forming a layer of ooze as unsubstantial
as the finest snow. A large part of the North Atlantic, par-
ticularly that vast level tract beneath the central portion of
the sea, known as the telegraphic plateau, because it was
crossed by the first telegraphic cable which was laid, is cov-
ered with this chalk-like substance. Along with these shelly
bits derived from animals which have dwelt near the surface,
there go into the waste which accumulates on the floor, the
remains of creatures which dwelt upon the bottom ; thus it
comes about that the fossils which we find in any stratum may
have been nurtured under very various conditions: in part
they may have dwelt on the floor of the deep sea, in the cold

io6

SEA AND LAND

'^mmi

^A

^^=«-

and dark waters of these regions, and, in part, in the tropical
climate of its surface.

We have already alluded to the coldness of the water
wliich is found at great depths beneath the surface of even the
warmest parts of the open oceans. Wherever in such situa-
tions examinations of the temperature at the bottom have

been made, it has been found to
be very near the freezing point.
There seems to be but one
possible explanation of this sin-
gular fact, which is the follow-
inof, viz. : On the surface of the
oceans there is a system of
warm currents, such as the
Gulf Stream, which flow in
great volume from the tropics
toward the poles. These tides
of water have to be, in some
manner, returned to the trop-
ical districts. In part this is
effected by certain counter cur-

A member of the Foraminifcra, a group of
lowly animals which live in the superficial parts reUtS wllich Set SOUthward alottg
of the warm open sea, and whose remains fall in

great quantities to the bottom. (Much manni- the SUrfaCe of the Sea \ but
fied.)

the volume of these superficial
movements flowing toward the tropics is small as compared
with the streams which flow over the surface into the circum-
polar seas. The principal return or compensating movement
of the water appears to be brought about by a massive drift
of the fluid which has been chilled nearly to the freezing point
in high latitudes and then creeps, probably with extreme slow-
ness, along the bottom until it may attain the equator. There,

Globergerina

VOLCANIC DUST ON OCEAN-FLOORS

107

very gradually, it rises and takes the place of the part of the
sea-water which has been driven away by the currents moving
toward the arctic and antarctic regions. The prime movers
of the superficial streams, like that which flows from the Gulf
of Mexico to the North Atlantic, are the trade-winds; and
thus it comes about that the really arctic climate of the deep
sea-floors of all the open oceans is caused by these wonderful
permanent winds.

On the bottom of all the seas there is constantly gathering
a coating of materials derived
from the bodies of animals and
plants which perish there, or
which fall down upon the floor
from the higher parts of the
water ; with this is mingled,
more or less finely divided
rocky matter. If the portion
of the submarine surface where
the accumulation is making is
near the coast line, these sev- Tomopteris

eral mineral substances may a curious wormUkeanimal inhabiting the surface

of tropical seas.

be derived from the land and

brought into the sea by the rivers or dragged away from
the beaches by the reflux of the tides. In high latitudes
the icebergs raft off from the land quantities of stony frag-
ments which, when the ice is melted, fall swiftly to the bottom.
But this importation of detritus from the continents can aftect
but a small portion of the ocean-floors : it is probable that the
greater part of the sediment, other than that derived from
orcranic remains which come to rest on these surfaces, is
thrown out from volcanoes. The amount of these ejections

I08 SEA AND LAND

from active craters is very great. It seems certain tliat in a
little over a century the volcanoes of the Javanese district
alone have cast into the sea not less than one hundred and
llfty cubic miles of dust and pumice. As this matter con-
tains a good deal of gas in the forni of small vesicles, it may
float to a great distance and undergo much chemical change
before it finally comes to rest on the ocean-floor. Each bit
of this pumice or ash may indeed journey all the world about
before it is decayed and falls to pieces or is weighted down by
the small animals and plants which adhere to its surface. The
(juaiUitN- of this igneous matter which is cast into the sea is
probably far greater than that brought down to the deep by
all the rivers, and in volume the contribution is probably only
exceeded bv that which is worn from the shores of the sea
itself by the action of the waves and tides.

In the endless procession of fragments which are brought
to the ocean-floor by the very varied actions which lead, in
time, all things down to its depths, there perhaps to await
their far-off resurrection into continents which are yet to be,
we must reckon the remains of man himself ; the debris of his
body and his arts which strew that portion of the earth hidden
from our eyes by the sea. There is a rather common, but
erroneous notion, to the effect that a human body, or even a
ship, will not sink to the bottom of the profounder abysses of
the oceans, but will, on account of the density of the waters
at a great depth, remain suspended at some distance above
the surface of the earth. This is an error. No other fate
awaits the drowned sailor or his ship than that which comes
to the marine creatures who die on the bottom of the sea ; in
time their dust all passes into the great storehouse of the earth
even as the ashes of those who receive burial on the land.

Suggestions as to the History of a Sunken Ship

In parts of the sea near the shore, where the accu-
mulation of sediment is rapid. Of the two ships
upon the bottom, that in the foreground must have
come to rest centuries before the other.

However deep the sea, it is but
a few hours before the body of a
man Avho finds his ofrave in the ocean
is at rest upon the bottom ; it there
receives the same swift service from
the agents which, in the order of
nature, are appointed to care ior the
dead, as comes to those who are rev-
erently inhumed in blessed ground.
All save the hardest parts of the
skeleton are quickly taken again
into the realm of the living, and
even those more resisting por-
tions of the body, in time are,
in large part, appropriated by

no SEA AND LAND

the creatures of the sea-floor ; so that before the dust returns
to the hrm-set earth it may pass through an extended cycle
of Hving' forms.

The fate of animal bodies on the sea-floor is well illustrated
by the fact that beneath the waters of the Gulf Stream, where
it passes by southern L'lorida, there are, in some places, quan-
tities of bones, apparently those of the manitee, or sea-cow,
a large herbivorous mammal, which, like the seal, has become
adapted to aquatic life ; these creatures plentifully inhabit the
tropical rivers which flow into the Caribbean Sea, and are,
though rarely, found in the streams of southern Florida. At
their death they drift out into the open water and are swept
away to the northward by the ocean current. For some
weeks, perhaps, the carcasses are buoyed up by the gases of
decomposition which are retained by their thick, oily skins ;
as these decay and break, the bodies fall to the bottom.
When the dredge brings up fragments of their skeletons we
find the bits bored through and through, like insect-eaten
wood, by the many animals which are fitted to consume them.
It is evident that in a short time these bones become reduced
to j)Owder.

It is otherwise with the ships wliich founder in the deep
sea. They doubtless remain for centuries as monuments of
the strange doings of the masterful creature of the land.
Whatever the attitude of the craft when it is overwhelmed by
the waters, it is likely that a moment after it descends below
their surface, it rights itself, assuming the position it occupies
when sailing in quiet waters. The weight of the ballast neces-
saril)' brings il into this position. In this attitude the vessel
falls steadfastly-, but not very swiftl)-, until it strikes the bot-
tom. It may require in the average depth of the sea, which

HUMAN REMAINS ON SEA-FLOORS 1 1 i

is about three miles, a quarter of an hour or more before an
ordinarily laden wooden ship finds its long resting- place.
The blow with which it strikes the sea-lloor is not likely
to dismast the vessel or to wreck its hull ; the shock usually
comes upon mud-like materials, sufficiently yielding to give
a little to the blow, so that the violence of the contact is
diminished, and the upright position and integrity of the hulk
may be maintained.

As soon as the sunken wreck is at rest we may imagine
that it becomes the subject of careful inc^uiry on the part of a
host of hungry creatures who await such ivindjalls from above.
Penetrating the spaces of the hold they make avail of all that
can serve them as food. More slowly certain forms, which
bore in wood, will honeycomb all the timber until the beams
and planks are reduced to mere shells. At the same time a
host of species which have the habit of attaching their living
■skeletons to any firm support, crust over and festoon with
their bodies all the external parts of the wreck, and serve to
bind the frail structure together. In the course of time the
fabric becomes a mere ghost of a ship ; it holds together only
because the ocean is perfectly motionless, and its parts are
buoyed up by the water about them. In the course of ages
the weight of the incrustation increases, so that at last some
part is borne down, and through the shock which this causes
the shadowy relict may at once melt into dust.

We must conceive a somewhat different fate for the
modern iron ships which find their last haven in the quiet
waters of the ocean-floor. Because of their greater weight
they will fall more swiftly and strike with greater violence on
the bottom. They are, on this account, more likely to be
ruined by the last blow they are to receive. Moreover their

I I 2 SEA AND LAND

Iron sides and beams afford no food to the marine animals ;
nevertheless they are attacked by the sea-waters, and tlieir
decay probably proceeds so rapidly, and the gravitative
energy of their metallic parts is so great, that they more
c|uickly fall into ruins, which can hardly be as picturesque as
those of the older type of vessels. It is doubtful if the
wrecks of any of the modern men-of-war which have foun-
dered at sea will hold together for fifty years, while those sunk
during the action of Trafalgar may endure for centuries in the
grim semblance of battle ships.

The idea that ships are likely to be buried in the accumu-
lations which are forming on the deeper sea-floor, rests upon
a mistaken conception as to the speed with which sediments
are laid down at a distance froni the shore. These deposits
of the open oceans are so slowly made that we must deem it
excessive to suppose that a depth of a single inch can be
formed in a thousand years. It is likely that in no case, save
near the coast-line, or in the rare places where the showers
of volcanic waste bring an unusually large amount of detritus,
can a ship be buried in the accumulating strata so as to be
preserved in a recognizable form. If the creatures of the far
future, to whom it ma)' l)e given to scan the rocks which are
now forming and are hereafter to be uplifted into dry land,
are to find a trace of their remote ancestors in the deposits,
they will secure it, not by discovering the hulks of great
vessels, probaljly not from the bones of men or the common
implements which serve them in seafaring, but from the
objects composed of glass, or more likely those made of the
rarer metals such as gold and platinum. Of the vast wreck-
age of an iron war-ship such as the "Captain," which sunk in
the Bay of Biscay, the hulk, great guns, shot, and shell, the

ASPECT OF WRECKED VESSELS II3

timber, and all the forms of its crew will probably disappear
before they are entombed in the slowly gathered strata. The
geological reniainder will perhaps be the coal of her fuel
store, the gold of the watches and trinkets, and the massive
glass objects which abound in such a ship ; in all but a small,
and little indicative, part of what went to the bottom of the
sea when the vessel foundered.

It has, to many persons, been an interesting speculation as
to the aspect of the countless wrecks which have been swal-
lowed up by the North Atlantic since that churn of waters has
been ploughed by the keels of ships. Their number is prob-
ably to be reckoned by the tens of thousands, and the greater
part of them lie in a comparatively small part of that field.
If we count this portion of the Atlantic which is most peopled
with wrecks as having an area of 3,000,000 square miles, and
estimate the total number of such ruins within this space as
30.000, we would have an average of one sunken ship for each
hundred square miles of surface. If all these crafts were at
once sailing over the surface of the sea, we should, from the
deck of any one of them, be likely to note the masts of several
others. But as they lie on the tloor of the ocean the greater
part of them are probably reduced to low mounds of rubbish,
so that if the ocean-floor were converted into dry ground, and
we crossed it in a railway, seeing the fields as we do the
prairies, it would require an attentive eye to discern the exist-
ence of many of these remains.

It is a singular, and perhaps somewhat humiliating fact,
that the most conspicuous and indelible record which man is
making in the strata now forming on the sea-tloor is written
in the bits of coal and ash which are cast from our steamships
as they pursue their way over the ocean. The quantity of

I 1 4 SEA AND LAND

this debris is very great, and unlike tlie wrecks it is very
evenly scattered along the paths followed by our steam
marine. It is likely that already in the track of our trans-
atlantic commerce, not a square rod would fail to give a
trace of this waste from our coal-burning engines. As this
material is not attacked by the marine animals, and is but
little affected by the other agents of decay, it will doubtless
be very perfectly preserved in the strata which are to bear
the records of our time.

ICEBERGS

Effect of Expansion of Water in Freezing.— Classes of Ice-Fields.— Orit^in of Ice-Floes. —
Migrations of Icc-Fioes. — Origin of Icebergs. — The Greenland (llacier. — Annual
Product of Icebergs ; their Voyages ; their Effect on the Ocean ; the Order of their
Movements ; their Decay ; their Gener.d Influence on Climate. — Transportation of
Rock Debris by Icebergs. — Effect of lee on Shores. — Iceberg Work in Former
Geological Periods. — Dangers to Ships from Collision with Icebergs.

Much has been said by optimists concerning; the many
advantages which arise from the simple but most exceptional
fact that, while all other substances contract, water expands in
passing from the fluid to the solid state. The consequences
of this peculiarity are indeed not overstated by those who
take an excessively pleasant view of man's relations to the
world about him, for the simple reason that it is not easy to
exaeeerate the beneficial effects which arise from them. If
water did not depart from the general law that substances
occupy less space in their solid than in their liquid form, the
ice on our seas and lakes would, as fast as it formed, sink to
the bottom, so that all the oceans and other water-basins in
high latitudes would normally be frozen to their floors, except
when the summer's heat had melted a thin hu'cr next the
surface. If it were really worth the while to theorize con-
cerning things which are out of the present order of nature,
we might easily show that such a condition of affairs would
make the earth essentially unfit for the uses of civilization.
It will, however, be more profitable to consider the points
which the pessimist might take, if his ever-smiling adversary

I I 6 SEA AND LAND

pressed the profit arisini;- from the fact tliat water expands, in
freezing, too far for patience to endure ; to show, in a word,
the list of considerable disadvantages which arise from this
law, which serve indeed, in some part, to countervail the
blessings it brings to us. In his argument he would have to
depend in the main upon the dangers which arise from the ice
which drifts from either Pole into the parts of the sea which
ships need to traverse, bringing with them an atniosphere of
fog, which, rendcM'ing the floating islands almost invisible,
adds much to the risks of navigation. These ice-masses not
onh' endanger vessels, but they chill the waters of the sea in
such a measure that, l)y the cold and misty air which sweeps
thence upon the land, extensive regions, like the island of
Newfoundland, are made unfit for agriculture. These migra-
tions of icebergs are nianifestly due, in the main, to the fact
that ice floats ; if it sunk, whatever other costs this condition
entailed, there would be no wandering ice-fields in the seas.

To understand the conditions which lead to the existence,
even in midsummer, of fioating islands of ice within the
warm nortliward-s(,-tting waters of the Gulf vStream, it is neces-
sary for us to consider many facts concerning the natural
history of ice, and the physical condition of the regions from
which these bergs are derived, as well as that of the districts
through which they journey to the central portions of the
North Atlantic; fortunateh' for our purpose, all these facts
are very interesting, and some of them are of the most pictur-
csc[ue features which the aspects of this world afford. The
biography of an iceberg brings us in contact with the frozen
regions about the Poles, and with the marvellous ocean cur-
rents which transport the tropical waters to those regions,
and with those other streams which send, in return, waters of

CLASSES OF ICE-FIELDS i i 7

nearly freezing temperature clown toward the equator. The
simpler phenomena of freezing and frozen water, which we
shall incidentally have to consider, are attractive parts of the
science of physics, for the reason that they are easily com-
prehended and are well illustrated by familiar and personal
experiences.

The ice which travels from the Arctic regions toward the
equator consists of two very different kinds of masses, the
difference being so plain that they are invariably recognized
by all observers; in part they are made up of flat or tabular
masses, which seldom if ever have a thickness of more than
one hundred feet even before they have begun their journey
to lower latitudes. Though limited in depth these fields of
floe-ice, as they are commonly termed, often have a great
horizontal extension. Near the southern extremity of Green-
land they sometimes have an area which is to be measured
by square miles. Though interesting, these floes have less
economic or geographic importance than the group of true
icebergs, for the reason that they do not journey so far from
their point of origin, and rarely come into the ordinary paths
of commerce. The true icebergs differ from the ice-floes in
that they are vastly thicker and do not have the same table-
like tops, but are usually serrate at their summits. It is
impossible to determine by actual measurement the depth of
the ice in the true berg, but we know from the specific grav-
ity of frozen water that only about one-seventh to one-ninth
of their mass rises above the level of the sea, and we can
safely infer from the extent of the emerged portion that their
bases are often two or three thousand feet below the surface
of the ocean. This estimate, though it does not need con-
firmation, is fairly proved by the fact that many bergs have

ii8

SEA AND LAND

been observed to run agrountl in water of this depth. These
o-reat variations in the proportions of ber^;s and floes afford
a fair presumption that there is some essential difference in
the origin of these two classes of ice-islands. A glance at

II""

%^

TtT^

View on the Coast of Greenland
Showing small bergs intermingled with floe ice, with polar bears in foreground.

the processes by which ice is made in high latitudes will show
us that this h)pothesis is amply justified.

When the Arctic explorers or the whalers make their way
to the fringe of small settlements which lie upon the western
margin of Greenland — the only part of that vast area which
is ever indeed green — they usually begin to encounter the
floe-ice, and as they go northward it increases in thickness
and in the extent to which it obstructs the surface of the sea,
so that the ships are compelled to creep through the rifts

ORIGIN OF ICE-FLOES II9

between the ice-fields, the narrow lanes of water which, now
opening, now closing-, afford most perilous and difficult ways
to the higher north. I'inally, where the western shoulder of
Greenland and Grinnell Island narrow the passage which
leads into the Arctic Sea, the ice is so firmly held together
that it has never been found sufficiently fissured to afford
room for the passage of the smallest boats. Thence on to
the long-sought but apparently inaccessible Pole, the sea is
covered with a connected sheet of ice, the upper surface of
which is exceedingly rough and hummocky, so that it is
impassable for sledges. The vast region covered by this
sheet of floe-ice, which probably has a depth of one hundred
feet or more, has been termed the Pakeocrystic Sea, or the
Sea of Ancient Ice. It is clear that its envelope of frozen
water is but a more consolidated area of sheet or floe accumu-
lations— in other regards exactly like the fields which float
out of Davis Strait and move down the coast of Labrador
until thev invade the Straits of Belle Isle, and through this
channel penetrate into the Gulf of St. Lawrence or crowd
into the inlets of northern Newfoundland.

It is evident that the origin of this floe-ice is as follows,
viz.: In the long winter of high latitudes the surface of the
sea, wherever it is not affected by the warm waters of the
south, freezes so that a considerable depth of ice is made. A
single winter will often accumulate it to a thickness of ten
feet or more. In the short summer this ice only in part
melts away, and the next season adds still more to it. When
the sheet breaks up into separate fields, these masses, often
square miles in area, are set in motion by the tidal currents
or the strong winds ; they collide with each other and with
the shore, and by these accidents the cakes of ice are shoved

I20 SEA AND LAND

over and under each other, thus thickening the floes in a very
rapid manner. As soon as these cakes of ice come to rest
in their new position, they are soklered together so that the
floe is a solid mass wliich ma)' drift away for great cHstances
in the control of the winds or the shallow currents of the sea.
So massive are they, indeed, and so vast in number and area,
that but for the nature of the current systems of the North
Atlantic, they might greatly embarrass the main line of ship
travel between the northern parts of Europe and those of the
northern United States and Canada; but the direction of
their southward migration is, as we shall now note, greatly
affected by the ocean currents.

All the superficial parts of the western Atlantic, except the
portion of its area next the coast of America, are pervaded
by a slow movement which sets the water toward the Poles.
This current is due to the Gulf Stream, which, emerging from
the troj^ics as a deep, narrow, swift-moving tide, skirts the
southern coast of the United States, gradually widens like an
opened fan, diminishing in depth and losing its velocity as it
comes toward the Arctic Circle. Although the speed of its
northward going is here slight, it has sufficient energy to push
l)ack the floe-ice which may be driven southwardly by the
winds, and thus limit its excursions to the American shore.
Setting out into the Atlantic from Davis Strait, there is, how-
ever, a strong stream of .Arctic water, which in part slips
under the Gulf Stream tide, and in part flows on the surface
of the sea next the Labrador coast. In this southward-setting
current the floe-ice drifts with a speed of about a mile an hour
down the American shore until it attains the mouth of the St.
Lawrence. The Labrador current, as this southward-movincr
water is called, would, Init for certain accidents of geography.

MIGRATIONS OF ICE-FLOES 121

send this floe-Ice much farther to the southward than it now
does. If Newfoundhmd and Nova Scotia should disappear,
so that there could be a nearly straight shore from Greenland
to Massachusetts Bay, it is likely that these Hoes would in
large quantities attain to the coast of New England, and give
to the shore lands of that part of the continent the sub-Arctic
and inhospitable climate of the islands of the eastern St. Law-
rence. This shore current bears few true icebergs with the
floe-ice, for the reason, as we shall see more clearly hereafter,
that these greater ice-islands are formed altogether on the
Greenland shores, and, pressed to the eastward by the pre-
vailing winds, do not come into that superficial, shore-skirting,
Labrador current. Moreover, any stray bergs that may find
their way against this margin of the mainland are almost
certain to take the ground in the shallows over which the
current passes, and so be arrested in their journey.

The character of the ice-floes, as well as the steadfastness
of their southward journeys, are well shown by the singular
experiences of a part of the crew of the exploring ship Polaris,
who, in 1872, were forced to abide for several months on these
ice-rafts. The ship was in close quarters in the ice-pack of
Baffin's Bay, and was pinched between the floes with every
prospect of being crushed like an egg-shell between the mov-
ing masses ; the crew, with supplies of provisions and boats,
were encamped, in two separate parties, on the ice near the
distressed vessel. A sudden change in the movements of the
ice caused the floes to separate, and one of the parties was
swiftly borne away from the ship, which, indeed, they thought
had sunk from the strains she had received in the squeezing
between the packs of ice. The forlorn party, consisting of a
score of sailors, several Esquimaux men, two women, and

122 SEA AND LAND

several children of that people, drifted away to the southward,
and for the time between October 15th and April 29th found
refuse on the lloe-ice, and were carried onward toward the
open Atlantic. As they came into the wider waters the waves
swept over the Hat surface of the ice and broke the original
wide field into small patches, each a few acres in extent, so
that they had from time to time to select a new refuge.
Their sufferings were considerable, but with the couraire and
hopefulness characteristic of our sailors, they undauntedly
met their difficulties, each dutifully caring for the other, so
that when rescued by a passing ship every meml)er of the
party was alive. The chronicle of this wonderful adventure
is one of the most picturesque stories of bitter experience and
fortitude which the literature of Arctic adventure affords.

In the regions about the Southern Pole, because of the
vast area of ice which is gathered there, the climate in sum-
mer is much less calculated to melt ice than in the region
about Greenland. The large area of this southern ice-cap is
caused by the failure of the warm currents from the tropics
to attain the Antarctic Circle? ; this is brought about by the
absence of any distinct land-bounded pathway of the waters,
as exists in the North Atlantic lands, which, in a way, serves
to confine; the; (iulf .Stream and lead it to the Arctic regions.
Moreover, the southern currents, which are diverted toward
the Antarctic Sea, are less strono; than those which flow north-
wardly from the equatorial parts of the oceans. Owing to the
frigid condition of the summer climate of the southern ice-dis-
trict, and the absence of warm water to melt the ice, the floes of
that region are thicker and form more extended fields than those
with which explorations of the Greenland district have made
us acquainted. Fortunately there are in the Antarctic district

ORIGIN OF ICEBERGS 123

no such strong currents as those which sweep down the shores
of Labrador to convey these packs of ice to the parts of the
sea which are most traversed by shipping ; they are rarely
encountered except by the whalers or the rare explorers who
have attained to these lonely waters of the far southern seas.
We have now completed our general account of the simpler
and least important of the groups of floating ice-fields. We
have next to examine into the processes which lead to the
formation of the far grander masses, the true icebergs.

We have already noted the fact that icebergs differ from
floes in that they are far greater in depth ; it is also character-
istic of them that they are composed of a dark blue variety of
ice, which is generally much more solid than that of the floes.
The berg-ice has also the peculiar feature that it tends to rift
in a vertical direction, which gives their crests the striking and
beautiful outlines so characteristic of them where they have
been much decayed by long exposure to the warm air of the
region of the sea to which they attain near the end of their
journeys. To understand these peculiar features it is again
necessary for us to consider the regions where these ice-
masses are formed. It is now well known that all true bergs
— and in this class are included all the floating masses which
find their way down to the line now followed by the trans-
atlantic steamers— have their origin in the glaciers of high
latitudes. Those which beset the pathway of ships moving
from Europe to America are all cradled in Greenland. All
the lands north and west of Spitzbergen are more or less
occupied by fields of perpetual snow, which, slowh' descend-
ing tlie valleys, is by pressure and by its forward movement
converted into pure translucent ice; all the little cavities con-
taining vesicles of air, which gives to snow or powdered ice

124 SEA AND LAND

its white color, become closed as the air escapes during the
onward journey of the stream. In more southern climes, as in
Norway and Switzerland, these crlaciers in their descent meet
a climate sufficiently \\*arm to melt them away before they
attain the level of the sea ; but in the greater part of the lands
within the Arctic Circle there is at the sea level an annual
average temperature below the freezing-point, so that any
glacier which is formed moves on until it thrusts its extremity
into the sea.

