54 COLORADO COLLEGE STUDIES. 



THE PEARLETTE ASH. 



The volcanic ash may be called the Pearlette ash, from 

 the old postoffice of Pearlette, in Meade county, where the 

 writer studied an ash- bed of this terrane in 1884. The 

 Pearlette rarely contains fossils. These do not differ from 

 those of the underlying Meade formation. The ash attains 

 a thickness of 13 feet in a bed southwest of Meade Center, 

 considerably less in Clark and the many other counties of 

 Kansas (especially western Kansas), Nebraska, etc., in 

 which the ash has been found. It occurs west at least to 

 Huerfano Park, Colorado (Hills), and east to Sioux City, 

 Nebraska (Todd), and Galena, Kansas (Williston). Ii 

 frequently passes into the Kingsdown by imperceptible 

 gradations. 



THE KINGSDOWN MARLS. 



For the marls, the name Kingsdown marls is proposed, 

 after the station of that name west of Bucklin on the Rock 

 Island railway, between which and the upper part of Bluff 

 creek, Clark county, they are finely exposed in deep ra- 

 vines. They are very rarely fossilferous. ElepJias was found 

 by the writer in them near Vanhem. They are typically de- 

 veloped in Meade county also. They are apparently not 

 less than 100 feet in thickness in Clark county, and more 

 than twice that thickness at certain localities on the divides 

 further westward. 



All three of the terranes here described are supposed 

 to be formations of the Tide division of Cummins (Equus 

 beds of Cope), and to represent late PHocene time. They 

 are conformable with each other, and unconformably over- 

 laid with local beds of marl, sand, diatomaceous earth, etc., 

 of supposed Quaternary age. 



