THE TRAVELS OF THE UNDERGROUND WATER
=The descent within the unsaturated zone.=—Of the moisture
precipitated from the atmosphere, that portion which neither evaporates
into the air nor runs off upon the surface, sinks into the ground and
is described as the _ground water_. Here it descends by gravity through
the pores and open spaces, and at a quite moderate depth arrives at a
zone which is completely saturated with water. The depth of the upper
surface of this saturated zone varies with the humidity of the climate,
with the altitude of the earth’s surface, and with many other similarly
varying factors. Within humid regions its depth may vary from a few
feet to a few hundred feet, while in desert areas the surface may lie
as low as a thousand feet or more.
The surface of the zone of the lithosphere that is saturated with water
is called the _water table_, and though less accentuated it conforms in
general to the relief of the country (Fig. 188). Its depth at any point
is found from the levels of all perennial streams and from the levels
at which water stands in wells.
[Illustration: FIG. 188.—Diagram to show the seasonal range in the
position of the water table and the cause of intermittent streams.]
During the season of small precipitation the water table is lowered,
and if at such times it falls below the bed of a valley, the surface
stream within the valley dries up, to be revived when, after heavier
precipitation, the water table has in turn been raised. Such streams
are said to be _intermittent_, and are especially characteristic of
semiarid regions (Fig. 188).
Wherever in descending from the surface an impervious layer, such as
clay, is encountered, the further downward progress of the water is
arrested. Now conducted in a lateral direction it issues at the surface
as a spring at the line of emergence of the upper surface of the
impervious layer (Fig. 189).
[Illustration: FIG. 189.—Diagram to show how an impervious layer
conducts the descending water in a lateral direction to issue in
surface springs.]
=The trunk channels of descending water.=—While within the
unconsolidated rock materials near the surface of the earth, it is
clear that water can circulate in proportion as the materials are
porous and so relatively pervious. As the pore spaces become minute and
capillary, the difficulty of permeation through the materials becomes
very great. Thus in the noncoherent rocks it is the coarse gravel and
the layers of sand which serve as the underground channels, while the
fine clays have the effect of an impervious wall upon the circulating
waters. In coarse sand as much as a third of the volume of the material
is pore space for the absorption and transmission of water. Even under
these favorable conditions the movement of the water is exceedingly
slow and usually less than a fifth of a mile a year.
[Illustration:
FIG. 190.—Sketch map of the Oucane de Chabrières near Chorges in the
High Alps, to illustrate the corrosion of limestone along two series of
vertical joints (after Martel).]
Within the hard rocks it is the sandstones which have the largest pore
spaces, but in nearly all consolidated rocks there are additional
spaces along certain of the bedding planes, the joint openings (Fig.
190), and the crushed zones of displacement, so that these parting
planes become the trunk channels, so to speak, of the circulating
water. It is along such crevices that in the course of time the
mineral matter carried in solution by the water is deposited to produce
the ore veins and the associated crystallized minerals.
=The caverns of limestones.=—Where limestone formations have a nearly
flat upper surface, a large part of the surface water enters the rock
by way of the joint spaces, which it soon widens by solution into
broad crevices with well-rounded shoulders. At joint intersections
solution of the limestone is so favored that the water may here descend
in a sort of vertical shaft until it meets a bedding plane extending
laterally and offering more favorable conditions for corrosion. Its
journey now begins in a lateral direction, and solution of the rock
continuing, a tunnel may be etched out and extended until another
joint is encountered which is favorable to its further descent into
the formation. By this process on alternating shafts and galleries
the water descends to near the surface of the water table by a series
of steps, and is eventually discharged into the river system of the
district (Fig. 191). Within the larger caverns the water at the lowest
level usually flows as a subterranean river to emerge later into the
light from beneath a rock arch.
[Illustration:
FIG. 191.—Diagram to show the relation of caverns in limestone to
the river system of the district and to the “swallow holes” upon the
surface.]
From the plan of a system of connecting caverns it may often be
observed that the galleries of the several levels are alike directed
along two rectangular directions which indicate the master joint
directions within the limestone formation. This is especially clear
from the map of the galleries in the explored portions of the Mammoth
Cave (Fig. 192).
