Sir Walter Scott - "The Monastery"

Kathleen Norris - "The Rich Mrs. Burgoyne"

J.G. Austin - "Outpost"

Charles Dickens - "Pictures from Italy"

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




LANDSLIDES. Another common and abrupt method of delivering waste
to streams is by slips of the waste mantle in large masses. After
long rains and after winter frosts the cohesion between the waste
and the sound rock beneath is loosened by seeping water
underground. The waste slips on the rock surface thus lubricated
and plunges down the mountain side in a swift roaring torrent of
mud and stones.

We may conveniently mention here a second type of landslide, where
masses of solid rock as well as the mantle of waste are involved
in the sudden movement. Such slips occur when valleys have been
rapidly deepened by streams or glaciers and their sides have not
yet been graded. A favorable condition is where the strata dip
(i.e. incline downwards) towards the valley (Fig. 11), or are
broken by joint planes dipping in the same direction. The upper
layers, including perhaps the entire mountain side, have been cut
across by the valley trench and are left supported only on the
inclined surface of the underlying rocks. Water may percolate
underground along this surface and loosen the cohesion between the
upper and the underlying strata by converting the upper surface of
a shale to soft wet clay, by dissolving layers of a limestone, or
by removing the cement of a sandstone and converting it into loose
sand. When the inclined surface is thus lubricated the overlying
masses may be launched into the valley below. The solid rocks are
broken and crushed in sliding and converted into waste consisting,
like that of talus, of angular unsorted fragments, blocks of all
sizes being mingled pellmell with rock meal and dust. The
principal effects of landslides may be gathered from the following
examples.

At Gohna, India, in 1893, the face of a spur four thousand feet
high, of the lower ranges of the Himalayas, slipped into the gorge
of the headwaters of the Ganges River in successive rock falls
which lasted for three days. Blocks of stone were projected for a
mile, and clouds of limestone dust were spread over the
surrounding country. The debris formed a dam one thousand feet
high, extending for two miles along the valley. A lake gathered
behind this barrier, gradually rising until it overtopped it in a
little less than a year. The upper portion of the dam then broke,
and a terrific rush of water swept down the valley in a wave
which, twenty miles away, rose one hundred and sixty feet in
height. A narrow lake is still held by the strong base of the dam.

In 1896, after forty days of incessant rain, a cliff of sandstone
slipped into the Yangtse River in China, reducing the width of the
channel to eighty yards and causing formidable rapids.

At Flims, in Switzerland, a prehistoric landslip flung a dam
eighteen hundred feet high across the headwaters of the Rhine. If
spread evenly over a surface of twenty-eight square miles, the
material would cover it to a depth of six hundred and sixty feet.
The barrier is not yet entirely cut away, and several lakes are
held in shallow basins on its hummocky surface.

A slide from the precipitous river front of the citadel hill of
Quebec, in 1889, dashed across Champlain Street, wrecking a number
of houses and causing the death of forty-five persons. The strata
here are composed of steeply dipping slate.

In lofty mountain ranges there may not be a single valley without
its traces of landslides, so common there is this method of the
movement of waste, and of building to grade over-steepened slopes.

ROCK SCULPTURE BY WEATHERING

We are now to consider a few of the forms into which rock masses
are carved by the weather.

BOWLDERS OF WEATHERING. In many quarries and outcrops we may see
that the blocks into which one or more of the uppermost layers
have been broken along their joints and bedding planes are no
longer angular, as are those of the layers below. The edges and
corners of these blocks have been worn away by the weather. Such
rounded cores, known as bowlders of weathering, are often left to
strew the surface.

DIFFERENTIAL WEATHERING. This term covers all cases in which a
rock mass weathers differently in different portions. Any weaker
spots or layers are etched out on the surface, leaving the more
resistant in relief. Thus massive limestones become pitted where
the weather drills out the weaker portions. In these pits, when
once they are formed, moisture gathers, a little soil collects,
vegetation takes root, and thus they are further enlarged until
the limestone may be deeply honeycombed.

On the sides of canyons, and elsewhere where the edges of strata
are exposed, the harder layers project as cliffs, while the softer
weather back to slopes covered with the talus of the harder layers
above them. It is convenient to call the former cliff makers and
the latter slope makers.

