902.] DOUGLASS — CRETACEOUS AND LOWER TERTIARY. 213 



cottonwoods that occasionally grow along the streams. They make 

 grass-clad rolling prairies, with small ravines cutting into the soft 

 shales. 



The transition beds between the Fort Pierre and Fox Hills are 

 usually obscured by the material washed down from the bluffs of 

 the latter ; but on the ranch of Mr. B. Forsythe, near the head of 

 a branch of Big Coulee Creek, they can be nicely seen. The shales 

 gradually become more sandy, and contain bands of sandstone 

 until the latter predominates and the shales become shaly sand- 

 stones or sandy clays. In them I found no trace of fossils. 



Fox Hills, 



In this formation the hard sandstones form a prominent ridge 

 adjoining the depression made by the Pierre. It is the next promi- 

 nent ridge above the Niobrara. I have followed its base for about 

 thirty-five or forty miles. In only one place was there any confusion 

 or any difficulty in tracing it, and this was caused by some change 

 in the geological structure obscuring the Pierre shales. The out- 

 crop extends southeast and northwest. It forms the southern rim 

 of the Lake Basin. It furnishes many springs which, uniting their 

 waters, produce little streams that cut through the rocky ridge and 

 flow out upon the Pierre flats. In the Fish Creek region they 

 empty into Fish Creek. In the Lake Basin, if the water does not 

 soak into the ground, they flow into the land-locked lakes. Where 

 the streams form little canons and ravines through the Fox Hills 

 strata, they are fringed with trees and shrubbery. In little valleys 

 and amphitheatres there are often springs surrounded by groves, 

 which are very picturesque, and in the heat of summer these places 

 form a delightful retreat from the almost treeless wastes around. 

 The trees, which are principally evergreens, cottonwoods, poplars 

 and willows, follow the streams a little way toward the Pierre flats 

 and then disappear. 



Though these beds usually appear to be sandstone ridges, yet in 

 places where conditions of weathering are favorable they are seen 

 to contain much sandy clay, and in places for a short distance 

 resemble '' bad land " forms. 



Fossil leaves and reptilian bone fragments were found in consid- 

 erable abundance. Dr. Farr brought back some of the fossil leaves, 

 but they have not yet been determined. Most of the bones are too 

 fragmentary to be of much use. Some teeth were recognized as 



