BUILDING STONES. 395 



alteration from their original and normal condition of comparative softness, 

 as displayed in the Manitou stone, to one of greatly increased hardness. 

 This is probably due to compression, developed in the general folding 

 "en echelon" of this region, and in a local, secondary folding and faulting, 

 which is noticeable at the several points where the quarries have been 

 opened. In the region about Bellevue, for instance, there is the unusual 

 occurrence within the foothills of a well-developed secondary fold, which 

 along a portion of its axis has quite possibly been relieved by faulting. 

 Near Stout contorted strata again appear, and, although of minor impor- 

 tance, are positive evidence of the early existence of compression. At 

 Arkins the quarries lie almost in the very axis of the synclinal portion of 

 the general echelon fold of this region. At Lyons they are in dose prox- 

 imity to another of these folds. Within the region including the above 

 quarries there is a tendency of the strata to thinner bedding than at many 

 points along the foothills, although there is, also, marked variation in the 

 thickness of individual beds. 



The Bellevue quarries. TllCSG ai'e situated ill tile foothills allollt 9 milt'S 



due west of Fort Collins. Their product is distinctively a building stone, 

 although suited to special rather than general uses. Beds of heavier 

 stratification predominate. The hardness and compressive strength of this 

 stone are greatly in excess of that of other building stones east of the 

 range; its color is slightly deeper and more somber than that usual for 

 the Trias of the foothills; and it is quarried with ease in blocks of any 

 desired size, lifts of 4 and (I feet being the more usual. It is composed 

 chiefly of fine quartz grains, with an occasional accessory mineral, the 

 mass being infiltrated with oxide of iron. Its texture is nearly uniform 

 throughout. Such a stone, while excelled by others in the ease with which 

 it is worked for ornamental building purposes, is nevertheless admirably 

 adapted to use in the lower courses of superstructures, in sills and caps, 

 and other portions of buildings requiring special strength, and in founda- 

 tions. It offers a resistance to compressive strains tar in excess of the 

 ordinary building stone of the Red Bed series. 



The Bellevue stone is geologicallv the lowest of the stones quarried in 

 the northern portion of the field, occurring several hundred feet below the 



