Jacques W. (Jacques Wardlaw) Redway.

Elementary physical geography : an outline of physiography online

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Physical Geography




The waste of the Old Land is the material of the New '







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The science of Geography sets forth the relations of life
S^ and its environment to the earth, and it is the function of
both the writer and the teacher of geography to explain
these relations. In the Elementary Natural Geography
7 the pupil studies the various peojsles of the earth and the
\jv^ countries in -which they live ; in the Advanced Geogi"a-
^ phy there is presented in addition a discussion of the
industries of life and their geographic distribution. In the
present volume, which the author has prepared as a log-
ical sequel, it is designed to show that the distribution of
life is governed very largely by the conditions of geo-
graphic environment, and that human history and indus-
tries are always closely connected with geographic laAvs
— in many instances the direct resultants of them.

The science of Geography as now understood includes
something more than a mere description of topographic
forms — it comprehends the gradual and progressive devel-
opment of these forms and their results as regards life, as
well. It includes also the effects of temperature and
moisture, for life and its activities depend also on them.
That is, it naturally involves the principles of Descriptive
Geography, Physiography, and Economics ; and the pres-
ent volume is designed to show their interrelation.

In scope this book contains all the principles recom-
mended by the Committee of Fifteen, and such other feat-
ures as have suggested themselves to the author. It is
designed to be used in t]n\ junior grades of the High



School, and iu Normal Schools. With judgment in the se-
lection of the topics, it may be begun in the last half of
the eighth year of the Grammar School. The arrange-
ment of the subjects is logical, but the "teacher may readily
organize a course of study in the subject without reference
to the present arrangement. To make this more easily
accomplished, the principles of the subject are set forth in
the larger tyj^e ; relevant matter that is illustrative but
non-essential is confined to the notes. In general, the
teacher should not hesitate to omit a topic the discussion
of which is too difficult for the class.

The Questions and Exercises are designed to stimulate
observation and independent thought. If, occasionally,
they leave the pupil in doubt, the design of the author will
be fulfilled. The pupil must learn by experience that
knowledge does not come in cut-and-dried ])ackages.

In the preparation of the work the author takes pleasure
in acknowledging the material assistance of Miss Frances
Bronson, and of his daughter, Miss Elizabeth Ebert Red-
way. But to more than anyone else, however, thanks are
due to Miss Stella Wilson, Instructor in Physical Geog-
raphy in the Central High School, Columbus, Ohio. To
Miss Wilson's keen judgment, excellent criticism, and ex-
perience are largely due the usefulness as a text-book which
this volume may have.

The books designated for reference and collateral read-
ing are intentionally few in number, and those most com-
monly cited should be in the school library. The teacher
will also find it very advisable to get in close touch with
the United States Geological Survey and the Weather
Bureau. The Bureau of Geography recently established
at Winona, Minn., will also be helpful.

J. W. R.





I. The Earth Among Planets ...... 9

II. The STRUf'TURE of the Earth . . . . .20

III. Land and Water, and their Outlines . . .41

IV. The Results op Slow Movements of the Rock

Envelope : Plains, Plateaus, and Mountains . . 56

V. Destructive Movements of the Rock Envelope : Vol-
canoes and their Phenomena ..... 80

VI. Destructive Movements of the Rock Envelope :

Earthquakes ........ 95

VII. The Wasting of the Land : The Work of Rivers . 105

VIII. The Wasting of the Land : The Work of Under-
ground Waters . . . . . • • .132

IX. The Wasting of the Land : The Work of Ava-
lanches and Glaciers 150

X. The Wasting of the Land: The Results of Im-
perfect Drainage and Obstructed Lakes and
Marshes 165

XI. Ocean Waters and their Movements: Waves, Tides,

and Currents . .190

XTI. The Atmosphere and its Properties : Winds . . 214

XI II. The Moisture op the Atmosphere: Seasonal and

Periodical Distrihution of Rainfall . . • 2.11



XIV. The Moisture of the Atmosphere : Cyclonic Storms 248

XV. Electrical and Luminous Phenomena of the Atmos-
phere 268

XVI. Climate and its Factors 287

XVII. The Dispersal op Life 303

XVni. Geographic Distribution of Plants and Animals . 315

XIX. Man 335

XX. The Industrial Regions of the United States . 352

Appendix ........... 375

Index 381


The Solar System (Colored) .