For a time after the slow-movins: stream of ice enters the
ocean waters, its height causes it to continue to rest on the
bottom ; but when it penetrates to a certain depth of the sea,
a depth depending on the thickness of the ice-sheet, the buoy-
ing action brought about by the relative lightness of the ice
tends to lift it from the bed over which it has ploughed. As
ice, though easily mobile under pressure, as the movements of
the glaciers themselves clearly show, is very brittle to any
cross strain, such as this tendency to float imposes, the
extremity of the ice-stream is continuall)- broken away, form-
ing detachable masses. The resistance of the ice to fracture
causes the projecting extremity of the glacier to hold together
for a little distance beyond the point where the weight of the
mass alone would liold it upon the bottom. When the berg
separates from the parent mass, the rupture is attended by a
violent movement, often causino^ a loud thunderincr noise
which may be heard for many miles. The rebound of the
newly freed mass from the bottom and the firm-set glacier
whence it came, causes it to swing violently, so that it sends
great waves sweeping from its base out into the sea, which,
though on a larger scale, are like those produced when a ship
is launched. The Esquimaux are so familiar with this process

SEPARATION OF ICEBERG FROM GLACIER 125

■b"^.

View of the End of a Glacier at the Head of a Greenland Fiord

During the recent greater extension of the ice the stream filled all the valley enclosed in the field of view
and overtopped the neighboring mountains.

of separating bergs from the land-Ice, that when they hear the
roar which it causes they say the glacier is " calving," or giv-

126 SEA AND LAND

ing- birth to its young-. By this savage description they seem
to indicate, in the manner common to primitive peoples, tlieir
sense of the activity which exists in the ghicial streams, as well
as tliat perception of life in nature which, though a common
feature with uncivilized people, disappears with the advance
in culture.

(ireenland is the o;reat source whence the icebcros of the
North Atlantic are " calved," and the physical conditions of
the country make it admirably fitted to be the breeding-place
for those monsters of the deep. Until very recently our
knowledge of this country was limited to the southern ex-
tremity of the island and the narrow strip along the western
shore, where there are a few villages which are visible from a
ship's deck. The eastern shore is so blocked by floe-ice that
few mariners have seen the mainland for more than a hundred
miles beyond its southernmost part. It has long been knowm,
however, that along the whole coast-line the glaciers descend
to the heads of the inlets or fiords which plentifully intersect
the shore. Both on the east and the west the ice-streams are
so deep and massive that they override the whole marginal
portion of the countr)-, hiding its irregularities in the vast
sheet of the glacier, which sweeps into the sea until it attains
a depth where the ice breaks off and iloats away in the form
of icebergs. The greatest of these ice-fronts, that of the
Humboldt Glacier, faces the water in the upper part of
Baffin's Bay with a continuous precipice of ice having a
length of about fifty miles. So far as is yet known, this is
the larg(;st of the Greenland berg factories, but it is possible
that even greater protrusions of the central glacial field may
occur on the eastern coast.

There has long been much natural curiosity concerning the

THE GREENLAND GLACIER 127

aspect of the interior district of Greenland, for naturalists
have felt that we should there secure much valuable informa-
tion concerninof the conditions which existed durino- the o^lacial
period over a larger part of Northern Europe and North
America. Many travellers have ascended the ice-streams for
a little distance, and have looked inland apparently upon fields
of snow. Recently some bold travellers, properly equipped
for traversing the ice, made their way to the eastern shore
of Greenland, and started on a hazardous journey with the
western shore for their destination. After passing for some
miles over a portion of the glacier, which was much broken
by crevasses — due probably to the existence of irregularities
in the floor of rock over which it was moving — they gradually
ascended until they came upon a vast, unbroken surface of
ice, which was apparently as level as a frozen sea, and which
stretched away beyond the field of vision. This portion of
the continental glacier, the first ever seen by civilized man,
rose gently until, by the barometers, it apparently attained a
heio-ht of about a mile above the sea. Thence it declined
with a grade so slight as to be invisible to the eye until near
the western shore, when it descended more steeply, and was
broken by rifts, as the travellers found it at the outset of
their journey.

This vast arch of ice doubtless occupies all the surface of
Greenland except the narrow belt next the shore, mainly on
the southern and western coasts, where the higher land is now
left bare. It would be most interesting to consider the gen-
eral conditions of this wonderful glacier, with reference to the
state of affairs during the last frozen period, for there can be
little doubt that we have in the region beheld by these hardy
explorers a very true picture of a continental ice-sheet, such as

128 SEA AKD LAND

in a recent g-eological age covered the eastern part of North
America as well as much of the Old World. But for our
immediate purpose we need onh' to note the immense extent
of this ice-field, its great dej)th, and the speed with which it
moves from the interior toward the sea. So far we have but
imperfect data concerning the rate at which the high northern
glacier passes from the land into the sea ; but it is clear that
the movement is much more rapid than in the case of the
relatively small ice-streams of the Alps. In the valley glaciers
of Switzerland, Norway, or the Himalayas, the speed of the
flow does not exceed on the average more than three feet per
diem. At the berg-making fronts of Greenland it probably
amounts on the average to more than tiiirty feet per day;
that is, a strip about half a mile wide would be fed into the sea
in tlie short summer season, and if the flow was maintained
during the whole year, there would be a field nearly two miles
wide discharged as floating ice along the whole front of the
streams which attain the sea. There is no satisfactory basis
on which to estimate the linear extent of the glacial front on
the Greenland sliore, but it is probably not less than two
hundred and fifty miles. If this be the size, we may reckon
that somewhere near five hundred square miles of icebergs is
each year set afloat along the shores of the island. Suppos-
ing that the original area of these masses was one-fourth of a
square mile, this supply would provide for a yearly fleet of two
thousand bergs, from which throng the ice which our Atlantic
ships encounter is derived.

The history of these bergs, after they have become sepa-
rated froni their parent glaciers, lias not yet been carefully
traced. It is evident that a large part of them never attain to
any considerable distance from the coasts where they were

ill!

View at the End of a Glacier, showing an Iceberg just ready to Separate

ANNUAL PRODUCT OF ICEBERGS

129

discharged into the ocean. Those which are hiunched in the
inlets are apt to be retained by the shores and melt before
they escape to the sea , of those which start on their journey
many become stranded on the shallows, and brc^ak into small
pieces, so that they are rapidl)- melted ; yet others, including'-
probably nearly all which are formed on the eastern shore of

View at the Mouth of a Greenland Fiord
Showing: the steep precipitous character of the coast, with a number of small bergs floating; from the inlet.

Greenland, are retained near their place of origin by the

action of the wind and the marine currents. It does not seem

likely that more than one or two hundred large icebergs make

their way each year in the only practicable path that can take

them beyond the Arctic Circle — that which is afforded by the

current which sets out of Uavis Strait, and down the Labrador

shore, and then eastward into the Atlantic. Although we
9

130 SEA AND LAND

have as yet l)ul little decided information concerning this
ocean-stream, save that afforded by tlie movements of the
berg and floe, we can readily see how it affects the journey
of these wanderinix fragments from the vast Greenland
olaciers. Though somewliat inconstant, this current is toler-
ably steady, setting south through the wide channel which
separates the shores of Greenland from those of the many
islands which beset the northeast coast of the American con-
tinent. By this southward-moving water the ice is propelled
out into the open sea. The stream continues to \X\v. south,
but widens and diminishes in the energy of its flow. It shortly
comes in contact with the Gulf Stream, which it somewhat
affects, and b}' which it is much affected. As we have already
noticed, a part of the southward-setting current passes down
along the shore of Labrador as a superficial stream of no
great width or speed. Another, and perhaps the larger part,
flows beneath the (julf Stream, and in tinie joins the great,
slow-moving procession of Arctic waters which, following the
bottom of the deeper sea, in the end attain the equatorial
district. For a considerable distance southeast of Greenland
there are thus two distinct currents in the ocean waters — a
lower, moving southwardly, and an upper, or superficial
stratum, creeping toward the north. The thin tloc-ice, l1oat-
ing altogether within a hundred feet of the surface, is beaten
back against the Labrador shore hy the surface stream ; but
the icebergs, because of their greater depth, are driven for-
ward by the under-current in a southwardly direction. Owing
to this peculiarity we sometimes may observe the bergs
l)lougliing their way through vast fields of floe-ice as stead-
fastly as a steamship when it breaks its way in the new-formed
ice of a harbor. This southward journey of the bergs is

VOYAGES OF ICEBERGS 131

facilitated by the action of the prevaihng winds, which, in
this region, in the spring and summer, often blow with great
energy from the northwest. A berg one hundred feet high
and a mile long spreads a vast surface to these winds, and is
slowly but effectually impelled by them in the manner of a
sailing ship.

From the time the berg is launched into the sea it is con-
stantly wasting ; unlike the lloc-ice, which receives important
accessions in freezing weather, the berg, on account of its
depth, whicli brings the greater part of the mass into water
above the freezing-point, steadfastly diminishes in volume;
the little ice-sheet which may form around the water-line
does not affect the size of the mass, yet this process of melt-
ino- goes on but slowly. In the first part of its journey it is
always in water which is at about the freezing-point. Most
persons are familiar with the fact that cakes of ice will float
for a long time in very cold water, and can thus imagine that
icebergs may journey a long way in the Arctic seas with but
little loss in bulk. It is when they come in contact with
the waters of the Gulf Stream that the dissolving process
beoins to go on in a rapid manner. The under-running cold
current, which moves southward toward the central parts of
the Atlantic, seizing on the great surface of the bergs which
extends downward — it may be to one or two thousand feet
below the surface — urges these masses of ice against the rela-
tively shallow and slow-running warmer tide. As they go
to the south the energy of the imjiclling stream constantly
diminishes, for the reason that the flow from the Arctic, no
lono-er confined within the channel between Greenland and
the mainland of North America, slackens, while with each
stage of the movement of the bergs toward the equator the

132 SEA AND LAND

strcncTth of the Gulf Stream flow becomes aiunnented. In
this way it comes about, that in the hititude of the Xew-
foundland banks, or shoals, the floating- masses attain a posi-
tion where there is a balance between the effects of the
diverse currents, and, as a result of this, the icebergs lie idly
in the sea or drift about in the varying winds until they
melt away.

The bergs from the North Atlantic nursery of ice, from
the glaciers of southern and western Greenland, have their
limit of migration set by this curious equation of the currents
which prevail in these waters. If the southward-setting cur-
rent were as strong in that region as it is on the west coast
of North America, there is no reason why these vast and
slow-moving ice-islands should not attain to near the tropics;
as it is, they are rarely if ever found much south of the New-
foundland banks. There are reports that in certain rare
instances considerable bergs have been seen nearly as far
west as the mouth of the Bay of Fundy and as far south and
east as the Azores, but these stories lack verification and may
be only sailors' yarns ; if true, it is probably to be explained
Ijy the fact that in a period of long-continued and strong
northwesterly winds deep bergs, which on account of their
depth projected high above the water, were urged far to the
southward and eastward of their normal course. Allowing
for such rare accidents, the fact remains that the icebergs of
the North Atlantic have their southward and eastward exten-
sion determined with admirable accuracy, and in a way to
show the observer how beautifully the physical conditions are
adjusted in the waters of that tumultuous sea.

The fact that icebergs can maintain themselves so long-
when they are floating with their upper parts bathed in the

EFFECT OF ICEBERGS IN THE OCEANS 133

warm water of the superficial [)()rtions of the sea, and the
deeper portions of their masses in a fluid which is a
Httle above the point where ice melts, is due to certain
circumstances which we shall have now to note with some
care. The icebergs, as they slowly melt, chill the water
about them to very near the freezing-point. This very cold
state extends, in the case of large masses, to the distance of
some miles from the face of the ice-cliffs. Next the berg
the temperature is always but a shade above that of a vessel
in which there is just enough water to float fragments of ice.
Only a very small part of this cooled portion of the sea is
derived from the melting berg ; in the main it consists of
that portion of the ocean which has been deprived of its
heat by the contact with the glacial mass. Here we must
consider the fact that the process of melting ice calls for a
great deal of heat. If we take a cubic foot of the frozen
water and put it over a regulated fire, as, for instance, that of
gas-flame, we observe that it requires a much longer time to
melt the mass than it would to bring an equal amount of ice-
cold water to near the boiling-point. If we conduct the
experiment in a more careful way, we may easily determine
that, starting with a block of ice at a temperature just a frac-
tion of a degree below the freezing-point, it takes more units
of heat to bring it to a point where it becomes molten than
is necessary to raise its temperature after it is melted to 74° F.
This heat, which the water hides away in the process of melt-
ing, is so great that it much affects not only the history of
icebergs, but all the phenomena of the seasons in countries
where a thick envelope of snow gathers during the winter
season. It is this peculiar absorption of heat which makes
it so difficult for the warm sun of spring to clear away the

134 SEA AND LAND

frostwork of winter and to fit the earth for the uses of vegeta-
tion. In the case of the icebergs the process of their melting
recjuires that some cubic miles of the relativel)' warm ocean
waters, hax'ing a temperature of, say, 50" 1' ., shall come in con-
tact with the ice before an ordinary berg will be dissolved.

As long as the icebergs are rapidly pushed forward by
the action of the undercurrent which urges them through the
superficial layer of warm water, the portions of their masses
which are exposed to the northward-setting stream rapidly
melt; because they are by their motion ever brought into
contact with the fresh fields of warm water, the cold portion
of the ocean which tlu;y have chilled being left behind. But,
as we have already noticed, the rate of this motion steadfastly
decreases until they finally cease-to travel over the surface,
and meet only such water as the winds or the gentle north-
ward - scttin^f current sends against them. In a certain
measure they provide by their owm action for a slight current
movement wdiich promotes their melting. The water next
their sides, being chilled by contact with the ice, becomes a
little heavier than that of the surrounding sea, and so tends
to sink into the depths, its place being taken by the warmer
tluid whicli Hows in over the surface. If w^ater became con-
tinuously heavier as it cooled, all the way down to the freez-
inc^-point. this action w'ould be much more effective than it is;
but among the many extraordinary features of this substance
we hav(! to note that it is the densest at about 39'' F., expand-
ing a little if the heat is decreased below that temperature.
Consequently this circulatory movement just described is
not strong.

The protection of the bergs from melting is also pro-
moted by the fleet-like manner in which they occupy large

ORDER OF MOVEMENT OF ICEBERGS 135

areas of the sea. They are generally found in troops, which
may number scores, or even hundreds, of separate masses ;
the result is that vast areas of the ocean have their super-
ficial waters so cooled down l)y the southernmost individual
bergs, that the greater part of the group have little chance
to come in contact with warm water ; it is only slowly, as the
advanced bergs are melted, that the more northern masses
are exposed to a temperature high enough to affect them in
any considerable measure. In much the same way the aggre-
gation of the icebergs hinders the air from affecting them by
its w^armth ; the atmosphere is chilled by the cold sea and
the ice with which it comes in contact, and the result is that
thick fogs are formed, which send off the rays of the sun and
convert the regions about the bergs into a natural ice-house
well fitted to preserve them from the effects of the more
southern realm into which they have journeyed. In fact, a
fleet of icebergs takes its native climate with it as it goes ; it
is enveloped by conditions of its own making, as perfectly as
if they were designed for the end which they attain.

The effect of the close order, which is such a common
feature of the berg fleet, is so important in their history that
w^e must consider the way in which it is brought about. As
is easily seen, the cause is found in the landlocked nature
of the waters whence they are derived. In the winter the
region about the West Greenland glaciers is occupied by a
sheet of floe-ice strong enough to retain the icebergs against
their native shores. Only for a brief period in summer, in
all perhaps, on the average, less than four months, is the
water open enough to permit their escape into the wide part
of the Atlantic Ocean. When the summer unlocks these
Arctic eates, the vast assemblao^e of ice-floes and the im-

1^,6 SEA AND LAND

prisoned squadrons of bergs from the several glaciers which
have accumulated in the sea during the enduring frost, pour
forth into tlie more southern part of the ocean. Then they
become separated — the bergs impelled by the deeper cur-
rent set forth upon their long cruise toward the mid-Atlantic,
while th(^ floes follow the surface stream adown the coast of
Labrador ; the former to wander, it may be, for years ; the
latter to vanish in the heat of a single summer.

In the process of destruction which a berg goes through,
its decay is aided by the frequent overturns to wliich it is sub-
jected. All the ice of the glacial streams, unlike that made
in the ordinary way, is moulded into shape under the great
strains to which it is subjected in its journey over the surface
of the earth. These strains are not all productive of move-
ment, but remain as tensions, much like those which we find
in unannealed glass, giving the mass a tendency to fly into
pieces. Moreover, glacier ice is peculiar in that it is always
penetrated by numerous rifts or imperfectly closed fissures,
which accelerate its breaking whenever it is violently dis-
turbed. Owing to tlie more or less irregular melting which
goes on upon the outside of a berg, its centre of gravity grad-
ual!)' clianges, so that from time to time it rolls over in the
sea. Such accidents are not infrequently observed by Arctic
explorers and whalers who haunt the waters where these ice-
fields most abound. As may be imagined, when one of these
vast masses somersaults, every part of it is subjected to vio-
lent stresses which would rack much more solid structures, and
also that, when they strand in some shallower part of the sea
a like trial of their strength occurs. In fact, when either of
these accidents happens, the berg often flies into pieces almost
as does a Prince Rupert drop of quickly cooled glass when it

s^

.r.J^

DECAY OF ICEBERGS 137

is treated with any violence. Even when saiHng in a quiet sea
the innate tensions of the ice, increased it may be by the
changes of temperature to which it lias been subjected since
it parted from the parent glacier, now and then cause large
fragments to tly from the steep cliffs, to float as satellites
of the mass until they melt away.

The processes of decay acting on the summit of the icebergs
reveal in the melting forms the existence of incipient rifts in
their masses. Unlike the surface of ordinary ice-sheets, which
commonly melt down somewhat evenly, the berg top is made
up of irregular pinnacles and chasms, which in the later stage
of its existence may take on forms of the utmost variety.
The picturesqueness of these floating islands of the north is in
large measure due to the exceedingly varied form.^ of their sky
lines. The architects of our day, who recognize the striking
effects which may be produced in edifices by means of pedi-
ments and pinnacles, might win suggestions from a study of
these fantastic structures. These indentations of the iceberg
top are produced by the same abundant planes of weakness
which cause the mass so readily to rend asunder whenever
subjected to strains such as may arise from the causes we
have considered. The warmth and rain penetrating into these
crevices eat the ice away while the less weakened parts
remain intact. In the case of many bergs, even when they
have been long atioat, the top is not much indented, for the
reason that the frequent changes of position have not given
the ice time to be affected by exposure to the air.

In the southern hemisphere, icebergs are limited to the
western Atlantic and eastern Pacific, and to the waters of very
high latitudes within the Antarctic Circle. They are almost
unknown in the North Pacihc, for the reason that the onlv

I-,8 SEA AND LAND

o

crlaciers which attain the sea in that reo^ion, those of the
Alaskan shore, are of relatively small size antl only send afloat
small masses of ice, and these being imprisoned in deep bays
do not often attain the open sea. In the Antarctic region the
little-known islands about the South Pole are the nursery of
more numerous bergs than are formed within the Arctic
Circle. The currents setting from these southern circum-
polar lands toward the equator are much less energetic than
those which bear the Greenland floods to the open sea, conse-
quently the parts of these waters frequented by ships are
not so affected by the ice invasions as are the waters lying
between North America and Europe. The only point where
the south polar bergs come upon a travelled ship-route is on
the western side of Cape Horn. In this field these wanderers
occasionally penetrate a portion of the way of vessels which
have rounded the South xA.merican cape, but they are on the
wdiole much less numerous and less dangerous to navigation
than those of the North Atlantic. It is a peculiarity of these
southern ice masses, that they are much larger than those
observed in the North Atlantic field. This is probably due
to the greater extent of the glaciers in the region about the
South Pole, and to the correlative fact that the process of
melting goes on more slowly in that region than in the Arctic
district.

Besides the greater size of the icebergs of the far south
as compared with those from the Arctic regions, it may be
noted that the tops of the floating masses are often described
as being table-like, lacking the pinnacled look which is so
generally exhibited by those which come from the Greenland
o-laciers. The reason for this is probably to be found in the
very great extension of the Antarctic ice-cap. About the

CLIMATAL EFFECTS OF ICEBERGS 139

North Pole the ice streams pass to the sea through valleys in
which tlie material becomes much rifted. In the Antarctic
realm the accumulations of frozen water extend beyond the
shores, and probably move over the bottom for a great dis-
tance before they attain a depth in which they can float.
Thus the bergs of this region are to a great extent made out-
side of the valleys, and thus have a homogeneous structure
which causes them to wear away more uniformly than those
which are made in Greenland.

We turn now to consider those parts of the general effects
of floating ice which may be supposed to have an interest for
the reader. First among these we must reckon the influence
they exercise on the climatal conditions of the countries bor-
dering on their paths. In the case of the floes and icebergs
which are borne southward by the Labrador currents, the
effect must be considerable ; they perceptibly cool the sea
over a large area, depriving a considerable part of its waters
of the warmth which their current would otherwise carry to
Northern Europe. If we could confine these wanderers from
the icy realm within the regions where they are formed, the
effect on the temperature of Northern Europe would be note-
worthy and even of economic importance. Their general
influence is to disseminate Arctic conditions over a wide area
of the more southern regions, where the climate tends through
the action of the ocean movements to partake of the tropical
warmth. The climate of the northeastern part of North
America would probably be distinctly warmer but for the
chilling of the neighboring sea which the abundant ice in-
duces. So, too, with the southern part of South America ;
the climate which now renders the country in good part unfit
for aoriculture would be much more tolerable but for the

140 SEA AND LAND

inlkicnce of the vast amount of ice froni the Antarctic Sea
which floats near to its shores. Though not of great impor-
tance in terrestrial conditions, icebergs must be reckoned as
a factor with which the meteorologists of the future will have
to deal. In forecasting the weather conditions not only of
the seas where they occur, l)ut also of the neighboring lands,
it will be necessary to take account of the migrations of these
wanderers froni the polar region, and to estimate their effects
upon the heat and moisture of those districts.

To the student of the geological processes which are now
going on upon the earth, icebergs, and ice-lloes as well, will
afford most interesting subjects of inquiry. Not only do they
affect the temperatures of the sea and land, and thus indirectly
influence the conditions of the life they bear, but they exert
certain curious direct effects upon the distribution of organic
species and in the carriage of sediments. We will first note
the action of these floating ice-fields in carrying animals from
one region to another. It is the habit of the animals of high
latitudes, particularly the polar bears, to seek the margin of
the sea for the food they may obtain from its waters. The
bears indeed win in winter their entire subsistence from this
source of supph' ; even in summer they obtain little else than
what the ocean affords them. Prow^ling along the shore and
swimming far in its waters, with occasional rests on. the float-
ing ice-islands, it frequently happens that they are borne away
to sea on these rafts. In most cases these creatures starve to
death or are drowned wht?n their supports melt away ; but it
sometimes happens that the wandering ice conveys them to
some other land, (irounding in the shallow water next the
shore, the animals, if not too much exhausted, may win the
shore and proceed to multipl\- in their new-found home.

TRANSPORTATION OF ROCKS BY ICEBERGS

141

From time to time the polar bear is thus conv^eyecl from
Greenland to Iceland, on which island it is not indifrenous.
The people of this Arctic realm are compelled to exterminate
the invaders lest they should destroy their cattle and ravage
their fields.

As the icebergs are derived from glaciers, they commonly

Showing small glaciers and floating icebergs. In the foreground are masses of rock dropped from float-
ing ice.

carry a great deal of rocky matter torn from the surface over
which they have found their way. The bottom portion of any
thick glacier is commonly filled, sometimes to the depth of a
hundred feet or more, with this fractured stone, varying in size
from grains of mud or sand to blocks the size of a small house.
When the icebergs float away from the land they bear the
mass of debris with them on their journey, it may be for a

142 SEA AND LAND

great distance from tlu-ir birthplace. If the berg remains for
a long time in the position in wliich it entered the sea, a rela-
tively slight amount of melting will release the stones and
earthy waste, which will then fall, bit by bit, into the sea-floors
in the paths of the wandering ice ; but as it often happens
that the berg is turned upside down before it has attained any
great distance from its point of origin, in this position the
waste from the land will remain afloat until the ice again
capsizes or melts away, when it will be- tumbled into a heap on
the ocean bottom. In this way a very large amount of the
land waste torn from the bed rocks by the action of the
o-laciers is distributed far and wide over the surface, where
new strata are constantly accumulating. The number of ice-
bercrs delivered to the open sea in the summer season, of
either Pole, must amount to many thousands. It wmII be prob-
ably safe to estimate the aggregate area of this floating glacial
material as not less than five hundred square miles in surface.
It will also be reasonable to reckon that the debris from the
circumpolar lands contained in tliese bergs is sufficient to form
a layer not less than one foot in thickness over all this field of
ice. On this basis we find that in one thousand years the
sea-floor, over an area of one million square miles, might
receive a contribution of debris having a mean depth of six
inches. Although these reckonings are to be taken only as
probable, or perhaps possible, estimates, it is evident from
them that the land areas about the Poles are rapidly wearing
away, and that their waste is being deposited with extreme
rapidit\- ui)on the lloors of the oceans in hii^h latitudes.

