William Morris Davis

“ The resistance which these masses have to contend with is of two kinds: first, the feeble, insensible attraction of the remaining mass; second, the resistance of the ether.
The first diminishes with the square of the increasing distance, but is never reduced to absolute zero; the second, however, diminishes with the diminishing speed, and finally becomes nothing, at which time the body stops.
Now, would these farthest masses return? Most certainly they would; for no distance can be named so great that the force of gravity shall become absolutely nothing. ”

“ The valley floors always join at accordant levels, as is the habit among normally subdued mountains; they thus contrast with glaciated mountains such as the Alps and the Canadian Rockies, where the laterals habitually open as “hanging valleys” in the side slope of the main valleys. It is a peculiar feature of the drainage in North Carolina that the headwaters lie to the east of the highest mountains, and that the chief rivers flow north-westward through the mountains to the broad valley lowland of the stratified belt and then through the plateau, as the members of the Mississippi system. ”

“ The till plains, although sweeping in broad swells of slowly changing altitude, are often level to the eye, and the view across them stretches to the horizon, unless interrupted by groves of trees along the watercourses, or by belts of low morainic hills. ”

“ To-day they are covered with farms. The cause of the treelessness has been much discussed. It does not seem to lie in peculiarities of temperature or of precipitation; for trees thrive where they are properly planted on the prairies; every town and farm to-day has its avenues and groves of trees; but it should be noted that west of the Mississippi river increasing aridity becomes an important factor, and is the chief cause of the treelessness of the Great Plains (see below) . The treelessness of the prairies cannot be due to insufficient time for tree invasion since glacial evacuation ”

“ If the ponderable moving matter of the universe be limited, then, by constant collision, its motion would all be converted into heat and light, and be radiated into the outer realms of space, never to return again, leaving all the ponderable matter to collect into one great mass, and to cool off to a state of perfect quiescence. ”

“ To discover the facts of inference and to demonstrate their connection with the facts of observation is the effort of all theorizing. A theory is, in brief, a statement in which the supposed facts of inference are reasonably connected with the known facts of observation. ”

“ A section of the coastal plain, from North Carolina to southern New Jersey, resembles the plain farther south in general form and quality of soils, but besides being narrower, it is further characterized by several embayments or arms of the sea, caused by a slight depression of the land after mature valleys had been eroded in the plain. The coastal lowland between the sea arms is so flat that, although distinctly above sea-level, vegetation hinders drainage and extensive swamps or “pocossins” occur. Dismal Swamp, on the border of North Carolina and Virginia, is the largest example. ”

“ Or, in other words, it may be forming a new bud, which, when properly vivified by another one, may blossom forth with the most brilliant rainbow hues, and finally ripen into planetary fruit which shall become the happy home of future intelligent races. ”

“ It is true that many of these ranges are characterized by the rounded tops and the rather evenly slanting, waste-covered slopes which normally result from the long-continued action of the ordinary agencies of erosion; that they bear little snow in summer and are practically wanting in glaciers; that forests are often scanty on the middle and lower slopes, the more so because of devastation by fires; and that the general impression of great altitude is much weakened because the mountains are seen from a base which itself is 5000 or 6000 ft. ”

“ Now, the tidal energy, as above calculated, causes the planet to pull the nearest pound with 1.6 grain greater force than it does the central pound, while, at the same time, it pulls the central pound with practically 1.6 grain greater force than it does the farthest pound; consequently the tensile pull between these two surface-pounds, which would be required to resist the tidal energy, must be equal to 2 x 1.6 grain, while they are drawn toward each other by the gravity of the satellite with the force of only 1.6 grain. ”

“ The middle section of the Appalachians, rather arbitrarily limited by the Hudson and the James rivers, may be described first because The Middle Appalachians. it contains the best representation of the three longitudinal belts of which the mountain system as a whole is composed. The mountain-making compression of the heavy series of Palaeozoic strata has here produced a marvellous series of rock folds with gently undulating axes, trending north-east and south-west through a belt 70 or 80 m. wide; no less wonderful is the form that has been produced by the processes of sculpture. ”

“ The second reading of the essays, directed to an examination of the scientific method employed by the author, should have for its most valuable result a better appreciation of the nature of "theorizing" than most persons possess. The immediately observable elements of such phenomena as light and tides are called "facts"; but an intelligent inquirer is soon persuaded that the facts of observation are really only a small part of the total phenomena. ”

“ These rings gradually approach the planets, till finally they fall upon their surfaces, and become part of them; while the planets themselves are approaching their primaries to succumb to a like fate.
Having absorbed their planetary attendants, and having cooled off so as to become cold, dark bodies, like the earth, they enter the sphere of each other's sensible attraction, and begin to approach with continually increasing velocity, till finally they meet, each arriving at the point of contact with a velocity of from 400 to 500 miles a second, depending on their mass and density. ”