Photograph of Moon

Order of Strata

North America in Arch^an Times

North America in Cenozoic Era

United States in Quaternary Age

Land and Water Hemispheres

Elevation op Lani> and Depth of Oceans (Colored)

Stretch of Norway CJoast

Barrier Beaches of Carolina Coast

Plateaus of the Colorado River .

Distribution op Volcanoes (Colored)

Loops and Cut-offs of the Lower Mississippi

Palmyra Bevel, Mississippi En'Eu .

Delta of the Mississippi River

Chesapeake Bay— A "Drowned" Valley

Old Stream-beds op the Tuolumne River

liivER Systems and Drainage (Colored)

Glaciated Re(jion of the United States

Marsh Lakes of Florida

Lagoons of Marthas Vineyaud


. 10
. 11
. 33
. 34
. 35
. 36
. 40
44, 45
. 46
. 52
. 63
. 92
. 108
. 110
. 116
. 117
. 122
130, 131
. 159
. 166
. 168


Lake St. Clair ......

Lake Bonneville and its Remnants
Section Along the Great Lakes .
Chart of Co-Tidal Lines . . , .
Ocean Currents (Colored) ....

Prevailing "Winds of the Atlantic

Chart of Winds (Colored) ....

Distribution of Rain (Colored)

Storm Maps — First and Second Days (Colored)

Chart of Magnetic Isogonics ....

Isotherms - January and July (Colored)
Distribution of Animals (Colored)
Distribution of Vegetation (Colored) .
Races of Man (Colored) ....

Physical Map of the United States (Colored)
New York Harbor and its Approaches (Colored)


. 173
. 174
. 176
. 199
. 201
. 218
. 221
. 239
. 260
. 274
. 292
. 318
. 325
. 339
. 353
. 369



Only a casual tliongbt is needed to make it apparent
that life ou the earth, as we now find it, depends on a very
delicate adjustment to its surroundings. Living beings
require certain conditions of heat, moisture, and geo-
graphic environment ; and if these are changed ever so
slightly the life forms must adjust themselves to the new
conditions, or else the}' must seek a new abiding-place ;
or, perhaps, they may perish altogether.

For instance, turf grass requires water at very short
intervals, and if for several successive years there are
droughts of five or six months' du)-ation, it will die. And
if there are herds of cattle in the region, they must adjust
themselves to the changed conditions. They must adapt
themselves to other food, or they must migrate. Other-
wise they too will perish.

Were the temperature of the earth to change only a few
degrees there would be a similar disturbance that would
involve almost every living thing. And if it should fall so
low that the water were everywhere frozen, life as \\«' now
know it could not exist any great length of time, because
living Ijeings need in their structiue a large propoition of
water, and the latter must be taken into the structure in
a licpiid foriii. For a similar reason, if all the water were
in the form of vapor, life could not long endure unless the




life forms were very different in structure from those with
Avhich we are acquainted.

Life is by no means evenly distributed over the earth,
however. A few species spend the greater part of their
existence in the air, and a larger number live in water only.
By far the greater number of species, however, live at the
plane of contact between the atmosphere and the earth's

Capable of producing abundant food-stuffs, and densely peopled.

rock envelope — that is, on the land surface of the earth.
Their distribution is governed by the conditions of warmth,
moisture, and surface, and if these conditions were to
change ever so slightly, the distribution would be disturbed.
Life and its distribution are governed by geographic laws ;
if the latter change, so must the former.

Man, who stands at the head of animate nature, is able
to endure a much wider range of warmth, moisture, and


surface features than most other living beings. He can
withstand extremes of heat and cold that are fatal to most
other animals, and he can live indiflerentl}^ in places of
great drought or of excessive moisture. The arctic re-
gions are not so cold, nor the tropical lands so hot that
man cannot dwell there ; and throughout the wide world
one can find scarcely an ice-clad summit or a sun-beaten
desert in which human beings have not lived.

