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THE LIBRARY

OF

THE UNIVERSITY

OF CALIFORNIA

LOS ANGELES






STATE NORMAL SCHOOL

LOa ahGEU&>, CALIFORNIA



\ki



JANS




Fig. i. — North America.

From a photograph of a relief map by Victor and Cosmos Mindeleff.
Scales of original : Horizontal, 120 miles to i inch; vertical, 40,000 feet to
1 inch ; proportion, I : 16.



NORTH AMERICA



BY



ISRAEL C. RUSSELL

PROFESSOR OF GEOLOGY IN THE UNIVERSITY OF MICHIGAN



With Maps and Diagrams



/330&



tfTHEREGIONS:-




OFTHEWORLP



NEW YORK

D. APPLETON AND COMPANY

1904






Copyright, 1904
By D. APPLETON AND COMPANY



t



PREFACE



The aim of this book is to give a condensed and, I
trust, readable account of the leading facts concerning the
North American continent which, from the point of view
of the geographer, seem most interesting and instructive.
The area of the continent is so vast and the diversity
among its various parts so great, however, that the com-
pleteness of treatment which characterizes the preceding
volumes in the series to which it belongs could not be at-
tempted. To obviate in a measure this confessed short-
coming, there has been appended to each chapter a list of
books which will enable the reader to continue the studies
outlined in it.

A complete review of the geography of a continent
should, as it seems to me, be divided into two parts: first,
a discussion of the natural conditions, or physical geog-
raphy, and, second, man's dependence on and use of the
natural resources, or economic geography. Each of these
two leading phases of the subject was embraced in the pre
Hminary outline of the present volume, but owing to a de-
sire to make each chapter as complete as practicable, and
also on account of limitations as to space, the treatmenl <»t
the economic phases of geography has been necessarily
brief. But little more can be claimed for the book as fin-
ished than that it is an attempt to describe some of the
more prominent and attractive aspects <>f the natural con-
ditions pertaining to North America.



vi NORTH AMERICA

While writing this book I have become more and more
impressed with the incompleteness and inadequacy of the
printed records relating to the geography of the continent
of which it treats. Extensive tracts, particularly in the far
North, have not been traversed by observant men, vast
areas throughout the continent have not been surveyed
and mapped, and even in the somewhat thickly inhabited
portions of the more enlightened countries there are large
districts in reference to the geography of which there is
but little critical information available. Under these con-
ditions it seemed best to select typical examples of various
geographical features from the better known portions of
the continent to represent the conditions throughout the
less thoroughly explored domain in which they are situ-
ated, and at the same time serve to illustrate the highly
creditable advances made by American geographers in
definitely formulating the principles of physiography. The
book may, in a measure, be considered as an attempt to
present in popular form a report of progress concerning
the study of the geographical development of North
America at the beginning of the twentieth century.

I. C. R.



CONTENTS



CHAPTER PAGE

I. The Margin of the Continent i

The continental shelf — The submarine topography of the
Caribbean region — Movements of the ocean waters — Islands —
Topography of the coast — Estuaries and harbours.

II. The Topography of the Land 60

Coastal plains and plateaus — The Atlantic mountains — The
continental basin — The Pacific mountains — The Antillean
mountains.

III. Climate 173

The elements of climate — Climatic provinces- 1 — Secondary dis-
turbances of the atmosphere — Evaporation.

IV. Plant Life 215

The forests — Prairies, treeless plains, and plateaus — The tree-
less mountain tops.

V. Animal Life 258

General principles of geographical distribution — Life-regions
and life-zones — The mammals — Some representative mammals
— The birds.

VI. Geology 299

The growth of the continent — The rocks of which the con-
tinent is composed — The concentration of mineral substances.

VII. The Aborigines 354

The Eskimos — The Indians.

VIII. Political Geography 4° 8

Classification of boundaries — Political control — Population in

[g ><<.