While th(; massive icebergs are carrying on this singular
work of depositing the waste of the circumpolar regions on
the wide fields of the oceans, the ice-floes are doing a similar,

EFFECT OF ICE ON SHORES 143

and perhaps equalh' important, work in conveying the detritus
from the shallow waters next the shore out to sea and along
the coast-lines in considc.-rable though less extended journeys.
In the winter season, when the floe-ice forms or thickens in
the shore-packs which beset the lands in high latitudes, the
stones and other movable detritus of the coast-line become
frozen into the sheets, and when they float off in the spring
season are rafted for some distance, and finally, but more
speedily than in the case of the materials conveyed by bergs,
are dropped upon the bottom. The carriage is for a less dis-
tance, because the floe-ice, being thin, survives for a less time
in the sea-water. The immediate effect of this action is to rob
the shore-line of the debris which the waves have plucked from
the cliffs, and thus to hasten the wasting of the shores ; it also
contributes a large amount of detritus to the ocean depths.
Although this action is of miost importance within the Arctic
Circle, its effects are felt all along the shores where ice forms
to the thickness of a foot or more, and after severe frosts
floats away seaward. Its influence has long been remarked in
the waters of the Baltic Sea. One of the English men-of-war
which was sunk during the attack on the Danish fleet in 1807,
was visited by divers seven years after that battle ; its deck
was found covered with blocks of stone which had drifted there
in ice-floes. It is said that all sunken ships in that part of
the sea quickly become overladen by a thick coating of rock
debris.

In the occasional severe winters which occur along the New
England coast as far south as Rhode Island, this floe-ice makes
to a thickness of three feet. Under the influence of the strong
tides and winds these ice-fields are often urged against the
shore, upon which they break into fragments, which are

144 SEA AND LAND

crowded by the great pressure from above and below until
they form extensive ramparts which are frozen solidly together.
When these masses float away they often carry with them
bowlders weighing one to two tons, and drop them at a dis-
tance from the land. In their collision w^ith the shore these
fields of rock-covered ice exercise a very great disruptive force.
At many points, even in Southern New England, it is difficult
to build piers, even of firm masonry, strong enough to with-
stand their assaults. The fact tliat these artificial construc-
tions fail to withstand the action of this floating ice, shows
how vigorous is tlie attack which it makes on the shore. All
persons who are familiar with the coast of New England,
especially those who have an intimate acquaintance with the
districts of any particular portion of it, must have remarked
the often conspicuous changes which a ver\' frigid winter
brings about in the appearance of the bowldery shores. We
have then only to conceive that in the ages these actions are
to be multiplied by the million-fold, in order to make it clear
that this agent is capable of accomplishing a great deal of
geologic work. In general this work is most effectively done
in the embayments of the shore, for on the headlands the
waves prevent the ice from forming, or keep it broken into
small blocks, so that it cannot seize upon the large stones ;
in this way the floe-ice serves to wear away the shores of re-
entrants more than those of the headlands. Sand-beaches are
but little affected by the ice which may form upon them, for
the reason that the continual movement of w^ater from the
land side j)revents their materials from freezing, so that they
do not become entanijled in the floe.

When geologists first sought to interpret the ice marks so
common on the surface of the lands in high latitudes, they

ANCIENT ICEBERG WORK 145

were almost necessarily led to the supposition that those
scorings of the rocks and carriage of detrital materials had
been brought about by berg action. Explorers who liad
cruised in high latitudes had noted that the floating ice con-
tained quantities of glacial waste, and also that the masses
were often driven by the wind against the bottoms of the
shallow seas. It was, moreover, well known that in the pro-
cess of geographical change regions which have recently been
sea bottom have been converted into dry land. Thus a
natural explanation of the facts appeared to be attained.
Further inquiry has shown, however, that the greater part of
the ice work in glaciated districts is not due to iceberg action,
but to the movement of vast united masses of ice such as now
covers the central portion of Greenland. Here and there,
however, along the shores, and even at heights of some hun-
dred feet above the sea level, we find indications that during
the waning stages of the ice epoch the land was lower than at
present, that it was cruised over by bergs which now and then
grounded and often dropped the waste embedded in their
masses, and released during the process of melting, upon the
surface of the earth. Thus the original theory adduced to
explain drift phenomena has, by the evidence, been pushed
into a very subordinate position.

In a number of ancient geological formations we find
evidence through the presence of stray blocks or heaps of
detrital matter embedded in finer materials, serving to show
that the seas in sucli periods were cruised over by icebergs.
These indices are of great value for the reason that the land
record made by a glacial period is quickh- destro)-ed by decay,
so that the work done by icebergs, the record of which is
quickly buried in the submarine strata, may be all that is

146

SEA AND LAND

left to show that glacial work had been done in the ancient
time.

As we have now considered the more important general
features which floating ice presents to the geologist's eye ; it
will not he uninteresting to devote a part of this paper to the
questions concerning those masses which liave a more human

\'-J^^

View showing Large Berg with Ice Arch

The overhanging ledge to the right of the arch shows a former sea-level on the face of the berg, and indi-
cates that the mass has recently slightly changed its position in the water.

interest, viz., their scenographic quality, and the dangers
which they bring to navigators.

In taking account of the place occupied by any natural
phenomena, it is well to consider the effect which they pro-
duce on the cesth(;tic sensibilities of man. From tliis point
of view we must give a high place to the greater ice-masses
of the sea. the bergs which come down from the circumpolar
glaciers. There is an architectural splendor in many of the

BEAUTY OF ICEBERGS 1 4/

aspects of frozen water, which is found in no other natural
forms. Majestic as is tlu- tunuilt of Niagara, the scene inex-
pressibly gains in sublimit)' when winter has framed it in an
encasement of ice. The Alps and the Himalayas have a
dignity which is in but small part due to the hardy forms of
their rocky slopes, but is lent them by the snows of their
uplands and the glaciers of the valleys. Even the snow-sheets
of an ordinary house-roof, and the fringe of icicles pendent
from its eaves, may make the most commonplace building a
curiously impressive and pleasing object.

There is, perhaps, no condition of frozen water in which this
element of the picturesque is more pronounced than where it
is exhibited in a fleet of icebergs within the regions where
they have not yet been worn out by long journeys. Those
who see them only in the usually traversed route between the
American ports and Europe behold but the scanty relics of
the vast structures which started from the Arctic Ocean
months before. The charm of these floating islands consists,
in part, in singularity and variety of forms, and in the beauty
of their coloration ; but in larger part the effect is due to
the weird loneliness and lifelessness of their crags and steeps.
Save for the splashing of the sea against their steep sides, or
the hoarser crash of the masses which now and then tumble
from the heights to the lower levels of the floating islands or
into the sea, we may journey for hours through the berg fleet
in perfect stillness. When the floating masses are near to-
gether, as they often are in the high north, where sometimes
hundreds may be seen in a day, they shut out the waves and
make an almost cavernous stillness in the space of water
between them. The impression made on the mind by a
strone sea breaking airainst a rock-bound shore, and that of

148 SEA AND LAND

a volcano in energetic eruption, are more startling; but it is
doubtful if any of the aspects of nature, save the ever-familiar
depths of the heavens, is so awe-inspiring as that exhibited by
a great fleet of bergs as they come forth from the icy moun-
tains of Greenland for their long southern voyage.

One of the most notable of the manifold modern develop-
ments of interest in the external world is that which leads
people to make long journeys to behold the more inspiring
scenes of nature. It seems likely that in a few decades this
relish for the flavor of scenery will, among cultivated people,
become as well developed as that of the Romans of the second
century for the luxuries of the tal)le. When this stage of our
social development is attained, we may expect that the fields
of the icebergs will be as much visited by the seekers after the
nobler aspects of nature as are the ice-streams of the Alps ;
certainly this world has no more impressive spectacles than
those afforded by the high northern seas -when their vast
annual fleet of bergs set forth on their journey into the broad
Atlantic.

Ao-ainst the crood which is oriven us in the grandeur and
beauty of the icebergs, we must set the grave and inevitable
danger which they bring to the seafarer who has to traverse
the waters where they abound. These dangers have always
been great, but are more serious in this age of swift steam-
ships than of old. Against the common perils of the sea the
skill of shipmaker and shipmaster, when at their best, can
effectively guard. The ocean is so well charted that there is
no island in the usual paths of commerce, hardly indeed a
rock which need be approached, the position of which is not
well known. The art and science of navigation is so well
explored and taught, that with the aid of his chronometers

PERILS DUE TO ICEBERGS 149

and sextants the navigator can often without risk almost graze
these obstructions with his keel. There is no longer much to
be apprehended from storms ; our abler commercial ships at
least can make light of the winds which might have over-
whelmed an ancient armada. Among the first-class ocean-
going vessels of this day, only the armor-laden men-of-war,
which are indeed rather floating fortresses than ships, have
any serious reason to apprehend the results of a tropical
hurricane in the open sea. But all these conquests of the
modern sailor depend upon the application of skill to well-
ascertained facts : the difficulty with icebergs is that their
position in the sea, where they lie until they melt, is essen-
tially anomalous.

The only information which the navigator can have as to
the existence of these obstacles in his path is derived in part
from the reports of the shipmasters who have recently trav-
ersed the path which he is following, and in part from the
conditions of the air and water about his vessel. The reports
of his predecessors may lead him to believe that in about a
certain field of the sea ice abounds. If he be a wary person —
and fortunately for the ocean travellers these men are care-
taking beyond the understanding of most landsmen — he will
watch the temperature of the water and attend to the condi-
tions of the air when he comes into the suspected district.
When his ship enters into a chill, foggy atmosphere, he will
suspect the neighborhood of ice ; if the thermometer shows
that the water has suddenly lowered to near the freezing-
point, he will know that he is very near the beres. But eood
as these indications are, they are not unerring. Small bergs,
though trifling remnants of greater masses, though they may
be less in bulk than the vessel itself, are sufficient to brine:

150 SEA AND LAND

about the destruction of the strongest ship that floats, if the
vessel encounters them when t^oing at a speed of fifteen or
twenty knots an hour. These berglets often float to a great
distance from tlie main fields of ice, and being small, do not
aft'ect the temperature of the water or of the air. Again, it
sometimes happens that a strong wind will drive the air and
water before it, so that there is no fog about the bergs and
no very cold water on the side from which the bergs are
approached. These exceptional conditions make the path of
a ship, which in the night-time traverses an iceberg-laden
portion of the sea. the seat of grave perils.

A collision with an iceberg has certain elements of hope-
lessness which belong lo no other calamities of the deep.
Colliding with another vessel, the blow is not likely to be so
severe as to damage more than one of the compartments of
a ship, the others may keep her afloat. An iceberg, owing to
its unyielding and massive nature, gives a much harder blow.
Moreover, as the experience of the steamer Arizona showed,
the fall of masses of ice from the cliffs of the berg upon the
bow of the shij^ is likely to add to the damage done to
her forward parts. When running against another ship, or
against the land, there is alwa)s some hope of rescue or of
refuge for the shipwrecked people, either on the shore or
the deck of the other vessel ; but no more hopeless condi-
tion can be imagined than that of people who might seek a
foothold on the inhospitable islands. The steep, generally
overhanging, cliffs, usually deny access to their summits, and
even if by chance the shipwrecked people attain the summit
of the ice, they would have little chance of rescue, for no craft
willingly comes near to those dangerous objects.

It has been suggested that the men-of-war of the great

METHOD OF AVOIDING DANGER FROM BERGS 15 I

navies should be employed in the destruction of the icebergs
of the North Atlantic, According to this plan the bergs are
to be bombarded with great shells, which, penetrating deep
into the ice and exploding there, will shatter them to i)ieces.
There is no doubt that this would be a far more profitable
expenditure of ammunition than the uses for which it is
designed ; for any target is better than the dear-bought
frame of man or the products of his skill of hand and mind ;
but it is more than doubtful if the end could be attained in
this way. In the first place, to accomplish the desired result,
it would be necessary for men-of-war to watch the exit
of Baffin's Bay in the spring-time, and break up the bergs
into relatively small bits, so that they would no longer
float with their bases in the deep southward-setting current,
but would drift with the floe-ice. To do this, with several
hundred great masses, would require an enormous expendi-
ture of money. Including the wear and tear of guns, the
shells from the great modern ordnance cannot be fired at a
less cost than five hundred dollars for each shell, and it
would probably require many hundred rounds of ammunition
to break up a single berg. It would not at all serve the
purpose to rend the ice to pieces in the mid-Atlantic district,
for there the fragments would float about and multiply the
dangers of navigation ; such work, if done, would make that
region nearly impassable for a portion of the year, though
from the readier melting of the ice the trouble would not
endure so long. On the whole, this interesting project does
not seem practicable.

The only way to avoid the perils due to this berg field
of the Atlantic is for ships to take a course which will lead
them to the south of the tolerably well-marked field into

152 SEA AND LAND

which the icebergs journey. The detour which it is neces-
sary to make, even in the years when the ice-fleets are most
numerous and journey the farthest south, would be but slight;
it would not add more than a day to the duration of the
voyage. The fleeter scouting ships of the war marine might
well be employed in reconnoitring the position of these ene-
mies, so that their place would be well known to the mer-
chantman. With these relatively slight precautions there is
no reason whv, in the centurv to come, w^hen the Atlantic
shipping is tenfolded in amount, this sea should not be tra-
versed without any danger from this source.

HARBORS AND CIVILIZATION

First Condition of Ships. — Origin of Maritime Habit ; Relation of Habit to Form of Shore ;
Effect on National Progress. — Condition of North America as regards Harbors.- -
Reeiuirements of a Good Port. — Classification of Harbors. — Delta Harbors. — Valley
Harbors : How Dependent on Changes of Level. — Fjord Harbors : The Conditions of
their Formation; Value as Ports. — Mountain Range Harbors. — Morainal Harbors.

One of the most im[)ortant steps which lead from the
primitive savage state toward the ways of culture and civili-
zation is taken when men contrive instruments of naviga-
tion. Almost all the peoples of the earth have accomplished
this first stage of advance. Only a few inferior races are
without devices in the way of boats. Although this art of
navigation is itself a powerful instrument of culture, inasmuch
as it teaches men to contrive and use tools, to face danger
and to associate their action in a very educative way, it was
only slowly and rarely that they attained sufficient skill in the
construction and management of boats to venture upon broad
waters. Ships of considerable size, fit to undertake long
voyages, appear to have been separately invented at several
different points in the Old World— by the Scandinavians, by
their kindred Aryans of the Mediterranean, by the Chinese,
and perhaps, separately, by the people of the Malay archipel-
ao-o and of Hindostan. The PhtLMiicians and other Semitic
people early acquired the art of constructing large boats, but
whether by their own invention or by copying those of other
people is uncertain.

154 SEA AND LAND

For a long time after sea-going ships were invented, they
were of small size ; they all ap[)car to have been without keels
and to ha\e been propelled by oars, with onl\' an occasional
use of sails. Craft of this sort were to a certain extent inde-
pendent of harbors, or at least needed them only as landing-
places, for it was a common custom to drag them on their flat
bottoms up the surface of any smooth beach. In other words,
they preserved the type of rovvboats such as are normally
used on inland waters. It was not until about two thousand
years ago, when the use of ships for war purposes on the
Mediterranean led to a great increase of their size, that
vessels lost tlieir amphibious character, became permanent
denizens of the sea, and had to be sheltered in good harbors
when they lay near land. After the invention of the keel,
merchant ships gradually abandoned the use of oars for
propulsion ; they w^ere increased in size, and so in time all
commercial craft came to require the protection of harbors
in receiving or discharging cargoes. During the last century
this enlargement of vessels has gone forward with exceeding
ra{)idity, so that at the present time the average tonnage of
sea-eoine ships is at least fivefold as orreat as it was a hundred
years ago.

The maritime spirit of the different peoples that resort to
the sea was developed and determined in the ages when
vessels had not passed beyond the stage of boats of small
size. Their first lessons in seamanship seem to have been
acquired in tolerably sheltered waters where bays or islands
favored tentative experiments in navigation. Wherever any
of the shores of the Old World abound in inlets or are beset
with islands, if the country was inhabited at an early day
by people capable of advance in the ways of life, we al-

FIRST CONDITION OF SHIPS 155

most invariabl)- find that the maritime spirit was developed
in a measure (juite up to the progress in other arts. On the
other hand, wherever the shore was not deeply embayed or
fringed with islands the folk seem never to ha\c ac(piired the
mariner's craft, how^ever far the\- have advanced in other
constructive arts. Thus the Egyptians, though marvellous
builders on the land, never became a seafaring people ; their
marine commerce appears to have been managed by other
folk, bred in districts more favorable to the development of
seamen. The Peruvians possessed architectural skill, but
they were never tempted by the conditions of their coast line
to venture far upon the sea. We thus perceive that natural
harbors, or rather the conditions of a shore line affording, as
it were, a gradual passage from the conditions of the land to
those of the wide ocean, favor the development of sailors.

The two most remarkable cradles of navigators are found
in the peninsulated and island-bordered shores of Europe and
in a somewhat similarly conditioned region in Southeastern
Asia. Both of these districts, where land and sea are much
entangled, have developed singularly maritime people. The
Malayan region, verging eastw^ard into the vast archipelagic
sea of the tropical Pacific, has bred a folk exceedingly skilful
in seafarinor. Althouorh the rancre of their arts as determined

o o o

by their share of natural ability has proved limited, they are
perhaps for their social estate the boldest voyagers in the
world. Their ventures, however, have been made in waters
tolerably exempt from severe storms, so that their relatively
frail vessels were insured from the graver perils of the deep.
The seafaring arts of Europe were developed under very
different conditions from those of the Malayan and Pacific
islands. All the shores of Europe are storm-swept. Even

I5C» SEA AND LAND

in the Mediterranean the cHmate is tempestuous, and ships
have to be well built and equipped to meet the heavy waves,
and sailors must be masters of their art. Moreover, in that
continent the Aryan people have their principal seat of em-
pire, and tliis race, by stern proof through centuries of trial,
has been shown to contain the preeminently seafaring men of
the world. The Semitic and Chinese races have exhibited a
comparable skill in various other arts, but the Aryans have
ploughed the seas with a courage and success unapproached
by any other variety of men.

The subdivisions of European people show a variation
in the measure of their maritime success generally propor-
tionate to the degree in which the physical conditions of the
countries the)' occupy favor training in the seafaring art. The
great peninsulas and islands of the northern part of the con-
tinent, Norway and Sw^eden, Denmark, and the British Isles,
have developed the preeminently maritime states and peoples.
The best of these nurseries of seamen was of old in the Scan-
dinavian peninsula, where our ancestors formed the cruising
hal)it, where they developed the courage and address required
for journeys over wide and unknown seas. The folk of these
peninsulas were nurtured in a country wdiich could not have
been better contrived for the maritime development of a
people. The shore is so intersected w^ith deep reentrants,
penetrating far into the land, that the navigating habit was in
a way imposed upon the people. No vigorous race could
develop in such a country without learning how^ to manage
a boat and without being invited to extend their voyages from
the simplest essays in narrow land-locked channels to ever-
enlarging ventures which finally led them to face the wide
ocean. The Northmen took with them their seafarine habit

ORIGIN OF MARITIMi: HABIT 1^7

when by successive steps the)' C()n([uered I>ritain, and it is in
the main their motive, transmitted by the inheritance of blood
and habit, which has made our own people for two centuries
successful in the exploits of war and peace upon the seas.
More than fi\e centuries before the Mediterranean people
dared to traverse the safe waters of the trade-wind belt which
separates Europe from America, the hardy Northmen found
their way, in their frailer craft, across the storm-swept waters
of the North Atlantic to the .American shores. Greenland at
least was the seat of pernianent settlement and the object of
innumerable voyages centuries before the Southern Europeans
dared venture far beyond the Pillars of Hercules.

The vast importance of the seafaring habit to the history
of a people may be judged by its effect upon the fate of the
English folk. Owing to their skill in seamanship and their
courage in facing the dangers of the deep they have been able
to establish their j)Ossessions in every part of the world which
may have particularly tempted them to colonizing ventures.
By way of the sea they have been led to become an almost
world-wide people. Of the three New-W^orld continents —
North America. South America, and Australia — they possess
Australia altogether, and almost all of North America ; only
the southern of the twin continents has escaped their grasp.
Nine-tenths of the valuable islands beyond the limits of luirope
belong to the English-speaking people, or to their kindred,
the Dutch ; in a word, through their maritime power those
North Eiiroi)eans bid tair in time to dominate every part of
the world which is ht for their occupation. These considera-
tions make it plain that the way to national power is over the
waves, and tliat this wa\' is the natural path of our race. It is
on this account that all those natural features which we are

158 SEA AND LAND

about to discuss may fairly claim the attention of our
people.

Although by means of modern engineering devices it has
proved possible to construct, though at very great cost, toler-
ably good shelters for ships even on harborless coasts where
the physical conditions are not favorable for such undertak-
ings, there seems no reason to expect that any advance in the
engineer's art will ever exempt a country from the disadvan-
tages which the absence of good natural ports entails. While
defective harbors ma)' be improved by engineering devices at
reasonable cost, the creation of havens is impracticable except
under peculiar conditions, such as occur at either extremity of
the Suez Canal. We may therefore assume that hereafter, as
heretofore, the well-harl)ored lands of the world will remain
the seat of the dominant seafarers, and that the Northmen
folk —the English, Scandinavian, Dutch and Oermans — and
their descendants in other parts of the world, will remain
masters of the sea and thereby retain and extend their power
in the conduct of the world's affairs.

The measure in which power rests upon the keels of ships
may be seen by contrasting the history of Great Britain and
that of Switzerland. In all that relates to manly qualities or
to intelligence in commercial affairs, the peoples of these two
countries may be regarded as equals. But the Swiss have
been limited to their mountains ; the power of the state has
never been felt more than a few hundred miles from its
borders, and its influence in the affairs of the world has been
accomplished altogether by its fame and its emigrants. On
the other hand, Great I)ritain, as before remarked, owing to
the long training in seafaring which its people have received,
has become the dominant power of the world. As will be

RELATION OF HABIT TO FORM OF SHORE 159

made evident in the sequel of tliis essay, North America, and
particularly the part of ii held by the United States, is more
advantageously placed in relation to marine navigation than
any other equally extensive portion of the lands of the earth.
Owing to the shape and position of this continent it faces the
two great divisions of oceanic waters, the Atlantic and the
Pacific, and nearly all parts of its area are readily accessible
from the shore by rivers or relatively short railways. At no
point on its coast line do we find a stretch of shore of more
than three hundred miles in length which is without a haven
suitable for modern shipping or which cannot readily be
made into a good harbor.

In addition to the advantages arising from the relation of
this continent to the oceans, North America is singularly well
placed for internal marine commerce. On its southeastern
side lie the great inclosed basins of the Caribbean Sea and the
Gulf of Mexico, which together form one lield of tropical
waters, exceeded in their extent and the richness of their
shores only by the Mediterranean Sea and the Sea of Japan.
This great American basin lies between and in a measure
unites the continents of North and South America. Owing
to their essential unity these basins might fitly be termed the
Columbian Sea in honor of the explorer who first penetrated
to this part of the world. A straight line drawn in this basin
from Galveston, Texas, to the western mouths of the river
Orinoco, has a length of about twenty-eight hundred miles.
The total area of its waters is about the same as that of the
Mediterranean, and the economic resources of its shores are
probably greater than those of the Old World's historic sea.
Into this basin discharge the waters of two great navigable
river systems, the Orinoco and the Mississippi. Thus there

l6o SEA AND LAND

may here be united by water transportation the products of
the temperate and tropical zones. Owing to the pohtical and
social conditions of this American Mediterranean, it has, as
yet. played but a small part in the commerce of the world, but
the possibilities of commercial development which it affords
are very great.

The northern part of North America, both on its eastern
and western faces, abounds in extensive embayed waters,
which in their general character resemble those of Scandinavia
and which are equally well fitted for the development of sailors.
On the Atlantic side, to the north of Newfoundland, the rigor-
ous climate is likely to debar the land from much use by civil-
ized man. On the western shore, however, north to Bering
Strait, the forests, mines, and fisheries are likely to make the
bays and fiords the seat of a great maritime life. On the
southern portion of the Pacific shore the Gulf of California,
one of the longest embayments of the sea in the world, has an
extensive coast line, and, though its shores are of an arid
nature, it is likely to have an importance in the development
of our semi-inland navigation.

In the central and northwestern part of the continent lies
a great system of lakes, which together constitute the most
extended series of fresh-water seas known in the world.
Already the Laurentian jjortion of these waters, which we
fitly term the Great Lakes, is the seat of a vast and contin-
ually augmenting commerce. With the development of the
Canadian Dominion, the yet more northern and western
basins which lie in the valleys of the Nelson and McKenzie
rivers are likely to attain much commercial importance. It
will thus be seen that North America, in all that relates to
water transportation, both that which lies within the continent

EFFECT ON NATIONAL PROGRESS i6l

and that wliich is favored b}' ready access to the open seas,
is better placed than an\- other of the continental areas. It
is therefore fit that our people should feel themselves inter-
ested in all questions which are connected with navigation.

