EXTENT OF THE DEXVElt. I'll 



Area between Bear and Clear creeks. This entire block < it' COUHtl'V east of <bvell 



and Table mountains is underlain l>v Denver strata wliich appear in numer- 

 ous places, as a rule either in the rounded knolls or in ravines and gullies. 

 Even in some cultivated or grassy fields any slight excavation, as small 

 irrigation ditches, will reveal crumbling brown sandstones or clays, which 

 a microscopical examination shows to be composed largely of andesitic 

 debris. The soil from disintegration of such material has a characteristic 

 dark yellowish-brown color. 



The northern bank of Bear Creek is abrupt, vet the slopes are usually 

 smooth and rounded, with numerous little drains cutting into them. 

 Though projecting rock faces are rare, this entire bank is practically one 

 continuous outcrop of Denver beds, and illustrates admirably the wa\ in 

 which the strata resist erosion, while seemingly so easilj attacked. A 

 prominent conglomerate horizon is often identifiable by the black pebbles 

 strewn abundantly over the surface. 



About one mile west from the Platte a dark conglomerate forms an 

 unusually prominent outcrop. It is evidently a local development, in much 

 reduced thickness, of some bed elsewhere found as a conglomerate. Peb- 

 bles 6 to S inches in diameter are not uncommon, though the greater 

 number do not exceed 2 inches. The variety is great, though all seem to 

 be andesites. Heulandite and calcite in plain crystals or grains compose 

 the cement of these pebbles. A total thickness of about 15 feet is mainly 

 conglomerate, and it grades off to sandstone or grit, with tew pebbles both 

 above and below, and probably laterally in a similar manner. 



The western hank of the Platte, from Bear < 'reek to Clear Creek, is 



formed by a line of low bluffs, along which, in many places, g 1 outcrops 



of the Denver beds are exposed. The Platte cuts into this bank at some 

 of its bends and lays bare dark concretionary sandstones, as at a point 

 opposite Overland Park. Small irrigation ditches and the cuttings on the 

 Denver, Leadville and Gunnison Railroad also reveal the characteristic 

 strata at many points. In addition to these outcrops the small water courses 

 often cut into the solid rock, and the edges of the hank, or knolls upon it, 

 frequently show rock in place in the same manner as along the Bear Creek 

 bluffs above referred to. 