=Swallow holes and limestone sinks.=—Above the caverns of limestone
formations there are selected points where the water has descended
in the largest volume, and here funnel-shaped depressions have
been dissolved out from the surface of the rock. In different
districts such depressions have become known as “sinks”, “swallow
holes”, _entonnoirs_, and _Orgeln_. Wherever the depressions have
a characteristic circular outline, there can be little doubt that
they are the product of solution by the descending water, and have
relatively small connections only with the subterranean caverns. They
have thus naturally collected upon their bottoms the insoluble clay
which was contained in the impure limestone as well as a certain amount
of slope wash from the surface. Inasmuch as the clays are impervious
to water, the bottoms of these swallow holes are better supplied with
moisture than the surrounding rock surfaces, and by nourishing a more
vigorous plant growth are strongly impressed upon the landscape (Fig.
193).
[Illustration: FIG. 192.—Plan of a portion of Mammoth Cave, Kentucky
(after H. C. Hovey).]
[Illustration:
FIG. 193.—Trees and shrubs growing luxuriantly upon the bottoms of
sinks within a limestone country (after a photograph by H. T. A. de L.
Hus).]
Certain of the depressions above caverns are, however, less regular in
outline, and their bottoms are occupied by a mass of limestone rubble.
In some instances, at least, these depressions appear to be the result
of local incaving of the cavern roofs. An incaving of this nature may
close up an earlier gallery in the cavern and divert the cave waters
to a new course. The destruction of the roofs of caverns through this
process of incaving may continue until only relatively small remnants
are left. From long subterranean tunnels the caves are thus transformed
into subaërial rock bridges that have become known as “natural
bridges.” The best-known American example is the Natural Bridge near
Lexington, Virginia. Much grander natural bridges have been formed in
sandstone by a totally different process, and must not be confused with
these limestone remnants of caverns.
=The sinter deposits.=—Just as water can dissolve the calcareous
rocks with the formation of caverns, it can under other conditions
deposit the material which has thus been taken into solution. Its
power to hold carbonate of lime in solution is dependent upon the
presence of carbonic acid gas within the water. Water charged with gas
and dissolved lime carbonate is said to be “hard”, and if the gas be
driven off by boiling or otherwise, the dissolved lime is thrown out of
solution and deposited in a form well known to all housekeepers.
Hard water flowing in a surface stream, if dashed into spray at a
cascade, may deposit its lime carbonate in an ever thickening veneer
wherever the spray is dashed about the falls. This material, when cut
in section, has waving parallel layers and is known as _travertine_
or _calcareous sinter_. Some of the most remarkable deposits of this
nature may be seen at the cascade of Tivoli near Rome, and most of the
Roman buildings have been constructed from travertine that has been
quarried in the vicinity.
=The growth of stalactites.=—Water, after percolating slowly through
the crevices of limestone, where it becomes charged with the carbonic
acid gas and with dissolved carbonate of lime, may trickle from the
roof of a cavern. Emerging from the narrow crevice, it may give off
some of its contained gas and is usually subject to evaporation,
with the result that the lime carbonate is left adhering to the rock
surface from which evaporation took place. If the water collects upon
the cavern roof so slowly that it can entirely evaporate before a drop
can form, the entire content of carbonate will be left adhering to the
roof. Evaporation is most rapid near the margins and over the center of
each drop as it develops, and the deposit which is left thus takes the
form of tiny white rings at those points upon the crevice where there
is the easiest passage for the trickling water. To the outer surface
of these rings water will first adhere and then evaporate, as it will
also slowly ooze through the passage in the ring, but here without
evaporation until it reaches the lower surface. A pendant structure
will, therefore, develop, growing outward in all directions by the
deposition of concentric layers which are thickest near the roof, and
downward into the form of a rock “icicle” through evaporation of the
water which collects near the tip. These pendant sinter formations are
known as stalactites and are thus formed of concentric layers arranged
like a series of nested cornucopias with a perforation of nearly
uniform caliber along the axis of the structure (Fig. 194).