From the time of the settlement of this country from
England to the beginning of our civil war, the English part
of our population was intensel)' interested in seafaring. In
the middle of the present century our commercial marine,
including the coastwise traffic and that of great lakes and
rivers, was the most extensive in the world. The disturb-
ances of the civil war to a great extent broke up our foreign
commerce. Since the reunion of the country the d(;velop-
ment of the region beyond the Mississippi and of the Cordil-
leras has absorbed the energies and occupied the capital of
our people to such an extent that we have been little con-
cerned with the trade beyond our own borders. Now that
the important task of wanning our internal empire to use is
in good part accomplished, there is reason to believe that we
shall enter upon the peaceful conquests of trade with remote
lands in the manner of our ancestors, but with vastly greater
resources for the development of that form of commerce.
It is safe to say that, at the end of the next century, and
perhaps near its very beginning, all that relates to the condi-
tions of our coast line will appear to us much more important
than at present. Therefore, we may presume that such
studies as are here essayed concerning American marine ports
will be timely and will at least in some considerable measure
anticipate the interests and needs of our people.

The conditions necessary to fit any part of the shore to
serve vessels as a shelter and landing place are in general as
follows, viz.: The haven must be protected from the incur-

I 62 SEA AND LAND

sion of heavy waves ; it must be provided with a channel of
sufficient depth leadin^^ from the ancliorage to the open
water ; the phice where the ships may He needs to be so
located that they may readily dischari^e and receive cargoes,
and the landing must be convenient of access to the internal
commercial routes of the district wherein it lies. When
these conditions are satisfied the haven in question is likely
to have a measurable importance, but many other conditions
have to be met before it will be entirely fit for commerce.
The sheltered waters of sufficient depth sliould afford good
anchorat^e ground and be roomy enough safely to accommo-
date many ships. The way of access from the sea should be
deep and direct ; it should, moreover, not be the seat of very
strong river or tidal currents, for the reason that such streams
are likely to put vessels in jeopardy. The shore near the
harbor should not be exposed to great masses of moving
sand, for these drifting with the currents are likely to endan-
ger the passage to the sea or by frequent changes to confuse
navigators. The refuge should be exempt from closure or
serious emljarrassment by ice. However good it may other-
wise be, such obstruction, even if temporary, very much
affects the value of a port.

We shall now proceed to consider the physical conditions
which lead to the formation, preservation, and destruction of
havens. In the treatment of the subject we shall naturally
be led to a classification of these basins, based upon the cir-
cumstances of their origin. We shall also be led to group in
due order the forms of energy which operate to preserve or
destroy ports, and the measure in which these actions may
be affected by the care of man.

The simplest condition which leads to the institution of

VALUE OF DELTA IL ARBORS 1 6

o

a harl)or arc found where a large river enters the sea. Ordi-
narily the i)assagc of the stream from the land to the deep
takes place through a considerable accumulation of detritus
which has been brouglu down by tlie stream and spread out
in the form of a delta, such as exists at the mouth of almost
all the great riv^ers of the world. These delta ports, as we
may term them, w^ere among the first to be used for marine
commerce, and remain among the most important harbors in
the world. Their commercial value is peculiarl)- great, for
the reason that they are always connected with an extensive
area of more or less navigable river waters which afford a
natural way by which the materials of commerce may l)e con-
veyed to and from the interior parts of the country. Thus,
in the case of the Mississippi system of waters, shores, hav-
ing an aggregate extent of tens of thousands of miles, are
accessible to the delta port at its mouth. The navigable
w'aters of the Amazon are of yet greater extent. There are
in the world at least a dozen of these delta ports w^hich,
from their commercial importance, are or in time will be
ranked as havens of the first order.

Along with their advantages delta harbors exhibit certain
grave defects. While the water in the channels which are
well within the area of the delta is usually deep (and this
for the reason that the motion of the stream keeps the
passage clear), the entrance to the river channel is commonly
made difficult by a widespread deposit of mud which stretches
for some niiles seaward beyond the mouth of the stream.
The formation of this outlying fringe of mutl fiats is brought
about in a manner which can be readily understood. When
the river waters enter the sea they are no longer under the
influence of the current of the stream which bore them on ;

1 64 SEA AND LAND

the nuul which they abundantly contain therefore settles
upon the bottom of the sea. Its precipitation is favored by
a mixture of the salt water with that which has come from
the land, for, as is well known, the infusion of a certain
amount of salt with water containing- suspended mineral par-
ticles hastens the |)rocess b)' which the sediments separate
and fall to the bottom. i\s long- as conimercial ships were
of small size, drawing- no more than twelve or fifteen feet of
water, delta ports of this class were generally suitable for
commerce ; but with the increase in draft of our modern
ships, these hax'cns require engineering v/ork to make them
fit for the needs of shipping-.

Another disadvantageous feature exhibited by delta ports
is found in the frequency with which the principal path of
exit of the river waters changes its position. By reference to
a map of the Mississippi delta or those about the mouths of
other great streams, it will be seen that the river commonly
has a number of sei)arate arms by which its llow may escape
to the sea. In most cases detailed study shows that only one
of these exits is at any particular time the seat of the prin-
cipal stream. The others have been temporarily abandoned,
but may from time to time be reopened l)y the varying move-
ment of the waters. Hydrographers who have studied the
laws of river movement recognize the fact that these delta
channels are naturally, indeed we may say necessarily, subject
to changes in jjosition. When after a time an outlet has
extended in the manner of the present channel of the Missis-
sippi for a considerable- distance seaward, the energy of the
current is slackened b\- the lengthening of the slope over
which it moves, and so the flood waters begin to rise to a
greater height in the up-river portion of the delta than they

DEFECTS TO BE OVERCOME 165

tlid before. Finally, they find their way by some shorter cut
to the margin of the land, and, for the reason of tlie shorter
distance, the slope over which the)- tlow is steeper than that
they have before pursued. Moving rapidly down the decline,
the water soon cuts open a new^ channel through which it
has for a time a freer exit ; the old and longer way then
gradually silts up, until it has no value as a pathway for the
stream or as a port.

The changes of channel which occur in a delta district
are often of formidable commercial importance. Thus the
Yellow River of China in 1853 opened a new outlet to the
sea, the mouth of which was some hundreds of miles from
that of its former path. At the present time the main out-
let of the Mississippi tends to change its place in the manner
and for the reasons above suororested. In cjeneral, it mav be
said that a few centuries represent the time during which a
delta mouth will normally maintain one position.

It is possible by means of engineering devices to overcome
some of the most considerable defects and dangers which
beset delta ports. The obstacles to upward navigation due
to the current of the stream, a hinderance which is often of a
serious nature to sailing vessels, may be met by the use of
steam tugs. Such accidents [is the change of channel, which
may at any time cut off the city which develops at the port,
and leave it in an unprofitable position, can be indefinitely
postponed by engineering devices. The most serious objec-
tion to this class of harbors, that due to the broad platform
of mud forming widespread shallows just beyond the margin
of the delta land, is more difficult to meet. For a long time
it seemed an insuperable difficulty, for the reason that,
although a channel miglit be cut open by artificial dredging,

i66 SEA AXD LAND

the action of the waves in times of storm, added to the work
naturally done by the river, operated rapidly to close the
opening. A method of meeting this difficulty has been found,
however, and has been successfully aj^plied to the delta
mouths of two great streams, the Danube and Mississippi. It
was first invented and applied in the European instance, but
it has been used with the greatest success by an American
engineer, Capt. James \\. Eads, in securing a deeper ship
channel leading to the port of New Orleans.

In the method of improvement above referred to, the
boundary walls to the channel are continued for some distance
beyond the point to which they have attained in the natural
extension of the delta. They are in fact led across the mud
flat which forms beneath the sea beyond the edge of the
marshy land, until the sloping bottom has attained a sufficient
depth of water for the convenience of incoming ships. The
principal disadvantage of the method is found in the fact that
the sediments brought down by the river frequently settle
next to the artificial mouth, as they did in front of the natural
opening, so as to require a constant building of the jetties
towards the sea. There is, of course, a limit to the con-
venient extension of the stream mouth in this artificial
manner, but for years the scouring action of the current
deepens the water of its enforced channel, and so makes the
entrance and the path of the stream suitable for commercial
needs. In the course of time it will probably be necessary
to open another and shorter pathway of escape for the Missis-
sippi, or to provide an artificial entrance by means of a canal
leading from the river to the sea, but there seems no good
reason why this channel should not be so selected as to pre-
serve the city of New Orleans as the port for the sea-going

V ALL FA' HARBORS 1 67

commerce of the stream. Tluis these modern imjjrovements
in the way of towboats and jetties promise to avoid all reall)-
serious inconveniences connected v\ith delta harbors.

Ports of the class which we are now to consider resemble
those just described, owing their origin to the work done by
considerable rivers. In every other [)articular, however, their
features are peculiar. The havens belonging in this second
group are formed where a river valley was carved in the land
at a time when the surface of the country in which it lies was
at a considerably higher level than at present. The depth
and form of the gorge so excavated by the flowing stream
may have varied greatly. In most cases we may assume that
there was a delta at its mouth like those formed at the mouths
of all great rivers along shores which have not recently sunk
down. When tlie coast line subsided, say to the depth of
one or two hundred feet, the sea was permitted to enter
the valley for a distance dependent upon the degree of its
slope and the amount of the downsinking of the land. Under
these conditions the path of the river next the sea is con-
siderably shortened, and at the head of the ba\- thus formed
the stream begins to make a new delta, which in time may
completely close the reentrant formed by the subsidence.

At first sight it may seem as if this were an improbable
means whereby harbors could be formed, but the fact is that
a large number of the great commercial ports, both in this
country and in Europe, owe their origin and much of their
value to such vertical movements of the land. The most im-
portant havens on the Atlantic coast from New York to the
Rio Grande, and probabl\- man\- of those on the Pacific shore
of the United States, doubtless owe their formation to this
subsidence of the shore lands. Delaware and Chesapeake

1 68 SEA AND LAND

Bays, Pamlico and Albemarle Sounds, the harbors of Charles-
ton and Savannali, and Mobile Bay afford perhaps the best
instances of this class of havens. At the time when the sub-
sidence which produced these reentrant delta harbors took
place, the valley of the Mississippi was occupied by the
greatest of these bays, which probably extended for several
hundred miles above New Orleans and had at some points the
width of fifty miles or more. Owing to the very large amount
of detritus which that stream bears to the sea, the whole of
the reentrant has become tilled by the newly formed delta, and
the accumulation now projects beyond the ancient valley and
thus has the normal form of such deposits.

It is characteristic of the ports which are formed in these
flooded valleys, that they were originally wide-mouthed, and
narrowed gradually toward their head waters. In many in-
stances the passage from these basins to the sea has become
constricted by the formation of sand spits, built in the manner
hereafter to be described. Owing to the plentiful incursion
of river waters heavily charged with sediment, the harbors of
this group are apt to become shallowed, and, except so far as
they are kept open by tidal currents, are often unfitted for the
use of large ships. This shallowing of the water is likely to
be most conspicuous in the parts of the basin near the existing
mouth of the true river. It occasionally happens, that, while
the floor of the bay over the greater part of its extent has
been converted into shoal water, some of the side gorges
originally occupied by small streams retain a great depth of
water. Perhaps the most notable instance of this kind is
afforded by Albemarle Sound. Where this estuary traverses
the Dismal Swamp, its main channels have, at low tide, only
four or five feet of depth, but the waterways which penetrate

IlOir DEPENDENT ON CHANGES OF LEVEL 169

into the Dismal Swamj), where they receive httle or no
detrital matter even in times of heavy rain, occasionally retain
a depth of twenty or thirty feet, their bottoms lying even
beneath that of the neighboring parts of the open sea.""

Few save those who have made a special study of geology
have any clear idea concerning either the nature or frequency
of those movements which take place in the shore districts of
the greater land masses termed continents. It therefore may
aid the reader to understand the extent to which havens are
formed by the submergence or flooding of old river valleys, if
he is presented witli some of the more important acts and con-
clusions concerning these curious movements. It is well at
the outset to understand, that although there is much evidence
to show that from the earlier geological ages the continents
have existed as areas of dry land, that of North America, for
instance, having been a geographic unit since the Carbonifer-
ous Period, or, at most, with its eastern and western parts
divided by a narrow sea, the outlines of this and other lands
have been subject to frequent and extensive changes of level.
Thus in the geologically brief period since the beginning of
the last Glacial Epoch, or, as we may fairly term it, since the
morning of the geologic yesterday, all the eastern coast of
North America has swayed up and down in several successive
oscillations ranging from a few score to a few hundred feet.
At the beginning of this last ice age the northeastern portion
of the continent was evidently somewhat higher than it is at
present. When the weight of the ice lay ui)on the land, it
sank down so that the depression along the coast of New
England as compared with the present level of the sea was

* See General Account of the Fresh-water Morasses of the United States, by

N. S. Shaler. Tenth Annual Report, pp. 327, et seq.

I70 SEA AND LAND

two hundred feet or more. Somewhat later this region was
elevated to a height a Httle above its present level. This
resurgence from the deep was followed by yet another down-
sinking, probably of relatively slight amount, but suf^cient to
carrv many areas of forested lands below the level of the tide.

In the region about the Dismal Swamp of Virginia, the
present writer has ascertained that there have been at least
three periods of successive elevation and subsidence, during
which the land swayed up and down through a range of about
fifty feet of altitude within a period which is probably to be
reckoned as of no greater duration than the time that has
elapsed since the last great invasion of ice began in the north-
ern part of the continent. Athough the study which has been
applied to the subject of land swayings is still very incomplete,
the results are sufficient to assure us that such instances as
have been given are by no means exceptional. They have
been indeed common in all stages of the earth's history which
are legibly chronicled in the pages of the great stone book
whose leaves are the strata of the earth's crust. It is proba-
ble, however, that these movements of the land are often
greatest next the shores ; they may indeed occur there with-
out corresponding alterations in the level of the interior parts
of the continent.

As yet geologists have not satisfactorily traced the several
causes which cooperate to bring about these upward and
downward movements of the earth's crust. They have, how-
ever, become convinced tliat the old idea to the effect that the
land masses were in some way permanently and rigidly upheld,
like the arclies of solid masonry, is an error. They are driven
to conceive these parts of the crust which are above the level
of the sea, as well as much of the ocean floor near the con-

EFFECT OF THE GLACIAL SHEET 171

tinents, to be in a state of very unstable equilibrium, easily
swayed up and down by forces which operate in the outer
part of the earth or upon its surface. Thus when the glacial
sheet was laid upon the northern lands the effect seems to
have been to bear down the surface of the earth on which it
was imposed, to a depth in a way proportionate to the thick-
ness of the ice. When the glaciers melted away the de-
pressed areas quickly recovered their position, and, as we
have noted above, rose even higher than they are at the
present time. The accumulations of sediment washed from
the land and deposited on the sea-floor appear also to bear
down the surfaces on which they rest, in substantially the
same way in which they are affected by the burden of a
glacial envelope. On the other hand the removal of weight
from the land by the action of rain-water, by which vast
quantities of material are taken away, appears to favor the
constant uprising of the land, so that, though endlessly
down-worn by the action of the elements, the continents
remain ever undestroyed.

As the central parts of the earth are constantly shrinking
from the loss of heat, while the portion next the surface
remains unshrunken for the reason that it has lono- since
parted with the greater part of its caloric, the outer envelope
of rocks has constantly to wrinkle into the broad upcurves of
the continents and downcurves of the sea-floor in order to fit
itself to the diminished internal mass. The action may be in
a measure paralleled by that which takes place in an apple.
the skin of which wrinkles as the juice dries away from the
inner parts. The folding of the outer envelope is due, as we
readily perceive, to the fact that the interior of the sphere
shrinks much, while the outer part thereof does not contract

172

SEA AND LAND

and therefore has to fold. It is evident that wlien a continent
has beL^un its growth the tendency is for the upward arching
curve to continue growing in tliat direction, while the down-
ward flexures of the sea-bottoms in the same general way per-
sistently tend to grow deeper. It is easily to be conceived
that in such a movement of uprising land and downsinking
sea-floor we necessarily have a neutral or fulcrum point of
the motion, in the manner indicated by the diagram. The

In diagrams I. and II. the lines a h represent the land before the movement, and a' b' represent the land
after the movement : s s the position of the shore-line ; // the pivotal points : /s the sea level. In dia-
ffram III. the curved line designates a shore, the line a b connecting pivotal points 2X /• p, the pivotal line
partly under the land and partly under the sea.

neutral ])oint, or position of no motion, on a line extending
from the interior of the continents to the areas of the neigh-
boring sea-basin, may occupy either of three positions in
relation to the shore-line. It may be just at the coast, in

RELATION TO HARBORS 1/3

which case a e^ood deal of upward and downward move-
ment at either end of the section ma)' take place without any
alteration in the position of the shore-line, or the pivotal
point may be some distance within the land, in which case
the movement may lead to a gain of the sea upon the con-
tinent. In the third possible condition the point of no motion
may be seaward of the shore, when, though the nature of the
movement may be exactly the same as before, the coast-line
will rise and the land gain upon the sea.

In the way above suggested we may account for the
frequent changes in the direction of the movement which
occurs in those parts of a continent which are near the shore-
line, without having to suppose that the whole mass of the
continent undero-oes like changes of level. The inland dis-
tricts may be in a somewhat constant manner rising into the
air, while the coast-line, ownng to slight accidental changes in
the position of the fulcrum points, may be subjected to con-
stant oscillations of movement.

If the sea-shore remains in the same position for a long
time, the ordinary effect of the coast-line actions is to close
the harbors, either through the accumulation of debris brought
into them by the streams or by the sands which the waves and
coastal currents are continually impelling into all the recesses
of the shore. Where such conditions occur we may reason-
ably expect to find a coast to a great extent destitute of
harbors, though we may trace the evidence of their former
existence by noting the basins filled with alluvium which
exist along the margin of the land.

Where any coastal region is without considerable rivers,
and where there are no conditions such as we have hereafter
to describe which lead to the formation of indentations,

174 SEA AND LAND

we commonl)- find that there are Init few and inadequate
shelters for ships ; thus on the west coast of the Americas
from northern Mexico to southern Chile, an essentially river-
less region, embayments suitable for havens are very rare.
Similar conditions prevail in all the seaboard regions near the
great deserts of north Africa. Although these shores are
subject to constant oscillation, they have no large troughs
such as the rivers cut on other coast-lines which may be filled
by the sea waters during the periods of subsidence. Where
the river valleys are deep the accumulations of debris formed
in them during the periods of temporary subsidence are often
not sufficient to obliterate their form. Thus, in the case of
the Hudson and other valleys along the east and west coasts
of North America, the depression occupied by the stream in
former periods of elevation is still traceable as a deep trough
for fifty miles or niore into the sea. If the shore near New
York were elevated even as much as two hundred feet, the
reentrant of the Hudson Valley would still appear as a deep
bay and afford, as it does at present, a serviceable port. Thus
it comes about that in periods of elevation, as well as of
depression, the irregularities of the coast-line, due to the
action of rivers, serve to maintain the varying outline of the
shore on wliich the existence of harbors depends. While
there are many other actions which operate to bring about
the formation of harbors, this which we are now considering
is probabh of more general importance and affects a larger
part of the coast-lines than any other class of actions at work
along the shores.

In certain parts of the world in regions of high latitude,
we find the coast-line fretted with very numerous channels
which often penetrate far into the land, while the shore for

CHARACTERISrJCS OF FJORD IX LETS 1/5

some distance seaward is bounded by a fringe! of rocky
islands. Shores of tliis character are common in the northern
hemisphere from the parallel of 40° to near the Pole. They
are noticeable also in the southern part of the earth along
the coasts south of the same parallel. The feature is less
conspicuous near the southern Pole, for the reason that the
greater portion of that realm is occupied by the sea. The
people of the Scandinavian peninsula have long applied to
the deep inlets of that coast the name of fiord. Geologists
therefore apply the term to all indentations of this character
wherever they are found, and to the regions in which these
indentations characteristically and plentifully occur they give
the name of fiord zone.

In their form the indentations of the coast in the fiord
districts differ widely from those which belong to the other
classes which we have already considered or have hereafter to
note. Where best developed this class of inlets exhibits the
following peculiarities : The valley occupied by the embayed
waters is remarkably deep. The shores are steep, so that a
cross section of the trough is distinctly U-shaped. If the
region in which a fiord lies be elevated, its sides may rise as
in Norway to mountainous heights, but indentations of this
description occur even where the shore lands attain to no
o-reat height above the sea. In characteristic fiords the water
within the basin may have the depth of many hundred feet ;
tracing a line of soundings from the interior of the liord
seaw^ard, the w^ater is often found to shallow near the
entrance of the indentation until the depth is onl\- a small
fraction of that which exists in the land-locked parts of the
valley. This sill or barrier near the mouth of the inlet is a
frequent but by no means an invariable feature in the fiord

176 SEA AND LAND

structure. It is most distinctly presented in the case of the
greater indentations bearing this name which lie along the
coast of Norway. Where the valleys of this nature are less
accented, as along the eastern coast of North America, there
is barely a trace of the sill or ridge between the basin and the
sea, or it may be altogether absent.

While in the main the fiord channels lie at right angles
to the coast-line of the sea into which they open, each of
these basins commonly exliibits numerous side bays extend-
ing more or less nearly at right angles to the axis or main
line of its trough. It generally is evident that these ramifica-
tions of the fiord are cut in the softer rocks or in the weak
places of the strata against which they lie. Where the side
embranchments of one fiord come in contact with those of
another and the valleys are cut to a sufficient depth, their
waters may be confluent and islands are formed. Thus it
comes about that in passing from the sea towards the firm
land of a fiorded coast there are usually encountered first a
fringe of islands and then the embayments which penetrate
the body of the land. A rational consideration of the facts
shows us that islands and bays alike are due to the same
cause. While it is easy to perceive that the conditions
which have determined the formation of fiords are peculiar,
much difficulty has been encountered in arriving at a clear
conception as to the nature of the forces which have exca-
vated them. Although their origin is yet under debate, the
facts point to the conclusion that fiords are mainly, if not
altogether, due to the peculiar kind of wearing which takes
place beneath a glacial sheet.

In examining the question as to the origin of fiords we
should in the first place note that this class of indentations

CONDITIONS OF THEIR FORMATION 1/7

is limited to the regions which were during the last glacial
epoch occupied by long-enduring ice, as is indicated by the
existence there of drift material, such as glaciers alone could
form and transport, and by the characteristic scorings on the
rock surfaces which glaciation alone can cause. This approxi-
mate coincidence between the field occupied by glaciers and
the shores abounding in fiords is of itself sufficient to raise
the presumption that this fretting of the shore is due to ice
action. This presumption is strengthened by the fact that
the fiords are deepest and of most characteristic form in those
parts of the world where we may fairly suppose the glacial
sheet to have been the thickest and to have remained active
for the longest time. Thus in Scandinavia and Scotland, in
Greenland. Labrador, and Alaska, in the extreme southern
part of South America, and in New Zealand, the fiord struc-
ture is greatly developed, while in the parts of those fields
which, though somewhat glaciated, lie in latitudes nearer the
equator the fiords are carved to no great depth. In other
words, where the ice was thick and abided long the pecuHar
carving of the land characteristic of the well-developed fiords
was the greatest, while in the regions in wliicli the ice action
was relatively weak the valleys were excavated to a much less
depth.

We furthermore note the fact that the form of surface
which along the coast-line gives rise to fiords is not peculiar
to the shore lands. It extends back for an indefinite distance
into the interior of the land in the latitude in which these
frineed shores occur. In a less distinct wav it is also con-
tinned for some distance seaward beyond the present margin
of the water. In other words, the fiord belt is not due to
some peculiar action which has taken place along the existing

1/8 SEA AND LAND

shore-line, but it owes its origin to a general character which
is stamped upon a large part of the lands that have been
eroded by glacial action. It is also clear that the institution
of fiords does not depend upon such carving of the land as
may be brought about by ordinar)- river action. If we com-
pare the character of the rocks in the peninsulas of Spain and
Scandinavia we iind that the strata of the two regions appar-
ently do not differ from each other in any essential way, at
least as regards their resistance to the erosion effected by
rain-water ; but th(! northern of these two areas everywhere
exhibits a horded coast-line while the shore of the more south-
ern land is as characteristically exempt from this peculiar
topography. In the same way, on the Western coasts of North
and South America the extreme northern and southern parts
of its extent are extensively fiorded, while the intermediate
section from the mouth of the Columbia River to Valparaiso
forms one of the least indented shore-lines in the world.