“ Snake river has cut a deeper canyon farther south-east where the plains are higher and has disclosed the many lava sheets which build up the plains, occasionally revealing a buried mountain in which the superposed river has cut an even narrower canyon. One of the most remarkable features of this province is seen in the temporary course taken by the Columbia river across the plains, while its canyon was obstructed by Pleistocene glaciers that came from the Cascade Mountains on the north-west. ”

“ The desire to theorize should not be resisted, but theorizing should be carefully cultivated and its results should be carefully held apart from those of observation. Notice, second, that, some facts of observation having been gained, the inquisitive mind at once sets about inventing schemes that may possibly include the mental counterparts of the unseen phenomena, or facts of inference, and then proceeds to determine the correctness of the inventions by certain logical devices or tests. ”

“ The western slope of the Sierra Nevada bears fine forests similar to those of the Cascade Range and of the Coast Range, but of more open growth, and with the redwood exchanged for groves of “big trees” (Sequoia gigantea) of which the tallest examples reach 325 ft. The higher summits in the south are above the tree line and expose great areas of bare rock: mountaineering is here a delightful summer recreation, with camps in the highland forests and ascents to the lofty peaks. ”

“ That this satellite of Mars and others in our system were much farther away from their primaries than they now are, will be proved, by proving that, if a nebulous satellite revolved around any primary in the short period in which most of the solid ones now do, the tidal energy—or tendency to elongation and disruption—which would, in that case, be generated on its opposite sides by such rapid revolution, would be sufficient to tear it into atoms. ”

“ The Great Plains.—A broad stretch of country under laid by nearly horizontal strata extends westward from the 97th meridian to the base of the Rocky Mountains, a distance of from 300 to 500 m., and northward from the Mexican boundary far into Canada. This is the province of the Great Plains. Although the altitude of plains increases gradually from 600 or 1200 ft. on the east to 4000, 5000 or 6000 ft. near the mountains, the local relief is generally small; the sub-arid climate excludes tree growth and opens far-reaching views. The plains are by no means a simple unit ”

“ Assuming the density of the earth to be 512 times that of ice, it follows that, if a globe of ice—say ten miles in diameter—be isolated in space, a small dense body, as a bullet, near its surface, should fall toward it—by the action of its gravity alone—through 160 inches during the first minute of its descent. ”

“ Farther south, through Oregon and northern California, many members of the coast ranges resemble the Cascades and the Sierra in offering well-attested examples of the uplift of masses of disordered structure, that had been reduced to a tame surface by the erosion of an earlier cycle, and that are now again more or less dissected.
Several of the ranges ascend abruptly from the sea; their base is cut back in high cliffs; the Sierra Santa Lucia, south of San Francisco, is a range of this kind; its seaward slope is almost uninhabitable. ”

“ If the entire nebulous mass could be preserved in the form of an expansible spherical shell, while the entire amount of heat-force should be acting upon its interior surface to force it outward, then, according to the above-named law of conservation, the entire mass would be thrown nearly to the limit of its sphere of sensible attraction ”

“ The fertility of the prairies is a natural consequence of their origin. During the mechanical comminution of the till no vegetation was present to remove the minerals essential to plant growth, as is the case in the soils of normally weathered and dissected peneplains, such as the Appalachian piedmont, where the soils, though not exhausted by the primeval forest cover, are by no means so rich as the till sheets of the prairies. Moreover, whatever the rocky under structure, the till soil has been averaged by a thorough mechanical mixture of rock grindings ”

“ The upturned stratified formations wrap around the flanks of the range, with ridges and valleys formed on their eroded edges and drained southward by the Pecos river to the Rio Grande and the Gulf of Mexico. The mountains rapidly grow wider and higher northward, by taking on new complications of structure and by including large basins between the axes of uplift, until in northern Colorado and Utah a complex of ranges has a breadth of 300 m., and in Colorado alone there are 40 summits over 14,000 ft. in altitude, though none rises to 14,500. ”

“ As is always the case in the broad denudation of the gently inclined strata of such plains, the weaker layers are worn down in sub-parallel belts of lower land between the oldland and the belts of more resistant strata, which rise in uplands.
Few better illustrations of this class of forms are to be found than that presented in the district of the Great Lakes. The chief upland belt or cuesta is formed by the firm Niagara limestone, which takes its name from the gorge and falls out through the upland by the Niagara river. ”

“ The central plains are divided by a hardly perceptible height of land into a Canadian and a United States portion; from the latter the great Mississippi system discharges southward to the Gulf of Mexico. The upper Mississippi and some of the Ohio basin is the prairie region, with trees originally only along the watercourses; the uplands towards the Appalachians were included in the great eastern forested area; the western part of the plains has so dry a climate that its herbage is scanty, and in the south it is barren. ”