The desert was flat, the rock formations and canyons plentiful.
Her laugh echoed down the rocky canyons of Zzz as the essence of abomination breathed his bloody last below her.
The Alleghany Plateau consists of nearly horizontal beds of limestone, sandstone and shales, including important seams of coal; inclines slightly toward the north-west, and is intricately dissected by extensively branching streams into a maze of narrow canyons and steep-sided hills.
There are stony wastes, or alluvial fans, where mountain streams emerge upon the plains, in time of flood, bringing detritus in their torrential courses from the mountain canyons and depositing it along the mountain base.
On its eastern slope the waters soon disappear within the bed of narrow canyons, but break out again at the foot in icecold springs that form the source of the Ruby and Franklin lakes; on its western side the descent is more gentle, and the waters form the South Fork of the Humboldt river.
Several varieties of poplar are found in the upper canyons, and trees of the willow-leaved species in the Humboldt Mountains often attain a height of 60 ft.
In the Great Plains region and in the TransPecos Province the rivers have cut deep canyons, and the character of the longer rivers in their upper courses varies from mere rivulets late in summer to swift and powerful streams during spring freshets.
In the canyons of the Edwards Plateau grow the pecan, live oak, sycamore, elm, walnut and cypress; on the hilly dissected borders of the same plateau are cedars, dwarf and scrubby oak, and higher up are occasional patches of stunted oak, called "shinneries."
There are also deep canyons which have been cut by the rivers in their present courses, especially by the Snake river and its tributaries.
On its slope, which rises abruptly from the Bitterroot Basin, glaciers have cut canyons between high and often precipitous walls, and between these canyons are steep and rocky ridges having peaked or saw-toothed crest lines.
Here the streams that drain the higher areas descend to the plains through narrow canyons in the mountain border, impassable for ordinary roads and difficult of entrance even by railways; a well-known example is the gorge of Clear Creek east of the Georgetown mining district.
Several smaller basins occur in Montana, all somewhat dissected and drained through narrow gorges and canyons by members of the Missouri system.
The few rivers of the region must have reached the quiescence of old age iii the earlier cycle, but were revived by uplift to a vigorous youth in the current cycle; and it is to this newly introduced cycle of physiographic evolution that the deep canyons of the Plateau province are due.
In the new altitude of the mountain mass, its steep eastern face has been deeply carved with short canyons; and on the western slope an excellent beginning of dissection has been made in the erosion of many narrow valleys, whose greatest depth lies between their headwaters which still flow on the highland surface, and their mouths at the low western base of the range.
Glacial erosion has been potent in excavating great cirques and small rock-basins, especially among the higher southern surmounting summits, many of which have been thus somewhat reduced in, height while gaining an Alpine sharpness of form; some of the short and steep canyons in the eastern slope have been converted into typical glacial troughs, and huge moraines have been laid on the desert floor below them.
Where the volcanic formations were spread uniformly over the flanks of the mountains, the contrast between the canyons and the plain-like region of gentle slope in which they have been excavated is especially marked and characteristic. The eastern slope is very precipitous, due to a great fault which drops the rocks of the Great Basin region abruptly downward several thousand feet.
The canyons are largely the work of rivers, modified by glaciers that ran through them after the rivers had formed them.
Above the basin floor; the eastern slope is more gentle, but both slopes are much scored by deep canyons, some of which have been modified in form by ancient glaciers.