Roy Benson, Jr. - "The Biography of a Rabbit"

Ralph Henry Barbour - "The New Boy at Hilltop"

James Sheridan Knowles - "The Love Chase"

Edmund Lester Pearson - "The Voyage of the Hoppergrass"

New Philadelphia Book Publisher Highlights Local Talent
Book and Publishing News from Publishers Newswire(tm)

Looking for Child to be on Cover of a New Book, 'The Model Child'
PHILADELPHIA, Pa. -- The Philadelphia literary world will celebrate the launch of two new players today, April 10th: Kay Square Press, a new publishing company focused on Philadelphia-area artists, their stories, and their art; and Kay Square's first release, 'With the Rich and Mighty: Emlen Etting of Philadelphia' (ISBN: 978-0-9815129-0-7), a critical biography by Kenneth C. Kaleta.

FlatSigned Press Alleges Don Imus Remarks Damage Legacy of President Gerald R. Ford
NEW YORK, N.Y. -- Nathan Yungerberg, an accomplished model scout and professional child photographer is launching a nation-wide casting call to find the cover model for his highly anticipated book release, 'The Model Child: A Parents Guide to the Child Modeling Industry' (ISBN: 978-0-9817018-0-6).

Books: The Elements of Geology

W >> William Harmon Norton >> The Elements of Geology




In its old age a region becomes mantled with thick sheets of fine
and weathered waste, slowly moving over the faint slopes toward
the water ways and unbroken by ledges of bare rock. In other
words, the waste mantle also is now graded, and as waterfalls have
been effaced in the river beds, so now any ledges in the wide
streams of waste are worn away and covered beneath smooth slopes
of fine soil. Ground water stands high and may exude in areas of
swamp. In youth the land mass was roughhewn and cut deep by stream
erosion. In old age the faint reliefs of the land dissolve away,
chiefly under the action of the weather, beneath their cloak of
waste.

THE CYCLE OF EROSION. The successive stages through which a land
mass passes while it is being leveled to the sea constitute
together a cycle of erosion. Each stage of the cycle from infancy
to old age leaves, as we have seen, its characteristic records in
the forms sculptured on the land, such as the shapes of valleys
and the contours of hills and plains. The geologist is thus able
to determine by the land forms of any region the stage in the
erosion cycle to which it now belongs, and knowing what are the
earlier stages of the cycle, to read something of the geological
history of the region.

INTERRUPTED CYCLES. So long a time is needed to reduce a land mass
to baselevel that the process is seldom if ever completed during a
single uninterrupted cycle of erosion. Of all the various
interruptions which may occur the most important are gradual
movements of the earth's crust, by which a region is either
depressed or elevated relative to sea level.

The DEPRESSION of a region hastens its old age by decreasing the
gradient of streams, by destroying their power to excavate their
beds and carry their loads to a degree corresponding to the amount
of the depression, and by lessening the amount of work they have
to do. The slackened river currents deposit their waste in Hood
plains which increase in height as the subsidence continues. The
lower courses of the rivers are invaded by the sea and become
estuaries, while the lower tributaries are cut off from the trunk
stream.

ELEVATION, on the other hand, increases the activity of all
agencies of weathering, erosion, and transportation, restores the
region to its youth, and inaugurates a new cycle of erosion.
Streams are given a steeper gradient, greater velocity, and
increased energy to carry their loads and wear their beds. They
cut through the alluvium of their flood plains, leaving it on
either bank as successive terraces, and intrench themselves in the
underlying rock. In their older and wider valleys they cut narrow,
steep-walled inner gorges, in which they flow swiftly over rocky
floors, broken here and there by falls and rapids where a harder
layer of rock has been discovered. Winding streams on plains may
thus incise their meanders in solid rock as the plains are
gradually uplifted. Streams which are thus restored to their youth
are said to be REVIVED.

As streams cut deeper and the valley slopes are steepened, the
mantle of waste of the region undergoing elevation is set in more
rapid movement. It is now removed particle by particle faster than
it forms. As the waste mantle thins, weathering attacks the rocks
of the region more energetically until an equilibrium is reached
again; the rocks waste rapidly and their waste is as rapidly
removed.

DISSECTED PENEPLAINS. When a rise of the land brings one cycle to
an end and begins another, the characteristic land forms of each
cycle are found together and the topography of the region is
composite until the second cycle is so far advanced that the land
forms of the first cycle are entirely destroyed. The contrast
between the land surfaces of the later and the earlier cycles is
most striking when the earlier had advanced to age and the later
is still in youth. Thus many peneplains which have been elevated
and dissected have been recognized by the remnants of their
ancient erosion surfaces, and the length of time which has elapsed
since their uplift has been measured by the stage to which the new
cycle has advanced.