Index 427



LIST OF ILLUSTRATIONS



COLOURED MAPS fac ,ng

PLATE PAGE

I. Orographical features 25

II. Mean annual rainfall and temperature 173

III. Climate and life provinces 185

IV. Leading geological features 306

V. Pleistocene glacial deposits . . 315

VI. Linguistic stocks of Indians North of Mexico .... 370

VII. Distribution of governments . 410

VIII. Characteristic vegetation 418

OTHER ILLUSTRATIONS

FIG. PAGE

1. Relief map of North America Frontispiece

2. Profile of a continental shelf 2

3. Map of Gulf of Mexico and the Carribbean region, showing topog-

raphy of the sea-floor 17

4. Cotidal lines 28

5. Profile of sea-cliff and cut-and-built terrace 33

6. Map of a portion of the Atlantic coast of the United States . . 35

7. Map of Mobile Bay 3°

8. Map of Cape Cod 37

9. Map of the coast of Texas . 29

10. Map of a portion of the coast of Maine ...... 45

11. Map of the coast of southeastern Alaska ...... -47

12. Map of the delta of the Mississippi 54

13. Map giving the names of the larger physiographic divi ions <>f N'orih

America 01

14. Altitude map of North America ........ 65

15. Map of the Appalachian Mountains /''"'V 74



NORTH AMERICA



FIG.
1 6.

17-

18.
19.

20.

21.
22.

23-
24.
25-

26.

27-
2S.

29.
30.

31.

32.

33-
34-
35-
36.

37-
38.
39-



Section of anticlinal valleys and synclinal mount



facing



facing



States



Profile showing relation of ancient peneplains in

Section through the Black Hills of Dakota .

Sketch of the Grand Canon of the Colorado Rive

Map of the Great Basin ....

Map of Crater Lake, Oregon

Mount Rainier, Washington ....

Map of Puget Sound .....

Map showing isobars for January and July .

Ice-palace, Montreal .....

Map showing tracks of West Indian hurricanes

Map showing depth of evaporation in the Unite

Map showing distribution of forests

Douglas firs, Vancouver ....

View in redwood forest of California, from photograph

Bureau of Forestry .....
Bison at Silver Heights, Winnipeg
Map showing range of bison

Maps showing the growth of the North Ameiican contment
Map showing the distribution of coal-fields
Ideal section through an oil and gas pool beneath an anticlinal
Lodge or tepee of Blackfoot Indians, Manitoba. . . . facing
Panorama of Uxmal, Vucatan
Pointed arches in Central Ameiican ruins .
Carved stonework, Uxmal, Vucatan ..... facing



the Appal



by U. S
facing



PAGB
73
8l
117
135
I3S
155
156
iGl

174
199
210
213
2l6
241

243

275
276

304

337
339
3S7
391

392
394



NORTH AMERICA



CHAPTER I

THE MARGIN OF THE CONTINENT THE

CONTINENTAL SHELF

3 3 O £

In beginning the study of the physical geography of
North America, one of the first facts to claim attention
is that the true continental border is in general many
miles seaward from the present margin of the land. The
boundary of our field of study is defined with considerable
accuracy by a line drawn on the bottom of the sea adjacent
to the present coast-line of the continent so as to pass
through all points where the soundings show a depth of
ioo fathoms of water. This ioo-fathom contour in the
topography of the sea-floor chances to coincide in a general
way with the outline of the submerged border of the conti-
nent; landward from it the bottom rises with a gentle slope,
while seaward the descent is usually steep down to a depth
of 2,000 or more fathoms.

A gently sloping shelf-like border surrounds the deep
central basin of the Gulf of Mexico (Fig. 3). To the west
and north of Yucatan and west of Florida the shelf is from
140 to 160 miles broad, with a surface slope towards the
centre of the Gulf of less than 6 feet to a mile — a slope so
gentle that were the surface of the shelf exposed to view,
no eye could distinguish it from a perfect plain. The
deepest sounding yet obtained in the central part of the
Ciulf, approximately midway between Yucatan and Florida,
shows a depth of 2,119 fathoms. The remarkable fact is
that the slope from the ioo-fathom line to the bottom of
the central basin of the Gulf is precipitous. In two pi ices

1



2 NORTH AMERICA

on the border of the Yucatan bank a descent of about
8,500 feet occurs within a horizontal distance of 15 or
20 miles.

- On the east side of the southern extremity of Florida,
and again on the eastern shore of Yucatan, the continental
shelf is only about 5 miles broad; these are the nearest
approaches of the present land to the actual border of the
continent to be found on the Atlantic coast. The explana-
tion of these exceptional conditions is that both Florida and
Yucatan are portions of the continental shelf which have
been raised so as to form low emerged plains.

