ROBERT HAY SANDSTONE DIKES. 



51 



northwestern Nebraska, which was likewise distant from eruptive centers, but 

 stated that the material was sandstone. Last winter, at the meeting < if the Geological 

 Society of America, Mr. J. S. Diller read a paper on sandstone dikes in California, 

 which, with its illustrations, forms a very attractive issue of the Society's memoirs.'" 

 Within a short time I have seen two sandstone dikes in northwestern Nebraska. 

 One is that referred to above as mentioned by Professor Hicks, which he had 

 already described to me. The second is only half a mile fn >m the first, and possibly 

 may be a continuation of it. I have seen the firston two different occasions, takinu 

 measurements both times; the second one was visited only once, on the same date 

 as the second visit to the first. On this occasion I was accompanied by Professor 





* 



y 



. v 





^*\s 



Figtjee 18 — Sandstone Dike number 1. 



Culver, who filled the chair of geology in the university of South Dakota. So far 

 as the measurements are concerned, Professor Culver is responsible as much as 

 myself. The general description he can verify. 



The town of Chadron is situated on the line of the Fremont, Elkhorn and Missouri 

 Valley railway, and" lies immediately under the heights of Pine ridge, where the 

 I ia r«ler Tertiary beds of this region are seen over the softer clays and marls forming 

 the " manvaises terres," which, beginning under Pine ridge, stretch away inward 

 the north and east ami, with occasional cappings of the harder beds, become the 

 " bad la in Is" proper of South Dakota. Pet ween Chadron and White river, however. 



♦ Bull. Geol. Soc. Am., vol. 1, L890, pp. Hl-442, pla. G-8. 