THE PIEDMONT BELT. As an example of an ancient peneplain uplifted
and dissected we may cite the Piedmont Belt, a broad upland lying
between the Appalachian Mountains and the Atlantic coastal plain.
The surface of the Piedmont is gently rolling. The divides, which
are often smooth areas of considerable width, rise to a common
plane, and from them one sees in every direction an even sky line
except where in places some lone hill or ridge may lift itself
above the general level (Fig. 62). The surface is an ancient one,
for the mantle of residual waste lies deep upon it, soils are
reddened by long oxidation, and the rocks are rotted to a depth of
scores of feet.

At present, however, the waste mantle is not forming so rapidly as
it is being removed. The streams of the upland are actively
engaged in its destruction. They flow swiftly in narrow, rock-
walled valleys over rocky beds. This contrast between the young
streams and the aged surface which they are now so vigorously
dissecting can only be explained by the theory that the region
once stood lower than at present and has recently been upraised.
If now we imagine the valleys refilled with the waste which the
streams have swept away, and the upland lowered, we restore the
Piedmont region to the condition in which it stood before its
uplift and dissection,--a gently rolling plain, surmounted here
and there by isolated hills and ridges.

The surface of the ancient Piedmont plain, as it may be restored
from the remnants of it found on the divides, is not in accordance
with the structures of the country rocks. Where these are exposed
to view they are seen to be far from horizontal. On the walls of
river gorges they dip steeply and in various directions and the
streams flow over their upturned edges. As shown in Figure 67, the
rocks of the Piedmont have been folded and broken and tilted.

It is not reasonable to believe that when the rocks of the
Piedmont were thus folded and otherwise deformed the surface of
the region was a plain. The upturned layers have not always
stopped abruptly at the even surface of the Piedmont plain which
now cuts across them. They are the bases of great folds and tilted
blocks which must once have risen high in air. The complex and
disorderly structures of the Piedmont rocks are those seen in
great mountain ranges, and there is every reason to believe that
these rocks after their deformation rose to mountain height.

The ancient Piedmont plain cuts across these upturned rocks as
independently of their structure as the even surface of the sawed
stump of some great tree is independent of the direction of its
fibers. Hence the Piedmont plain as it was before its uplift was
not a coastal plain formed of strata spread in horizontal sheets
beneath the sea and then uplifted; nor was it a structural plain,
due to the resistance to erosion of some hard, flat-lying layer of
rock. Even surfaces developed on rocks of discordant structure,
such as the Piedmont shows, are produced by long denudation, and
we may consider the Piedmont as a peneplain formed by the wearing
down of mountain ranges, and recently uplifted.

THE LAURENTIAN PENEPLAIN. This is the name given to a denuded
surface on very ancient rocks which extends from the Arctic Ocean
to the St. Lawrence River and Lake Superior, with small areas also
in northern Wisconsin and New York. Throughout this U-shaped area,
which incloses Hudson Bay within its arms, the country rocks have
the complicated and contorted structures which characterize
mountain ranges. But the surface of the area is by no means
mountainous. The sky line when viewed from the divides is unbroken
by mountain peaks or rugged hills. The surface of the arm west of
Hudson Bay is gently undulating and that of the eastern arm has
been roughened to low-rolling hills and dissected in places by
such deep river gorges as those of the Ottawa and Saguenay. This
immense area may be regarded as an ancient peneplain truncating
the bases of long-vanished mountains and dissected after
elevation.

In the examples cited the uplift has been a broad one and to
comparatively little height. Where peneplains have been uplifted
to great height and have since been well dissected, and where they
have been upfolded and broken and uptilted, their recognition
becomes more difficult. Yet recent observers have found evidences
of ancient lowland surfaces of erosion on the summits of the
Allegheny ridges, the Cascade Mountains (Fig. 69), and the western
slope of the Sierra Nevadas.

THE SOUTHERN APPALACHIAN REGION. We have here an example of an
area the latter part of whose geological history may be deciphered
by means of its land forms. The generalized section of Figure 70,
which passes from west to east across a portion of the region in
eastern Tennessee, shows on the west a part of the broad
Cumberland plateau. On the east is a roughened upland platform,
from which rise in the distance the peaks of the Great Smoky
Mountains. The plateau, consisting of strata but little changed
from their original flat-lying attitude, and the platform,
developed on rocks of disordered structure made crystalline by
heat and pressure, both stand at the common level of the line AB.
They are separated by the Appalachian valley, forty miles wide,
cut in strata which have been folded and broken into long narrow
blocks. The valley is traversed lengthwise by long, low ridges,
the outcropping edges of the harder strata, which rise to about
the same level,--that of the line cd. Between these ridges stretch
valley lowlands at the level ef excavated in the weaker rocks,
while somewhat below them lie the channels of the present streams
now busily engaged in deepening their beds.

