BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 10, pp. 383-396, PLS. 42-44 DECEMBER 22, 1899 



JURASSIC FORMATIONS OF THE BLACK HILLS OF SOUTH 



DAKOTA * 



BY N. H. DARTON 



{Read before the Society December 28, 1898) 

 CONTENTS 



Page 



Field of investigation , 383 



General character of Black hills 384 



Previous investigations of Black Hills Jurassic beds 385 



Relations of the base of the Jurassic 386 



Classification, composition, and nomenclature of Black Hills formations 386 



Sundance formation 387 



General characteristics 387 



Fossils of the formation 388 



Geological succession at various localities 388 



Vicinity of Catholicon Springs hotel, Hot Springs 388 



Hot Springs vicinity . . 389 



Buffalo Gap vicinity .' . 389 



Fuson Creek locality 390 



Lame Johnny locality 390 



Region south of French creek 390 



Dry Creek canyon 390 



Squaw Creek locality , 391 



Spring Creek locality ... 391 



Rapid Creek area 391 



Locality at Cascade 391 



Southern margin of uplift 392 



Vicinity of Newcastle and Cambria 392 



Section in Belle Fourche valley 392 



Unkpapa sandstone 393 



Beulah shales 393 



History of the Jurassic deposits 394 



Field of Investigation 



During the past two seasons I have been engaged in making a de- 

 tailed study of the sedimentary formations of a portion of the Black 



* Printed by permission of the Director of the United States Geological Survey. 

 LV— Bull. Geol. See. Am., Vol. 10, 1898 (383) 



