paralleliped

The thinner walls are composed of a single depth of the paralleliped, while the thicker ones consist of two or more depths: these walls pass the river at several places, rising from the water's edge much above the sandstone bluffs which they seem to penetrate; thence they cross in a straight line on either side of the river, the plains over which they tower to the height of from ten to seventy feet, until they lose themselves in the second range of hills: sometimes they run parallel in several ranges near to each other, sometimes intersect each other at right angles, and have the appearance of walls of ancient houses or gardens.

History of the Expedition under the Command of Captains Lewis and Clark, Vol. I. To the Sources of the Missouri, Thence Across the Rocky Mountains and Down the River Columbia to the Pacific Ocean. Performed During the Years 1804-5-6. William Clark 1804