384 N. H. DARTON — JURASSIC FORMATIONS OP THE BLACK HILLS 



hills of South Dakota and Wyominfij. The principal observations were 

 made in the southern half of the area, but some atttention was given to 

 the northern extension of the Mesozoic formations. Tlie fossil fish de- 



FiGURE 1. — Outline Map of Black Hills 



scribed by Doctor Eastman in his paper, which immediatelj^ follows this 

 one, were discovered in 1898 in tlie Jurassic beds near Hot Springs, 

 South Dakota, near the southern margin of the region. 



General Character of Black Hills 



The Black Hills uplift is an irregular dome-shaped anticlinal, having 

 in its more obvious features an oval area 120 miles in length and 60 



