264 Annals of the Carnegie Museum. 



to the Deer Lodge River. It has a very uneven topography. There 

 were long lateral moraines, ridges, hogbacks, rounded hills, and cor- 

 respondingly varied depressions. Granite boulders are extremely 

 numerous, sometimes forming a very large proportion of the hills and 

 moraines. 



Near Pioneer we found quite considerable natural outcrops of White 

 River deposits, and large areas had been uncovered by placer-mining 

 operations. The beds are gray, nearly white, and are in part well 

 stratified. The only fossils obtained were fresh-water mollusca (snails) 

 and bones and scales of fishes. The excursions above mentioned were 

 made from the 21st to the 25th of October. 



We went next to the Bitter Root Valley, northeast of Stevensville, 

 where short excursions were made. The region certainly does not 

 abound in fossiliferous rocks, as many a fruitless tramp in the Missoula 

 and Bitter Root valleys had previously taught me. On account of 

 this scarcity of organic remains, the geological history of nearly all of 

 the extreme western portion of Montana is very obscure. 



In his valuable paper, "A Geological Reconnaissance across the 

 Bitter Root-range and Clearwater Mountains in Montana and Idaho," 

 Mr. Waldemar Lindgren says : 



" An exact statement of the geological history of this region is 

 difficult to give on account of the few exactly determinable datum 

 planes. There are really only two determinations of time on which 

 we may rely. The first is the date of the Columbia River lava as 

 Miocene; the second is the Glacial epoch as early Quaternary."" 

 Later in the same paper (page 30) he says : " No direct evidence of 

 the former existence of a lake within the valley has been found. The 

 east side, however, has not been carefully examined, and from the 

 general configuration it would seem possible that the depression, like 

 many other intermontane valleys of this region, was occupied by a 

 lake in Tertiary times." 



In 1889 and 1901, while living in the Bitter Root Valley, I spent 

 much time in exploring the benches east of the Bitter Root River in 

 the eastern portion of the valley. The deposits, which form the 

 benches, are composed of sand, gravel, and volcanic ash, resembling 

 some of the Tertiary beds in other portions of the state ; but in all 

 my search I succeeded in finding only a very few isolated fragments 

 of mammalian fossils. Of these only two were determinable. One 



■'Professional Paper No. 27, U. S. Geological Survey, 1904, p. 26. 



