182 EEPOET UNITED STATES GEOLOGICAL SURVEY. 



lu a letter, Professor Lesquereux says "all" these leaves "are char- 

 acteristic of the Lower Lignitic or of the Lower Eocene, and have been 

 found at Point of Eocks, Black Butte, and Golden, especially, the most 

 abundant fragment being nf Fiais planicostata, and its variety Goldiana. 

 These plants were obtained from a sandstone at the very top of the 

 group which I have referred to, the Laramie group; and this bed may 

 perhaps be referred in the future to the Wahsatch group. 



TERTIARY. 



The Tertiary strata cover larger ])roportionate areas in the northern 

 district (Area B) than any other. The accompanying map (Plate'XI) 

 will give the best idea of their extent. In Area A there are no beds 

 referable to the Tertiary. 



The Tertiary strata capping the Book Cliffs extend northward into 

 Dr. Endlich and Dr. White's districts, dipping gently away from the 

 edge of the cliff's. The Green Eiver group forms the summit as an 

 escarpment, in which the beds weather of a white color, from which the 

 variegated beds beneath are distinctly separable in the eastern portion 

 of the area. Toward the west, however, the distinction is not well 

 marked, as the Wahsatch beds consist of harder sandstones and the 

 variegated character is almost entirely lost. 



The following table will show at a glance the differences at the different 

 points. The third section was made in 1874, but is in the same neigh- 

 borhood : 