Differential weathering plays a large part in the sculpture of the
land. Areas of weak rock are wasted to plains, while areas of hard
rock adjacent are still left as hills and mountain ridges, as in
the valleys and mountains of eastern Pennsylvania. But in such
instances the lowering of the surface of the weaker rock is also
due to the wear of streams, and especially to the removal by them
from the land of the waste which covers and protects the rocks
beneath.

Rocks owe their weakness to several different causes. Some, such
as beds of loose sand, are soft and easily worn by rains; some, as
limestone and gypsum for example, are soluble. Even hard insoluble
rocks are weak under the attack of the weather when they are
closely divided by joints and bedding planes and are thus readily
broken up into blocks by mechanical agencies.

OUTLIERS AND MONUMENTS. As cliffs retreat under the attack of the
weather, portions are left behind where the rock is more resistant
or where the attack for any reason is less severe. Such remnant
masses, if large, are known as outliers. When

Note the rain furrows on the slope at the foot of the monuments.
In the foreground are seen fragments of petrified trunks of trees,
composed of silica and extremely resistant to the weather. On the
removal of the rock layers in which these fragments were imbedded
they are left to strew the surface in the same way as are the
residual flints of southern Missouri. flat-topped, because of the
protection of a resistant horizontal capping layer, they are
termed mesas,--a term applied also to the flat-topped portions of
dissected plateaus (Fig. 129). Retreating cliffs may fall back a
number of miles behind their outliers before the latter are
finally consumed.

Monuments are smaller masses and may be but partially detached
from the cliff face. In the breaking down of sheets of horizontal
strata, outliers grow smaller and smaller and are reduced to
massive rectangular monuments resembling castles (Fig. 17). The
rock castle falls into ruin, leaving here and there an isolated
tower; the tower crumbles to a lonely pillar, soon to be
overthrown. The various and often picturesque shapes of monuments
depend on the kind of rock, the attitude of the strata, and the
agent by which they are chiefly carved. Thus pillars may have a
capital formed of a resistant stratum. Monuments may be undercut
and come to rest on narrow pedestals, wherever they weather more
rapidly near the ground, either because of the greater moisture
there, or--in arid climates--because worn at their base by
drifting sands.

Stony clays disintegrating under the rain often contain bowlders
which protect the softer material beneath from the vertical blows
of raindrops, and thus come to stand on pedestals of some height.
One may sometimes see on the ground beneath dripping eaves pebbles
left in the same way, protecting tiny pedestals of sand.

MOUNTAIN PEAKS AND RIDGES. Most mountains have been carved out of
great broadly uplifted folds and blocks of the earth's crust.
Running water and glacier ice have cut these folds and blocks into
masses divided by deep valleys; but it is by the weather, for the
most part, that the masses thus separated have been sculptured to
the present forms of the individual peaks and ridges.

Frost and heat and cold sculpture high mountains to sharp,
tusklike peaks and ragged, serrate crests, where their waste is
readily removed.

The Matterhorn of the Alps is a famous example of a mountain peak
whose carving by the frost and other agents is in active progress.
On its face "scarcely a rock anywhere is firmly attached," and the
fall of loosened stones is incessant. Mountain climbers who have
camped at its base tell how huge rocks from time to time come
leaping down its precipices, followed by trains of dislodged
smaller fragments and rock dust; and how at night one may trace
the course of the bowlders by the sparks which they strike from
the mountain walls. Mount Assiniboine, Canada (Fig. 20), resembles
the Matterhorn in form and has been carved by the same agencies.

"The Needles" of Arizona are examples of sharp mountain peaks in a
warm arid region sculptured chiefly by temperature changes.

Chemical decay, especially when carried on beneath a cover of
waste and vegetation, favors the production of rounded knobs and
dome-shaped mountains.

THE WEATHER CURVE. We have seen that weathering reduces the
angular block quarried by the frost to a rounded bowlder by
chipping off its corners and smoothing away its edges. In much the
same way weathering at last reduces to rounded hills the earth
blocks cut by streams or formed in any other way. High mountains
may at first be sculptured by the weather to savage peaks (Fig.
181), but toward the end of their life history they wear down to
rounded hills (Fig. 182). The weather curve, which may be seen on
the summits of low hills (Fig. 21), is convex upward.

