Douglass : A Geological Reconnalssance. 265 



was a small piece of a tooih. o{ z. Mastodon and another the lower 

 portion of the ulna-radius of a fairly large Procamelus. This shows 

 that a portion at least of the upper beds belonged to the Miocene. 



In 1905 on Ambrose Creek northeast of Stevensville, where the 

 bench-land begins to slope gently upward toward the mountains, we 

 found scattered over the loose sandy soil, a few fragments of bones 

 and teeth, some of the latter of which belonged to the high-toothed 

 type of later Miocene horses. Thus the observations of previous years 

 were confirmed. There are, however, beds which lie lower and are 

 exposed — one or two hundred feet in thickness — in a bend of the 

 Bitter Root River, twelve or fifteen miles below Stevensville. These 

 beds I believe to be Oligocene, though no characteristic fossils were 

 found in them. 



One day we made a trip eastward to near the mountains. The first 

 deposits (Miocene) encountered were composed of sand, which was 

 perhaps slightly water-worn, but not very distinctly assorted by the 

 action of streams. Nearer the mountains were higher benches com- 

 posed of sand and gravel, which were in some places slightly consoli- 

 dated. On ascending the bench I saw, a mile or more distant what 

 appeared to be good exposures of gray Tertiary deposits. On reach- 

 ing the spot it was seen that what appeared to be Tertiary rocks were 

 pure decomposing granite. The slopes were covered with grains of 

 quartz and crystals of feldspar, which by atmospheric agencies were 

 being moved down the hillsides toward the streams. Here then we 

 have near the mountains sand composed of quartz and feldspar caused 

 by the decomposition in place of granitic rock. A little farther away 

 toward the west is the same kind of sand, little or not at all water- 

 worn, but mixed with other material and forming the high bench- 

 land. Still farther to the west nearer the river, are similar sands, 

 perhaps slightly water-worn, mixed with lighter-colored material 

 ( volcanic ash ?, etc), and containing remains of Miocene mammals. 

 There are similar conditions in other portions of western Montana. 

 A careful study of these beds would undoubtedly throw much needed 

 light on their origin. I do not see that there is much evidence that 

 these Miocene deposits in the Bitter Root Valley were formed to any 

 great extent in a lake, and a large portion of them are evidently not 

 river deposits. 



On the Flathead Indian reservation, we stopped at Ravalli and ex- 

 amined the soft buff-colored deposits between that place and Arlee, 