[Illustration:
FIG. 194.—Diagrams to show the manner of formation of stalactites,
stalagmites, and sinter columns beneath parallel crevices upon the
roofs of caverns (in part after von Knebel).]
=Formation of stalagmites.=—Wherever the water percolates through
the roof of the cavern so rapidly that it cannot entirely evaporate
upon the roof, a portion falls to the floor, and, spattering as it
strikes, builds up a relatively thick cone of sinter known as a
stalagmite, and this is accurately centered beneath a stalactite
upon the roof. In proportion as the cavern is high, the dropping
water is widely dispersed as it strikes the floor, with the formation
of a correspondingly thick and blunt stalagmite. As this rises by
growth toward the roof, it often develops upon its summit a distinct
crater-like depression (Fig. 194, lower figure). When the process is
long continued, stalactites and stalagmites may grow together to form
columns which may be ranged with their neighbors like the pipes of an
organ, and like them they give out clear tones when struck lightly with
a mallet. At other times the columns are joined to their neighbors to
form hangings and draperies of the most fantastic and beautiful design
(Fig. 195).
[Illustration: FIG. 195.—Sinter formations in the Luray caverns,
Virginia.]
In remote antiquity limestone caverns afforded a refuge to many species
of predatory birds and animals as well as to our earliest ancestors.
The bones of all these denizens of the caves lie entombed within the
clays and the sinter formations upon the cavern floors, and they tell
the story of a fierce and long-continued warfare for the possession of
these natural strongholds. The evidence is clear that these cave men
with their primitive weapons were able at times to drive away the cave
bears, lions, and hyenas, and to set up in the cavern their simple
hearths, only in their turn to be conquered by the ferocity of their
enemies. Some of the European caves have yielded many wagonloads of the
skeletons of these fierce predatory animals, together with the simple
weapons of the primitive man.
=The Karst and its features.=—Most so-called limestones have a large
admixture of argillaceous materials (clays) and of siliceous or sandy
particles. Such impurities make up the bulk of the clays and muds which
are left behind when the soluble portions of the limestone have been
dissolved.
[Illustration: FIG. 196.—Map of the dolines of the Karst region near
Divača.]
Swallow holes we have found to be characteristic features within such
districts. When limestones are more nearly pure, as in the Karst
region east of the Adriatic Sea, similar features are developed, but
upon a grander scale, and certain additional forms are encountered. In
place of the sink or swallow hole, there appears the “karst funnel” or
_doline_, a deep, bowl-shaped depression having a flat bottom. Such
funnels may be 30 to 3000 feet across and from 6 to 300 feet in depth
(Fig. 196). Though in one or two instances known to be the result of
the break down of cavern roofs (Fig. 197), yet like the swallow holes
of other regions these larger funnels appear generally to be the work
of solution by the descending waters. Where they have been opened in
artificial cuttings along railroads or in mines, the original rock is
found intact at the bottom, with small crevices only going down to
lower levels. Over the bottoms of the dolines there is spread a layer
of fertile red clay, the _terra rossa_, like that which is obtained
as a residue when a fragment of the limestone has been dissolved in
laboratory experiments.
[Illustration:
FIG. 197.—Cross section of the doline formed by inbreak of a cavern
roof. The Stara Apnenka doline in Carinthia (after Martel).]
=A desert from the destruction of forests.=—Between the dolines is
found a veritable desert with jutting limestone angles and little if
any vegetation. The water which falls upon the surface either runs off
quickly or goes down to the subterranean caverns by which so much of
the country is undermined. Hence it is that the gardens which furnish
the sustenance for the scattered population are all included within
the narrow limits of the doline bottoms. Although to-day so largely a
barren waste, we know that the Karst upon the Adriatic was in remote
antiquity a heavily forested region and that it supplied the myriads of
wooden piles upon which the city of Venice is supported. The vessels
which brought to this port upon the Adriatic its ancient prosperity
were built from wood brought from this tract of modern desert. In the
days of Venetian grandeur the fertile terra rossa formed a veneer upon
the rock surface of the Karst and so retained the surface waters for
the support of the luxuriant forest cover. After deforestation this
veneer of rich soil was washed by the rains into the dolines or into
the few stream courses of the region, thus leaving a barren tract which
it will be all but impossible to reclaim (plate 6 A).