On account of these varving conditions — all the result of
geographic laws — the stud}' of the earth is both important
and interesting, because it is the home of man. Like all
forms of life, man requires food ; more than any other ani-
mal, he needs shelter. His food, of which he consumes
about eighty tons during the three or four score years of
his existence, comes from the earth — the land, the water,
and the air each yielding part — and the materials that are
used for clothing and shelter come also from the same
source — the earth.

So, in order to understand the story of life, its history
and its industries, one must learn about the physical geog-
raphy of its surroundings — that is, about its environment,
or the various conditions of heat, moisture, and surface
features. Land animals could not live until the waters
were separated from the land. Before they could main-
tain life, vegetation must have spread itself over the land ;
and before vegetation could endure there must have been
soil. And before there could be soil, the surface of the
land must have been folded, broken, worn, and furrowed,
so that the fragments of rock could be ground fine and
formed into soil. All these earth-weathering processes
must have been going on before the higher forms of life
could exist, and all over the surface of the land such
changes are even now going on from day to day. Scarcely
a summer shower falls that does not leave its marks; and,


indeed, tliroughout the physical history of the earth the
most apparent feature is constant change.

From the time the land was first divided from the waters,
the continents, or great bodies of land have been ever
changing. In places, alternately sinking, rising, and
warping in various Avays, the shore outlines have taken
various forms. Hiigged coasts sinking below sea-level
have resulted in the fjorded shores, such as those of the


Too cold ami iiol enough soil for the support of life.

North Atlantic States, making the harbors where so much
of the manufacture and commerce of the country have
centred. Rising coasts have lifted natural harbors above
sea-level, making the approaches to the land so difficult
that vessels can find no sheltered anchorage. Old sea-
bottoms, covered with sediments that form the richest
soil, have been lifted above the sea, and in time have be-
come densely peopled areas.


Certain forces are causing the surface of the rock en-
velope to wrinkle and fold, forming plateaus, mountains,
and vallej's ; and at the same time the waters of the atmos-
pbere, falling as rain or snow, are constantly at work wear-
ing away the wrinkles and folds, carrying the material back
to the sea.

It is necessary to know about these processes, and to
understand how they are going on, because almost every
form of life is more or less modified by them, and certainly
the history and the industries of man are very largely gov-
erned by tliein. Man may rise superior to his environ-
ment — that is, his geographic surroundings — but he is al-
ways more or less modified by it. Mountains and valleys,
plains and plateaus, oceans and rivers, have all been potent
factors in making the destiny of peoples.

The rugged and barren slope of Norway forbade any
great development of agriculture, while the deeply fjorded
shores invited the pursuits of the sea. The Norse people,
therefore, became sea rovers and magnificent sailors. The
uncultivable mountains of Greece could not well yield the
food-stuffs necessary for the population, so we find a his-
tory of " Greece scattered." From the remotest times the
rich valley of the Tigris and Euphrates, because of its fer-
tility, has always attracted people, and we therefore find it
a densely settled region.

Unless there is something to unfit them for human habi-
tation, lowlands are favorite places of dwelling, and by far
the greater part of the world's population is found in them.
How is the statement borne out in the case of the Central
Plain of North America?— tlie swampy, forest plain of
the Amazon ? — the great lowland region of southeastern
Asia? — the northern })laius of Eurasia?

River bottom-lands, also, are nearly always densely peo-
pled. How is this illustrated in the history of Egypt? —


with regard to the nations dwelling in the Mesopotamia
— the valley of the Ganges?— the bottom-lands of tli(
Mississippi River? — the Sacramento-San Joaquin Valley'
Extensive desert regions are always sparsely peopled

A locality not suitable for farming ; a few food-plants may be grown.

why? How is this illustrated in the eastern and west-
ern halves of the United States? The population of
rugged highlands and mountain ranges is usually sparse ;
is there a good reason therefor ?

