MARVixE.] GEOLOGY ROCKS EAST OF FRONT RANGE LIGNITIC. 109 



hard lava, which has preserved the lower beds from erosion. The sec- 

 tion is from the artesian boring for water at Denver City. The first 

 part is constructed from samples from the well, given me, with descrip- 

 tions, by Mr. Brooks, the engineer superintending the boring, the lower 

 part being furnished by Mr. Brooks directly, his section being indicated 

 by quotation marks. * The sections illustrating the character of the strata 

 associated with the coal will be given later. 



Section of tlie Ugnific strata at Golden City, Colorado Territory, from a 

 cross-section made hy E. L, BertJioud, civil engineer. 



No. 





14 







c3 







13 



a 



O 



12 



N 









O 



11 



P^ 





>j 







10 



c3 



9 





8 





7 



t3 



6 



-s 



s 



0) 



4 



> 

 >> 



3 



Th 



2 





1 



^ 



Nature of strata. 



Thickness 

 in feet. 



Doleritic lava, thickness averaging 125 feet : 



Conglomerate and dark sandstone, with layers of buff clay 

 containing fossil leaves and plants 



Yellow, gray, and rusty sandstones and conglomerates 



Red, yellow, and gray clays, with streaks of coal, fossil ca- 

 ries, sedges, and grasses 



Yellow, gray, and white sandstones and conglomerates, with 

 beds of buff and yellow clay, with fossil leaves 



Rusty sandstones, with obscure casts of stems and leaves . . 



Conglomerates and clays, probably 



Green clays and marls, with septaria : 



Dark conglomerate 



Clays and marls 



Fire and potter's clay, with rusty red sandstone 



Clays and marls 



Bog-ore bed, with fossil bones and plants 



Sandstone and fire-clays 



Coal-measures, (five seams or veins of coal) 



Sandstones and clays, probably 



Total thicknesss of lignitic, from 



25 

 135 



45 



130 



30 



900 or 1,000 



70 

 260 

 150 

 250 » 



GO 



260 



350 



400 or 500 



3, 060 to 3, 360 



Section of artesian icell near Denver City, hy Eli Brooks, engineer. 



Nature of strata. 



Surface-soil, probably indurated clay decomposed in place by atmo- 

 spheric agencies ,, 



Light-giay clay ; some sand 



Fine black sand 



Irregular black sand 



Light siliceous sand and clay 



Light-gray unctuous clay 



Fine black sand 



Light sandy clay 



Sand, rather coarse, with clay 



Light-gray clay, mingled with some sand 



Fine, clean, gray, siliceous sand ; water 



Clay, mingled with sand ' 



Graj', indurated, unctuous clay, (soapstone) 



Coarse, dirty, irregular sand, with clay below 



Fine, clean, gray siliceous sand ; some mica tlakes ; coarser sili- 

 ceous sand hear base ; water rising high in the well 



" Soapstone " 



" Sandrock " , 



"Soapstone" 



"Sandrock" 



" Soapstone " 



Depth of well February 8, 1874 



Thickness 

 in feet. 



20 

 55 

 20 



5 

 16 

 16 

 68 



8 



8 

 35 



5 



84 



160 



30 



10 

 10 



40 

 30 

 90 



85 



795 