[Illustration: FIG. 198.—Sharp _Karren_ of the Ifenplatte Allgäu
(after Eckert).]
Upon the steeper slopes over the purer limestones, the rain water runs
away, guided by the joints within the rock. There is thus etched out a
more or less complete network of narrow channels (Fig. 190, p. 181),
between which the remnants rise in sharp blades to produce a structure
often simulated upon the fissured surface of a glacier that has been
melted in the sun’s rays (Fig. 401). These almost impassable areas of
karst country are described as _Schratten_ or _Karrenfelder_ (Fig. 198).
=The ponore and the polje.=—To-day large areas of the Karst are
devoid of surface streams, nearly all the surface water finding its
way down the crevices of the limestone into caverns, and there flowing
in subterranean courses. The foot traveler in the Karst country is
sometimes suddenly arrested to find a precipice yawning at his feet,
and looking down a well-like opening to the depth of a hundred feet or
more, he may see at the bottom a large river which emerges from beneath
the one wall to disappear beneath the other. These well-like shafts are
in the Austrian Karst known as _Ponores_, while to the southward in
Greece they are called _Katavothren_.
┌──────────────────────────────────────────────────────────────────────┐
│ PLATE 6. │
│ │
│ [Illustration: _A._ Barren Karst landscape near the famous Adelsberg │
│ grottoes. │
│ (_Photograph by I. D. Scott._)] │
│ │
│ [Illustration: _B._ Surface of a limestone ledge where joints have │
│ been widened through solution. │
│ Syracuse, N.Y. │
│ (_Photograph by I. D. Scott._)] │
└──────────────────────────────────────────────────────────────────────┘
Elsewhere the karst river may emerge from its subterranean course in
a broader depressed area bounded by vertical cliffs, from which it
later disappears beneath the limestone wall. Such depressions of the
karst are known as _poljen_, and appear in most cases to be above the
downthrown blocks in the intricate fault mosaic of the region. Some of
these steeply walled inclosures have an area of several hundred square
miles, and especially at the time of the spring snow melting they are
flooded with water and so transformed into seasonal lakes (Fig. 199
and p. 422). It appears that at such times the cave galleries of the
region with their local narrows are not able to carry off all the water
which is conducted to them; and in consequence there is a temporary
impounding of the flood waters in those portions of the river’s course
which are open to the sky and more extended. The rush of water at
such times may bring the red clay into the subterranean channels in
sufficient quantity to clog the passages. The Zirknitz Lake usually has
high water two or three times a year, and exceptionally the flooding
has continued for a number of years. It has thus in some districts been
necessary to afford relief to the population through the construction
of expensive drainage tunnels.
[Illustration:
FIG. 199.—The Zirknitz seasonal lake within a polje of the Karst
(after Berghaus).]
The conditions which are typified in the Karst area to the east of the
Adriatic Sea are encountered also in many other lands; as, for example,
in the Vorarlberg and Swiss Alps, in Lebanon, and in Sicily.
=The return of the water to the surface.=—Water which has descended
from the surface and been there held between impervious layers, may be
under the pressure of its own weight or “head”; and will later find its
way upward, it may be to the surface or higher, where a perforation is
discovered in its otherwise impervious cover. Such local perforations
are produced naturally by lines of fracture or faulting (widened at
their intersections), and artificially through the sinking of deep
wells. The water, which at ordinary times reaches the surface upon
fissures, is usually concentrated locally at the intersections of the
fracture network, where it issues in lines of fissure springs (Fig.
200); but at the time of earthquakes the water may rise above the
surface in lines of fountains (p. 83), or occasionally as sheets of
water which may mount some tens of feet into the air.
[Illustration:
FIG. 200.—Fissure springs arranged upon lines of rock fracture at
intersections, Pomperaug valley, Connecticut.]
In contrast to the flow of surface springs, which varies with the
season through wide ranges both in its volume and in temperature of
the water, the volume of fissure springs is but slightly affected by
the seasonal precipitation, and the water temperature is maintained
relatively constant. Rock is but a poor heat conductor, and the
seasonal temperature changes descend a few feet only into the ground.
