.„PVTvvi GEOLOGY EAST OF FEONT EANGE CKETACEOUS. - 101 



almost without losing it for a moment, from the Big Thompson to the 

 South Platte, unless it be somewhat obscured near Golden City. Be- 

 tween the cross-cutting streams for all this distance and beyond, it rises 

 in its long characteristic ridge, capping the soft Jurassic beds below, 

 and whether the dip be high or low its top usually reaches to about the 

 same general level. These sandstones are usually clean, gritty, even- 

 grained and siliceous in texture, varying from a siliceous conglomerate, 

 ou the one hand, to a hard quartzite on the other, and only occa- 

 sionally becoming soft. . Their color is usually light yellow or light gray, 

 or even white, varying to rusty yellow, and only occasionally red in the 

 softer portions. These are the hard and massive portions which charac- 

 terize the group, and which are separated by thin shaly layers which 

 may be quite argillaceous or even carbonaceous in character, with many 

 broken remains of fossil plants. 



Section of Cretaceous No. 1 at Bear Canon. 



No. 



Nature of strata. 



Thickness 

 in feet. 



Hard siliceous sandstone .. - 



Same as 3, ■with Lard blue siliceous shales , 



Siliceous sandstone, gray to flesh-red above, white below ; even-grained, 

 particles rather free, gritty ; few feet of siliceous conglomerate at 

 base ; obscure vegetable impressions near top 



Total, (about) ■ 



40 

 50 



150. 



240 



Dr. Peale has allowed me to use the following section made by him 

 near the South Platte : 



Sect 



ion of Cretaceous No. 1 near the South Platte Uiver. 



—Br. A. 



C. Peale. 



No. 



Nature of strata. 



Thickness 

 in feet. 



4 



Gray and yellow sandstone, rather massive 



70 



8 



Shaly sandstone, carbonaceous, Proteoides, &c . . 



12 



9 



Fine-grained white sandstone 



3 



1 



Rusty -yellow sandstone, rather massive . . 



300 





Total, (about) - 







385 









"Near the summit of the sandstone-ridge No. 1, on Turkey Creek, there 

 is an asphaltum spring which has been wrought for oil. A considera- 

 ble thickness of the sandstone seems to be thoroughly saturated with 

 the pitch or bitumen, and between the layers of the sandstones are 

 accumulations of tar. This spring is located on the east side and near 

 the summit of the 'hog-back.'"* 



CRETACEOUS NO. 2. 



In this group we have a series of shaly beds which may be either 

 highly argillaceous or quite arenaceous in character, there being as- 

 sociated with them in either case a few thin brown sandstones, the 



* Hayden, Tliird Annual Report, 1869, reprint, p. 13G. 