In Figure 22, representing a cubic block of stone whose faces are
a yard square, how many square feet of surface are exposed to the
weather by a cubic foot at a corner a; by one situated in the
middle of an edge b; by one in the center of a side c? How much
faster will a and b weather than c, and what will be the effect on
the shape of the block?

THE COOPERATION OF VARIOUS AGENCIES IN ROCK SCULPTURE. For the
sake of clearness it is necessary to describe the work of each
geological agent separately. We must not forget, however, that in
Nature no agent works independently and alone; that every result
is the outcome of a long chain of causes. Thus, in order that the
mountain peak may be carved by the agents of disintegration, the
waste must be rapidly removed,--a work done by many agents,
including some which we are yet to study; and in order that the
waste may be removed as fast as formed, the region must first have
been raised well above the level of the sea, so that the agents of
transportation could do their work effectively. The sculpture of
the rocks is accomplished only by the cooperation of many forces.

The constant removal of waste from the surface by creep and wash
and carriage by streams is of the highest importance, because it
allows the destruction of the land by means of weathering to go on
as long as any land remains above sea level. If waste were not
removed, it would grow to be so thick as to protect the rock
beneath from further weathering, and the processes of destruction
which we have studied would be brought to an end. The very
presence of the mantle of waste over the land proves that on the
whole rocks weather more rapidly than their waste is removed. The
destruction of the land is going on as fast as the waste can be
carried away.

We have now learned to see in the mantle of waste the record of
the destructive action of the agencies of weathering on the rocks
of the land surface. Similar records we shall find buried deeply
among the rocks of the crust in old soils and in rocks pitted and
decayed, telling of old land surfaces long wasted by the weather.
Ever since the dry land appeared these agencies have been as now
quietly and unceasingly at work upon it, and have ever been the
chief means of the destruction of its rocks. The vast bulk of the
stratified rocks of the earth's crust is made up almost wholly of
the waste thus worn from ancient lands.

In studying the various geological agencies we must remember the
almost inconceivable times in which they work. The slowest process
when multiplied by the immense time in which it is carried on
produces great results. The geologist looks upon the land forms of
the earth's surface as monuments which record the slow action of
weathering and other agents during the ages of the past. The
mountain peak, the rounded hill, the wide plain which lies where
hills and mountains once stood, tell clearly of the great results
which slow processes will reach when given long time in which to
do their work. We should accustom ourselves also to think of the
results which weathering will sooner or later bring to pass. The
tombstone and the bowlder of the field, which each year lose from
their surfaces a few crystalline grains, must in time be wholly
destroyed. The hill whose rocks are slowly rotting underneath a
cover of waste must become lower and lower as the centuries and
millenniums come and go, and will finally disappear. Even the
mountains are crumbling away continually, and therefore are but
fleeting features of the landscape.





CHAPTER II

THE WORK OF GROUND WATER


LAND WATERS. We have seen how large is the part that water plays
at and near the surface of the land in the processes of weathering
and in the slow movement of waste down all slopes to the stream
ways. We now take up the work of water as it descends beneath the
ground,--a corrosive agent still, and carrying in solution as its
load the invisible waste of rocks derived from their soluble
parts.

Land waters have their immediate source in the rainfall. By the
heat of the sun water is evaporated from the reservoir of the
ocean and from moist surfaces everywhere. Mingled as vapor with
the air, it is carried by the winds over sea and land, and
condensed it returns to the earth as rain or snow. That part of
the rainfall which descends on the ocean does not concern us, but
that which falls on the land accomplishes, as it returns to the
sea, the most important work of all surface geological agencies.

The rainfall may be divided into three parts: the first DRIES UP,
being discharged into the air by evaporation either directly from
the soil or through vegetation; the second RUNS OFF over the
surface to flood the streams; the third SOAKS IN the ground and is
henceforth known as GROUND or UNDERGROUND WATER.

THE DESCENT OF GROUND WATER. Seeping through the mantle of waste,
ground water soaks into the pores and crevices of the underlying
rock. All rocks of the upper crust of the earth are more or less
porous, and all drink in water. IMPERVIOUS ROCKS, such as granite,
clay, and shale, have pores so minute that the water which they
take in is held fast within them by capillary attraction, and none
drains through. PERVIOUS ROCKS, on the other hand, such as many
sandstones, have pore spaces so large that water filters through
them more or less freely. Besides its seepage through the pores of
pervious rocks, water passes to lower levels through the joints
and cracks by which all rocks, near the surface are broken.