THE VALLEY LOWLANDS. Were they planed by graded or ungraded
streams? Have the present streams reached grade? Why did the
streams cease widening the floors of the valley lowlands? How long
since? When will they begin anew the work of lateral planation?
What effect will this have on the ridges if the present cycle of
erosion continues long uninterrupted?

THE RIDGES OF THE APPALACHIAN VALLEY. Why do they stand above the
valley lowlands? Why do their summits lie in about the same plane?
Refilling the valleys intervening between these ridges with the
material removed by the streams, what is the nature of the surface
thus restored? Does this surface cd accord with the rock
structures on which' it has been developed? How may it have been
made? At what height did the land stand then, compared with its
present height? What elevations stood above the surface cd? Why?
What name may you use to designate them? How does the length of
time needed to develop the surface cd compare with that needed to
develop the valley lowlands?

THE PLATFORM AND PLATEAU. Why do they stand at a common level ab?
Of what surface may they be remnants? Is it accordant with the
rock structure? How was it produced? What unconsumed masses
overlooked it? Did the rocks of the Appalachian valley stand above
this surface when it was produced? Did they then stand below it?
Compare the time needed to develop this surface with that needed
to develop cd. Which surface is the older?

How many cycles of erosion are represented here? Give the erosion
history of the region by cycles, beginning with the oldest, the
work done in each and the work left undone, what brought each
cycle to a close, and how long relatively it continued.





CHAPTER IV

RIVER DEPOSITS


The characteristic features of river deposits and the forms which
they assume may be treated under three heads: (1) valley deposits,
(2) basin deposits, and (3) deltas.

VALLEY DEPOSITS

FLOOD PLAINS are the surfaces of the alluvial deposits which
streams build along their courses at times of flood. A swift
current then sweeps along the channel, while a shallow sheet of
water moves slowly over the flood plain, spreading upon it a thin
layer of sediment. It has been estimated that each inundation of
the Nile leaves a layer of fertilizing silt three hundredths of an
inch thick over the flood plain of Egypt.

Flood plains may consist of a thin spread of alluvium over the
flat rock floor of a valley which is being widened by the lateral
erosion of a graded stream (Fig. 60). Flood-plain deposits of
great thickness may be built by aggrading rivers even in valleys
whose rock floors have never been thus widened.

A cross section of a flood plain shows that it is highest next the
river, sloping gradually thence to the valley sides. These wide
natural embankments are due to the fact that the river deposit is
heavier near the bank, where the velocity of the silt-laden
channel current is first checked by contact with the slower-moving
overflow.

Thus banked off from the stream, the outer portions of a flood
plain are often ill-drained and swampy, and here vegetal deposits,
such as peat, may be interbedded with river silts.

A map of a wide flood plain, such as that of the Mississippi or
the Missouri (Fig. 77), shows that the courses of the tributaries
on entering it are deflected downstream. Why?

The aggrading streams by which flood plains are constructed
gradually build their immediate banks and beds to higher and
higher levels, and therefore find it easy at times of great floods
to break their natural embankments and take new courses over the
plain. In this way they aggrade each portion of it in turn by
means of their shifting channels,

BRAIDED CHANNELS. A river actively engaged in aggrading its valley
with coarse waste builds a flood plain of comparatively steep
gradient and often flows down it in a fairly direct course and
through a network of braided channels. From time to time a channel
becomes choked with waste, and the water no longer finding room in
it breaks out and cuts and builds itself a new way which reunites
down valley with the other channels. Thus there becomes
established a network of ever-changing channels inclosing low
islands of sand and gravel.

TERRACES. While aggrading streams thus tend to shift their
channels, degrading streams, on the contrary, become more and more
deeply intrenched in their valleys. It often occurs that a stream,
after having built a flood plain, ceases to aggrade its bed
because of a lessened load or for other reasons, such as an uplift
of the region, and begins instead to degrade it. It leaves the
original flood plain out of reach of even the highest floods. When
again it reaches grade at a lower level it produces a new flood
plain by lateral erosion in the older deposits, remnants of which
stand as terraces on one or both sides of the valley. In this way
a valley may be lined with a succession of terraces at different
levels, each level representing an abandoned flood plain.