Not only are fiords limited to glaciated areas, but the
general topography upon the existence of which their pres-
ence depends can, so far as we know, be created only by a
glacial action. As we have just noted, it is characteristic of
well-developed fiords to have a basin- or bowl-like character
in the upper part of a reentrant, and an elevation or sill
between this depression and the sea. Now it is a well-known
fact that in glaciated countries we always find more or less
numerous lakes having essentially the same shape as the fiord
basins ; deep depressions, rock-walled on every side, are
among the most familiar results of extensive glacial w^earing.
The eastern portion of North America abounds in such
depressions, and they are extensively developed in the valleys
of Switzerland, where we know by indisputable evidence that

EFFECTS OF GLACIAL WEARING 1 79

glacial work has been very extensively done in recent geo-
logic time. It is indeed characteristic of glacial wearing, as
distinguished from the erosion effected by flowing water, that
the ice can carve out depressions in the rock. If we examine
any considerable area which was worn by ice, we find every-
where pits upon its surface, which may be from a few feet to
a hundred feet or more in depth. Owing to the essential
plasticity of ice it can, when moving in the manner of a
glacier, descend into and rise up from tolerably deep depres-
sions ; it will, indeed, deeply carve out any soft portion of
rock which it may encounter, leaving the surrounding
materials as a rim to the basin. \\ hile it is true that onl\'
a small part of the lakes which beset the glaciated countr\- of
North America are due to the fact that the water is contained
in basins completely surrounded by firm-set rock, there can be
no question that there are thousands, if not tens of thousands,
of such cavities on the glacially worn surface of this countrw
It is a noteworthy fact that the form of the fiord basins
is essentially the same as that of our glacial lakes wliich
are surrounded by rock margins. The fiords, which are
characterized by a sill or barrier rising to near the surface
of the water on their seaward side, may be regarded as
basins essentially like those which are occupied by the rock-
bordered lakes, the outer margins of which are slightly
submerged below the level of the sea. The fact that these
basins are due to rock-carving and in no considerable meas-
ure to river action is clearly shown, as I have elsewhere
indicated, by the arrangement of the fiords on the islands of
Mount Desert, Maine." To a certain extent these basin-

* See Geology of Mount Desert, Eighth Annual Report United States Geo-
logical Survey, pp. 1005-1009.

l8o SEA AND LAND

shaped valleys, formed by glacial erosion, are related to
those wliich are produced by ordinar}- rivers. In part, the
cutting action accomplished by the glacier is performed by
streams of fluid water coursiuL: beneath the ice and movine
forward with the violence which the weight of the over-
lying frozen water gives to their flow. Unlike ordinary
rivers, these streams beneath the ice flow up hill and down
as they follow the devious outline with which the sheet of
frozen water rests upon the surface. Athough the carving
of valleys is in part accomplished by these subglacial streams,
the work is doubtless in good part done by the abrading
action of bits of stone which are contained in the slow-
moving ice.

In many if not in most cases, fiords are doubtless pro-
duced w^here river valleys, which existed before the glacial
period, have been deepened and widened by the flowing
ice. Owintj to the fact that a orlacier in creneral cuts
with a measure of energy proportionate to the depth of
the ice above the particular point, the tendency of the ac-
tion is generally to wear down the bottom of the valleys
more rapidly than tlie intervening upland country. At the
same time, owing to the width of \\\v. slow-moving current,
the channel is widened far beyond the limits given it by
the river which formerly flowed in the gorge. If the ice
action be long continued, all distinct trace of these ancient
rivers may be eft'aced, but in the greater portion of southern
New England, where the glacial wearing was relatively small
in amount, these old streamways are still evident and with
shapes not greatly altered from their [)re-glacial form. Thus
the principal hords from New Jersey to Nova Scotia are
manifestly old river valleys which have been somewhat

VALUE OF FIORDS AS PORTS l8i

modified by the ice stream which recently occupied their
beds.

In their characteristic development in high latitudes fiords
offer singularly good harbors for ships. The main channels,
however, are often too deep to afford safe anchorage ground,
but in the shallower branches of these bays it is generally
possible to find perfectly landlocked havens exactly suited to
all the needs of shipping. Inlets of this description are, as
a rule, admirably protected from the action of those agents
which tend to destroy many other harbors. The streams
that enter them rarely convey any considerable quantities
of sediment which micrht effect a shallowinir of the basin.
The waters of these rivers are unmincrled with sediments,
for the reason that they flow from drift-covered countries
which send little muddy matter, and, moreover, the streams
themselves commonly pass through lake basins which afford
settling pools for such sediments as the flood waters may
bear. The fringe of islands which commonly lies off the
shores of a horded district often affords shelter of a valua-
able sort for craft which are undertaking coastwise voyages.
Thus for the greater part of the distance from Portland to
Eastport, Maine, it is possible for small craft to journey
without being exposed to the ocean waves, within the pas-
sages between the islands and the mainland. The protec-
tion afforded by such island fringes is even more continuous
on the western coast of North America, where the barrier
of islands extends from Puget Sound northward for a dis-
tance of more than seven hundred miles, with but slight
breaks which expose a vessel to the open sea.

The effect of a well-developed fiord structure is greatly
to increase the length of a shore-line. The measure of this

-l82 SEA AND LAND

extension, even where the fiords are only moderately devel-
oped, may be judged by the following- examples. The direct
distance from Portland to Calais, Maine, is only a little over
two hundred miles, but the aggregate coast-line of mainland
and islands between these two points is more than ten times
as great. The beautiful fiord termed the Bras d'Or on
Cape Breton, an island at the eastern extremity of Nova
Scotia, though one of the smaller inlets of this description, is
said to have an aggregate coast-line, including the periphery
of the islands which it contains, of more than one thousand
miles. The aeofreeate leno-th of the coast-line of the Scan-
dinavian peninsula and its associated islands is probably much
greater than the circumference of the earth. We understand,
therefore, how it is that the people who dwell on coasts of
this description naturally become trained for a seafaring life.

The indentations of the shore which are to be considered
as belonging to this class are formed where the upfolded
strata which constitute mountain ridges lie in such a posi-
tion that the sea may penetrate for a greater or less distance
between the axes or lines of the elevations. /\lmost all
mountainous belts are composed of such more or less dis-
tinct ridges, separated by equally definite troughs. In general
the mountain ranges of any country run parallel to the shores
near which they lie, but it occasionally happens that the end
of such an association of elevations and furrows abuts against
the sea, in which case the ocean waters may enter the valleys
for a sufficient distance and form considerable bays. In-
stances of this nature, though rare in North America, are
frequent in the Old World. Thus where the western ex-
tremity of the Pyrenees, or rather the western prolongation
of that range, comes to the Atlantic at the northwestern angle

MOUNTAIN RANGE HARBORS 1 8

o

of the Spanish pcninsuhi, a number of bays h'e between the
projecting mountain spurs ; so, too, the deep embay men ts
of Greece appear to be the flooded valleys which lie between
the numerous mountain chains of that country, while a large
part of the islands of the Archipelago are made up of peaks
belonging to those portions of the same ranges which lie
mostly below the level of the sea.

Occasionally where mountains run parallel with the sea-
shore near which they lie, some of the ranges are so placed
that their parallel valleys may be low enough to receive the
waters of the sea and thus form straits between mountainous
islands and the mainland. The elongate islands which border
the eastern side of the Adriatic appear to belong to this class
of inlets. On the coast of North America the only conspicu-
ous instances of this kind occur along the Pacific coast, of
which perhaps the most characteristic is that of Victoria, lying
immediately north of Puget Sound. A closely related group
of harbors formed by the projection of peninsulated mountain
ranges into the sea is well illustrated by the promontory of
Lower California. Owing to the large scale of these inlets
formed by the projection of mountain ranges into the sea, or
islands extending parallel to the shore, made by the summits
of ranges which are in good part submerged, the waters which
they enclose are generally too extensive to serve the best
uses of havens, though they are sometimes valuable as road-
steads where ships may at least be sheltered from the heavier
waves. Inlets of this description are much more common on
the coast of Europe than on the shores of North America, for
the reason that the mountain ranches of the former continent
are more numerous and more frequently come to the shore-
line than in the New World.

1 84

SEA AND LAND

At the front of every glacier there is accumulated a mass
of rocky debris which is shoved, dragged, or carried by the ice
and dropped at its margin. The vast ice-sheet which recently
covered the eastern coast of the continent as far south as New

Edgartown Harbor. Martha's Vineyard

Jersey here and there built these morainal accumulations to
a great height. During the greatest extension of this ice-
sheet its edge passed beyond the shore at New York and lay
beyond the coast from that point for an undetermined dis-

MORAINAL HARBORS 1 85

tance northward. The greater part of the accunuihitions
which were formed along this outer edge of ice lie beneath
the level of the sea. Here and there, howe\er, the)- [)roject
above the water, forming islands which may be of considerable
elevation. Nearly the whole of that part of Long Island, New
York, which lies above the sea level is made up of such mo-
raines. The greater part of Martha's \Mneyard, Nantucket,
and Cape Cod are of the same nature. North of the last-
named cape the more advanced moraines almost everywhere
lie wholly beneath the surface of the sea.

As the glacier retreated it constructed many of these
parallel walls of debris, separated from each other by intervals
of greater or less width. It occasionally happens that the sea
penetrates into these low grounds between the morainal walls
and thereb\- forms considerable bays. The sheltered waters
about Sag Harbor at the eastern end of Long Island, New
York, were formed in this manner. Harbors of this nature
are generally shallow, and, save for the protection afforded by
the scouring action of the tide, are almost certain to become
filled with debris washed from the cliffs of drift materials
which rapidly yield to the assaults of the waves and currents.

At the time when the moraines were fornied there were
flowing from beneath the ice considerable rivers which cut
deep channels through the walls of bowlders, sand, and clay
which constituted the moraines. Where the sea enters these
channels it not infrequently forms harborage grounds of con-
siderable value. Thus on the southern shore of Massachusetts
there are a number of ports lying in these depressions which
were scoured out by the rivers flowing from under the ice.
The havens at Edgartown, Holmes' Hole, Wood's Holl,
Quick's Hole, Robinson's Hole, are instances of this nature.

1 86 SEA AND LAND

These harbors are (generally shallow and are not comi:)letely
landlocked. Inasmuch as they lie amid drifting sands they
are likely to be rapidly shallowed unless carefully guarded
from the invasion of sediment by engineering skill. Although
these inlets, as compared with those produced by other agents,
are of relatively little size and not well suited to afford shelter
for ships, they occur on parts of the coast which are otherwise
without havens, and on this account have a considerable eco-
nomic importance.

Besides the morainal deposits, the glacial sheet left upon
the country which it had occupied a vast amount of drift
materials disposed in an irregular manner, so that the result-
ing surface of the earth consisted of innumerable ridges and
valleys. At the close of the ice period the sea, penetrating
into the depressions of the surface, formed innumerable shal-
low bays. The greater portion of these has been filled with
sediments or closed by the growth of marine marsh deposits.
Here and there, however, they still afford shallow harbors, in
most cases suitable only for small vessels engaged in shipping
or in coastwise traffic. Wareham and Chatham harbors on
the southern coast of Massachusetts are good instances of
this peculiar variety of havens. Farther north on this con-
tinent and in the glaciated districts of Europe about the North
Sea, inlets of this nature are of common occurrence, but as
they lie in districts provided with shelters for ships by other
and more effective haven-making agents, they have little
value to mariners.

THE FORMATION AND PRESERVATION
OF HARBORS

Lagoon Harbors; their Origin and History. — Effect of Wind-hlown Sands. — SandSiiit
Harbors. — Effect of Water-borne Sands. — Crater Harbors. — Coral-Reef Harbors ;
Division into Two Classes ; Ways in which constructed. — Preservation and Destruction
of Harbors ; Ways in which they act ; Tidal Action ; Changes of Level ; Accumula-
tion of Sediments ; Invasion of Marine Waste. — Relative Importance of Damaging
Agencies in Lake and Sea Harbors. — Effect of Pocket-Beaches.

Wherever the water next a shore is shallow and the
bottom sandy and the waves have considerable strength, we
find a series of elongate low-lying islands which more or less
completely enclose a shallow field of waters commonly termed
a lagoon. Although sand-bar islands of this description fre-
(jucntly occur along the shores of other continents, they are
perhaps most characteristically exhibited on the eastern coast
of North America. T^rom the high nortli southward along
the shore to Portland, Maine, the water is so deep and the
bottom so free from sand that the waves moving toward
the shore do not obtain possession of sufficient detritus to
form extensive barriers of this description. South of Port-
land and thence to Cape bdorida these sand reefs are so
generally developed that they form a tolcrabl)- connected
barrier between the mainland and the open sea. From the
waters of Chesapeake Pay to tliose of Biscayne Bay, a dis-
tance of about seven hundred miles, this natural rampart
of sand is so continuous and the hiLroons which it shelters so

1 88 SEA AND LAND

connected, tliat one ma)- journey in a small boat nearly all
the way without being exposed to the open sea.

The lai^oon bar element in our shoredlne topography is so
important, both from the [)oint of \'iew of science and that of
economics, that the reader should attain a clear understanding
as to the mannt,'r in which these bars are formed. We shall
therefore examine in a somewhat detailed wa)' the process
of construction. Whenever these reefs abound next the
coast, we find on examining charts of soundings which depict
the shape of the bottom of the neighboring sea that the coast
is bordered by a wide belt of shallow w^ater which extends
as a gradually inclined plane, declining toward the open
ocean with a descent of from five to ten feet to the mile, its
surface covered with tolerably fine sand, mingled with the
debris accumulated by the marine life which inhabits the
ocean floor. From a line commonly lying from fifty to one
hundred miles from the coast, this broad, gently sloping con-
tinental shelf suddenly declines into deep water, its outer
margin often having a slope of one hundred feet or more
to the mile. It is clearly recognized by geologists that this
continental shelf is in the main made up of debris worn from
the land which has been distributed over the sea-floor by the
action of currents and waves, operating through a number
of geologic ages, during whicli the shore, although occasion-
ally rising and sinking in slight oscillations, has maintained
nearly its present position.

Wherever this continental shelf is well developed beneath
the sea we are likely to find that a portion of the terrace
built during periods when the coast was somewhat lower
than at present extends inland in the form of broad, slightly
rolling, sandy plains. Such an emerged portion of the con-

EFFECT OF WAVE-ACTION 189

tinental sliclf borders the shor(; from near New York to
near the Rio Grande. Similar areas of recently emerj^red
shallow sea bottom occur on almost all the extended sea-coasts
of the world, though they are perhaps nowhere else so well
exhibited as in the southern seaboard states of this country,
where the present coast-line happens to lie near the middle
point in the slope of the continental shelf.

As the form and structure of this continental shelf
clearly indicate that the materials have been arranged by
wave action, we can readily understand how portions of the
detritus may be thrust against the shore by the heavier
waves which run from the deep sea toward the coast-line.
It is important, however, to perceive in just what manner
the wave does this work. We should first note the fact
that in the deeper parts of the sea a wave of the first
magnitude, though it may have a height of as much as fifty
feet from trough to crest, is essentially a superficial move-
ment of the waters, in which the particles of the fluid do
not go forward in any considerable way, but merely revolve
in a kind of orbital movement. The wave motion which
we make in shaking a carpet is in all essential respects
comparable to that of an ocean surge where the water be-
neath its base is a mile or more in depth. Much as the
surface of the ocean is heaved and tossed by these waves,
the amount of movement imparted to the water is slight.
If we could observe what takes place on the sea- floor,
five thousand feet below the tempest- swept surface, it would
require instruments of exceeding delicacy to indicate the
trifling motions which the waves produce.

As the waves from the deeper seas attain the shallow
water next the shore — say, when they come where the sea has

]go SEA AND LAND

a depth of five hundred feet — they beg-in to have a sensible
effect upon the bottom, oj)erating- to brush the finer materials
in the direction in which the surges are moving; attaining
yet shallower water, this rubbing action is proportionately in-
creased. At the depth of a hundred feet the effect of these
waves in sweeping sands in toward the shore may be con-
siderable. The action is probably of sufficient energy to
drive even small pebbles up the slope toward the land.
Owing to the friction which the front part of the wave
encounters beyond that which the following part meets as
it passes over the upward slope of the bottom, the surge
becomes ever narrower in cross section as it approaches
the shore — that is to say, it is higher in proportion to its
width. As this friction of the bottom of the wave on the
lloor of the sea increases, the upper part of the surge, for
the reason that the lluid there is less hindered in its for-
ward movement by the resistance of the bottom, shoots
forward, cjuickly acquires a wall-like front, and finally its
upper part flies clear beyond the base and combs over in
the form of a "roller." Owing to the long-continued friction
on the bottom which the wave has encountered in its move-
ment over the shallows toward the shore, its volume and
energy are commonly very much reduced from the conditions
presented in the open sea. Usually the surge when it breaks
upon the shore has not more than the fourth to the tenth
of the power which it had in the water a thousand feet
deep. Were it not for this loss of energy, the effect of the
ocean surges on the land would be vastly greater than it
usually is.

Watching the action of ocean waves along a gently slop-
ino- shore, we observe that the lesser undulations, such as

FORMATION OF BARRIER SAND REEFS 191

occur whcMi the sea is affected only by in-shore winds of sli_L^ht
energy, break very near the waterdine. Heavier surges —
say, those having a height of three or four feet — comb and
fall over at a distance of some scores of feet from the actual
margin of the sea; while waves of the greatest volume, such
as are formed at rare times of heavy tempests, may break a
mile or more away from the strand. Wherever the over-
turning occurs, the power of the wave is broken and whatever
debris it may have been urging forward is left upon the
bottom. If we clearly perceive these features in the action
of waves, it is easy to understand how the bar islands which
enclose lagoons are formed. Thus in case our southern shore
should be depressed below the level of the sea, so that the
barrier sand reefs were covered, a result which would be pro-
duced if the region were lowered to the depth of thirty or
forty feet below its present level, the immediate effect would
be to brine the ocean waters into free contact with the shore
of the mainland in a manner found on coast-lines where there
are no such outlying islands. At once the submerged barrier
would be taken to pieces by the waves, and the accumula-
tions of sand would be spread over the bottom of the sea,
still further shallowing the water near the shore. W^ith the
advent of the next ensuing great storm the waves would
break at a distance from the shore ; it might be even some
miles away from it, and on this new line of breakers the con-
struction of a new series of barrier sand reefs would begin.
If the storm were great, so that the waves, were of the first
magnitude, the breaking might take place in water having a
depth of as much as fifty feet. Waves of a volume to break
in water of this depth would carry a good deal of sand to the
point where they topple over. Here this transported detritus

192 SEA AND LAND

would lodge, and if the storm were long continued the sands
might be built up to a sufficient height for the ridge to emerge
above the level of the sea and form a beach. Unless this
emergence of the crest were effected, the succeeding storms
of lesser energy would tend to destroy the imperfect barrier
by sweeping waves over its crest without breaking, in which
case, as will be readily perceived without further explanation,
they would tend gradually to scour away the elevation, dis-
tributing the sand between its position and the neighboring
shore. The shallowing of the water thus brought about
might go on by the successive temporary formation and
distribution of submarine sand reefs, until finally, in some
great storm, a ridge was built up of considerable length,
perhaps along a great distance of shore, which rose above the
level of ordinary low tide. When such a ridge had been so
formed, high enough to escape the scouring action of waves
of any considerable magnitude, operating by overrunning its
top, each succeeding storm, even those of ordinary energy,
would tend to add to the mass by bringing in more sand from
the continental shelf.

As will be noted hereafter, the Inner portion of the
continental shelf, the part which lies in shallow water next
the shore, commonly receives considerable contributions
of sand, which work along the coast from regions beyond
the limit of the barrier reefs. Thus on our Atlantic coast
a good deal of arenaceous material may have journeyed
from as far north as New Jersey, where it was contributed
to the sea during the last glacial period, or washed into the
ocean from deposits of sandy matter formed during the ice
time. In this way the waves can continually bring in sandy
matter without diminishing the depth of water on the out-

ACTION OF WIND-BLOWN SANDS 1 93

lying shallows. So far as depends upon the action of the
waves the coastal sand islands cannot rise more than a few
feet above the level of low tide ; but as soon as a beach is
formed, the winds operate to form sand heaps or dunes above
the level of the sea, which may considerably increase its
elevation above the ocean level.

The wind-blown sands of these wave-built islands play
an important part in the history of our sandy shores. Even
before the barrier ridge has attained to a sufificient height
above the tide to give a foothold for land vegetation, the
formation of these dunes begins. When the tide is out a
broad section of the beach is left bare, the superficial sands
of which in an hour or two become dry enough to be blown
in-shore whenever the winds come strongly against the coast,
and moving up the slope of the beach they form a ridge
parallel to the coast-line. As long as the sand is on the slope
of the dune toward the sea, it is exposed to the wind and is
likely to be kept in motion. When it passes the crest of the
elevation it drops into a lee and comes to rest ; at least until
the wind changes direction so as to again obtain possession
of it. As soon as the land vegetation fitted to orrow in such
places obtains a foothold on the island, the growth of the
dunes is favored by the fact that the sand catches amid the
stems and leaves and becomes tied together by the roots, so
that the occasional storms from the land, in most cases less
energetic than those from the sea, cannot blow it back into
the ocean. Under these conditions the wind-blown materials
may accumulate in sharp ridges, which attain a height of
from ten to a hundred feet or more.

Although the species of plants, such as our beach grass
of northern dunes or the dwarf palmettos and other plants of

194 SEA AND LAND

the southern coast have, by loner education, become well
adapted to the peculiar task of holding- wind-blown detritus,
much of the finer arenaceous material is blown across the
sand hills next the sea and distributed in a more sheet-like
form over the lai^oon which lies between the g-rowing barrier
and the mainland. This accumulation is often much greater
in amount than the coarser sands lying in the distinct dune
ridees on the seaward side of the island. It is likely to shal-
low the lagoon waters until they are completely closed, and
become converted into a strip of lowland which slowly widens
toward the main shore. In many cases these blown sands
would occlude the shallow waters of the lagoon in a complete
way, were it not for a peculiar effect of the tide which we
shall now consider. On examining the map of any lagoon-
bordered shore it will be perceived that these basins, though
shallow, are often very extensive in a horizontal direction,
and they are always receiving a considerable share of water
from the land. Thus it comes about that where the sand
reef encloses a great extent of shore, the lagoons become
overfilled with the land waters and break away through to
the sea. This opening is apt to be scoured out to a consider-
able depth by the energy with which the imprisoned waters
discharge through the easily eroded material.

As soon as a channel is cut through the sand barriers it
naturall)- becomes a way through which the tidal waters ebb
and llow. Where, as is often the case, the lagoon area acces-
sible to the tide is of great extent, the volume of water which
four times a day passes through the inlet may be so large as
to develop a channel having a width of several miles. To a
considerable extent this tidal ebb and flow serves to scour out
not only the passage of the inlet but a number of channels.

JlOir LAGOONS ARE FORMED 195

branching in the manner of a river, which often extend many
miles beyond the entrance. The principal of these occupy a
position between the mouths of the main rivers which enter
the lagoon and the passage through the barrier reef, but others
lie parallel to the shore to the point where the tidal How,
which enters from a neighboring passage, produces a field of
waters in which there is practically no current. At these
nodal points or positions of no current the accumulation of
sand blowing across the island from the sea beach, together
with such vegetation as can inhabit the brackish water and by
its decay serve to fill the inlet, is likely to produce a low
barrier or isthmus uniting the neighboring islands and the
mainland. Such a barrier between adjacent inlets is commonly
known by the name of " haulover," a term derived from the
fact that small vessels are often dragged across it.

Where the lagoon is narrow and shallow these isthmuses
or "haulovers" are likely to be developed between the prin-
cipal inlets. Where, however, the lagoon is large and fairly
deep, certain peculiar accidents are apt to keep united a great
stretch of the enclosed waters communicating with the sea by
several inlets. The formation of the isthmuses is mainl)-
prevented by the action of winds which occasionally produce
currents of sufficient strength in the relatively shallow water
of the lagoon to scour away the debris whenever it tends to
accumulate. Moreover, as will shortly be explained, these
inlets of the sand reef tend to become closed so that the Hoods
from a particular river are compelled from time to time to
make journeys in diverse directions in order to find an open
channel by which they may escape to the sea. Thus in the
long^est connected laeoon of the American coast — that on the
eastern shore of Florida known as the Indian River — each

196 SEA AND LAND

inlet, for the reason that tlie sands of tlie island beaches are
constantly moving southward, gradually travels in a southerly
direction until it abuts against some obstacle. Then the
further incursion of sand from the north closes the opening.
At some later time, when the streams fiowing into this part of
the lagoon are in the state of Hood, and the wind is blowing
in a direction to heap up the waters, the closed channel will
be replaced by a new opening, which in turn proceeds to
travel southward like its predecessor, until in due process of
time it also is closed. Thus by watching the direction in
which these migrating inlets journey we can ascertain the
average direction in which the sands are impelled along the
shore.

Where an inlet remains for a considerable time in one
position, the debris which passes through it toward the sea
accumulates in the form of an extensive platform on the sea-
ward side of the opening. Through this submerged, outward-
curving, delta-like accumulation the currents make tortuous
channels, generally two or more in number and containing no
great depth of water even at high tide. The formation of this
curious platform is due in part to the efTect of the current in
arresting the coastwise march of the sands, and in part to the
force of the str(,'am which sets outwardly through the opening.
The strength of the outward-setting current is always stronger
than the influx, by the proportion which the excurrent river
waters bear to the tide which passes through the inlet twice
each day. As soon as the inlet has shifted its position or
become closed, the waves and currents proceed to break up
this peculiar delta formation and distribute its component
sands in an even manner over the neighboring sea bottom.
15\' a simple inspection of the soundings on the Coast Survey

INLET CHANNELS

i97

maps it is possible to determine in a tolerably accurate way by
the extent of this inlet delta how long the particular entrance
to the lagoon has remained open.

