12 Annals of the Carnegie Museum. 



northern portion of the butte, are quite hard sandstones, not many 

 feet in thickness, which break off, and the slabs are found on the slopes 

 below. These sandstones, which are overlaid by others more mas- 

 sive and probably grade laterally into them, contain many beautifully 

 preserved fossil leaves. It is here that those which were identified by 

 Knowlton were obtained." Apparently the sandstones which cap the 

 butte are in places laminated and in places massive at the same geo- 

 logical level ; and in some places they are parted by beds of shale, 

 while in other places there are thick masses without intervening 

 shales. The massive sandstones contain some impressions of bark or 

 stems of plants. There are fossil gasteropods in some portions of these 

 beds. 



A section of the bluffs south of Bear Butte, near where the road to 

 Melville leaves Widdecombe Creek and ascends to the plateau, does 

 not show any very massive sandstones, but they appear again in the 

 face of the bluffs farther west. In the former locality the beds dip 

 strongly to the southward, while at Bear Butte they are much more 

 nearly horizontal. Following the road toward Melville, after ascending 

 the bench, one passes for a long distance over a grassy prairie, but 

 within three or four miles of Melville there are again outcrops of the 

 Fort Union strata. The beds here are continuous with those which 

 surround Bear Butte and are the same which the present writer exam- 

 ined in 1905. 



Mr. A. C. Silberling has spent a considerable time in searching for 

 fossil mammals in the vicinity of Bear Butte and Melville, and has 

 obtained an interesting collection of remains, especially teeth, of early 

 Eocene mammals. Only a small portion of these are the property of 

 the Carnegie Museum. It is extremely interesting in the varied fauna 

 which it suggests and the problems which it raises. It is of the 

 greatest importance that collections be made from these beds accom- 

 panied by data as to the exact horizons from which the specimens 

 come, as they may represent successive faunas instead of only one 

 fauna. This is important in any collection, but especially so when 

 the remains represent the earliest of the higher mammalian faunas which 

 we know in this country. 



The larger remains found here most nearly represent the Torrejon 

 stage, but we have also a micro-fauna, part of which is different from 



2 See " Cretaceous and Lower Tertiary Section, etc.," Proc. Amcr. Philos. Soc, 

 Vol. XLI, No. 170, pp. 217-218. 



