146 STANTON & KNOWLTON — LARAMIE AND RELATED FORMATIONS. 



neighborhood of Castle Gate and Pleasant Valley junction, Utah, where 

 the Wasatch seems to be conformable on the Laramie, without interven- 

 ing beds. Another very fossiliferous bed, some 400 feet higher, yielded 

 the following characteristic Eocene mollusks : 



Unio shosltonensis, White. Goniobasis tenera (Hall). 



Unio wasJiakiensis, Meek. Viviparus paludinseformis, Hall. 



This section beneath the Fort Union plants has a close general resem- 

 blance to that of the Ceratops beds in Converse county, and the paleon- 

 tological evidence is in favor of correlating them. 



POINT OF ROCKS. 



At Point of Rocks, 11 miles northwest of Black Buttes, a lower series of 

 coal-bearing rocks is well exposed in cliffs and high hills north and east of 

 the station. Here as at Black Buttes the base of the exposure is formed 

 by a massive light-colored sandstone about 100 feet thick, and this fact, to- 

 gether with evidence of local faulting along the railroad between the two 

 places, has led several geologists to regard the two exposures as represent- 

 ing about the same horizon. Our observations confirmed those of Meek 

 and Bannister in putting the Point of Rocks coal beds several hundred feet 

 lower than those at Black Buttes, and we discovered the additional fact 

 that a considerable portion of the intervening strata consists of marine 

 beds and contains a Fox Hills fauna. The uneven upper surface of the 

 heavy sandstone at Point of Rocks was regarded by Powell as evidence 

 of an erosion interval which separated the Point of Rocks group below 

 from the Bitter Creek group above. The larger number of the fossil 

 plants described from this locality were obtained in argillaceous lenticu- 

 lar masses in the upper part of the sandstone. Others are associated 

 with the coal beds, of which there are several in the series of soft sand- 

 stones, sandy shales, and claj^s exposed in the bluffs north of Point of 

 Rocks station to a thickness of about 260 feet above the massive sand- 

 stone. About the middle of the coal-bearing part of the section two 

 fossiliferous bands have yielded a few species of invertebrates consisting 

 of one marine shell, Pectunctdtis holmesianus (White) ; four brackish-water 

 forms, Ostrea, glabra, var. Wyoming 'ensis, Meek ; Corbula undifera, Meek ; 

 Corbicula occidentalism M. and H., and Anomia sp., and one fresh- water 

 form, Campeloma velula, M. and H (?). A lower horizon below the massive 

 sandstone and exposed two miles west of the station has a similar as- 

 semblage of forms as follows : 



Ostrea glabra, M and H. Corbula subtrigonalis, M. and H. 



Anomia gryphorhynchus, Meek. Melania insculpta, Meek. 



Corbicula cytheriformis, M. and H. Odontobasis buccinoides, White. 



