52 



PROCEEDINGS OF WASHINGTON MEETING. 



there is but little of harder mortar beds, the deep ravines being almost entirely in 

 the softer marls and clays. In places they are cut down to Cretaceous shales, prob- 

 ably here of the Montana group. 



Directly southward from the western part of the town of Chadron, and at a dis- 

 tance of a little over two miles, or just over the ridge (from which the entire valley 

 of White river and the labyrinth of "bad land" ravinesare visible), and just a little 

 to the left of the road running northward, is the first dike, or number 1. It is in the 

 upper part of a ravine, which joins many others near by. It is so inconspicuous 

 that it may be easily missed, yet was once much better developed than now and 

 had the name of the " natural wall." Notwithstanding this name, there is a very 



-, 





Figure 10 — Eastern End of D ; ke number 1. 

 Showing thai the dike * 1 i < 1 not teach the top pf the Muff. 



common impression that it is the work of human art, and was made by ancient 

 Chadronites to corral the buffalo. But a wall it is, stretching straight across a 

 ravine whose width is only three or four feet greater than the exposed length of 

 the dike. It is said that early settlers saw it at least four feet high in the bottom 

 of this ravine. 



The dimensions obtained in June last were as follows: Length of the wall (across 

 the ravine), 120 feet; average width, 8 inches; range in width, 6 to 10 inches. 

 There must he added to this thickness from five to ten inches for a vertical lam- 

 inated accompaniment which varies from 2', to 5 inches thick on each side of the 

 wall. Tlu- dike is almost perfectly straight, and trends N. 48° E. 