From Cape Hatteras northward to the extremity of the
Newfoundland Banks the shelf increases gradually in
breadth from about 15 miles in the region of the Carolinas



Shallow Water on Ocean

Continental Shelf Deep Water



: t

Fig. 2. — Ideal profile through a continental shelf.

to over 100 miles off the coast of Maine. The outer border
of the shelf is an irregular curving line. Opposite the
coast of Massachusetts and Maine an extension of the Atlan-
tic basin reaches within 1 5 or 20 miles of the present margin
of the land. The manner in which the low plain fringing
the eastern border of the United States passes beneath the
waters of the Atlantic and becomes a continental shelf is
illustrated by Fig. 2.

Southeast of Newfoundland the continental shelf has
an irregular surface, marked by shoals and depressions, and
furnishes the most valuable fishing-banks in the world.
The 100-fathora curve is there over 500 miles from the
coast. This & the broadest portion of the continental shelf
now known on the Atlantic border of the continent.
Northward of Newfoundland the Atlantic basin extends
far into Davis Strait and Baffin Bay, and then its border
swings outward about Greenland, but its true margin is
there but imperfectly known.





THE MARGIN OF THE CONTINENT 3

To the north of the arctic coast of North America,
aa is suggested in part by the soundings made by Nansen,
the submerged margin of the continent is probably broad
and presents a steep escarpment to the arctic basin, but the
outline of the true continent, as in the case of the present
land extension in that direction, is unknown.

Soundings to the north of Cape Lisburne, on the
northwest coast of Alaska, show that the ioo- fathom
curve is there over 200 miles from land. The exception-
ally shallow sea covering this portion of the shelf contin-
ues westward to the coast of Asia, and southward through
Bering Strait, so as to embrace the eastern portion of
Bering Sea. The continental mass of North America is
thus directly connected with the continental mass of
Asia. A rise of the bottom of less than 200 feet in Bering
Strait would bring about a land connection between the
Old and the New World. This, as will appear later,
is a most significant fact to students of geography and
geology.

On the Pacific coast of North America the continental
shelf is throughout much narrower than its average breadth
on the Atlantic side of the continent, and is also more
deeply submerged on its seaward border. The broad plat-
form beneath the northern and eastern portions of Bering
Sea — from which rise the low islands, St. Lawrence, St.
Matthew, Nunivak, an'd the Pribilof group, now separated
by water from 25 to 35 fathoms dee]) — extends to the
south of the more easterly of the Aleutian Islands, and is
prolonged eastward along the south border of Alaska,
where the 100-fathom curve is from 10 to 20 miles from the
coast-line, and approaches still nearer the land in the neigh-
bourhood of the islands of southeastern Alaska and British
Columbia. The shelf is narrow but well denned along the
coasts of Washington and Oregon. Adjacent to Califor-
nia, Mexico, and Central America, its outer margin is
barely 10 miles from land. Throughout the entire distance
from the Aleutian Islands to Panama the outer border of
the shelf is in general well defined, and its seaward escarp-
ment descends abruptly to the floor of the vast Pacific



4 NORTH AMERICA

basin, where the sounding-line shows depths of from 2,000
to 3,000 fathoms.

Could the waters of the sea be removed and North
America viewed from a distance, in the manner we are
enabled to examine the surface features of the moon through
a powerful telescope, an observer would behold a great
plateau, having the present well-known triangular shape of
the continent, rising boldly between the Atlantic and the
Pacific basins. The surface of the plateau would be rough,
in comparison with the generally smooth contours of the
adjacent troughs, but even the highest mountains would be
less in elevation above its general surface than the crests
of its bordering escarpments above the adjacent depres-
sions. The mountain-peaks when illuminated by the sun
would appear as points of light with long, tapering morn-
ing and evening shadows, and the east and west pla-
teau-borders would be strongly drawn bands of light or
shadow, according to the time of day, 6.000 or S.oco miles
in length. The Bermuda, Hawaiian, and other islands
now rising above the surface of the deep sea would stand
on its desiccated floor as isolated, gigantic moun-
tains — " Bermuda mountain" with an elevation of 15.000
feet, and the Hawaiian group of peaks with a culmi-
nating point of light 30,000 feet above the surrounding
plain. The bordering slopes of the " North American
plateau " and its slightly bevelled margin forming the
present continental shelf would be lacking in details, and
appear as a vast, smooth, curving belt of light or shadow,
in striking contrast to the roughened surface now above
water.

