Stevenson.] ttO'i . [June 18, 



indurated sands and clays. In the neighborhood of Fort Steele the sand- 

 stones, seen at Medicine Bow, are found resting on Cretaceous clays, and 

 passing up into the coal-bearing strata. These contain a characteristic 

 fucoid, which Mr. Lesquereux has designated by the name of Halymenites 

 major. 



Along the Union Pacific Railroad, from Como to St. Mary's, nearly fifty 

 miles, the lignitic rocks prevail and the heavy sandstone at the base 

 is traceable to Carbon, where a coal overlying it is mined. This is 

 the fucoidal or lignitic sandstone, showing the fucoid just referred to. 

 The overlying rocks contain vast numbers of deciduous leaves. Beyond 

 Rawlings' Springs this series is again seen, overlying Cretaceous clays, and 

 at Separation a coal, probably the same as at Carbon, is worked. At this 

 locality leaves and fresh-water shells are found in the upper portion of 

 the group which appears to be not far from two thousand feet thick. 



From Separation to Bitter Creek Station horizontal Tertiary beds pre- 

 vail, but occasional borings have demonstrated that the coal-strata are not 

 deeply buried. These Tertiary beds are of fresh-water origin and con- 

 tain TInio, Melania, and other fresh-water species. They are unconform- 

 able to the lignite series and occupy a synclinal trough formed by these 

 rocks. 



According to Messrs. Meek and Bannister, there occurs between Bitter 

 Creek Station and Green River an enormous accumulation of coal-bear- 

 ing rocks, not much less than 4000 feet thick, and underlaid by about 

 1000 feet of sandstone. The greater portion of the upper series is clear- 

 ly of brackish-water origin, as it contains layers at various horizons, from 

 which Ostrea, Corbula, Melania, and Goniobasis were obtained. Many 

 layers are rich in deciduous leaves, and from one in the upper portion of 

 the series the remains of a saurian were obtained. These were after- 

 wards desci'ibed by Prof. Coj)e, under the name of Agatliauimis sylvest7'is. 

 Before reaching Green River, these rocks under-run, unconformably, a 

 later series, known as the Green River shales. 



Messrs. Meek and Bannister made no examination at Point of Rocks . 

 At this locality Mr. Lesquereux found an anticlinal which exposed the 

 shales of CretaceouSj No. 4, underlying conformably the great fucoidal 

 sandstone. This rock is 185 feet thick, and contains Halymenites major, 

 Lesqx. This sandstone has a striking lithological character, which is 

 widely persistent in the Rocky Mountain region. It is a little strange 

 that these Cretaceous rocks do not appear under the Bitter Creek series 

 at Salt Wells, where Meek and Bannister found the great mass of sand- 

 stone. 



From Green River westward to Bear River the coal rocks are not seen, 

 and the same is true respecting the region between Bear River and Coal- 

 ville. These areas seem to be utterly isolated. Mr. Emmons finds them 

 surrounded on all sides by the Tertiary beds in such a way as to prevent 

 any junction by stratigraphy with other areas. 



At Bear River, the strata have been so distorted that it is not easy to 



