244 Geology and Botany of Northern Pacific Railroad. 



A few miles below the railroad crossing, the valley. expands 

 and opens into the famous mauvaises terres, or "bad lands of 

 the Missouri." The course of that stream is here nearly east and 

 west ; and the valleys of the tributaries running north and south, 

 coalesce, and form in the old lake-bed a picturesque but danger- 

 ous labyrinth. 



As soon as one enters the valley of the Yellowstone, he finds 

 himself surrounded by transported material. Gravel and bould- 

 ers of crystalline, sedimentary and volcanic rocks form the bed 

 and bars of the river, increasing in coarseness and quantity all 

 the way to Livingston ; but in all this material I was unable to 

 find anything that was to me even presumably of eastern origin. 

 Dr. 0. A. White,. (Am. Journal of Sci., vol. XXV, 1883, p. 206,) 

 reports finding what he considers eastern glacial drift along the 

 valley of the Missouri and that of the Yellowstone ; but my 

 search for such material was vain. As will be seen further on, 

 I found in the valley of the Missouri about the Falls, great quan- 

 tities of drift with boulders of fossiliferous limestone, quartzite, 

 gneiss and granite, all remarkably like the Eastern drift, but 

 which I subsequently traced to their places of origin in the Belt 

 Mountains. 



The surface geology of the Y 7 ellowstone Park has been de- 

 scribed in considerable detail by Mr. W. H. Holmes and Mr. 

 A. C. Peale ; but I was surprised to find the traces of glacial 

 action so wide-spread and unmistakable. It is probably not 

 too much to say that every valley of the Park was once filled 

 with ice ; for moraines, boulders, glacial lakes, and more rarely 

 glacial striae, give testimony that cannot be disputed. Ice-borne 

 blocks are seen on the sides of the Yellowstone valley, below 

 the mouth of Gardner's River ; and about Mammoth Hot Springs, 

 every depression once held a glacier. Swan Lake is of glacial 

 origin, and is bounded on the south by a moraine, while lateral 

 moraines and striated rock-surfaces mark the old ice-level 

 high up on the sides of the valley. Near Marshall's, the 

 road leads over a succession of great moraines of clay and 

 boulders, which continue to and around the Fire Hole basin, 

 and prove that this also was once largely, filled with ice. From 

 all that I could learn, the evidences of glacial action, found here 

 in the lowest portion of the Park, may be traced through all 

 parts of it. 



