322 FF. V. Hayden on the Geological formations of 
Art, XXXIV.—Remarks on the Geological Formations along 
the Eastern margins of the Rocky Mountains ;* by F. V. 
HAYDEN, 
On several former occasions I have described the different 
U. P.R. W. E. D., there are massive beds of this chalk which 
18s sawed into building blocks with a common saw, and in many 
instances it is nearly as white as our chalk of commerce and 
__ * This article refers only to the eastern ranges of the Rocky Mountains, extend- 
ing south to the Arkansas. The same seed may so may not apply to other 
_+ The different divisions of the Cretaceous period, as shown on the Missouri 
river, have received geographical names, as Fort Benton group, &c.. but I use the 
old divisions by figures for brevity. oie, 
4 
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