Where a shore-line is now in process of subsidence, as
appears to be the case along the Atlantic coast from Cape
Florida to New York, the depth of water in the channels

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Tidal Deltas at Ocracoke and Hatteras Inlets

which lead from the inner side of the inlet to the mouths
of the principal rivers is often sufficient to accommodate the
largest ships. Unfortunately, however, these down-sunken
and therefore deep channels are often separated from the sea
by the broad and shifting barrier of sands in which the inlet
lies, and which stretch for some distance beyond its seaward
mouth. Owing to the unstable character of the sands which
constitute this barrier, and the constant movement of (/3r/s

igS SEA AND LAND

aloni^ the shores, it is very difficult to secure any permanent
increase in depth of water Ijy any appHcation of engineering-
skill.

A century ago, when trading ships had less than half their
present tonnage, rarely drawing more than hfteen feet of
water, lagoon harbors were excellently suited to the needs of
commerce ; but at the present time, when many vessels trad-
ing with foreign countries have a draft of twenty feet or
more, such ports have become less useful, and have to be
bettered by engineering appliances or they are likely to pass
out of use except by relatively small coasting vessels. As
the greater part of the harbors between Norfolk and the Rio
Grande are of the lagoon type, the question as to the im-
provability of these ports is clearly of very great importance.

The group of embayments which we have to consider
under the head of sand-spit harbors, are, as regards their
origin and nature, closely related to the lagoon harbors last
described. They have, however, sufficient individual charac-
ter to deserve mention under a sei^arate head. Sand spits
are formed where the beach materials of a shore are forced
by the prevailing direction of the waves or currents to travel
in a more or less continuous manner in a particular direction
along the coast. Except for careful observations, this move-
ment may not be detected until the materials attain a point
where there is a more or less definite bay extending into the
mainland. At such a point the sands, instead of flowing back
into the reentrant, may be built out in the form of a long spit
which grows steadfastly at its outer end until it may project
more or less completely across the mouth of the opening.
Excellent examples of these spit beaches are traceable along
our American shore from northern Massachusetts to Mexico.

SAND-SPIT HARBORS 199

Ordinaril)' the projections arc straight, but where in the course
of their c^rowth their extremities come in contact with strono-
currents, they may ho. turned so as to make hooks of remark-
ably curved or anguhir outHne, occasionally enclosing consid-
erable sheets of water of sufficient depth to have value for
harborage purposes. Provincetown Harbor, on Cape Cod, is
an example of this nature. That at Cape Pogue, on Martha's
Vineyard, though the embayed waters are very shallow and
have no value for jnirposes of shelter, is, as an illustration of
\the process b)- which these hooks are formed, one of the most
interesting structures belonging in the group.

The directions in which sands journey along the shore, as
well as the speed of their movement, depends mainly on the
attitude of the coast-line in relation to the prevailing winds
and currents. These effects may be traced, not only in a
local way, but sometimes throughout a far-reaching extent of
shores. Thus on the Atlantic coast from Chesapeake Bay to
Cape F"lorida, the prevailing course of the sand is to the
southward. The beaclies have been characterized by a move-
ment in that direction since they first came to be observed.
To this endless procession of sands is due the southward
march of the ever-changing inlets in the manner indicated
in the description of lagoon harbors. This movement of
sands toward the south along the Atlantic shore is due, in
part at least, to the fact that while that coast-line extends
in a general northeast and southwest direction, the prevailing
winds and tlie waves which they produce are from tlie points
between east and north, so that the surges strike the coast at
an oblique angle and tend to urge the detritus toward the
southern part of Florida. At the cape of that name we find
the southern extremitv at which these marching sands have as

200 SEA AND LAND

yet attained in their movement between high-tide and low-
tide mark. At this extreme southern position the (quantity
of the sand is not orcat, and the ofrains of silex of which it is
composed are much rounded by their long and arduous jour-
ney, at every step of w^hich they have been beaten by the
waves. It appears likely that in time these wandering sands
w^ill attain to the extreme southern part of Florida, destroying
or diminishing the coral-producing polyps as they go. Prob-
ably to their action is due, in part at least, the diminution of
the reef, which is but feebly exhibited in the district to w^hich
this detritus has attained.

Although sand-spit harbors or equivalent structures com-
posed of gravel or shingle of themselves form few impor-
tant havens, they are a concomitant feature in the natural
defences of many ports. They are often conspicuous at the
mouths of reentrant delta harbors, and serve to protect that
class of ports from the incursion of the weaves to wdiich their
naturally broad mouths ordinarily exposed them. This effect
may be clearly seen at the mouth of Mobile Bay, Galveston
Bay, and various other points on the Atlantic coast. Not
only do these spits afford protection from the ocean's surges,
but they often serve to deepen the channels which give access
to the port, and thereby to render the harbor accessible to
larger vessels. Where they do not exist it is often necessary
to accomplish the work which they might do, by means of
artificial construction. We may furthermore note the fact
that when once formed these spits tend to prevent the en-
trance into a bay of the sands which the weaves scour from the
shallowed bottom over which they roll, and which, but for the
presence of these barriers, might penetrate far enough into
the harbor seriously to reduce the depth of water. Thus the

VOLCANIC CRATER HAVENS 20I

first stag-es of a sand spit's formation arc often advantageous
to the haven at the mouth of which they form. In the course
of time, however, as the drifting sands accumuhite, they force
the entrance to the port to the side toward which they are
travelling, and as they cannot readily pass the tideway chan-
nel provided the stream be vigorous, they accumulate on
either side of its mouth in broad shallows, such as are de-
scribed as lying in front of the passages which lead throuo-h
the lagoon barriers to the sea.

In tideless seas or large fresh-water lakes these spits
are perhaps the most serious menaces to the harbors. ()win<'-
to the weakness or absence of currents to break through
the barriers which they form, they are apt to wall across the
inlet, leaving no larger channel than suffices to discharge
the waters of the rivers which enter the embayment. A
comparison of the spit harbors in our great lakes or other
non-tidal basins shows how important are these alternatino-
currents for the preservation, and often also for the con-
struction, of havens. Along shores of such seas and lakes
the spits are not so neatly formed as on the open sea-shore.
A large part of the migrating sand is sure to enter the
currentless harbor and shoal its waters.

The group of volcanic crater havens will be mentioned
only in order to complete the list of the causes by which
harbors fit to shelter ships are formed. It is a familiar fact
that volcanic craters commonly have a cup-shaped form, and
in most instances the rim which surrounds the central cavity
is broken down at one or more places by the outrush of lava
or by the ruptures which are naturally formed during the
throes of an explosion. It is also a well-known fact that
by far the greater part of the well-preserved craters of the

202

SEA AND LAND

world lie alon^- the coast-lines of the continents or upon the
islands which border the shores of the mainland and are scat-
tered over the wide seas. On account of their position with
reference to the ocean level, it not infrequently occurs that the
sea enters an inactive crater through a relatively narrow breach
and forms a large and well-sheltered basin in the middle of
the cone. If such havens occurred in convenient positions

.--"S'?*^'--

Volcanic Harbor

for commerce and if their bottoms afforded good anchorage
grounds, they might have great economic value; but occur-
ring, as they almost invariably do, on small and desolate
islands, they have no other than a scientific interest. They
may be compared to the interesting lakes which frequently
form in the cups of long-inactive volcanoes, such as those
found in the region north and south of Rome, which are
very striking and beautiful features in the landscape, but

CORAL-REEF HARBORS 203

interestirif^ only on account of tlicsc qualities. So far as
the present writer is aware, no settlement deserving" the
name of a port exists on the shores of a crater harbor, though
there are sundry of these peculiar havens in the eastern
Mediterranean and the East Indies which are occasionally
used as shelters by ships.

The harbors which are produced by the reef-building
corals, together with the various marine animals and plants
which are associated with them, are among the most inter-
esting and important of all classes of havens. They are not
only in origin the most peculiar of all inlets of the sea,
but the conditions of their development and the circum-
stances which lead to their preservation and destruction are
also curious and noteworthy. Moreover, in the district of
southern Florida organic reefs of this nature are numerous
and extensive, and the ports which they form, though as
yet relatively little used, are destined in course of time to
have great value to this country.

Coral-reef harbors may be divided into two classes,
determined by the physical character of the reefs which
lead to their formation. The structures belonging to these
distinct groups are barrier reefs, and circular or elliptical
formations of the same nature, commonly known as atolls.
As the history of these two groups of reefs is essentially
that of the harbors which they form, we must briefly trace
in outline the methods and conditions of their growth. The
growth of all coral reefs depends upon certain polyps which
secrete a limestone support for their bodies, having the
oro^anic habit of arowinor together in closelv associated com-
munities which unite their limestone framework so as to
form rock-like masses. These creatures add to the number

204 SEA AND LAND

in their several societies by a process of budding, while
the)- multiph' the communities themselves by reproduction
from the ^%'g. Thus they are able to grow continuously,
after the manner of forest trees, the living resting upon the
framework which the dead have left behind them. By means
of this double growth they are able to construct vast lime-
stone ridges wherever the conditions of the sea favor their
development.

Although solitary corals and communities of insignificant
growth plentifully develop far and wide over the sea-floors
of tropical and even of temperate regions, the reef-building
species can do their characteristic work of construction onh'
where tolerably swift moving currents of pure water, having
the temperature of the tropical seas, flow against shores or
shallows where the water is less than about a hundred and
twenty feet in depth. Where such oceanic currents impinge
upon a shore or shallow, the germs of the reef-building corals
develop upon the bottom, spread over the surface which has
less than twenty fathoms of water upon it, and proceed to
grow with great rapidity. The evidence goes to show that
some of the species may rise above the bottom, at the rate of
as much as three inches a year, and it is not improbable that
these reefs may grow upward, if the conditions be favorable
for rapid growth, to the extent of a foot in from one hundred
to two hundred years. This, though slow in terms of human
history, is In a geologic sense extremely rapid. As the reef
gains in thickness, the outer part of the growth, that which
faces the deeper sea. waxes more rapidly, for the colonies of
polyps which occupy that position arc most effectively bathed
by the ocean currents from the waters of which the animals
take their food. The nearer this swiftly growing margin

I/O IV CORAL-REEF HARBORS ARE CONSTRUCTED 205

comes to the surface of the water, the more effectively it
debars the polyps on the interior of the reef from the visi-
tation of the nourishing streams flowing inward from the
sea. The result is that when a reef has attained to about
the level of low^ tide, which is the limit of its growth, there
is generally an unfdled channel occupied by a lagoon-like
expanse of waters on its inside, the basin communicating
with the sea by various passages or breaks in the line of
the reef.

Where such a coral reef is formed against the shore of a
mainland or island, the reef usually extends in a direction
generally parallel to the coast for the distance through which
the ocean currents exercise their effect on the development
and growth of the polyps. Thus along the coast of Florida
the Gulf Stream has favored the formation of these reefs,
from the shoals at the southern and western extremity of the
peninsula to a point a score or two of miles north of Cape
Florida. As far north as Biscayne Passage at the above-
mentioned cape, the reef, except for the occasional open chan-
nels, rises to near low-tide mark. North of that point, owing
perhaps to the coolness of the water, as well as to the south-
ward movement of sands above described, the reef is stunted,
its summit does not rise to the level of the sea, and the whole
structure gradually fades away.

As soon as the outer part of a coral reef has risen to near
the surface of the water, the sea in times of storm breaks upon
the barrier, so that the lagoon between the rim of the reef
and the mainland may afford excellent shelter for ships. If
the coast be long and straight the enclosed channel may be
open to the rake of the winds in certain directions, but in gen-
eral at points betw^een the site of the channels through the

2o6 SEA AND LAND

reef various accumulations of or^^anic waste shoal the water or
construct spits across it so that the lagoon, much after the
manner of those enclosed by sand reefs, as above described,
becomes divided into sections of no very great extent. It
occasionally happens, as in the case of a great reef off the
eastern coast of Australia, that the wall is very far from the
land, so that the lagoon area, being very wide, has little value
as a harbor.

A large part of the coral matter which is developed on the
front of the reef is broken off in times of heavy storms and
ground to powder in the surf. A portion of this waste is tossed
over the reef or drifts in through the inlets, and is thus added
to the sediments accumulatinof on the bottom of the la<roon.
Another portion of the debris is dragged seaward by the under-
tow and distributed in front of the reef. In this way the sea-
floor next the barrier is gradually shallowed. When in the
course of this process it is elevated to the level where the water
is only a little more than a hundred feet deep, a new coral reef
may begin to form which will in time rise to such a height as
to deprive the older barrier of its due share of food-giving
water. When this condition comes about the old reef dies,
and the frail materials of wliich it is composed may to a cer-
tain extent, at least in the upper part of the structure, become
broken up by the waves or dissolved by their waters so that the
once marked ridge may lose its distinct character. In certain
cases, where the sea waters are not saturated with limy matter,
they may take into solution and bear away to other regions a
part of the material which is afforded by the dead coral and
other organic remains in the section within the growing reef.
It is perhaps to this solvent action that we owe, in part at
least, the sometimes remarkably deep channels which penetrate

RELATION TO THE SHORE-LAND 207

through the reef and extend for some distance across the floor
of the lagoon.

While alono;- the coasts of the mainlands and greater islands
where coral reefs occur they commonly appear in the general
form of broad shelves with the rim of hi^^her and livino- reef
next the sea and a prevailing shallow lagoon or channel between
this barrier and the shore, their form is sometimes much affected
by the upward and downward movement of the shore-land dis-
trict against which they lie. An elevation such as frequently
occurs and has lately happened along the coast of Florida may
bring the reef and the lagoon as well above the level of the
sea ; in some cases successive elevations have thus developed
a considerable breadth of shore country composed of reef
deposits. Through these easily dissolved rocks the river waters
may carve, mainly by their dissolving action, tolerably deep
channels which may serve as harborages. In other cases the
subsidence of the coast may lower the barrier reef more rapidly
than the coral animals can effect its elevation, and in this way
the ridge which at one time sheltered the coast from the waves
may no longer afford such protection.

The group of atolls or annular reefs is imperfectly repre-
sented in the Atlantic district, but attains a remarkable devel-
opment in the Pacific and Indian Oceans. In their character-
istic forms these wonderful islands consist of a steeply sloping
obscurely conical elevation rising from the floor of the sea,
which often exceeds a mile in profundity, to the surface of
the water. Above the sea level there is a more or less com-
plete ridge composed of decayed and broken-up coral which
has been swept into position somewhat inside of the living
reef by the action of the waves. The central parts of the
island are occupied by a shallow basin of water which in

2o8 SEA AND LAND

almost all cases communicates with the open sea by one or
more channels. If the waters of the Pacific and Indian
Oceans in the districts occupied by these atolls could be
drained away, the observer would bften be able to journey
for many hundred miles through fields occupied by towering
mountain-like elevations, each rising with steep and regular
slopes to a certain level, and nearly all of them containing
a shallow, cup-shaped cavity on the summits. In some cases
these mountains would be in figure very nearly true cones,
but by far the larger number of them have elongated forms.
Here and there in the Pacific Ocean where the sea-floor has
been subject to recent elevation, these atolls have been lifted
until their summits are some hundreds of feet above the
plane of the sea. So far as has been observed, these high-
lying coral islands have lost their characteristic cup-shaped
summits by the process of erosion.

There is much debate at present as to the origin of these
interesting atolls. Until recently the explanation adduced
by Charles Darwin found universal acceptance. This was
in effect that the coral reefs began to grow in the form of
a barrier surrounding some island of ordinary rock such as
is often formed in the sea by a partially submerged moun-
tain peak or a volcanic cone. The sea-floor on which the
elevation rested being in process of gradual subsidence, but
at a rate not sufiicient to destroy the corals of the reefs, the
living rock gradually built upward until when the original
land disappeared beneath the waters nothing was left to mark
its former site except the limestone deposits formed by the
zoophytes and ()th(.;r animals which continued to develop upon
its submerged summit. One of the proofs of this hypothesis
was found in the occasional cases where ordinary islands

ATOLL LAGOON HAVENS 2O9

present a more or less complete ring of reefs about their
shores. In case such an island should gradually sink, the
result would necessarily be the creation of an atoll.

Lately Dr. Murray and others have contended for the
view which explains the formation of an atoll on the sup-
position that a coral bank forms at any point on the sea-floor
where the depth of water is not too great and where there
is a continuous marine current of sufficient temperature to
maintain the growth of the reef-building species. The
cavity or lagoon within the reef is explained by the solvent
action of the water, which tends to take up and to bear
away the lini)' material with which it comes in contact. It
seems not improbable that these islands with cup-shaped
centres may be produced in the v.'ays indicated by both these
hypotheses. That advanced by Dr. Murray, however, seems
to be the simplest and most rational explanation of the
facts.

From the point of view of the student of harbors it is
only necessary to remark that, owing to the small amount
of fertile soil which the narrow strip of land enclosing the
atoll lagoon affords, these havens can never have much com-
mercial importance. 1 hey serve as shelters for a few small
trading ships, and they may in time be prized by yachtsmen ;
but they can never have much relation to commerce. Though
much more striking and beautiful features than the barrier
reefs, they are of very much less economic value. Probably
far more ships have been cast away upon these coral reefs
of mid-ocean than have been protected from storms in the
beautiful but generally inaccessible havens which they afford.
Thus as a whole we must look to the barrier reefs as affording

the only really important harbors which are produced through
14

2IO SEA AND LAND

the agency of organic life. Although in the realm of the
tropics there are innumerable ports which owe their origin
to this last-named class of reefs, none of them have as yet
any great commercial importance. They at present serve
mainly for small vessels. They can in general only be made
useful to our modern marine by a continuous and expensive
process of dredging, to make head against the rapid growth of
the zoophyte communities and the accumulations of sediments
brought about by the intensely vigorous organic life which
develops within the coral reefs.

The port of Hamilton on the Bermudas is perhaps the
best instance of an important haven situated on a coral reef
belonging to the class of atolls, while the beautiful Biscayne
Bay on the east coast of Florida is an excellent example
of a haven which is enclosed by barrier reefs.

In the foregoing summary account the several classes of
natural actions which lead to the formation of harbors have
been considered. We have now to take into account the
other modes of operation of the geologic forces which tend
to alter for better or for worse the physical conditions of
our havens in determining the ease with which they may be
approached, the character of their shores, and the depth of
water which they afford. All these changes are brought about
as a result of the application of energy, operating in diverse
ways along our shores. Therefore the reader will the more
readily come to an understanding of the questions with which
we have to deal if we begin the inquiry by noting the gen-
eral nature and mode of action of these forces.

There are four modes in which energy is applied in a
way to modify the conditions of coast-lines. Three of these
have their origin in the celestial spaces ; one only comes from

EFFECT OF SOLAR INFLUENCES 211

tlie earth itself. The most important source of energy which
is applied to the earth is the heat of the sun. This takes
effect on the earth in two diverse ways. In the first place,
by warming the water it lifts the vapor of that fluid into the
air, whence it is precipitated in the form of rain or snow.
In either of these states the part of the precipitated water
which falls upon the land moves back toward the sea in the
form of rivers or glaciers, bearing with it a share of the
earthy or rocky matter with which it comes in contact. This
abraded material is in large part deposited next the coast-
line ; the principal portion of it, indeed, finds its way to the
bottom either within or at the mouth of the natural harbors
of our shores. The solar heat also operates in another way,
by which it does yet more effective work upon the coast-line.
Owing to the differences of temperature which it induces,
and the variations in weight of the atmosphere dependent on
those variations of heat, the radiation from the sun brings
about the movement of the winds. Where these sweep over
water surfaces they create waves of a magnitude proportional
to the width and somewhat to the depth of the water basin
w^iich is traversed, and to the continuity and energy of the
air movement. Where these waves roll aeainst the shore
they apply the energy which they have received from the
wind in rasping the bottom of the shallow water and in
beating against the coast-line.

The two modes of geologic action just adverted to are
due to solar heat, and, though widely different in their manner
of operation, they have a like origin. The third mode of
action which we have to consider is that which arises from
the gravitative impulse exercised upon the earth by the nearer
and larger celestial bodies, the moon and the sun. While

212 SEA AND LAND

all the orbs of space exercise a measure of attraction on our
own sphere, the moon and sun, owing to nearness and mass
respectively, are the only bodies which effect a recognizable
influence upon its surface. These two bodies pull so strongly
upon this planet that in the widest and deepest ocean they
form two tidal waves opposite each other, each some thousands
of miles wide and a foot or two in height. If the whole surface
of the earth were occupied by the sea waters everywhere to
the depth of four miles, say, the maximum height of the tide
w^ould probably be about a foot. Although this tide would
move around the earth beneath the equator with the speed
of a thousand miles an hour, it could exercise no considerable
effect on the conditions of the sphere, for, according to the
supposition, it would meet no shores or shallows ; the whole
consequences of the tidal movement would be the application
of a slight friction to the bottom, which, being applied against
the direction of the earth's rotation, would tend very slowly
to overcome the momentum with which this sphere turns
upon its axis.

In the existinij condition of the earth the lunar and solar
tides, though of slight altitude in the wider parts of the great
southern sea and Pacific Ocean, become wedged in between
the convercfincf shores of the lesser water basins in such a
manner that the water may be lifted in each tidal interval t(3
much greater heights. Very commonly this increase in alti-
tude amounts to ten or twelve feet, and in exceptional cases to
fifty feet or more. As the energy which a tidal wave applies
to a coast-line is in a general way proportional to the rise
and fall of the undulation, it is easy to see that the share
of this impulse derived from the attraction of the sun and
moon, exerted on different parts of the shore, is exceedingly

MOVEMENTS OF THE SEA-FLOOR 213

varied. In fresh- water lakes and lesser seas the tidal wave
is not developed at all. In greater basins such as the Med-
iterranean the undulations are so slight that their influence
is scarcely perceptible ; but about the head of such oceanic
reentrants as the North Atlantic, where the wave rolling in
from the south is compressed between converging shores, a
vast amount of tidal work is done.

The fourth group of actions effective on sea-shores is
derived from the movements of subsidence, elevation, and
sudden jarring which may take place on the sea-floor. Some
of the most important alterations of our harbors are effected
by the uprising or downsinking of the portions of the earth
near which they are situated. Movements of this sort, if
they take place over very extensive portions of the ocean-
floor, may, by displacing the water of all the oceans and
open seas, lead to changes in the depth of water in harborages
all over the world. Thus, if, as seems probable, an area
of several million square miles in the central district of the
Pacific Ocean is undergoing subsidence at the present time,
the influence of the movement, long continued and extensive,
may be felt in all marine ports. In general, however, local
accidents in the way of subsidence and elevation are so con-
siderable as to make these wide-spread oscillations of the
ocean-floor relatively unimportant.

Besides the long-continued oscillations of level of shore
land and sea bottom, an effect is exercised upon the coast-
line through the sudden movements of the earth beneath the
seas, due to earthquake shocks. These seismic jarrings.
create an elevation of the water over the shaken surface,
which is in its nature a broad wave, having, it mav be,
an altitude of several feet, and which maN' roll across the

2 14 SEA AND LAND

wide oceans and break upon their shores with calamitous
effects.

With this preliminary statement as to the nature and origin
of the classes of energy which operate on a coast-line we
shall now proceed to consider somewhat in detail the effects
produced by these causes in increasing or diminishing the
value of our havens. First among them we have to note the
effect of the sediment brought into harbors by the rivers.

The waste of the land which is brought down to the shore
by the rivers is conveyed in two different forms : in part as
completely dissolved sediment, which does not discolor the
water ; and in part as materials which are visible to the eye
as mud, rendering the water turbid, or grains of sand or small
pebbles rolled on the bottom, or at most carried a little dis-
tance above it. As long as the water of the river is held
within distinct banks, the energy of its flow to a great extent
prevents the mud from sinking to the bottom and the sand
and pebbles from coming to rest, so that the channel may
remain substantially unchanged as regards its position or the
depth of the stream. At the outlet, however, where the river's
tide is discharged into an open basin, the current is soon
arrested, and gravitation is free to act on all the mud it con-
veys. Only the completely dissolved materials, such as salt,
lime and various other substances, are free to journey onward
for indefinite distances in the ocean currents.

Where the river discharges into a lake of fresh water the
suspended materials, at least the finer portions, find their wa)'
to the bottom much more slowly than where they enter a salt-
water basin, because the saline matter of the sea water has a
peculiar effect in hastening the precipitation of mud. In an\'
case, however, it rarely occurs that the river mud journeys

ACCUMULATION OF SEDIMENTS 215

more than a few score miles from the point where it enters
any large water basin. In the greater streams the quantity of
this detritus which is carried to the sea is often very great.
Thus the Mississippi sends out each year somewhere near one-
twentieth of a cubic mile of undissolved material, the whole of
which doubtless comes to rest on the broad margin of the
ofrowinof delta ; and the Amazon, owinof to the ereater rainfall
of its basin, probably contributes several times as much sedi-
ment to the sea-fioors near its mouth. The result of this
effusion of sediment into the basin near the mouth is that all
rivers which pour forth turbid waters are apt to have wide
shallows without very distinct channels at their points of exit.
Where, as in the case of the Amazon, the entrance to the delta
mouth is not thus obstructed, a condition which rarely occurs,
we have to account for the fact either by a recent subsidence
of the land or through the action of powerful currents such as
are produced by tides, cooperating", it may be, with oceanic
movements brought about in other ways.