Thus water which rises from depths of a few hundred feet only is
apt to be icy cold, while from greater depths the effect of the
earth’s internal heat is apparent in a uniform but relatively higher
temperature of the water. Such “warm” or _thermal_ springs are apt to
contain considerable mineral matter in solution, both because the water
is far traveled and because its higher temperature has considerably
increased its solvent properties.
It has long been recognized that lines of junction of different rock
formations at the base of mountain ranges are localities favorable for
the occurrence of thermal springs. These junction lines are usually
within zones where by movement upon fractures the widest openings
in the rock have formed, and the catchment area of the neighboring
mountain highland has supplied head for the ground water. A map of the
hot springs within the Great Basin of the western United States would
present in the main a map of its principal faults.
=Artesian wells.=—From the natural fissure spring an artesian
well differs in the artificial character of the perforation of the
impervious cover to the water layer. The water of artesian wells may
flow out at the surface under pressure, or it may require pumping to
raise it from some lower level. Ideal conditions are furnished where
the geological structure of the district is that of a broad basin
or syncline. The water which falls in a neighboring upland is here
impounded between two parallel, saucer-like walls and will flow under
its head if the upper wall be perforated at some low level (Fig. 201,
3).
[Illustration:
FIG. 201.—Schematic diagrams to illustrate the different types of
artesian wells, (1) A non-flowing well; (2) flowing wells without basin
structure caused by clogging of the pervious formation; (3) flowing
wells in an artesian basin. The dotted lines are the water levels
within the pervious layers (after Chamberlin).]
A monoclinal structure may furnish artesian conditions when the
generally pervious layer has become clogged at a low level so as
to hold back the water (Fig. 248, 2). Pumping wells may be used
successfully even when such clogging does not exist, for the
slow-moving underground water flows readily in the direction of all
free outlets (Fig. 201, 1).
=Hot springs and geysers.=—Thermal springs whose temperature
approaches the boiling point of water are known as _hot springs_.
A _geyser_ is a hot spring which intermittently ejects a column of
water and steam. Both hot springs and geysers are to be found only in
volcanic regions, and appear to be connected with uncooled masses of
siliceous lava. In two of the three known geyser regions, Iceland and
New Zealand, the volcanoes of the neighborhood are still active, and
the lavas of the Yellowstone National Park date from the quite recent
geological period which immediately preceded the so-called “Ice Age.”
Wherever found, geysers are in the low levels along lines of drainage
where the underground water would most naturally reappear at the
surface. Their water has penetrated to considerable depths below the
surface, but has been chiefly heated by ascending steam or other
vapors. The water journey has been chiefly made along fissures, as is
shown by the cool springs which often issue near them. Though some hot
springs and geysers may disappear from a district, others are found
to be forming, and there is no good reason to think that geysers are
rapidly dying out, as was at one time supposed.
The action of a geyser was first satisfactorily explained by the great
German chemist Bunsen after he had made studies of the Icelandic
geysers, and the mechanics of the eruption was later strikingly
illustrated in the laboratory by an artificial geyser constructed by
the Irish physicist Tyndall. In many respects this action is like that
of the Strombolian eruption within a cinder cone, since it is connected
with the viscosity of the fluid and the resistance which this opposes
to the liberation of the developing vapor. In the case of the geyser, a
column of heated water stands within a vertical tube and is heated near
the bottom of the column.
[Illustration:
FIG. 202.—Cross section of Geysir, Iceland, with simultaneously
observed temperatures recorded at the left, and the boiling
temperatures for the same levels at the right (after Campbell).]
Though the water may at its surface have the normal boiling temperature
and be there in quiet ebullition, the boiling point for all lower
levels is raised by the weight of the column of superincumbent liquid,
and so for a time the formation of steam within the mass is prevented.