The North American continent is not exceptional in
being partially submerged at the present time. Similar
conditions occur about the margins of other continents
which, as is well known, are fringed with broad submarine
terraces built in part of their own debris. In fact, every
large land mass on the earth under existing climatic condi-
tions and present distribution of life, if it remained moder-
ately stable for a sufficient length of time, would have a
submarine shelf built about its borders.



THE MARGIN OF THE CONTINENT 5

Of what is the Continental Shelf Composed.'' — The rocks
forming the present land surface of North America extend
seaward from the existing shores and constitute the basal
portions of the continental shelf, thus suggesting that the
submerged platform is due, in part at least, to shore erosion
— the waves having eaten into the land so as to make a ter-
race. That this is not the true explanation, however, may
be shown in several ways.

The superficial covering which gives the continental
shelf its smooth contours is composed largely of sedi-
ments such as rivers bring from the land. This material
is coarsest and in greatest abundance near shore and de-
creases both in the size of the particles composing it and
in abundance towards the seaward borders of the shelf.
The wash from the land is mostly deposited within a few
miles of the coast-line and, as has been shown by dredg-
ing, is seldom carried, even under the most favourable
conditions, more than about ioo miles seaward. Sup-
plementing the fragmental material derived from the land,
and increasing in thickness towards the seaward margin of
the continental shelf — coincident with the increase in depth
of the water — is a deposit of light-coloured calcareous mud
or ooze, formed of the hard parts of animals and plants
which live in the waters of the sea. The organisms which
supply this material are in the main microscopic and live
especially in the warmer seas in countless myriads. Their
dead shells or cases fall to the sea-floor in a constant sin »v\ er,
much as the snow falls from the air, but continuously year
after year and century after century. This descent of the
hard parts of organisms, both calcareous and silicious, from
the waters of the sea has led to the accumulation of a sheet
of slimy sediment over almost the entire sea bottom. How
thick this layer is we have no means of knowing, but it i^
pr< ibably many hundreds of feet.

The organic debris falling on the continental shelf de-
scends through only a few hundred fret of water and is but
little affected by its solvenl action. The great number <<i
organisms, such a- the Foraminifera which secrete calca-
reous tests or " shells " causes the slime on the continental



6 NORTH AMERICA

shelves to be calcareous and in the condition to form lime-
stone if cemented or subjected to sufficient pressure. In
the deep sea, where the hard parts of dead organisms fall
through many thousands of feet of water, their more
soluble portions are removed and the bottom is covered
throughout vast areas with a pinkish clay composed of the
more insoluble residue of the calcareous shells and the
cases of silica-secreting animals and plants.

The continental shelves are, in general, within the influ-
ences of ocean currents, and fine debris, as we seem justified
in concluding, is removed from their surfaces, carried be-
yond their margins, and deposited on their seaward slopes.
The shelves are thus built outward and are largely con-
structional topographic forms. Their outer slopes, where
best defined, represent about the " angle of repose " in
water of the fine material of which they are composed.
These slopes are in several regions so precipitous that they
probably would not retain their present forms, but descend
in landslides, should the restraining pressure of the sea-
water be removed.

In certain favoured regions, as about the southern ex-
tremity of Florida, over an extensive area in the West
Indies, and on both sides of Central America, the conditions
favour the growth of reef-building coral-polyps, and por-
tions of the continental shelf in that region are covered with
an irregular layer of living coral and dead coral-rock. The
importance of this resistant superficial layer on the minor
features of the relief of the submarine banks, etc., needs
to be considered in studying the secondary topographic
features of many portions of the floor of shallow trop-
ical seas.

In addition to the debris from the land and the rain of
the hard parts of organisms from the water covering the
continental shelf there is in northern regions a third but
less important source of material furnished by floating ice.
About the northern shores of America sea ice forms in
winter, some of which is frozen fast to boulders and stones
in shallow water, and when this ice-foot, as it is termed, is
adjacent to steep cliffs, rock debris falls upon it. When