Wherever a stream conveying a considerable amount of
detritus enters any bay or other indentation of the coast, we
find indication of its damaging action upon the harborage.
Beginning at the head of the reentrant it constructs a delta-
like accumulation, which gradually converts the basin into
marshy land. In front of the distinct delta there is a wide,
gently sloping surface over which the finer mud is laid down.
If a part of the debris escapes from beyond the harbor mouth
the currents and waves of the shore, acting in a manner here-
after to be described, are apt to build the accumulation into the
forni of bars or spits which may more or less close the entrance
to the port. In this way some of our more important havens,
such as that of Mobile Bay, are subjected to a constant

2l6 SEA AND LA AW

depreciation. So far no successful means have been discovered
whereby the effect arising froni this constant importation of
sediments into a harbor may be arrested. The only recourse
seems to be dredging — a slow and costly process, by which the
deposits of mud are removed from the important channels and
conveyed by boat to some point where they will not return to
the basin.

It is fortunate that, thouMi our bavs and other harborasfe
places are generally entered by rivers, only a few of these
shelters suffer any rapid depreciation by the action of the
streams. Moreover, in the case of very many of our rivers
of this continent, as well as those of northern Europe, there
are certain conditions which fortunately limit the amount of
detritus which the flowinsf water brinsfs down to the sea level.
Because they lie in glaciated districts the streams of the
northern lands generally drain from regions which are deeply
covered with sandy and pebbly waste. In such cases the
greater part of the rain-water passes into the porous drift
material, and is only gradually yielded to the streams. Thus
the river system of a glaciated district has in proportion
to the outflow very few torrents, such as characterize the sur-
face of regions not underlaid by glacial waste. It is the swift-
moving currents of these torrents which do almost all the
work of breaking up rocky matter into the shape in which
it may be transported as mud by the largest streams.

Almost all the considerable rivers of glaciated districts
pass through lakes, where their waters are for a time brought
to a state of almost complete rest and are thus led to lay down
their burden of sediment before they flow on to the sea. An
excellent instance of this is found in the case of the St. Law-
rence, which has a chain of great lakes in its main path, in

ACTION OF THESE FORCES IN THE ARTIC OCEAN 2 1 -J

addition to which all the important tributari(!S that enter its
channel below the mouth of Lake Ontario pass throiiL,di smaller
but sufficient natural catch-pools, that retain the debris. The
result is that the vast tide of the St. Lawrence waters comes
to tile sea level almost without burden of sediment, and
nothing like a delta deposit appears at the mouth of the
stream.

Owing- to certain peculiarides in their conditions, the
laro-e rivers which flow into the Arctic Ocean, the Macken-
zie of North America, and the Lena, the Obi and the Yenisei
of Asia, discharge much larger amounts of sediment than any
other streams of high latitudes. The cause of this is peculiar.
In the winter season the ice forms in the lower and more
northern portion of these streams to such thickness that they
are often frozen to their very bottoms, so that when the spring
floods send down a great tide of water from the southern trib-
utaries the current is unable to break up the ice which fills the
accustomed channel of the river, and the inundations sweep far
and wide on either side of their fit path. In these movements
the}' erode a great deal of earthy matter and bear it to the
mouth of the streams. The result is that the mud deposits
in the delta districts about the Arctic Ocean are much more
extensive than in other parts of the northern realm, but as the
harborages of this sea-shore have no commercial value the
effect of these mud accumulations is of no economic impor-
tance.

If the sea-shore maintains this position for any considerable
eeoloo-ic time, the effect of ri\er action would be to make the
mouth of every stream discharging into the ocean the seat of a
delta, and as almost all our ports have tributary rivers, the num-
ber of harbors, except such as the delta channels afford, would

2i8 SEA AND LAND

be very few. As it is, there are only a few score of conspicuous
deltas in the world, and the limitation in the number is clearly
to be explained by the frequent oscillations of the shore-
line.

The mode of action of the solar heat which is brought about
by the intervention of waves has a more wide-spread effect on
the conditions of harbors, and on the whole a more important
one, than that which is induced by the transportation and depo-
sition of river-borne detritus. Every coast-line, even if it be
only that of an inconsiderable lake, is sure to be affected by
wave action. Every cliff shore is a natural factory for the pro-
duction of detritus. This material is composed of small discon-
nected bits, which are readily moved by the waves and currents.
The heavier waves can swing masses each of which weighs
many tons; the undulations of less size can move fragments pro-
portionate to their energy ; and even the wavelets which, wlien
they break, have a height of no more than a foot, can toss bits
of rock as laree as marbles several feet to and fro in each oscil-
lation. Not only does the dchj'is produced by wave action sway
to and fro up and down the beach in the oscillating movement
of the water, but it is in all cases liable to be carried along the
coast by wave action either directly through their stroke or
secondarily by the currents which they induce. If the wave
rolls in against the shore at right angles to its trend, the movable
debris on the beach merely rolls up and down the slope without
changing its position in any important way. If, however, as is
oftenest the case, the waves strike at a more or less considerable
angle to the shore, the fragments as they move to and fro work
along tlie coast in the direction in which the waves are
trending.

Besides the motion imparted to the debr^is of the sea-coast by

illililllMii!'.^ 'i

INFLUENCE OF MIGRATING SANDS 219

the direct action of the waves we have to take account of tlie
movement effected by the currents which the winds procUice
alonof a shore. Such wind-induced streams, more or less reen-
forced by tidal movements, often flow with a speed of ordinary
rivers, and are equally effective in conveying detritus. The
action of these varying currents can often be noticed in cases of
shipwreck, when the debris from the castaway vessel is in the
course of a few hours scattered along many miles of shore
which lies leeward of the point where the disaster occurred.
The effect of these currents is to transport the detritus which
the waves grind up along the shore until the drifting material
attains a point where it may enter some recess which is so
deeply embayed that no change in the direction of the wind can
cause it to be removed by wave action. As this indentation of
the coast-line is apt to be a natural harbor, the effect of the
coastwise movement of detritus is often in hiirh measure destruc-
tive to the usefulness of ports.

The damage done by wandering sands is greatest where
there is no tidal action, as along the shores of the larger lakes
and lesser seas. Along such coasts as are not tide-swept, the
wave- and current-borne detritus rapidly finds its way into all
the recesses. In course of time the waters of the embayments
become so far shallowed as to be unserviceable to ships. The
effect of this action is conspicuous on the shores of our great
lakes of North America, particularly those which lie in the
valley of the St. Lawrence River. Although the present shore-
line of these lakes has been where it now is for but a short
geologic time, so that the harborages are relatively very new,
the influence of migrating sands has been already effective in
closing many originally good ports. The damage done in this
way is most conspicuous in the lower lakes of this series. In

2 20 SEA AND LAND

Lake Superior less injury has been effected by the coastwise
wandering detritus, for the reason that the shore is more rocky
than that of the other basins, and as yet the platform at the
base of the cliffs has not been sufficiently developed to make
as continuous beaches as we find along the coasts of Lakes
Michigan, Erie, and Ontario.

Where a coast-line has an irregular front which is bordered
b)- distinct salient capes or fringed with islands, the coastwise
migration of sediments under the influence of waves and cur-
rents is much less continuous and therefore less menacing to
harbors than where the shore is characterized by long, straight
line beaches. On the uninterrupted shores the march of the
detritus may be singularly steadfast; it may, indeed, be com-
puted from year to year as at a certain rate. A change of wind
may set the materials temporarily this way or that, but the
average movement is in most cases subject to no considerable
alterations in its course. Where, however, the shore-line is
embayed, the recesses form pockets in which the waste accumu-
lates and beyond which it cannot journey until the basin is filled
and the beach is extended across its front. Thus along the
fiord zone, where embayments are very numerous, the coastwise
marching of debris is hardly to be noticed, while on the sand
beaches farther southward we may trace a continuous procession
of detritus, often moving straight away along the shores for
scores or hundreds of miles.

Where, as is generally the case in the fiord zone, there are
islands or shoals lying on either side of a considerable reentrant,
a curious action arises, which leads to the formation of
pocket-beaches. Wliere the islands lie in the manner which
favors the formation of pocket- beaches, they may prove useful
elements of protection to a haven. Where, however, they are

FORMATION OF POCKET-BEACHES 22 r

immediately in front of the port they are apt to yield detritus
which may be, indeed generally is, carried directly into the
port by the ocean waves. In this respect they are much
more daneerous than headlands, for the latter often have
conditions which favor the development of pocket-beaches
on one side of their faces, but all the waste worn from an
island is apt to tail around either end of its mass and march
straight away toward the channel of the port. Along our
northern shores it not infrequently happens that insular masses
of glacial drift, frequently in the form of drumlins, lie at the
mouth of the haven or within it. As the drift materials of
which they are composed are easily broken up, even by slight
waves, and much of the matter is in the form of clay, which
can be borne to great distances by currents, such shores as
these isles afford are a constant menace to the neighboring
harborages.

Almost all the important ports of the world have to con-
tend against the inconveniences which arise from the immi-
gration of detritus which wanders toward them from along the
neiehborine shores. One of the first tasks of the engineer
who has charge of the defences of such harbors against their
natural enemies, the waves, is to secure protection as far as
possible by constructing walls or other revetments which may
serve to keep the sea from assailing cliffs of a nature to be
easily washed away. In this manner much can be effected to
aid the work of the natural pocket-beaches. In other cases
artificial pockets may be constructed by building moles from the
shore ; but while with such contrivances it is generally possible
to prevent the incursion of the coarser sands and pebbles, the
finer mud which sweeps along the bottom in even tolerably
deep water cannot thus be debarred entrance to the harbor.

22 2 SEA AND LAND

The main protection against this evil is afforded by the tidal
currents combined with the river waters which reenforce their
action. In their unaided work, or with the direction which the
en^^ineer mav C'ive to their currents, the tidal movements are
after all the best natural defences of a harbon

TIDAL CURRENTS AND ORGANIC LIFE

IN HARBORS

Effects of Tides on Harbors : Organization of Tidal Streams ; Effect of Tidal Bars. — Action
of Organic Life in Harbors ; Classes of Work done.— Effect of Marine Plants ; Flow-
ering Species ; Sea-weeds.— Growth of Marine Marshes : their Relation to Tidal Cur-
rents ; their Value for Tillage. — Tropical Marine Marshes. — Effect of Mangroves on
these Areas. — Effects of Organic Life on Harbors : Work done by Mollusks ; by the
Common Oyster ; Comparison of Northern and Southern Marine Marshes ; Work done
by other Animal Species. — Synopsis.

The effect of tides upon a shore-line is in admirable con-
trast to that of waves. Although both of these movements
of the water are in their nature undulations, the difference
in their form leads to an entire contrast in their action. Thus
wind waves strike ordinary blows ; the tidal wave delivers
no stroke whatever. The surges are most effective on the
headlands ; the friction which the\' encounter on the bottom
causes them rapidly to diminish in size as they pass in between
the convercrine shores of an enibavment. On the other hand
the tidal wave, because of its breadth from front to rear, heai^s
up in a bay in a very remarkable manner. It may often hap-
pen that a recess of the shore having a length of not more than
twenty miles with a width at its mouth of say ten miles will
have a tidal rise at its head near twice as great as that at its
mouth. So too in larger bays as that of Fundy, a rise of tide
of about ten feet at its eastern cape becomes an uplift of fitty
feet or more at the landward end of the basin. Owing to this

2 24 SEA AND LAND

\ariation in the amount of tides in different parts of the ocean
and even on neighborin^j^ portions of the same shore the work
which they perform is exceedingly variable as regards the
measure of the effects, but it is almost everywhere of great
importance, and therefore merits careful consideration.

At first sight it might seem that, inasmuch as the tide
enters and leaves a harbor with the same volume and velocity
in the movements of flow and ebb, the effect of these con-
trasted motions would neutralize each other. This, however,
as w^e shall see, is not exactly the case. There is always a
difference in the effect of the incoming and the outgoing
tide which though not great is of momentous importance
from its accumulated effects. The nature of this difference
is easil)' apprehended. When the tide enters an inlet it gen-
erally flows up an inclined bottom extending from the outer
sea to the head of the recess and when it ebbs away it moves
down this slope or rather, we should say, out over it. In the
movement of the flood the tidal current if it have any con-
siderable energy bears a certain amount of detritus up the
incline toward the interior of the reentrant. The distance
to which it will be carried will depend upon the energy of
this current and the rise of the slope over which it moves.
In the reflux the tide will convey the same detritus with the
same energy of current, but as it is carrying the debris down
a slope it can carry it farther outward than it did inward.

The ordinary action of the tide, operating in the manner
just dc?scribed, is of itself sufficient to cause its currents to
scour away materials from the open shores as well as from
harbors and to convey them out to sea to a depth of water
where the currents are no longer sufficient to bear them
farther. In many if not in most bays and harbors there are

EFFECTS OF TIDES OX HARBORS 225

Other conditions which serve to accent in a certain measure
this outward setting action which takes place during the period
of ebb. Ahnost all harbors receive a certain share of river
water. Owing to the momentum of the tide in entering this
water is in a measure banked up ; if the discharge from the
streams be not large it may all be retained in the basin until
the tide turns. This retained water is then permitted to flow
out, increasing the energy with which the harbor water goes
seaward. The admixture of fresh water, provided it be not
heavily charged with mud. probably somewhat increases the
capacity of the tide to dissolve and bear along sedimentary
materials.

Where, as is often the case, the tide rises higher in the
interior parts of the harbor than at the mouth, the currents
which are generally in proportion to the altitude of the rise
weaken as they pass toward the entrance of the inlet. The
effect of this action is unfortunate, for the stronger currents
near the head of the harbor are likely to stir up and transport
toward its mouth more or heavier sediment than the weaker
streams. In this way the tidal currents are apt to cooperate
with other agents in producing something like a bar oil the
mouth of the port. On the other hand if the harbor have
considerable area and depth of water and the tidal rise and
fall is great the outrush is certain to keep a channel open for
a distance sufficient to cross the zone of migrating sands which
borders the shore. The tidal channel does not usually arrest
the movement of the coastwise journe\ing detritus. The
effect of the migrating sands is generally to push the tidal
scourway against the side of the bay toward which the dtbris
is journeying until after a time it breaks a fresh opening
through the partial barrier. Where, as in the principal

226 SEA AND LAND

entmnce to New York harbor, the direction of motion of
the coastal sands is not very definitely determined, the course
followed by the tide may be pretty steadily maintained for
many years. On the other hand, as on the inlets to the
laeoons of the Florida coast, where the march of the sands
is tolerably constant, the effect of their movement in altering-
the position of the troughs in which tidal rivers flow is often
readily observable from year to year. Even a single great
storm may bring about very great changes in the position
of these channels.

One of the most interesting features connected with tidal
action in the embayed portions of our coast is found in the
tendency of the waters when moved by the tidal impulse
to organize the flow into regular though sometimes ramifying
channels. Rarely if ever do we find the movement diffused
as a broad, even sheet over the surface of the embayment ;
the flow is along lines determined by accidents, often too
slight to escape apprehension. Distinct, more or less sinuous
and rather sharp, walled ways are carved, through which the
body of the tide passes in flooding and ebbing, and from
which and to which the waters move from the higher lying
mud flats or marine marshes on either side of the streams.
If there be any considerable rivers falling into the harbor a
tidal channel commonly extends to the mouth of each stream.
These are usually much the deepest and widest, but similar
troughs extend into each ramification of the embayment, so
that at low tide the basin may appear like a large map of a
land river district. It is easy to see how these channels are
maintained, though the conditions of their institution are not
apparent. They are kept relatively free from sediments by
the tide, which, owing to the depth of water, finds less friction

CONTROLLING TJDAL STREAMS 227

in them in i)roportion to tlie mass of tlie current than on
the shoaler bottom at either side and so the currents tlow
faster, thus preventing- the deposition of sediment during
the period of ebb and flow and removing such materials as
may have come to rest at high and low tide when the currents
cease to act.

Fortunately for the interest of ports which are visited
by tides, the forces which they apply to our harbors are
often readily controllable by engineering constructions. By
means of jetties it is fre(|uently practicable to direct the run
of streams or by concentrating them to increase their energy
in such manner that the character of the exits may be im-
proved. It has been found to be an important precaution in
the management of harbors to restrict all natural or artificial
chansfes which tend to diminish the volume of the tidal
water that moves through the inlet. This is the case where
about the great cities which have developed on the margins
of our harbors it is found commercially desirable to fill in a
portion of the shallow sea bottom. The harbor autliorities
properly require that a compensation be made in the way of
dredging other portions of the basin so that the total amount
of water which moves with each tide ma\' not be diminished.
Those ports are fortunate which have a great extent of tidal
waters extending inland beyond the points where the ships
seek access to the shore, for such an extensive storage in-
sures a strong flow of tide, and consequentK- open pathways
to the sea. Thus in the case of the port of New York, the
Hudson, which is a marine inlet rather than a river, aftords
a vast storage basin for the water which passes through the
harbor mouths.

The effect of tidal action is much like that brought about

2 28 SEA AND LAND

by rivers where they emerge through deltas to the sea, only
in one case the current is continuous in one direction and in
the other it flows alternately to and fro. Where a tide of
considerable height enters the mouth of a large river the
effects of the two actions are curiously commingled. The
most noticeable feature arising from their cooperation is the
occasional occurrence at such points of a singular great in-
rushino- wave, called the bore or eagre. The production of
this curious phenomenon appears to be due to the fact that
the swift current of the river for a time pushes against the
incoming tide, causing it to mount until it attains a height
sufficient to quickly reverse the direction of the stream, when
the resulting wave moves in with such speed, volume, and
height as often to produce disastrous effects. Although some-
thino- of this action is perceptible at the mouths of many
rivers which course swiftly through deltas to the sea and
there meet tides of great height, they are best shown at the
Amazon, the principal mouth of the Ganges, and the Tsientang
in China. In the case of the Tsientang the wave is said
sometimes to attain the height of thirty feet, and to move up
the stream for the distance of eighty miles with the speed of
twenty-five miles an hour. \Miere the bore is well developed
the effect of this action is gready to scour the channel and the
banks of the stream, and. as in the Amazon, to deliver very
large amounts of mud to be moved by the currents of the
river or those of the tide. It is probable that the peculiar
form of the Delta of the Amazon, especially the exceedingly
wide river mouth, is due, at least in part, to the intense scour-
ino- action which these singular waves produce.

Where the tidal rise and fall is slight, as about the mouth
of the Mississippi, the movement in and out of the channel

ACTION OF ORGANIC LIFE IN HARBORS 229

of the stream is insigrnificant, and the only effect exercised
by the oscillations is found in a somewhat wider distribution
of the river detritus after it is discharged into the sea. The
tendency of the tides in such a case seems to be on the
whole to obliterate the channels which the stream would
make across the submerged apron of the delta. The general
tendency of this class of movements is to withdraw from the
shore and scatter over the sea bottom all the fine grained
detrital materials which are brought into the sea by the streams
or contributed to it by the beating of the waves on the coast-
line. The effect of this long continued action is indicated by
the formation on the borders of the continents and some of
the greater islands of a broad, submerged platform, which
has received the name of the continental shelf.

The effect of organic life on harbors is generally very
o-reat. Save where, as in the case of coral reefs, the growth
of particular species tends to the institution of barriers which
may afford roadsteads or harbors, the influence is almost
wholly detrimental, for it leads to the accumulation of sedi-
ments and the consequent shoaling of the water of the basin
and along the ocean shore to the diminution in the amount
of the tide entering each inlet. Along the margins of our
o-reat lakes the harborages are less affected than is the case
with the havens of the sea-board, for the reason that fresh
water sustains a much less abundant life than does the brine
of the oceans. For convenience of presentation, we shall
divide the account of this organic work so as to consider,
first, the action which is accomplished by plants, and, next,
that which is brought about by animals. It must be said,
however, that in most cases the work of these two groups
of oro-anisms is, to a great extent, intermingled.

230 SEA AND LAND

The part played by vegetable life in the organic economy of
the seas is quite as important as is its rcMe upon the land. In
both realms the plants act as mediators between the mineral
kingdom and the higher animal life, which exists solely by
means of the mineral elements that the vetjetation has brought
into a state where animals can make it useful in maintaining
their functions. In the seas plant life appears to be almost
altogether limited to shallow water next the shores, or to super-
ficial parts of the open ocean. Except in the case of the vast
growths of gulf weed which exist in the central parts of the
north and south Atlantic and Pacific oceans and the abundant
diatoms which develop, particularly in high latitudes far from
the land, almost all the vesfetable life of the ocean erows near
the shores in less than a hundred feet of water. The fact is
that vegetable life generally demands^^lie liglit> and with few
exceptions is not known to develop in marine waters below the
level which has some share of the sun's rays. Only one species,
the giant kelp of the Pacific, is known to fasten itself to the
bottom at depths of two hundred feet or more, and this unique
form elevates its fronds to the surface of the water on a mar-
vellously long and strong stalk.

The species of plants the growth of which is favored by
salt water belong to two great groups — the algae or seaweeds,
that have no true roots or flowers and otherwise possess only
a lowly organization, and flowering plants that have adapted
themselves in an exceptional way to the conditions which a
station in salt water imposes. In general the seaweeds are
most common in more open water than harbors aflbrd, and the
larger part of their species grow only below low-tide mark.
The higher flowering plants which live in the sea water rarely
meet with fit conditions for nurture beyond the limits of the

INFLUENCE OF MARINE PLANTS 231

more or less slu-ltered inlets ; they are indeed characteristically
harbor plants. Therefore it is mainly to this group that we
must look for the effect of vegetable life on the conditions of
havens.

The only group of seaweeds which to an)' considerable
extent affects the history of our embayed waters belongs to the
family of rock weeds — forms which dwell in the section between
high and low tide. In the colder waters of high latitudes, espe-
cially on the rocky, embayed shores of the fiord zone, plants of
these species are often exceedingly abundant. Thus along the
cliffs which border the inlets of the Bay of Fundy, the rocky
steeps are usually covered from near high tide to the lowest
level of the water with a singularly thick and massive coating
of those plants. When the tide is out in this region of great
rise and fall, this vegetation may form an almost continuous
sheet over the surface left bare by the receding waters. The
immediate influence of this envelope is to a considerable extent
favorable to the ])reservation of the harbors of the districts in
which it abounds. The dense and springy nature of the cover-
ing somewhat diminishes the efficiency of the blow which the
waves strike upon the shore. A yet more important effect is
produced by the nonconductive influence of these plants. When
in freezing weather the rocks are laid bare, this coating of vege-
tation serves in a more or less perfect way and often very
efficiently to prevent the frost's taking effect on the rock to
which it is attached. Wherever in the fiord zone we find an
area of jointed rocks between high and low tide, unprotected by
this vegetable mantle, we can always clearly note how the frost
has shattered the stone into fragments, which ma\- readily be
tossed about and still further broken up by the waves. At some
points on the coast of Maine the effect of this absence of sea-

232 SEA AND LAND

weeds is traceable in the extensive deposits of angular debris
ruptured from the cliffs and distributed over the bottom in part
by the waves, but in a more considerable measure by the action
of ice. In the winter season the water freezing next the shore
entangles large quantities of the detrital matter formed in the
manner above described and when this shore ice drifts away
with the tide the rocky fragments' are likely to fall at some
distance from the marofin of the water.

Where a harbor is of moderate depth over all of its area,
where the low tide comes against cliff shores and the bottom
is of a rocky nature, we ordinarily perceive little effect upon its
conditions arising from marine vegetation. Where, however,
the floor of the basin is to a large extent bare at low tide, and
especially where mud is formed in considerable quantities, we
can ordinarily notice the results arising from the growth of salt-
loving water plants. They are very evident to the eye and
may be traced on any well-made charts. As before remarked,
the most of this work is done, not by algae, but by the higher
flowering species, of which the greater part belong to the
families of grasses and sedges. The constructive work, how-
ever, which leads to the filling in of the harbor is, at least in
the regions north of Cape Hatteras, begun in the depths of the
water by the species known commonly as the eelgrass (yZostera
niaritima), a flowering plant which has the almost unique
characteristic of blossoming, fertilizing its flowers, and fruiting
beneath the level of the water. The conspicuous parts of the
plant consist of thin blade-like leaves, about a fifth of an inch in
diameter, but sometimes eitrht or ten feet lon^r. Owino- to their
strength these blades of the eelgrass withstand the impulse
of surges, such as act in the protected waters of harbors,
and by their thick- set order they diminish or entirely arrest

EFFECT OF FKLGRASS 233

the currents of the tides which s\v(-ep throu^jh their inter-
stices.

When the tide is high, tlie tops of the eelgrass plants are
some feet below the surface. Dm in;^- the period when there is
little motion to the water the sediment whicli ma\- have been
broLicrht up into it during the time when it was moving swiftly
settles between the stems of the plants aad-liradual]\'_a£cumu-
lates at their base w^here it is protected fromJ"urther disturbance.
Many species jof animals ^Iwell amid the close-set herbao^e^ find-
ino- inthose-jcaftditiaas--a-_jlieasure of protection and a^good
share of food. The remains of these creatures are also con-

i!lllfs:r-

!,;^,,

b:KiiiliilllilllMi!liliiMl!llllllllllilllilllili!B^ :: :.'SiC:.:K.».J^ : , , i:;, :.:,;„„v , , i!,:i. ,:,:„:::;|!.|:„ ■ , I , li I, „ , „

Diagrammatic Section through a Growing Marino Marsh

tributed to the grrowinor mass of detritus. In time these accu-

o o _______

mulations rise to near the level of low tide. In this position
the eelgrass will no longer flourish, and for a time the deposit
of mud is apt to be left as uncovered ooze, or at most it bears
an imperfect coating of alga-. At this elevation, however, the
detrital matter is protected from the action of the swifter flow-
ino; tidal streams, for these move with considerable energy only
in the deeper water channels. The facts observable along our
northern harbors clearly show that the eelgrass does an exten-
sive work in diminishing the depth of water over large portions
of the harbor floors.

