Dinocerata, a Monograph of an Extinct Order of Gigantic Mammals

Abstract

ON the high plateau that lies to the west of the Rocky Mountains, along the southern borders of Wyoming Territory, the traveller who is moving westwards begins to enter upon a peculiar scenery. Bare, treeless wastes of naked stone, crumbling into sand and dust, arise here and there into terraced ledges and strange tower-like prominences, and sink into hollows where the water gathers in salt or bitter pools. Under the cloudless sky, and in the dry clear atmosphere, the extraordinary colouring of these landscapes forms, perhaps, their weirdest feature. Bars of deep red alternate with strips of orange, now deepening into sombre browns, now blazing out again into flaming vermilion, with belts of lilac, buff, pale green, and white. And everywhere the colours run in almost horizontal bands, the same band being continuous and traceable from hill to hill, and tower to tower, across hollow and river-gorge for mile after mile through this rocky desert. These parallel strips of colour mark the nearly horizontal stratification of the rocks that cover all this wide plateau country. They are the tints characteristic of an enormous accumulation of sedimentary rocks that mark the site of a vast Eocene lake or succession of lakes on what is now nearly the crest of the continent. These lacustrine sediments, in all somewhere about two miles in vertical thickness, were doubtless laid down during a slow subsidence of the lacustrine area, when the subterranean movements were in progress that finally gave the mountain-ranges and plateaux their present forms and altitudes. They represent a vastly protracted period of quiet sedimentation, in the immediate proximity of an extensive land-surface plentifully clothed with a tropical vegetation, and abounding in varied forms of animal life. They consequently offer to the geologist peculiar facilities for investigating the evolution of a fauna apparently exposed to the minimum of interference from changes in its environment.

Dinocerata, a Monograph of an Extinct Order of Gigantic Mammals.

By O. C. Marsh. Monographs of the U.S. Geological Survey. Vol. X. (1884.)