THE MARGIN OF THE CONTINENT 7

the ice becomes broken into cakes in the spring-time or
during storms, it floats away, under the influence of the
winds and currents, and as it melts drops its freight on the
floor of the sea. This shore ice seldom travels far, and is
probably not an important factor in the building of conti-
nental shelves. Of greater interest are the bergs derived
from glaciers, especially in Greenland, many of which con-
tain hundreds of thousands and even millions of cubic feet
of ice and travel hundreds of miles before melting. In some
instances these bergs carry with them rock masses, mud,
etc., derived from the land over which their parent glaciers
flowed, and as they melt, distribute this material over the
sea-floor. The greater portion of this ice-carried freight
derived from Greenland is dropped on the continental shelf,
and not infrequently reaches the latitude of Halifax, and
even journeys farther south. This berg-carried debus is
mainly deposited on the continental shelf, for the reason
that the cold currents which bring the bergs southward
follow the coast in a general way, and are bordered on their
seaward margins by warmer currents flowing northward.
To the north of Nova Scotia the additions of material to
the continental shelf through the agency of bergs is consid-
erable in the aggregate, and as the process has been in opera-
tion for thousands of years, the banks or shoals in the
sea off the Newfoundland coast are due in part to this
cause.

Ice-carried debris forms an important source of material
for the building of the continental shelf from New England
northward and westward about the shores of North Amer-
ica, including Greenland, to Bering Sea. and to a less extent
on the south coast of Alaska, where many comparatively
small bergs are set afloat by glaciers which reach tide-
water. Supplementing the distribution of debris over the
continental shelf by shore ice and bergs, is the similar work
carried on by the ice discharged into the sea by northern
rivers, such as the St. Lawrence, Mackenzie, and the
Yukon.

1 )uring the glacial ep< K'h great ice sheets like tli' >se now
discharging bergs along the Greenland coast, Ian vastly



8 NORTH AMERICA

larger, entered the Atlantic all the way from New York to
the Arctic Ocean, and along the Pacific coast from the
Aleutian Islands to the State of Washington. During cer-
tain periods of this time of intense giaciation great addi-
tions of ice-borne debris must have been made to the conti-
nental shelf. The banks to the east of Newfoundland and
other similar shoals as far south as Nantucket are probably
due in large part to the debris deposited by the glaciers
which formerly entered the sea in that region. It is of inter-
est in this connection to note that the glaciers, even at the
time of their greatest expansion, could not have extended
beyond the seaward margin of the continental shelf, for
the reason that on passing that boundary and entering
deep water they must have broken off and given origin
to bergs.

Submerged River Channels. — One of the most interest-
ing: features in connection with the continental shelf border-
ing North America is that its generally plane surface is
trenched in several places by canon-like depressions similar
to the narrow steep-sided valleys which streams sometimes
cut in the surfaces of plateaus. This suggestion that the
surface of the continental shelf is crossed by stream-cut
channels is supported by the fact that several such depres-
sions, leading seaward from the present mouths of large riv-
ers, have been discovered by the sounding-line. The best-
known example occurs off the mouth of the Hudson and
has been traced from New York Bay about 120 miles sea-
ward to the edge of the continental shelf. It is deepest
and best defined on the outer portion of the submerged
plateau, where for a distance of 23 miles, beginning 97 miles
from Sandy Hook, it has an average width of 3 miles and a
maximum depth of about 2.500 feet below the surface of
the bordering submarine plain, which has 20 fathoms of
water over it. This canon opens out in the seaward face of
the plateau and forms a deep notch in the generally uniform
crest-line of that escarpment. Farther " up-stream," so to
speak, the channel narrows to a mile and a quarter, with
some irregularities in depth, and near Sandy Hook it is not
apparent, owing to the amount of debris, largely sand, swept



• THE MARGIN OF THE COXTIXEXT 9

into it by shore currents. This evidence, strengthened by
the fact that the true rock-cut valley of the Hudson as far as
Troy is tilled with clay and sand to a considerable but
unknown depth, is abundant proof that the land was for-
merly higher than at present by at least 3,000 feet, and that
the now submerged continental shelf off Long Island was
then a plain above water, across which the ancient Hudson
was extended. The river flowed across this plain for a
sufficient length of time to excavate a canon over 2,500
feet deep and 3 miles wide from crest to crest of its walls
in its seaward portion. This submerged channel has the
characteristics of a young, stream-cut valley and suggests
that the plain across which it flowed to the eastward
of Long Island was a submerged continental shelf pre-
vious to being upraised so as to be trenched by the
Hudson.

The evidence as to changes in the elevation of the At-



Online LibraryIsrael C. (Israel Cook) RussellNorth America → online text (page 1 of 38)