Earth Features and Their Meaning An Introduction to Geology for the Student and the General Reader

=A mountain defined.=—As ordinarily understood, mountains are elevations upon the earth’s surface which rise above the general level of the country. Their summits need not be at...

=The mechanics of crater explosions.=—If we now turn from the lava volcano to the active cinder cone, we encounter an entire change of scene. In place of the quiet flow and conv...

A mountain defined—The festoons of mountain arcs—Theories of origin of the mountain arcs—The Atlantic and Pacific coasts contrasted—The block type of mountain—Mountains of outfl...

=The inland ice of Greenland.=—In Greenland and in Antarctica the land is almost or quite buried under a cover of snow and ice—the so-called “inland ice”—which always assumes th...

=Freshwater and saline lakes.=—Lakes require for their existence a basin within which water may be impounded, and a supply of water more than sufficient to meet the losses from...

=Prevalent misconceptions about volcanoes.=—The more or less common impression that a volcano is a “burning mountain” or a “smoking mountain” has been much fostered by the schoo...

=Earlier cycles of glaciation.=—Our study of the rocks composing the outermost shell of the lithosphere tells us that in at least three widely separated periods of its history t...

=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, si...

=Interference of glaciers with drainage.=—Every advance and every retreat of a continental glacier has been marked by a complex series of episodes in the history of every river...

=Features in and about the Niagara gorge.=—A striking example of those permanent alterations of drainage which have resulted from the presence of the late continental glacier in...

=The lithosphere and its envelopes.=—The stony part of the earth is known as the _lithosphere_, of which only a thin surface shell is known to us from direct observation. The re...

=The zones of fracture and flow.=—It is easy to think of the atmosphere and the hydrosphere as each sustaining at any point the load of the superincumbent material. At the sea l...

=Experimental demonstration of earth movements.=—The study of the Alaskan earthquake of 1899 showed that during this adjustment within the earth’s shell some of the local blocks...

=The characters in which the record has been preserved.=—The peculiar forms into which the sea has etched and molded its shores have been considered in the last chapter. Of thes...

=The wandering dunes.=—Over the broad expanse of the desert, sand and dust, and occasionally gypsum from the saline deposits, are ever migrating with the wind; on quiet days in...

=The intricate pattern of river etchings.=—The attack of the weather upon the solid lithosphere destroys the integrity of its surface layer, and through reducing it to rock débr...

=The law of the desert.=—It is well to keep ever in mind that there is no universal law which dominates Nature’s processes in all the sections of her realm. Those changes which,...

=Contrasted sculpturing of continental and mountain glaciers.=—In discussing in a previous chapter the rock pavement lately uncovered by the Greenland glacier, we learned that t...

=The response of the earth’s shell to its ice mantle.=—There is now good reason to believe that the earth’s outer shell makes a response by oscillations of level due to the load...

=The rigid quality of our planet.=—For a long time it was supposed that the solid earth constituted a crust only which was floated upon a liquid interior. This notion was clearl...

=The motion of a water wave.=—The motions within a wave upon the surface of a body of water may be thought of in two different ways. First of all, there is the motion of each pa...

=The processes by which rocks are formed.=—Rocks may be formed in any one of several ways. When a portion of the molten lithosphere, so-called _magma_, cools and consolidates, t...

=The newly incised upland and its sharp salients.=—The successive stages of incising, sculpturing, and finally of reducing an uplifted land area, are each of them possessed of d...

=The system of the fractures.=—In referring to experiments made upon the fracture of solid blocks under compression (p. 41), it was shown that two series of parallel fractures d...

=The glacier flow.=—The downward flow of the ice within a mountain glacier has been the subject of many investigations and the topic of many heated discussions since the time wh...

=Nature of earthquake shocks.=—Man’s belief in the stability of Mother Earth—the _terra firma_—is so inbred in his nature that even a light shock of earthquake brings a rude awa...

=Conditions essential to glaciation.=—Wherever for a sufficiently protracted period the annual snowfall of a district is in excess of the snow that is melted, a residue must rem...

=The two contrasted processes of weathering.=—It has already been pointed out that change and not stability is the order of nature. Within the earth’s outer shell and upon it ro...

=The sources of the history.=—The science which deals with the chapters of earth history that antedate the earliest human writings is geology. The pages of the record are the la...

=Lakes as settling basins.=—Of all the processes which conspire to blot out the lakes with which our northern landscapes are dotted, the one of greatest importance is in most ca...

=The weathering processes under control of the fracture system.=—In an earlier chapter it was learned that the rocks which compose the earth’s surface shell are intersected by a...

=Transition from the ice cap to the mountain glacier.=—A study of existing glaciers leads inevitably to the conclusion that although subject to short period advances and retreat...

Contrasted sculpturing of continental and mountain glaciers—Wind distribution of the snow which falls in mountains—The niches which form on snowdrift sites—The augmented snowdri...