Even the closest-grained granite has a pore space of 1 in 400,
while sandstone may have a pore space of 1 in 4. Sand is so porous
that it may absorb a third of its volume of water, and a loose
loam even as much as one half.

THE GROUND-WATER SURFACE is the name given the upper surface of
ground water, the level below which all rocks are saturated. In
dry seasons the ground-water surface sinks. For ground water is
constantly seeping downward under gravity, it is evaporated in the
waste and its moisture is carried upward by capillarity and the
roots of plants to the surface to be evaporated in the air. In wet
seasons these constant losses are more than made good by fresh
supplies from that part of the rainfall which soaks into the
ground, and the ground-water surface rises.

In moist climates the ground-water surface (Fig. 24) lies, as a
rule, within a few feet of the land surface and conforms to it in
a general way, although with slopes of less inclination than those
of the hills and valleys. In dry climates permanent ground water
may be found only at depths of hundreds of feet. Ground water is
held at its height by the fact that its circulation is constantly
impeded by capillarity and friction. If it were as free to drain
away as are surface streams, it would sink soon after a rain to
the level of the deepest valleys of the region.

WELLS AND SPRINGS. Excavations made in permeable rocks below the
ground-water surface fill to its level and are known as wells.
Where valleys cut this surface permanent streams are formed, the
water either oozing forth along ill-defined areas or issuing at
definite points called springs, where it is concentrated by the
structure of the rocks. A level tract where the ground-water
surface coincides with the surface of the ground is a swamp or
marsh.

By studying a spring one may learn much of the ways and work of
ground water. Spring water differs from that of the stream into
which it flows in several respects. If we test the spring with a
thermometer during successive months, we shall find that its
temperature remains much the same the year round. In summer it is
markedly cooler than the stream; in winter it is warmer and
remains unfrozen while the latter perhaps is locked in ice. This
means that its underground path must lie at such a distance from
the surface that it is little affected by summer's heat and
winter's cold.

While the stream is often turbid with surface waste washed into it
by rains, the spring remains clear; its water has been filtered
during its slow movement through many small underground passages
and the pores of rocks. Commonly the spring differs from the
stream in that it carries a far larger load of dissolved rock.
Chemical analysis proves that streams contain various minerals in
solution, but these are usually in quantities so small that they
are not perceptible to the taste or feel. But the water of springs
is often well charged with soluble minerals; in its slow, long
journey underground it has searched out the soluble parts of the
rocks through which it seeps and has dissolved as much of them as
it could. When spring water is boiled away, the invisible load
which it has carried is left behind, and in composition is found
to be practically identical with that of the soluble ingredients
of the country rock. Although to some extent the soluble waste of
rocks is washed down surface slopes by the rain, by far the larger
part is carried downward by ground water and is delivered to
streams by springs.

In limestone regions springs are charged with calcium carbonate
(the carbonate of lime), and where the limestone is magnesian they
contain magnesium carbonate also. Such waters are "hard"; when
used in washing, the minerals which they contain combine with the
fatty acids of soap to form insoluble curdy compounds. When
springs rise from rocks containing gypsum they are hard with
calcium sulphate. In granite regions they contain more or less
soda and potash from the decay of feldspar.

The flow of springs varies much less during the different seasons
of the year than does that of surface streams. So slow is the
movement of ground water through the rocks that even during long
droughts large amounts remain stored above the levels of surface
drainage.

MOVEMENTS OF GROUND WATER. Ground water is in constant movement
toward its outlets. Its rate varies according to many conditions,
but always is extremely slow. Even through loose sands beneath the
beds of rivers it sometimes does not exceed a fifth of a mile a
year.

In any region two zones of flow may be distinguished. The UPPER
ZONE OF FLOW extends from the ground-water surface downward
through the waste mantle and any permeable rocks on which the
mantle rests, as far as the first impermeable layer, where the
descending movement of the water is stopped. The DEEP ZONES OF
FLOW occupy any pervious rocks which may be found below the
impervious layer which lies nearest to the surface. The upper zone
is a vast sheet of water saturating the soil and rocks and slowly
seeping downward through their pores and interstices along the
slopes to the valleys, where in part it discharges in springs and
often unites also in a wide underflowing stream which supports and
feeds the river (Fig. 24).

