BUILDING STONES. 397 



in hardening and increased resistance. The fold is of the e'chelon type, 

 and lies just north of St. Trains Creek. The quarries are located on the 

 western leg of the compound flexure in the uppermost members of the 

 Creamy Sandstone, at the very top of the lower division of the Trias. 



The sandstone is considerably modified from the normal by impregna- 

 tion with iron, and a consequent reddening, and by a tendency to gradually 

 pass into the lower beds of the upper division of the Trias, which are 

 uniformly red and inclined to a shaly or more thinly bedded structure. It 

 is quarried exclusively for flagging, curbing, and sills. To the first and 

 last of these purposes it is admirably adapted, but it is a little soft for 

 curbing. The laminae vary in thickness from 1 to 12 inches, but the 

 product of the quarries is chiefly the thinner plates, ranging in thickness 

 from 1 to 4 inches, and in area up to oil square feet. The stone is very 

 homogeneous in texture and composition, and its durability lias been well 

 tested in a comparatively long period of use in Denver; in outcrop, also, 

 the strata show but slight disintegration, and the amount of stripping 

 requisite is light. 



The physical properties of the above varieties of building and other 

 stone are not completely determined, but their ratio of absorption is 

 undoubtedly small, their compressive strength great, and their composition 

 such as to render alteration through atmospheric agencies slight. 



ciencoe quarries. — The Glencoe quarries are located on Ralston ('reek, 

 in the top of the < Ireamy sandstone. They have been worked at intervals, 

 affording a handsome and durable stone. 



CRETACEOUS BUILDING STONES. 



The building stones of this age in the vicinity of the Denver Basin 

 are at present derived from the summit of the Fox Hills formation. At 

 various points in the West, however, the Laramie sandstones afford excel- 

 lent structural material, and near (Jan von extensive quarries have been 

 developed. The quarries on the confines of the Denver Basin are located 

 along the north bank of St. Vrains Creek about 3 miles east of Longmont 

 and 28 miles north of Denver. The summit sandstones of the Fox Hills 

 here form a bluff of 50 feet, capped at a distance from the face by a shell 