The hot regions of the laud are almost always densely
peopled, the deserts and forest swamps excepted. Is this


true of tlie intensely cold regions? Life thrives best in
regions of warmth and of strong sunlight. Are alt parts
of the earth equally warmed ? Have all parts the same in-
tensity of light ? Compare the density of population of

Both temperature and moisture are favorable to a great proiliictivity o/' food -stuff's.

cold and dimly liglitod parts of the earth with that of the
warm and strongly lighted parts: in which is it greatest?

The study of the distribution of heat and cold, of rain
and drought, of highlands and lowlands, and of fertile and
unffu'tile regions form an essential part of the study of
geography ; the study of the progressive changes that have
been and are now taking place on the earth's surface con-
stitutes the science of phj'siography, or " nature-writing."


The object of this book is to show that the fundamental
laws of geographic science not only control the structure
of life forms and their distribution over the earth, but that
they also largely control and modify the history, the activi-
ties, and the various economies of man, as well.

QUESTIONS AND EXERCISES.— What are the leading industries
of the city or town in which you live ? Note and describe a geographic
feature that favors any one of these industries, and without which the
industry could not thrive.

What would be the effect, so far as the habitability of the sur-
rounding region is concerned, were the rainfall to be diminished one-

How would a material change in the surface features affect the indus-
tries ?

On p. 369 is a map of New York Harbor ; what would be the effect on
the commerce of the port if the surface of the water were lowered two
hundred feet ?

Mention two or more reasons why lowland regions are more densely
peopled than highlands.

Quito, the capital of Ecuador, is in the midst of a fertile region nearly
two miles above sea-level ; what are its advantages over the coast plain
region to the westward ?

Make a list of half-a-dozen or more extensive regions that are not
habitable, and explain the geographic reasons for their condition.


Mill.— Realm of Nature, pp. 331- 33G.
Shaler.— Nature and Man in North America.



The Solar System. — The cluster of heavenly bodies
called the solar system is one of a great number of groups
in space. The members of this group revolve about a
common centre of gravity, however, and for this reason
they are called collectively a system. The number of
bodies composing it is unknown.

The members of this system vary greatly in size. The
largest is about 836,000 miles in diameter, and the small-
est are probably too minute to be measured by ordinary
standards. Eight of them, however, are three thousand
miles, more or less, in diameter, and a large number, about
four hundred, vary from ten miles to less than five hundred
in diameter.

The largest member of the solar system, the sun, is
about eight hundred times as large as all the others to-
gether, and the common centre of gravity around which
they revolve is very near to it or, perhaps, within its mass.
The eight bodies next in size are called planets, and all but
two of them are attended each by one or more satellites or
moons. The four hundred or more small planets are called
asteroids,^ or, more properly, jjlanetoids. In addition
there are several comets '■* and groups of meteors ^ that
have a permanent place in the solar system.

There is much evidence to show that the planets are
composed of the same kinds of substance or material, but
it seems certain that they are very unlike one another in




physical conditiou ; for while some, bulk for bulk, are but
little heavier thau water, others are about as lieav}' as iron
ore. It seems certaiu also that this difference is largely a
result of temperature ; for while some of the planets have

The space within the orbit of Jupiter sliows the relative si^e of the Sun.

apparently lost the greater part of their heat, others still
are very hot. The sun, for instance, is a glowing mass
surrounded by white-hot vapors, and its heat is probably
greater than any artificial heat known.



The Sun and the Planets. — The similarity of the sun
and the planets to one another is far more marked than
their points of difference. All whirl around a common
centre of trravity in a direction from west to east, and each
turns or spins on its axis in the same direction. Each is
nearly spherical in shape, differing from a sphere liy a

From a photograph.

curvature that in nearly every instance is a slight flatten-
ing at the poles of their axes. Several are known to be
sun-ounded each with an atmosphere, and there is some
evidence that this is true of all.

It is now generally believed that the members of the
solar system formerly existed as a l^ody of gaseous matter ;'
because the force of gravity drew the j)articlcs together,


toward the centre of gravity, a rotation of the mass around
the centre of gravity resulted. Finally, parts of the mass
were thrown oflf, one after another, forming the planets.
In the same manner, the rapid rotation of each planet
threw off portions of its mass forming the satellites.