While the eelgrass serves to shallow the water of our har-
bors to near high-tide mark, a number of plants are at work
in a different manner around the margins of these water areas.

234 SEA AND LAND

Wherever the shore is of an earthy nature at high-tide level
a number of species of flowering plants, principally belonging
to the grasses, take root a little below high-tide mark, grow
luxuriantly, and develop a dense mat of lowly vegetation. The
tops of these plants die down each winter, but their roots
are perennial and closely interlaced, forming a very dense
and elastic tangle, which is well fitted to resist the blows
of the waves. In course of time the interwoven living and
dead roots form a mass, having a thickness of from one to two
feet. Its upper surface is always so placed as to be covered
by each high tide, except perhaps on a few days in the year.
In most cases the water rises high enough to cover all but
the tops of the full grown stems. When the tide is low the
whole of these marine marshes is laid bare ; generally, in-
deed, they do not extend below the level of half tide.

In the process of its growth the mass of marine marsh
pushes horizontally outward toward the mud flats. The margin
of the accumulation is commonly somewhat undermined by
the action of the waves, so that it falls as a sloping curtain,
and in a measure protects the bank from such surges as may
form in a tolerably well sheltered basin. From time to time
the waves and ice break off masses from the low cliff which
borders the mud flat. This debris is commonly distributed
over the bottom next the growing marsh and helps to shal-
low the water to the point where the grasses can take root.
In this manner the growth is extended over the deposits
of ooze, it may be for a distance of miles. The limitation
in the spread of the marsh is effected in some cases by the
fact that the margin comes into a position where the waves
break it up, but more commonly the restriction is brought
about by the action of the tide in keeping open channels by

MARINE MARSHES '^H

which the water enters and leaves the area occupied by the
marine marshes. .

As orcHnary tides cover salt meadows to the depth of a foot
or more it is evident that if the area of these fields be extensive
the quantity of water which enters upon and departs from them
twice each day may be large in amount. The movements of
this flux and reflux are in a spontaneous w^ay accurately organ-
ized. Lookine over an extended field of marine marsh when
the tide is low we observe a system of channels in areal extent
proportionate to the surface occupied by the water at high tide,
the whole appearing, as before remarked, like a condensed map
of a great river system. At many points on the marsh, rarely
separated by more than a few hundred feet, we note shallow
drain ways, often from ten to twenty feet wide and only a foot or
two dee[). Close observation will show that the general surface
of the area about these troughs slopes with a very gentle inclina-
tion toward their margins. Following the w^ater in the ebbing
tide we note that it drains into these grooves which, as they
extend, become deeper and with more distinct banks, the natu-
ral result of the additional energy of the streani occupying it.
One of these grooves coalesces with another, the united chan-
nels become deeper, until, in a distance of a mile, the gathered
waters are strone enoucjh to cut a channel extendin^r to below
low-tide mark. If a number of these permanent waterwa)'s
unite they may form a broader tidal river.

Where the process of development of a marsh growth in
a harbor basin is complete, the whole of its area which is
not required for the ingress and egress of the tide is occupied
by the mat of vegetation or by the decayed vegetable matter
that forms beneath it. In this condition the marshes can no
longer extend themselves either in a vertical or horizontal

236

SEA AND LAND

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Plum Uland Marshes near Newburyport, Massachusetts

direction. They cannot grow upward for the reason that the
species which live upon them require to be flooded with salt
water eacli day for a certain number of hours. When this

altitude is attained, tlic L^rowtii of tlui plants becomes retarded ;
the species of animals which aid in the formation of the marsh
deposits cease to live in the localit\- and the rate of decay
of the vegetable matter is sufficientl\' rapid to balance the
deposition which growth brings about. The fict that the
marshes cannot attain to the level of high tide is of mo-
mentous consequence to the condition of our harbors, for
the reason that it insures a permanent and considerable flow
of water through the remaining tidal channels. But for this
limitation many of our harbors which have attained to the
state where the marshes can no longer develop would already
have been closed.

The marginal growth of the marshes when the develop-
ment of the held is near maturity comes to a point where
the efforts of the vegetation to win new ground are successfully
opposed by the flow of the tide that is made more energetic by
the extent to which it is confined within narrow limits through
the growth that has fenced it in. When the development is
complete there is no mud bank left for the roots to extend over ;
the slope toward the stream descends steeply into tolerabK-
deep water which often affords an excellent haven for ships.
So far as possible the grcnvth of the marsh plants anil the
formation of their dense mat of root fibers deepen the tidal
stream by narrowing the horizontal distance between the banks.
In fact, the ultimate conditions of the area are not completely
attained until the principal creeks have been forced to excavate
their beds to a depth below that which they had before the
shelf of the marsh began to press upon the streams. Hence it
comes about that in most cases the depth of water in their chan-
nels is considerably greater than in the part of their path which
lies beyond the limits of the grassed fields.

238 SEA AND LAND

The way in which the growth of these marshes is effected
varies somewhat, so far as details are concerned, according to
the pecuHarities of their site. The carbonaceous matter which
forms a large part of the fibrous layer is taken from the atmo-
sphere and by the process of decay gradually returns to it.
The permanent accumulations of the marsh are contributed in
part by the mud which is stirred into the sea water by the
incoming tide as it rubs upon the bottom and is then distributed
among the grass stems where it settles during the time when
the motion of the water is arrested, as it is for an hour or two
when the level is highest. This mud is effectively confined
amid the vegetation and adds to the mass of the marsh shelf.
Another element of increase is found in the development of
shell-bearing animals, principally mollusks and crustaceans,
which find a suitable site for their development amid the dense
herbaee. At their death these creatures leave their shells to
be built into the growing deposit.

Marine marshes of the nature above described can in most
cases readily be won to agriculture and afford lands of extra-
ordinary fertilit)'. Unfortunately, however, the means whereby
they may be so brought under tillage are necessarily prejudicial
to the conditions of the harbors where they lie. In their natural
state they afford only light crops of poor hay. To fit them for
other use it is necessary to bar out the sea waters, an action
which necessarily diminishes the energy and consequent scour-
ing power of the tidal streams. A good instance of this effect is
shown by an experiment made ten years ago on a tract of about
fifteen hundred acres of marsh in the county of Plymouth,
Massachusetts. On the seaward border of this area there was
a small harbor which was useful to fishing vessels and other
craft drawine not more than six feet of water. When, how-

TUlilR VALUE FOR TJLLAGK

239

ever, a dike was constructed which debarred the tide from the
area it had visited the haven was rapidly shoaled by the incur-
sion of sands and became almost worthless for the shelter of
such craft as had previously resorted to it. On this account it
will be necessary carefull\' to consider the effect of all opera-
tions looking to the reclamation of tidal marshes.

Dike and Marshes, Green Harbor River, Marshfield. Massachusetts

It is a very general fact that in hiq;h latitudes, usually in all
districts to the north and south of the tropical realm, vegetation
of the marine marshes consists altogether of plants which have
only annual tops, though their roots may endure for years. No
bushes or trees will grow on these marshes so long as they are
visited by the tide. In the warmer districts, within or near the
tropics, we find certain species of trees which have become
reconciled to the peculiar conditions imposed by havmg their

240 SEA AND LAND

roots in salt water and wliich have indeed developed a variety
of remarkable structures favoring- their life in such positions.
These species are commonly known by the name of mangroves.
Of the many thousand species of trees there are probably less
than a dozen which have effected this curious adaptation ena-
blinof them to dwell on lands below hiofh-tide mark. Thouoh
these forms are few, there being but two species known in this
country, the part which the\' pki)' in the history of the harbors
in the warmer parts of the continent is most important. The
work which the}' do in m()dif)-ing the inclosed marine waters
is even greater than that effected by the salt-loving grasses
which flourisli in colder climes. It will therefore be well for us
to trace, somewhat in detail, the way in which the mangrove
attains its peculiar development.

The seed of the mangrove is remarkably large and is a
slender cxlinder, tapering at either end and about six or eight
inches in length. The lower extremity is armed with a number
of small booklets, and is so weighted that when the seed falls
into the water, as it normally does when it parts from the parent
stem, it floats beneath the surface in a nearh' vertical position.
As it absorbs water it settles near the bottom, so that when
driven around b\- the currents it is likely to become attached to
a bit of seaweed or other object lying on the floor of the harbor.
Thus fixed it quickly takes root and sends its shoot towards the
surface of the water. If that surface be only a foot or so away
at low tide it ma\- manage to obtain access to the air, subsisting
the while (mi the considerable store of nutriment contained in
the relatively large seed. Rising above the surface of the sea,
it soon develops its first leaves and establishes the crown or
point between tlie roots and stem at about high-water mark.
Above this level the trunk and folia'-e much resemble the India-

TROnCAL MARINE MARSHES 241

rubber tree, or Indian fig, which is a familiar object in green-
liouses. The branches, however, have a widespreading, rather
low habit, and from them as well as from the crown of the tree
there ^rrow off long, runner-like processes which extend for a
distance of some feet in a horizontal direction, and then curving
sharply downward descend through the water until they attain
the bottom, where they take root. These curious processes,
though at first slender, gradually increase in size and become
strong supports, from which new crowns, with their trunks and
branches, may spring. Thus a single tree may rapidly march
away from the original planting-point until its outer verge may
be an indefinite distance from its place of origin.

Underneath the close-set crowns of the mangrove the
roots make a dense tangle, where a host of marine animals har-
bor and contribute their dlhris, in the way of sediments,
to the bottom. At the same time the tidal waters, having
their current arrested by the obstructions which they encoun-
ter in the submarine part of the forest, deposit quantities of
mud. These accumulations, mingled with the leaves and
branches which fall from above, serve rapidly to shoal the
water until marshes take the place of fields which were before
inundated even at low tide. When this state in the growth
of a mangrove plantation is attained, the species which have
won their way against the sea gradually die out and their
place is taken by others which, though they can not live in
contact with salt water, can flourish on the marshy accumula-
tion formed by their predecessors.

Owing to the vigor of growth of the mangrove trees and

to the peculiar roots which they put forth, they can withstand

the assaults of much heavier waves than the frailer marsh plants

of higher latitudes. The mangroves of southeastern Florida
16

242 SEA AND LAND

march in such a sturdy way against the sea that they can
resist waves which occasionally attain the height of four or five
feet. Much of the Everglade district has been won from the
condition of shallow water to the state of swamp by their action
during relatively modern times. Their rate of advance over
the shallows is much more rapid than that of the grasses
which form the northern marine marshes, and is limited only
by water which is too deep for their root-like runners to
descend through it and fix themselves upon the bottom.
Where the water which they seek to penetrate is tolerably
deep, their growing ends are apt to be swayed by the current
so that they can not readily attain a foothold. Moreover, they
are more or less eaten by certain fishes which have a fancy for
vegetable food.

In regions which are sufficiently warm to permit the free
development of mangroves, they take possession of all the mud
flats which in more northern districts would be occupied by
grass marshes. The result is that margins of the harbors
have a totally different aspect from that which is presented by
the shores of the havens in higher latitudes. Their general
effect, however, is the same as that which is brought about by
the lower growing plants which dwell between high and low
water mark. They narrow the channels of the reentrants, and
by concentrating the tidal flow into a small space serve some-
what to increase the scouring action of the currents through
the acceleration of their velocity which is thus induced.
Owing, however, to the fact that the mangroves elevate the
marshes somewhat above the level of high tides, these trees
by debarring the tidal water from entrance to extensive dis-
tricts are on the whole more deterimental to havens than are
the grassy marsh growths. The last named type of vegetation

SHELL-BEARING ANIMALS /X I/ARJWRS 243

never extends to liigh-tide mark, but always leaves a foot or
two in depth above the surface to be filled by the water at
high tide. The result is that the tidal channels in the man-
grove district are relatively much shallower than those beyond
the field.*

In discussing the influence of vegetation on harbors we
have already had occasion, incidentally, to refer to the action
of certain forms of animals which dwell amid salt-loving plants
and contribute their remains to the marshy accumulations.
We have now to extend our consideration of the work done
by the various shell-bearing animals to those parts of harbor-
ages where they dwell apart from vegetation. Wherever
an inlet of the sea is the seat of a considerable tidal flow we
are sure to find that the conditions favor the abundant devel-
opment of animal life. Along the shores of the sea, near the
mouth of the reentrant, the waves are continuously at work beat-
ing the remains of marine animals and plants into a finely divided
state, where they readil)' float in the water and afford large
amounts of nourishment to the living beings with which they
come in contact. A host of species dwell in this water and
draw their sustenance from it. With each oscillation of the
sea the food-giving fluid is swept past the multitudinous
mouths of the animals which dwell on the floor of the harbor,
and which thus at once obtain the shelter of its recesses and
a supply of nutriment fitted to their nurture.

The most important sediment-producing animals of havens
are found in the group of moUusks. The most of the species
in this type are shell-bearing. They grow rapidly, and at
death a large part of their bodies is contributed to the sedi-

* For further information concerning mangrove marshes, see Tenth Annual

Report of the United States Geological Survey.

244 ^^A A^'D LAND

ments. There is a very great diversity in the mode of life
adopted by these molluscan species. The most of the uni-
valves are unattached to the bottom, and are apt to be swept
about by the tidal currents where the movements are partic-
ularly strong. The bivalve shells which are prevailingly
laro-er and make more considerable accumulations of detritus
are usually fixed to the bottom or dwell in the mud, in which
they excavate chambers large enough to give shelter to their
bodies. Some species which lie upon the floor of shallow
water are not attached, and at their death their shelly cover-
ings are often w^ashed ashore. In some cases the accumulation
made along the margin of the harbor is sufficient in quantity
to lead to the formation of a shelf, which gradually extends
toward the deeper water. Generally, if not always, this accu-
mulation of shells is more or less associated with vegetable
matter formed by the marine marsh plants.

By far the most important of our mollusks in the work of
accumulating sediments in harbors is the common oyster, which
exists in the form of numerous ill-determined species along the
greater part of the shores in the temperate and warm portions
of the world. The most of the varieties of this interesting
animal have become especially adapted to life in brackish
water, such as our harbors afford. In general they require a
mixture of from one-fourth to three-fourths of water from the
land with that from the sea to afford conditions for their fullest
development. Where these conditions are combined with
shallow water the oysters may grow rapidly, their shells form-
ino- an almost continuous sheet over wide areas, the living lying
upon the dead in a deposit many feet in thickness. In the
northern part of the field which they occupy — as, for instance,
between New York and Newfoundland, where the situations

WORK DONE BY THE OYSTER 245

are least favorable for their growth — these mollusks are rarely
very efficient agents in shallowing the water ; yet, even about
Boston, Massachusetts, certain of the estuaries, particularly the
part of the Charles River known as the Back Bay, has some
hundreds of acres of its area occupied to the depth of several
feet by the shells of this species. For many years the living
forms have disappeared from these waters, but it is evident
that a considerable part of the accumulations which have served
in good part to close the original entrance of Boston Harbor
are composed of their remains.

South of New York the importance of the oyster in the
history of the harbors steadily increases until we attain the
coast of Florida. In its maximum development from near the
mouth of the Savannah River to Jupiter Inlet the larger part
of the shallow bottom inside of the ocean beach is occupied
by beds of these shells. So crowded are these forms that they
push their growth above the level of low-tide mark and in the
region where the mangroves abound they cluster on the roots
of the trees in such numbers as often to hide them from
view. The waves break off great quantities of shells and
toss them upon the beach which borders the widespread marine
marshes of this district, the so-called savannas of our southern
coast. In this position the debris is rapidly covered by the
swiftly extending vegetable growth. Between Charleston,
South Carolina, and Biscayne Bay, Florida, there is an aggre-
gate area of nearly a thousand square miles which, when the
shore assumed its present elevation, was occupied by tolerably
deep water that has now become filled to near the level of high
tide by sediments composed in large part of oyster shells.
The singularly rapid growth of these savannas as compared
with the marine marshes on the more northern parts ot our

246 SEA AND LAND

shore is largely to be exphiined by the great and swiftly accu-
mulated deposits of such shells which are formed in the south-
ern district.

In proportion as we go southward the share of vegetable
matter which is built into the marine marshes rapidly dimin-
ishes until in the Georgia district, although the species of
the salt-loving grasses and rushes, as well as other plants,
are more numerous and, as regards growth, more vigorous
than in the northern districts, the contribution which they
make in the way of sediments is inconsiderable. The reason
for this is easily seen. Owing to the greater warmth of
the southern realm the process of decay of the dead vege-
tation is much more rapid and complete than in the north.
On the other hand, the warmth of the water in the southern
field favors the rapid development of shell-bearing animals,
particularly of the oysters, which contribute vast amounts of
debris to the growth of the marsh deposits. The result is
that the southern growths of this nature are formed with far
greater rapidity than those of the northern realm. Along
the o-reater part of the coast south of Charleston the devel-
opment of these organic benches has attained the point
where their further extension is arrested on account of the
energy of the tidal movement. In fact the conditions have
come to the balanced state, which, as we have seen, is the
natural result of the struggle between the organic actions
which tend to construct marine marshes and the physical
forces which contend against their growth.

There are many other marine animals which here and
there in varying quantities form organic sediments which
lead to the shallowing of harbors. Of these we can only
incidentally note a few of the more important. The common

CONTRIBUTIONS OF OTHER ANIMALS 247

clam (^Mya arcnaria Linn.) is in northern regions a species
which adds rapidly to the growth of the mud banks so com-
monly lying between the margins of the marine marsh shelf
and the edge of the deeper tidal streams. This species
has the habit of abiding beneath the surface of the mud,
holding communication with the water by means of its long
protrudable siphon. Owing to its curious habit of life the
shells of this species are not visible on the mud flats, and
are not often washed ashore, and thus the important work
performed by this creature in shoaling the water, a work in
which it is only less important than the oyster, is apt to be
unnoticed by the casual observer. The Pectens or scallops
also play an important role in sedimentation, but the fields
on which they grow are much more limited thai; those of the
species above mentioned. Owing to the lightness of their
shells they are more commonly swept against the harbor
beaches than any other species, except some of the tropical
kinds.

Besides mollusks there are numerous other animals which
make important contributions to the detritus accumulating
in our harbors. Of these the crustaceans are the most note-
worthy. The crabs, lobsters, and their lower kindred, the
shrimps and sand hoppers, grow rapidly, exist in great num-
bers, and at their death leave tolerably solid skeletons as
contributions to the growing sheet of sediment. Much of
the exceeding fertility which characterizes all marine marsh
lands won to tillage is due to the phosphate of lime which
exists in the shells of these creatures whose forms have been
buried in the deposit. A group of lowly organisms known
as Foraminifera affords a host of small and swift sfrowinsf
forms which secrete hard skeletons, mostly of limy matter.

248 SEA AND LAND

These species abound in many harbors which are visited
by warm waters, and often bring about the formation of a
lime ooze composed of such finely divided matter that the
material is readily swept about by the tidal currents. De-
posits formed of the remains of these creatures abound in
the regions of coral reefs. In such reef-bordered shores the
species of coral which dwell within the lagoon are very effective
agents in shoaling the waters which they inhabit. This result
is, however, combined with that which is effected by a host
of other orsfanic forms.

Before taking leave of the interesting phenomena exhibited
by the organic deposits of the coast-lines it is well to con-
sider them in a somewhat more general manner than we
have hitherto done. In the first place we should notice
that the amount of these contributions made to the sea-floor
and the importance which they have to the life of man are
alike singularly great. Although the ocean bottom is almost
everywhere receiving contributions of organic sediment, the
quantity of this material which is laid down next the shore
is far greater than that deposited beneath the deeper seas.
The reasons for this accentuation of the coastal deposits
which are laid down by animals and plants is easily per-
ceived. It is due in part to the large quantities of material
fitted to be the food of animals and plants which is con-
veyed from the land to the sea by streams of fresh water.
In part it is contributed by the action of the waves, which
are constantly at work grinding up organic and inorganic
material and diffusing it in a way to serve the needs of
living beings. Still farther along the shallows next the
shore the light of the sun penetrates through the water to
the bottom and there stimulates the growth of a host of species

VARIETY AND BEAUTY OF MARSH LIl'E 249

which develop far more rapidly than is possible with organisms
abiding in the midnight darkness which exists in deeper parts
of the sea.

Owing to their novelty and in a measure to their singular
features the coral reefs have appealed to the imaginations of
observers and have received a share of attention and interest
which is much out of proportion to their real value among
our coastal accumulations. The less noticed because more
familiar deposits, such as are contained in our marine marshes,
art* not only on the whole more important, but are in their
way as beautiful, and from a scientific point, as noteworthy
as the barrier reefs and atolls which here and there occur
within and near the tropical realm. To the thoughtful observer
the marine marshes of New England or Georgia afford b)-
the variety and beauty of their phenomena even more in-
teresting structures than any which the zoophytes build. The
part they play in relation to the interests of man is much
more important than that which is performed by the reef-
building animals. In their aspect they are much more in-
teresting than the constructions due to the pohps. There
is nothing in the coral islands to compare with the brilliancy
of coloring which the marshes of New England exhibit at
certain seasons of the year ; nothing like the variety of hue
which characterizes these prairies by the sea in the different
seasons, and which makes it possible for the naturalist to
trace the changes in their aspect month by month through
the annual cycle. None of the elements of form of the coral
reefs approach in beauty those afforded by the marine marshes.
The growing portion of the reef is almost altogether hidden
from the eye ; all that is evident consists of ruins tossed up
by the waves or elevated with the uprisings of the shore but

250 SEA AND LAND

in all the stages of water below mid tide the marshes present
a beautiful plain of vegetation the tints of which vary from
month to month and even from hour to hour as they re-
ceive or discharge their waters. Nothing in the geographic
world is more graceful than the curves of the creeks through
which the tidal waters enter and depart in their constant
movement.

The variety in the character of the marine marshes which is
brought about by the slight changes in the amplitude of the
tidal swino- and other variations in the conditions of the shore is
singularly great and is unparalleled in the physiognomy of coral
reefs. Thus for each hundred miles of distance along the
Atlantic coast from the Straits of Belle Isle to Key West the
aspect of the mud flats and grass-covered plains so constantly
varies that anyone who was well acquainted with their peculiari-
ties could tell pretty nearly whereabouts he had landed on the
shore by the appearance of these fields. All organic life is
beautifully and variedly adjusted to the conditions of its environ-
ment, but it is doubtful if in any other zone of the organic world
the accommodations are more exquisitely ordered than in the
marshes of the ocean shore.

It is otherwise with the harborages of our fresh water lakes.
In those tideless waters the action of organic life is practically
limited to the growth of certain rushes and sedges which spring
from the bottom of shallow water and gradually accumulate a
deposit of ordinary peat such as is so generally formed in our
fresh water bogs. In many cases, as, for instance, about the
Great Lakes of the Northwest, this accumulation of decayed
vegetable matter goes so far as to close a large part, if not
the whole, of many havens, even those which were originally
extensive in area. We fail, however, to find in these situa-

SYNOPSIS 251

tions any plants so well adjusted to the work of winning the
ground from the sea as are those which dwell along the sea-
board. This lack of variety in the water-loving vegetation,
tocrether with the relative absence of acquatic animal life and
the non-existence of the tides, makes these fresh water accu-
mulations of comparatively little interest except that which is
due to the fact that they injure or destroy a large part of the
shallow harbors of our navigable lakes. We shall therefore
dismiss them without further consideration and close our
general account of the organic influences which affect harbors
with a brief resume of the facts, as follows, viz.:

First, the land plants which have become reconciled to
living in salt water are the principal organic agents in effect-
ing injurious changes in harbors. Their influence on the
whole seems greater than exercised by any other single agent.
Second, the greater part of this work is done by the plants
belonging to the kindred of the grasses.

Third, the efficiency of the work is due in large measure to
the cooperative effect of the tides, which nourishes the vegeta-
tion and the animal life which dwells amongst it.

Fourth, the effect of the tide-water grasses is to diminish
the area of harbors and usually to deepen the creeks which
remain. The eff"ect of mangrove growth is to occlude the
harbor by altogether cutting out the storage of water at high
tide.

Fifth, the effect of animal life other than that associated
with the marine grasses is purely destructive to the interests
of harbors, serving to shoal the water throughout the basin.

Sixth, all the organic deposits next the land — coral reefs,
mano-rove and erass marshes — are to be reloaded as belonging
in one great group of coastal accumulations, of which the

-D-

SEA AND LAND

divisions including the formations built up by plants are of
much more general importance than those which owe their
origin to the growth of polyps.

Seventh, the greater portion of the embayed waters of the
ocean shore have been closed by organic action during the
last geologic period.

UNIVERSITY OF CALIFORNIA LIBRARY

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