MEANDERS. Valleys aggraded with fine waste form well-nigh level
plains over which streams wind from side to side of a direct
course in symmetric bends known as meanders, from the name of a
winding river of Asia Minor. The giant Mississippi has developed
meanders with a radius of one and one half miles, but a little
creek may display on its meadow as perfect curves only a rod or so
in radius. On the flood plain of either river or creek we may find
examples of the successive stages in the development of the
meander, from its beginning in the slight initial bend sufficient
to deflect the current against the outer side. Eroding here and
depositing on the inner side of the bend, it gradually reaches
first the open bend whose width and length are not far from equal,
and later that of the horseshoe meander whose diameter transverse
to the course of the stream is much greater than that parallel
with it. Little by little the neck of land projecting into the
bend is narrowed, until at last it is cut through and a "cut-off"
is established. The old channel is now silted up at both ends and
becomes a crescentic lagoon, or oxbow lake, which fills gradually
to an arc-shaped shallow depression.

FLOOD PLAINS CHARACTERISTIC OF MATURE RIVERS. On reaching grade a
stream planes a flat floor for its continually widening valley.
Ever cutting on the outer bank of its curves, it deposits on the
inner bank scroll-like flood-plain patches. For a while the valley
bluffs do not give its growing meanders room to develop to their
normal size, but as planation goes on, the bluffs are driven back
to the full width of the meander belt and still later to a width
which gives room for broad stretches of flood plain on either
side.

Usually a river first attains grade near its mouth, and here first
sinks its bed to near baselevel. Extending its graded course
upstream by cutting away barrier after barrier, it comes to have a
widened and mature valley over its lower course, while its young
headwaters are still busily eroding their beds. Its ungraded
branches may thus bring down to its lower course more waste than
it is competent to carry on to the sea, and here it aggrades its
bed and builds a flood plain in order to gain a steeper gradient
and velocity enough to transport its load.

As maturity is past and the relief of the land is lessened, a
smaller and smaller load of waste is delivered to the river. It
now has energy to spare and again degrades its valley, excavating
its former flood plains and leaving them in terraces on either
side, and at last in its old age sweeping them away.

ALLUVIAL CONES AND FANS. In hilly and mountainous countries one
often sees on a valley side a conical or fan-shaped deposit of
waste at the mouth of a lateral stream. The cause is obvious: the
young branch has not been able as yet to wear its bed to accordant
level with the already deepened valley of the master stream. It
therefore builds its bed to grade at the point of juncture by
depositing here its load of waste,--a load too heavy to be carried
along the more gentle profile of the trunk valley.

Where rivers descend from a mountainous region upon the plain they
may build alluvial fans of exceedingly gentle slope. Thus the
rivers of the western side of the Sierra Nevada Mountains have
spread fans with a radius of as much as forty miles and a slope
too slight to be detected without instruments, where they leave
the rock-cut canyons in the mountains and descend upon the broad
central valley of California.

As a river flows over its fan it commonly divides into a
branchwork of shifting channels called DISTRIBUTARIES, since they
lead off the water from the main stream. In this way each part of
the fan is aggraded and its symmetric form is preserved.

PIEDMONT PLAINS. Mountain streams may build their confluent fans
into widespread piedmont (foot of the mountain) alluvial plains.
These are especially characteristic of arid lands, where the
streams wither as they flow out upon the thirsty lowlands and are
therefore compelled to lay down a large portion of their load. In
humid climates mountain-born streams are usually competent to
carry their loads of waste on to the sea, and have energy to spare
to cut the lower mountain slopes into foothills. In arid regions
foothills are commonly absent and the ranges rise, as from
pedestals, above broad, sloping plains of stream-laid waste.

THE HIGH PLAINS. The rivers which flow eastward from the Rocky
Mountains have united their fans in a continuous sheet of waste
which stretches forward from the base of the mountains for
hundreds of miles and in places is five hundred feet thick (Fig.
80). That the deposit was made in ancient times on land and not in
the sea is proved by the remains which it contains of land animals
and plants of species now extinct. That it was laid by rivers and
not by fresh-water lakes is shown by its structure. Wide stretches
of flat-lying, clays and sands are interrupted by long, narrow
belts of gravel which mark the channels of the ancient streams.
Gravels, and sands are often cross bedded, and their well worn
pebbles may be identified with the rocks of the mountains. After
building this sheet of waste the streams ceased to aggrade and
began the work of destruction. Large uneroded remnants, their
surfaces flat as a floor, remain as the High Plains of western
Kansas and Nebraska.