Although the assumed formation of the solar system by
this process is a matter of theory, it is a theory supported
by evidence. The telescope reveals many such masses of
gaseous matter showing planetary formation. The spec-
troscope, an instrument for analyzing light, shows, not
only the matter of which they are composed, but also that
the matter is in rapid motion. It shows also that the
earth and the sun contain the same kinds of matter. Cal-
cium, hydrogen, iron, and sodium, the substances of greatest
abandance at the surface of the sun, are also among the
most abundant substances in the composition of the earth.
■^ The Form of the Earth. — The earth is one of the
planets. From Table I. {Appendix), find how it ranks
among the other planets in size ; — in distance from the sun.
In form the earth resembles the other planets, being nearly
spherical, but slightly flattened at the poles. It is usually
said to be an oblate spheroid — that is, a sphere flattened
at its polar diameter, but it deviates slightly from this
form ; hence the term geoid is sometimes used to apply to
its irregular shape.

The spherical form of the earth is shown in various
ways that are well known, but it is demonstrated most
clearly by surveying a horizontal straight line along a level
surface, such as that of a pond.^ The line thus projected
does not lie parallel to the surface ; the latter recedes or
curves away from it, and the curvature is such as corre-
sponds to the surface of a spherical body.

Were the earth a true sphere, the weight of a body
would be the same at every part of its surface. There is


a measurable diflference, however/' and it is foimd that a
given body weighs a little more in polar than in equatorial
latitudes, and from the careful experiments based on this
fact tlie amount of Hatteuing at the poles has been deter-

The following are its dimensions :

Polar diameter 7,901.5 miles

Equatorial diameter 7,926.6 miles

Circumferenee at equator 24,912 2 miles

Surface (approxinuite) 197,000,000 square miles

What is tlio difference between the polar and the equa-
torial diameter ? On a globe one foot in diameter the dif-
ference would be what part of one inch ? Compare the
diameter of the earth with that of the sun (Table I., Jp-
[K'udix). Large as the earth seems to us, it would require
about one and a quarter million bodies of its size to
make a globe as large as the sun.

Motions. —The earth has several distinct motions. It
revolves about the common centre of gravity in an ellipti-
cal path, making a complete journey in very nearly 8()5|^
days — a period of time called a year. It also rotates, or
spins on its axis. The time required to make a complete
rotation is called a day and is commonly used as a unit for
the measurement of short intervals of time. The poles of the
earth also move or oscillate in a nearly circular i)atli. The
mtjtion resembles that of the poles of a " sleeping " top.

The first motion combined with the inclination of the
a.xis gives rise to the successive change of the seasons and
the varying hiugth of sunshine and darkness. The second
motion causes the succession of day and night ; it is "day"
ill all ])arts of tlio stuface turned toward the sun and
" jiight " on tlie op[)osite side. The tliiid motion causes the
ph<!iir)inonon or movenujnt coinuionly l<iiowii as th(i pre-



cession of ihe equinoxes. In long intervals of time it is
thought that this motion is connected Avith certain changes
of climate. It is a subject, however, that belongs to the
science of astronomy, and not t(^ physical geography.

Effects of the Inclination of the Axis. — The axis of
the earth is not perpendicular to the earth's path (called
i\\e plane of the ecliptic), but inclines about '23^ degrees, as
shown in the accompanying figure. In long intervals of
time the amount of inclination varies. Practically, how-
ever, the axis points ahvays in the same direction and
therefore is said to be parallel to itself. The northern end
of the axis prolonged would extend nearly in the direction
of a star named Polaris ; this star is therefore often called
the north star.

If the earth's axis were perpendicular to the plane of its
orbit, each place would have the same uuvarjdng season.

March 21-23

June 21 2^x

The unshaded hemisphere shows the position of the light circle at each of the four seasons.

It would be hot in equatorial regions, mild in mid-lati-
tudes, and cold in polar regions, the intensity of heat in-
creasing from the poles toward the equator.


With the axis inclined, however, the case is different.

Online LibraryJacques W. (Jacques Wardlaw) RedwayElementary physical geography : an outline of physiography → online text (page 1 of 25)