394 GEOLOGY OF TUE DENVER BASIN. 



STONE FOR SUPERSTRUCTURE. 



Manitou stone. — The first of the above varieties is known in the trade as 

 Manitou stone, from the locality affording- the chief supply. It is of a warm, 

 light-red color and soft texture, but of somewhat varying compressive 

 strength. This, however, rarely falls below the required degree for private 

 residences, but in selecting the stone for tall office buildings a careful 

 choice of quarries should be made. The stone is chiefly an aggregate of 

 fine, well-rounded quartz grains, with a slight amount of feldspar and an 

 occasional grain of magnetite, the whole impregnated with the sesquioxide 

 of iron. The rock lies in beds from T> to 15 feet thick, separated by 

 occasional narrow seams of clay or shaly sandstones. Weathering lias 

 extended usually but a slight distance beneath the surface. The dip of 

 the beds varies between 45° and 90° usually east — at the Manitou quarries 

 between 80° and 90° — the strike being with the trend of the range, a 

 few degrees off north. The jointing is on a larg-e scale, permitting the 

 quarrying of blocks of enormous size when necessary. At the quarries in 

 operation the rift of the rock is not often utilized, the beds standing so 

 nearly vertical and being usually of such thickness that simple channeling 

 is advantageously employed. The Manitou stone works with great ease 

 and is employed in various forms of architectural ornamentation as well as 

 in the ordinary layers of superstructures. The capabilities of the stone 

 are extensively illustrated in the architecture of Denver, in business blocks 

 ami private residences. It is among the most beautiful of the building 

 materials of the United States. The geological position of the stone is 

 about 400 feet below the top of the lower division of the Trias. 



STONE FOR FOUNDATIONS. LOWER COURSES OF BUILDINGS, FLAGGING, CURBING, 



AND PAVING. 



Stone used for foundations, flagging, curbing, and paving occurs at 

 approximately the same horizon as the Manitou stone, and, also, from this 

 to the summit of the Creamy sandstone. The quarries are located at 

 Bellevue, Stout, Arkins, and Lyons, towns in the foothills from 25 to 40 

 miles northwest of Denver. 



The strata along this portion of the range have undergone an incipient 



