This plateau, however, is not a plain, but contains many buttes and mesas and isolated mountain ranges rising from 1000 to 8000 ft.
Several valleys often unite into a large elevated plain, broken only by scattered buttes and spurs.
The region of the Colorado river is largely desert, with occasional buttes and spurs.
The valleys of the principal streams are deeply eroded; bluffs are common along their borders, and buttes elsewhere on the plains.
The surface of this plain, however, ranges from level river valleys in the east to irregular plateaus broken by buttes and scored by canons in the west.
The faces of buttes and ravines that are turned toward the sun are usually devoid of vegetation.
The plains are by no means a simple unit; they are of diverse structure and of various stages of erosional development; they are occasionally interrupted by buttes and escarpments; they are frequently broken by valleys: yet on the whole a broadly extended surface of moderate relief so often prevails that the name, Great Plains, for the region as a whole is well deserved.
A little north of the centre of the valley rise the Marysville Buttes, the remains of a maturely dissected volcano (2128 ft).
Erosion buttes and mesas occasionally rise as picturesque monuments above the general level of the plains, and in the vicinity of the mountains the plains strata, elsewhere nearly horizontal, are bent sharply upward and carved by erosion into " hogback " ridges.
In the region between the Northern and Southern Rockies, the plains are interrupted by minor Mountain groups, volcanic buttes and lava flows, among which the Leucite Hills and Pilot Butte are prominent examples.
Contains the Little Missouri Buttes and the Mato Tepee (or Devil's Tower), prominent erosion remnants of volcanic intrusions.
Taylor volcano (11,389 ft.), which is surrounded by lava tables and some of the most wonderful volcanic buttes in the world.
It is dominated by high mountains, gashed by superb canyons of rivers, scarred with dry gullies and washes, the beds of intermittent streams, varied with great shallow basins, sunken deserts, dreary levels, bold buttes, picturesque mesas, forests and rare verdant bits of valley.
The most prominent features of this part of the state are the arid Snake river plains and three mountain-like elevations - Big, Middle and East Buttes - that rise from their midst.
Its surface consists of a thick sheet of pumiceous sand and dust, from which arise occasional buttes and mesas.