20 



of a gravelly coiLslitiilion. They arc fissured in comparatively large masses, 

 wliicli assume a rounded lorm as lliey are worn away, so that a ledge of 

 sandstone projecting from the declivity of a Ijutte will appear like a row of 

 cotton Itales. As they disintegrate less rapidly than the contiguous clays, 

 masses are olten ol)served resting upon cones and columns of the latter, con- 

 triljuting greatly to the picturesque and sometimes fantastic appearance of 

 the l)uttes. 



Many of the table-lands and lesser buttes in the vicinity of the Uintah 

 Mountains are thickly covered with drift from the latter, consisting of gravel 

 and bowlders of red and gray compact sandstones or quartzites. The drift 

 material is usually firmly imbedded in the surface of the plains so as to 

 appear like a pavement. The bowlders are generally small, but assume larger 

 proportions approaching the Uintahs. In many cases the drift completely 

 covers the terraces or buttes, descending upon the declivities s© as entirely to 

 conceal their structure. Usually, however, it accumulates in the ravines of 

 the declivities, leaving bare the intervening ridges of light-colored clays and 

 sandstones. Many of the buttes are nearly or quite free of drift material. 

 Some, again, are strewn with fragments of rock, consisting of tlie harder materials 

 from the terraces themselves, and these likewise occur mingled with the 

 drift-pebbles and bowlders from the mountain-heights. 



The stone-fragments from the buttes consist of harder siliceous and cal- 

 careous clays, impure limestones, jaspers, and less frequently agate and chalce- 

 dony. In some instances they consist of singularly black incrusted and 

 niinided sandstones, somewhat of the character of scptaria. Specimens ot 

 these occasionally !;)ear a resend:)lance to fossil turtles, and when found wWh 

 I he harder crust broken tluy look like turtle-shells filled with a sandstone 

 matri.x. 



In the buttes in the vicinity of Carter Station, on tiie Union Pacific Rail- 

 road, I observed many large nodular and cylindroid masses of agate. These 

 have a concentric arrangement of layers resembling that of fossil wood, for 

 which they arc, taken. Many of the masses contain a nucleus of amber- 

 colored crystals of calcitc. 



Nodules of chalcedony wilh dendritic markings occur in some of the 

 buttes. These, together with the condition of many of the fossils of the 

 buttes, indicate the presence of a considerable proportion of soluble silica in 



