Douglass: A Geological Reconnaissance. 227 



cept White Butte, seemed to have the same general appearance and 

 structure as the one on which I was standing ; and they are undoubt- 

 edly similar in origin. They are the scattered monuments, left by 

 erosion, of an ancient plain, the surface of which was once higher than 

 are the highest hill-tops at the present time. 



On the north side of the Black Butte are good exposures showing 

 the rocks of which it is composed. Near the base are shales, usually 

 laminated, containing in many places large brown concretions, which 

 break into angular fragments. Above these is a seam of lignite twenty 

 feet or more in thickness. In the soft shaly clay above this seam are 

 many dark impressions of plants. These shales, which are gray, con- 

 tinue upward eighty or ninety feet. They are usually laminated and 

 soft, but some layers are a little harder, while others are very sandy 

 and incoherent. One layer, sixty or seventy feet above the seam of 

 lignite, is crowded with fossil ferns and leaves of deciduous trees, the 

 lower portion being almost entirely made up of them. These were 

 determined by Dr. Frank H. Knowlton, of the United States Geological 

 Survey, and were found to consist of ferns {Asplenium), scouring rushes 

 (^Equisetuvi), poplars (^Popiiliis), arborvitae {Thuja), bitter-sweet 

 (^Celastrus), and others. 



Above the shales are beds which contain more sand, and there are 

 some layers of sandstone ; still higher, there are strata, about one 

 hundred or one hundred and twenty-five feet in thickness, of sand 

 and clay, mostly gray or white in color, and containing brown concre- 

 tionary layers. These beds are not so distinctly laminated as those 

 below. Some distance above these beds is a considerable thickness of 

 brownish sandstone of a sugary texture. The sandstone, forming the 

 top or "rim" of the butte, is thick, and often quite massive. It 

 is this which protects the softer strata beneath, preserving the butte 

 and giving it its characteristic form. The top of the butte is not so 

 flat as it appears from the sides, but is more or less grooved by ravines. 



Some of the plants which were noticed on Black Butte were ash 

 {Fraxiniis viridis), thorn apple ( Cratcegus), birch {Beiuia), and aspen 

 {Populus iremuloides) . Near it were ash (^Fraxinus viridis), choke- 

 cherry (^Pruniis virginiafid) kinnikinnick {Cornus ammomim ?), wolf- 

 berry i^Syinphoricarpos occidentalis ?), rose, sage (^Artemisia), wild 

 sunflower, golden-rod, etc. Among the birds were grouse, brown 

 thrushes, king-birds, and various species of sparrows and hawks. 



I regret that there was not time to make a more careful study of the 