The mechanics of crater explosions—Grander volcanic eruptions of cinder cones—The eruption of Volcano in 1888—The eruption of Taal volcano on January 30, 1911—The materials and...

The characters in which the record has been preserved—Even coast line the mark of uplift—A ragged coast line the mark of subsidence—Slow uplift of the coasts; the coastal plain...

The inland ice of Greenland—The mountain rampart and its portals—The marginal rock islands—Rock fragments which travel with the ice—The grinding mill beneath the ice—The lifting...

Interference of glaciers with drainage—Temporary lakes due to ice blocking—The “parallel roads” of the Scottish glens—The glacial Lake Agassiz—Episodes of the glacial lake histo...

Prevalent misconceptions about volcanoes—Early views concerning volcanic mountains—The birth of volcanoes—Active and extinct volcanoes—The earth’s volcano belts—Arrangement of v...

Earlier cycles of glaciation—Contrast of the glaciated and nonglaciated regions—The “driftless area”—Characteristics of the glaciated regions—The glacier gravings—Younger record...

The response of the earth’s shell to its ice mantle—The abandoned strands as they appear to-day—The records of uplift about Mackinac Island—The present inclinations of the uplif...

The intricate pattern of river etchings—The motive power of rivers—Old land and new land—The earlier aspects of rivers—The meshes of the river network—The upper and lower reache...

The lithosphere and its envelopes—The evolution of ideas concerning the earth’s figure—The oblateness of the earth—The arrangement of oceans and continents—The figure toward whi...

Features in and about the Niagara gorge—The drilling of the gorge—The present rate of recession—Future extinction of the American Fall—The captured Canadian Fall at Wintergreen...

The newly incised upland and its sharp salients—The stage of adolescence—The maturely dissected upland—The Hogarthian line of beauty—The final product of river sculpture: the pe...

The descent within the unsaturated zone—The trunk channels of descending water—The caverns of limestones—Swallow holes and limestone sinks—The sinter deposits—The growth of stal...

The motion of a water wave—Free waves and breakers—Effect of the breaking wave upon a steep, rocky shore: the notched cliff—Coves, sea arches, and stacks—The cut rock terrace—Th...

The processes by which rocks are formed—The marks of origin—The metamorphic rocks—Characteristic textures of the igneous rocks—The classification of rocks—Subdivisions of the se...

The zones of fracture and flow—Experiments which illustrate the fracture and flow of solid bodies—The arches and troughs of the folded strata—The elements of folds—The shapes of...

Fresh water and saline lakes—Newland lakes—Basin-range lakes—Rift-valley lakes—Earthquake lakes—Crater lakes—Coulée lakes—Morainal lakes—Pit lakes—Glint or colk lakes—Ice-dam la...

Nature of earthquake shocks—Seaquakes and seismic sea waves—The grander and the lesser earth movements—Changes in the earth’s surface during earthquakes: faults and fissures—The...

The two contrasted processes of weathering—The rôle of the percolating water—Mechanical results of decomposition: spheroidal weathering—Exfoliation or scaling—Dome structure in...

The system of the fractures—The space intervals of joints—The displacements upon joints: faults—Methods of detecting faults—The base of the geological map—The field map and the...

The rigid quality of our planet—Probable composition of the earth’s core—The earth a magnet—The chemical constitution of the earth’s surface shell—The essential nature of crysta...

The wandering dunes—The forms of dunes—The cloudburst in the desert—The zone of the dwindling river—Erosion in and about the desert—Characteristic features of the arid lands—The...

Lakes as settling basins—Drawing off of water by erosion of outlet—The pulling in of headlands and the cutting off of bays—Lake extinction by peat growth—Extinction of lakes in...

Experimental demonstration of earth movements—Derangement of water flow by earth movement—Sand or mud cones and craterlets—The earth’s zones of heavy earthquake—The special line...

The sources of the history—Subdivisions of geology—The study of earth features and their significance—Tabular recapitulation—Geological processes not universal—Change, and not s...

The law of the desert—The self-registering gauge of past climates—Some characteristics of the desert waste—Dry weathering: the red and brown desert varnish—The mechanical breakd...

Conditions essential to glaciation—The snow-line—Importance of mountain barriers in initiating glaciers—Sensitiveness of glaciers to temperature changes—The cycle of glaciation—...

The glacier flow—Crevasses and séracs—Bodies given up by the _Glacier des Bossons_—The moraines—Selective melting upon the glacier surface—Glacier drainage—Deposits within the v...

The weathering processes under control of the fracture system—The fracture control of the drainage lines—The repeating pattern in drainage networks—The dividing lines of the rel...

Transition from the ice cap to the mountain glacier—The piedmont glacier—The expanded-foot glacier—The dendritic glacier—The radiating glacier—The horseshoe glacier—The inherite...