RIVER DEPOSITS IN SUBSIDING TROUGHS. To a geologist the most
important river deposits are those which gather in areas of
gradual subsidence; they are often of vast extent and immense
thickness, and such deposits of past geological ages have not
infrequently been preserved, with all their records of the times
in which they were built, by being carried below the level of the
sea, to be brought to light by a later uplift. On the other hand,
river deposits which remain above baselevels of erosion are swept
away comparatively soon.

THE GREAT VALLEY OF CALIFORNIA is a monotonously level plain of
great fertility, four hundred miles in length and fifty miles in
average width, built of waste swept down by streams from the
mountain ranges which inclose it,--the Sierra Nevada on the east
and the Coast Range on the west. On the waste slopes at the foot
of the bordering hills coarse gravels and even bowlders are left,
while over the interior the slow-flowing streams at times of
flood spread wide sheets of silt. Organic deposits are now forming
by the decay of vegetation in swampy tule (reed) lands and in
shallow lakes which occupy depressions left by the aggrading
streams.

Deep borings show that this great trough is filled to a depth of
at least two thousand feet below sea level with recent
unconsolidated sands and silts containing logs of wood and fresh-
water shells. These are land deposits, and the absence of any
marine deposits among them proves that the region has not been
invaded by the sea since the accumulation began. It has therefore
been slowly subsiding and its streams, although continually
carried below grade, have yet been able to aggrade the surface as
rapidly as the region sank, and have maintained it, as at present,
slightly above sea level.

THE INDO-GANGETIC PLAIN, spread by the Brahmaputra, the Ganges,
and the Indus river systems, stretches for sixteen hundred miles
along the southern base of the Himalaya Mountains and occupies an
area of three hundred thousand square miles (Fig.342). It consists
of the flood plains of the master streams and the confluent fans
of the tributaries which issue from the mountains on the north.
Large areas are subject to overflow each season of flood, and
still larger tracts mark abandoned flood plains below which the
rivers have now cut their beds. The plain is built of far-
stretching beds of clay, penetrated by streaks of sand, and also
of gravel near the mountains. Beds of impure peat occur in it, and
it contains fresh-water shells and the bones of land animals of
species now living in northern India. At Lucknow an artesian well
was sunk to one thousand feet below sea level without reaching the
bottom of these river-laid sands and silts, proving a slow
subsidence with which the aggrading rivers have kept pace.

WARPED VALLEYS. It is not necessary that an area should sink below
sea level in order to be filled with stream-swept waste. High
valleys among growing mountain ranges may suffer warping, or may
be blockaded by rising mountain folds athwart them. Where the
deformation is rapid enough, the river may be ponded and the
valley filled with lake-laid sediments. Even when the river is
able to maintain its right of way it may yet have its declivity so
lessened that it is compelled to aggrade its course continually,
filling the valley with river deposits which may grow to an
enormous thickness.

Behind the outer ranges of the Himalaya Mountains lie several
waste-filled valleys, the largest of which are Kashmir and Nepal,
the former being an alluvial plain about as large as the state of
Delaware. The rivers which drain these plains have already cut
down their outlet gorges sufficiently to begin the task of the
removal of the broad accumulations which they have brought in from
the surrounding mountains. Their present flood plains lie as much
as some hundreds of feet below wide alluvial terraces which mark
their former levels. Indeed, the horizontal beds of the Hundes
Valley have been trenched to the depth of nearly three thousand
feet by the Sutlej River. These deposits are recent or subrecent,
for there have been found at various levels the remains of land
plants and land and fresh-water shells, and in some the bones of
such animals as the hyena and the goat, of species or of genera
now living. Such soft deposits cannot be expected to endure
through any considerable length of future time the rapid erosion
to which their great height above the level of the sea will
subject them.

CHARACTERISTICS OF RIVER DEPOSITS. The examples just cited teach
clearly the characteristic features of extensive river deposits.
These deposits consist of broad, flat-lying sheets of clay and
fine sand left by the overflow at time of flood, and traversed
here and there by long, narrow strips of coarse, cross-bedded
sands and gravels thrown down by the swifter currents of the
shifting channels. Occasional beds of muck mark the sites of
shallow lakelets or fresh-water swamps. The various strata also
contain some remains of the countless myriads of animals and
plants which live upon the surface of the plain as it is in
process of building. River shells such as the mussel, land shells
such as those of snails, the bones of fishes and of such land
animals as suffer drowning at times of flood or are mired in
swampy places, logs of wood, and the stems and leaves of plants
are examples of the variety of the remains of land and fresh-water
organisms which are entombed in river deposits and sealed away as
a record of the life of the time, and as proof that the deposits
were laid by streams and not beneath the sea.