SMITHSONIAN EXPLORATIONS, I929 



33 



to determining the age of the various sedimentary deposits of the 

 vSnake River A^alley and to secure material for study and exhibition 

 purposes in the National Museum. Guided by our preliminary survey 

 of the whole territory, certain more favored localities were chosen 

 for operation, and the work was carried on with good success through 

 two months, nearly 3 tons of fossils resulting from the expedition. 



From a geologic standpoint one of the important developments of 

 the expedition was the rather conclusive demonstration that most of 

 the heavy gravel and sand deposits of the valley were accumulated 

 during the last geologic epoch known as the Pleistocene, or " Ice 

 Age." The fauna represented by the various fossil bones collected 

 proved interesting and important. The pioneers of the Old Oregon 



Fig. 25. — Typical view of Snake River Valley. Idaho. 



trail, as has already I^een remarked, saw much big game on their 

 journeys through this desert country, but the big game of our 

 pioneer days was quite tame hunting as compared with what it would 

 have been in that much earlier time of some 500,000 years ago. There 

 were bison in that day also, but what bison ! One kind common in that 

 distant Pleistocene time was much like the present day type, both in 

 size and general appearance ; but a contemporary form, apparently 

 quite as numerous, very much overtopped him in both size and devel- 

 opment of horns. This bison was provided with great horns, each 

 bony core of which was about two feet long and more than 6 inches 

 in diameter at the base. In life these horns must have had a spread 

 of not less than seven feet. But even this giant bison was not undis- 

 puted king of the range, for sharing it with him were great musk-ox- 



