26 STUDIES IN GEOLOGY, No. i 



Meters 



.15 Compact gray sandstone 



NOTE. The better plant material comes from this horizon 

 and a thickness of 2 or 3 inches on either side of the plant 

 layer is copper-stained 

 .04 Plant layer 



.12 Gray shale layer, more compact in lower half 

 .15 Gray cross-bedded coarse sandstone 

 .62 Finer black stained sandstone 

 1.50 Light brownish coarse cross-bedded sandstone 

 i. oo Brownish sandy shale 

 .40 Soft fine-grained banded sandstone 

 6.00 Red shale 



70.50 Light reddish to gray' sandstone with some shaly bands, in 

 places showing regular 8- to lo-inch alternations of shaly 

 and coarse materials becoming more distinctly thin-bedded 

 near the top 

 8.25 Red shale with 6- to 8-inch bands of sandstone 



.60 Ledge of coarse red friable sandstone 

 9.75 Shaly hackly sandstone 

 3.00 Lighter gravelly sandstone 

 .40 Brown sandstone 

 .60 Light-brown irregularly-bedded very coarse sandstone with 



angular quartz gravel 

 3.00 Hackly argillaceous sandstone 

 8.25 Fine red shale (mudstone) 

 .80 Coarse brownish gravelly sandstone 

 .20 Fine-grained reddish sandstone N.22 W.55W. 

 .40 Coarse brownish sandstone with some fine gravel 



Red clay 



239.00 Poorly exposed red shale and sandstone 

 Corocoro fault 



In the 534 in. of detailed section, shales constitute 38 

 per cent of the beds, sandstones 57 per cent, conglomeratic 

 sandstones 3 per cent, and conglomerates 2 per cent. The 

 shales are almost invariably red, but are not gypsiferous 

 nor do they enclose beds of gypsum. Though much of the 

 sandstone is red, the prevailing color is gray and as the 

 sandstones and conglomerates make up such a large part of 

 the section, the red color is less pronounced than the gray 

 in the outcrops. All copper-stained beds are in sandy 