A city in a region of copious rains, built on the narrow flood
plain of a river, overlooked by hills, depends for its water
supply on driven wells, within the city limits, sunk in the sand a
few yards from the edge of the stream. Are these wells fed by
water from the river percolating through the sand, or by ground
water on its way to the stream and possibly contaminated with the
sewage of the town?

At what height does underground water stand in the wells of your
region? Does it vary with the season? Have you ever known wells to
go dry? It may be possible to get data from different wells and to
draw a diagram showing the ground-water surface as compared with
the surface of the ground.

FISSURE SPRINGS AND ARTESIAN WELLS. The DEEPER ZONES OF FLOW lie in
pervious strata which are overlain by some impervious stratum.
Such layers are often carried by their dip to great depths, and
water may circulate in them to far below the level of the surface
streams and even of the sea. When a fissure crosses a water-
bearing stratum, or AQUIFIER, water is forced upward by the
pressure of the weight of the water contained in the higher parts
of the stratum, and may reach the surface as a fissure spring. A
boring which taps such an aquifer is known as an artesian well, a
name derived from a province in France where wells of this kind
have been long in use. The rise of the water in artesian wells,
and in fissure springs also, depends on the following conditions
illustrated in Figure 29. The aquifer dips toward the region of
the wells from higher ground, where it outcrops and receives its
water. It is inclosed between an impervious layer above and water-
tight or water-logged layers beneath. The weight of the column of
water thus inclosed in the aquifer causes water to rise in the
well, precisely as the weight of the water in a standpipe forces
it in connected pipes to the upper stories of buildings.

Which will supply the larger region with artesian wells, an
aquifer whose dip is steep or one whose dip is gentle? Which of
the two aquifers, their thickness being equal, will have the
larger outcrop and therefore be able to draw upon the larger
amount of water from the rainfall? Illustrate with diagrams.

THE ZONE OF SOLUTION. Near the surface, where the circulation of
ground water is most active, it oxidizes, corrodes, and dissolves
the rocks through which it passes. It leaches soils and subsoils
of their lime and other soluble minerals upon which plants depend
for their food. It takes away the soluble cements of rocks; it
widens fissures and joints and opens winding passages along the
bedding planes; it may even remove whole beds of soluble rocks,
such as rock salt, limestone, or gypsum. The work of ground water
in producing landslides has already been noticed. The zone in
which the work of ground water is thus for the most part
destructive we may call the zone of solution.

CAVES. In massive limestone rocks, ground water dissolves channels
which sometimes form large caves (Fig. 30). The necessary
conditions for the excavation of caves of great size are well
shown in central Kentucky, where an upland is built throughout of
thick horizontal beds of limestone. The absence of layers of
insoluble or impervious rock in its structure allows a free
circulation of ground water within it by the way of all natural
openings in the rock. These water ways have been gradually
enlarged by solution and wear until the upland is honeycombed with
caves. Five hundred open caverns are known in one county.

Mammoth Cave, the largest of these caverns, consists of a
labyrinth of chambers and winding galleries whose total length is
said to be as much as thirty miles. One passage four miles long
has an average width of about sixty feet and an average height of
forty feet. One of the great halls is three hundred feet in width
and is overhung by a solid arch of limestone one hundred feet
above the floor. Galleries at different levels are connected by
well-like pits, some of which measure two hundred and twenty-five
feet from top to bottom. Through some of the lowest of these
tunnels flows Echo River, still at work dissolving and wearing
away the rock while on its dark way to appear at the surface as a
great spring.

NATURAL BRIDGES. As a cavern enlarges and the surface of the land
above it is lowered by weathering, the roof at last breaks down
and the cave becomes an open ravine. A portion of the roof may for
a while remain, forming a "natural bridge."

SINK HOLES. In limestone regions channels under ground may become
so well developed that the water of rains rapidly drains away
through them. Ground water stands low and wells must be sunk deep
to find it. Little or no surface water is left to form brooks.