Douglass : A Geological Reconnaissance. 287 



tion I judged that the Lower White River beds extended northward to 

 the region west and north of Dickinson, but I may be mistaken in this. 

 The region has recently been more carefully examined by a member 

 of the North Dakota Geological Survey and probably a report on this 

 region will soon be published. East of the Little Bad Lands are 

 clusters of hills, apparently composed of Lower White River deposits. 

 They rise to a greater height than the exposure of the middle and 

 upper beds. The lithological character of the beds changes in the 

 direction of Dickinson ; whether this is due to local differences at the 

 time of deposition, or whether lower levels are exposed, is difficult to 

 determine. I had supposed that the deposits near Dickinson, from 

 which the Dickinson Brick Company gets its clay, to be lower Oligo- 

 cene, but from the leaves which were collected there, Professor 

 Knowlton judges them to be Eocene. 



There is presumptive evidence that the White River formations in 

 North Dakota represent the deposits made in an old river valley 

 traversed by streams which had their origin in the region of the Black 

 Hills. The Lower White River beds both at White Butte and in the 

 Little Bad Lands, contain in places granite and quartzite pebbles, 

 some of the latter of which are quite large, two or more inches in 

 diameter. A large portion of the deposits consist of clear white quartz 

 sand evidently derived from the decomposition of granitic rock. A 

 very large proportion of the upper beds is also sand, but deposited 

 under different conditions, for where the sands are consolidated into 

 sandstone the cementing material is often green, undoubtedly on ac- 

 count of the presence of iron. White River deposits have now been 

 certainly identified in the Little Bad Lands about i6o miles north of 

 the Black Hills and at White Butte about 30 miles nearer. Professor 

 J. E. Todd, of the South Dakota Geological Survey, has found what 

 he believed to be "Miocene" (White River and Loup Fork) de- 

 posits on the Cave Hills nearly 40 miles, and on Slim Buttes 55 or 60 

 miles, nearer the mountains, also on Short Pine Hills and on Deers 

 Ears Hills.'-" Mr. O. A. Peterson informs me that in the region north 

 of the Black Hills there are areas of coarse sand and gravel of Lower 

 White River age. 



-"See South Dakota Geological Survey, Bull. No. 2, p. 60. On page 17 of this 

 bulletin Professor Todd says : " Two important geological discoveries were made : 

 First, a development of White River and Loup Fork Formations, 300 or 400 feet in 

 thickness about Slim Buttes, and traces of them were found in the upper portion of 

 most of the buttes of the region. ' ' 



