442 J. L. 



Rich — Large Bowlders in Gravel Deposits. 



An occurrence of such bowlders in a desert gravel deposit 6 

 miles east of Silver City, New Mexico, happens to be so 

 related to surrounding topographic features that a cine as to a 

 possible mode of accumulation independent of water or ice 

 presents itself. The belief that the explanation suggested for 

 this particular occurrence is one of general application where 

 topographic conditions are favorable, and should be considered 

 and eliminated before resort to glacial ice, even in the neigh- 



Fig. 2. 



Fig. 2. Nests of large bowlders in piedmont gravels (at Y, fig. 1). The 

 size of the bowlders in the group in the foreground may be judged by com- 

 parison with the Cittle. A second "nest" lies in the background to the 

 left. 



borhood of glaciated mountains, leads me to present a de- 

 scription of the bowlders, in relation to their surroundings, 

 together with an outline of the proposed explanation of their 

 origin. 



The location of the masses of bowlders in question with 

 respect to the gravel deposit in which they lie, and of this to 

 surrounding higher lands, is indicated on the accompanying 

 block diagram (tig. 1) constructed from the Silver Citv, N. M. 

 Sheet, U. S. G. S. (see also Silver City Folio, U. S. G~. S., soon 

 to be published). The gravels constitute the partially dissected 

 northern and mountainward edge of an extensive piedmont 

 alluvial plain, continuous toward the south with a series of 



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