SOME AMERICAN MONSTERS. 157 



earth or rising ground. It is also applied in a limited sense to 

 the more prominent irregularities of the deeply sculptured slopes 

 of the larger terraces. These buttes, therefore, vary in extent, from 

 a mere mound rising slightly above the level of the plains to hills 

 of varied configuration reaching to the level of the broader buttes 

 or terraces. 



The debris resulting from the continual wearing away, or 

 demolition of these buttes and terraces, now lies spread out on 

 the plains below. From the lower plains the smaller terraces 

 appear like vast earth-work fortifications, and when not too much 

 cut up by erosion, remind one of long railway embankments. 

 But in many cases the terraces are so much cut up by narrow 

 ravines that they appear as great groups of naked buttes rising 

 from the midst of the plain. Nothing can be more desolate in 

 appearance than some of these vast assemblages of crumbling 

 buttes, destitute of vegetation, and traversed by ravines, in 

 which the watercourses in midsummer are almost all dried up. 

 To these assemblages of naked buttes, often worn into castellated 

 and fantastic forms, and extending through miles and miles of 

 territory, the early Canadian voyageurs gave the name Mativais 

 Terres. They occur in many localities of the Tertiary formations 

 west of the Mississippi River. Professor Leidy, who with two 

 friends made an expedition in search of fossils to Dry Creek Canon 

 in this region of the " Bad Lands," about forty miles to the south- 

 east of Fort Bridger (Wyoming), thus describes his impressions : 



" On descending the butte to the east of our camp, I found 

 before me another valley, a treeless barren plain, probably ten 

 miles in width. From the far side of this valley butte after butte 

 arose and grouped themselves along the horizon, and looked 

 together in the distance like the huge fortified city of a giant 

 race, the utter desolation of the scene, the dried-up watercourses, 

 the absence of any moving object, the profound silence which 

 prevailed, produced a feeling that was positively oppressive. 

 When I thought of the buttes beneath our feet, with their 



