S4 The American Geologist. February, 1894- 
Around Edgeniont, south of the Mills, the country for some 
distance is occupied by the Fort Benton shales. A steep escarp- 
ment which constitutes the vertical face of the first terrace south 
of the Cheyenne, reveals, with their usual characteristics, the 
Inoceramus beds of the Niobrara ; but passing on southwest 
over the hills toward the valley of Cottonwood creek, the Fort 
Benton is again exposed. Erosion of the shales has formed a 
series of Bad Lands on a diminutive scale. It has at the same 
time made prominent certain beds of impure limestone from 
which we obtained numerous fossils. Among the material 
collected here were specimens of Prionocyclus Wyoming en sis 
Meek, Scaphites warreni Meek, 8. wyomingensis Meek. Luna- 
tin concinna M. & II., Tnoceramvs pseudo-mytiloides Schiel, 
two or three other species of Inoceramus, a Pteria or two, and 
many other less obtrusive forms that have not yet been iden- 
tified. 
At the town of Hot Springs some portions of the valley are 
occupied by horizontal beds of a very coarse conglomerate that 
lies unconformably on the folded and tilted Red Beds. The 
thickness of the conglomerate is about forty feet. It is com- 
posed of fragments of all the harder formations from the crys- 
talline rocks at the center of the uplift to the purple limestone 
of the Red Beds, and the quartzite of the Cretaceous. When 
the conglomerate was deposited the valley had essentially its 
present depth. In some cases the streams have just fairly 
completed the work of cutting through the conglomerate, in 
other cases they have cut twenty or thirty feet below its base. 
This conglomerate is probably the equivalent of that lying at 
the base of the White River Miocene. If so, it would indicate 
an enormous amount of erosion between the beginning and 
middle of the Tertiary as compared with the amount accom- 
plished since. 
Returning finally to the main object for which these obser- 
vations were undertaken, it is clear that Bennettites daeo- 
tcnsis Macbride belongs to the Cretaceous period, and the 
evidence is practically conclusive that the exact horizon at 
which the individuals of the species were imbedded is repre- 
sented by the uppermost layers of the Dakota sandstone. 