In Fig. 202 is shown a cross section of the Icelandic _Geysir_ from
which our name for such phenomena has been derived, and to this section
have been added the actual observed temperatures of the water at the
different levels as well as the temperatures at which boiling can take
place at these levels. From this it will be seen that at a depth of 45
feet the water is but 2° Centigrade below its boiling point. A slight
increase of temperature at this level, due to the constantly ascending
steam, will not only carry this layer above the boiling point, but the
expansion of the steam within the mass will elevate the upper layers of
the water into zones where the boiling points are lower, and thus bring
about a sudden and violent ebullition of all these upper portions. Thus
is explained the almost universal observation that just before geysers
erupt the hot water rises in the bowls and generally overflows them.
[Illustration:
FIG. 203.—Apparatus for simulating geyser action in the lecture room
(by courtesy of Professor B. W. Snow).]
The water ejected from the geyser is considerably cooled in the air;
and after its return to the tube must be again heated by the ascending
vapors before another eruption can occur. The measure of the cooling,
the time necessary to fill the tube, and the supply of rising steam,
all play a part in fixing the period which separates consecutive
eruptions. If the top of the tube be narrowed from its average
caliber, as is commonly observed to be true of the geysers within the
Yellowstone National Park, the escape of the steam is further hindered,
and frequent geyser eruption promoted.
An artificial geyser for demonstration of the phenomenon in the lecture
room is represented in Fig. 203. The cut has been prepared from a
photograph of an apparatus designed by Professor B. W. Snow of the
University of Wisconsin. In this design the tube is contracted so as
to have a top diameter one fourth only of what it is at the bottom,
where heat is directly applied by multiple Bunsen lamps. The water once
sufficiently heated, this artificial geyser erupts at regular intervals
of time which are dependent upon the dimensions of the apparatus and
the quantity of heat applied.
In case of natural geysers a considerable quantity of heat escapes
between eruptions in steam which issues quietly from the bowl of the
geyser. If this heat be retained by plugging the mouth of the tube with
a barrowful of turf, as is sometimes done with the geyser _Strokr_
in Iceland, eruption is promoted and so takes place earlier. Another
method of securing the same result is to increase the viscosity of the
water through the addition of soap, as was accidentally discovered by
a Chinaman who was utilizing the geyser water in the Yellowstone Park
for laundry operations. After this discovery it became a common custom
to “soap” the Yellowstone geysers in order to make them play; but this
method was prohibited under heavy penalty after the disastrous eruption
of the Excelsior Geyser.
=The deposition of siliceous sinter by plant growth.=—Geysers are
known only from areas of siliceous volcanic lava, and this may perhaps
have its cause in the easier solution of the geyser tube from such
materials. The silica dissolved in the heated waters is _again_
deposited at the surface to form _siliceous sinter_ or _geyserite_.
This material forms terraces surrounding the geysers or is built up
into mounds which are often quite symmetrical, such as those of the Bee
Hive and Lone Star geysers of the Yellowstone Park (Fig. 204).
[Illustration:
FIG. 204.—Cone of siliceous sinter built up about the mouth of the
Lone Star Geyser in the Yellowstone National Park.]
The greater part of this separation of silica from the heated geyser
waters is due to the action of plants or algæ that are able to
grow in the boiling waters and which produce the beautiful colors
in the linings to the hot springs. The wonderful variety of the
tints displayed is accounted for by the fact that the algæ take on
different colors at different temperatures. The silica is deposited
from the water in the gelatinous hydrated form, which, however, dries
in the sun to a white sand. The growth within the pools goes on in
a manner similar to that of a coral reef, the algæ dying below and
there becoming encased in the rock lining while still continuing to
grow upon the surface. Whereas sinter of this nature, when deposited
by evaporation alone, can produce a maximum thickness of layer of a
twentieth of an inch each year, the growth from alga deposition within
limited areas may be as much as eight inches during the same period.
READING REFERENCES FOR CHAPTER XIV
General:—
F. H. KING. Principles and Conditions of the Movements of Ground
Water, 19th Ann. Rept. U. S. Geol. Surv., 1899, Pt. ii, pp. 59-294,
pls. 6-16.
C. S. SLICHTER. The Motions of the Underground Waters, Water Supply
Paper No. 67, U. S. Geol. Surv., 1902, pp. 1-106, pls. 1-8; Field
Measurements of the Rate of Movement of Underground Waters, _ibid._,
No. 140, 1905, pp. 1-122, pls. 1-15.
M. L. FULLER. Occurrence of Underground Water, _ibid._. No. 114, 1905,
pp. 18-40, pls. 4; Bibliographic review and index of papers relating
to underground waters published by the United States Geological
Survey, 1879-1904, _ibid._, No. 120, 1905, pp. 1-128.
Caverns:—
E. A. MARTEL. Les abimes, les eaux souterraines, les cavernes,
les sources, la spélæologie. Delagrave, Paris, pp. 578. (Lavishly
illustrated.)
H. C. HOVEY. Celebrated American Caverns. Cincinnati, 1896, pp. 228;
The Mammoth Cave of Kentucky. Louisville, 1897, pp. 111.
J. W. BEEDE. Cycle of Subterranean Drainage in the Bloomington
Quadrangle, Proc. Ind. Acad. Sci., 1910, pp. 1-31.
Karst conditions:—
J. CVIJIC. Das Karstphänomen, Geogr. Abh., vol. 5, 1893.
ÉMILE CHAIX. La topographie du desert de platé (Hautes Savoie), Le
Globe, vol. 34, 1895, pp. 1-44, pls. 1-16, pp. 217-330.
W. V. KNEBEL. Höhlenkunde mit Berücksichtigung der Karstphänomene.
Vieweg, Braunschweig, 1906, pp. 222.
A. GRUND. Die Karsthydrographie, Studien aus Westbosnien, Geogr. Abh.,
vol. 7, No. 3, 1903, pp. 200.
ÉMILE CHAIX-DU BOIS et ANDRÉ CHAIX. Contribution a l’étude des lapies
en Carniole et au Steinernes Meer, Le Globe, vol. 46, 1907, pp. 17-56,
pls. 26.
P. ARBENZ. Die Karrenbildungen geschildert am Beispiele der
Karrenfelder bei der Frutt in Kanton Obwalden (Schweiz). Deutsch.
Alpenzeitung, Munich, 1909, pp. 1-9.
F. KATZER. Karst und Karsthydrographie. Sarejevo, 1909, pp. 95.
M. NEUMAYR. Erdgeschichte, vol. 1, pp. 500-510.
E. DE MARTONNE. Traité de Géographie Physique, pp. 462-472 (excellent
summaries in this and the last reference).
E. A. MARTEL. The Land of the Causses, Appalachia, vol. 7, 1893, pp.
18-149, pls. 4-13.
Fissure springs:—
A. C. PEALE. Natural Mineral Waters of the United States, 14th Ann.
Rept. U. S. Geol. Surv., Pt. ii, 1894, pp. 49-88.
WILLIAM H. HOBBS. The Newark System of the Pomperaug Valley.
Connecticut, 21st Ann. Rept. U. S. Geol. Surv., Pt. iii, 1901, pp.
91-93.
Artesian wells:—
T. C. CHAMBERLIN. Requisite and Qualifying Conditions of Artesian
Wells, 5th Ann. Rept. U. S. Geol. Surv., 1885, pp. 131-173.
Hot springs and geysers:—
A. C. PEALE. Yellowstone Park, Thermal Springs, 12th Ann. Rept. Geol.
and Geogr. Surv. Ter. (Hayden), Pt. ii, Sec. ii, pp. 63-454 (many
plates and maps).
W. H. WEED. Geysers, Rept. Smithson. Inst., 1891, pp. 163-178.
ARNOLD HAGUE and W. H. WEED (on hot springs and geysers of Yellowstone
National Park), C. R. Cong. Géol. Intern., Washington, 1891, pp.
346-363.
W. H. WEED. Formation of Travertine and Siliceous Sinter by the
Vegetation of Hot Springs, 9th Ann. Rept. U. S. Geol. Surv., 1889, pp.
613-676, pls. 78-87.
M. NEUMAYR. Erdgeschichte, vol. 1, pp. 500-510.
ARNOLD HAGUE. Soaping Geysers, Trans. Am. Inst. Min. Eng., vol. 17,
1889, pp. 546-553.
JOHN TYNDALL. Heat as a Mode of Motion, New York, 1873, pp. 115-121
(artificial geyser).