MARm-E.J GEOLOGY EOCKS EAST OF FRONT RANGE JURASSIC. 99 



Section of Jurassic heds exposed near Saint Vrain^s GreeTi. — William H, 



Holmes. 



No. 



Nature of strata. 



Thickness 

 in feet. 



14 

 13 

 12 

 11 



10 

 9 



8 



Top. 



Argillaceous saudy shales, variegated and irregular, crumbling. , 



Hard, blue, beautiful limestone, solid 



Argillaceous and sandy shales, same as No. 15 



Fine-grained, calcareous quartzite, with seams of crumbling gypsif 



ercus shales 



Limestone 



Shaly -, 



Red sandstone 



Shales, with seams of quartzite 



Shales and sandstones 



Soft yellow massive sandstone 



Soft red massive sandstones 



Red shaly sandstones 



Cherty limestone 



Red shaly sandstones 



Base. 

 Total 



20 



4 



30 



20 



2 



5 



4 



12 



20 



30 



60 



200 



or 



300 



400-500 



Section of Jurassic heds exposed in Bear Canon. — William H. Holmes. 



No. 



Nature of strata. 



Thickness 

 in feet. 



11 



10 



Top. 



Light gray, fine, siliceous shale, almost quartzite 



Sandstones, shaly, variegated, (white, snuff, orange,) containing a 



shaly limestone 



Limestone, hard, gray; conchoidal fracture, with beds of variegated 



argillaceous, arenaceous, and calcareous shales 



Covered 



Soft massive sandstone, white, with hard siliceous seams 



Limestone, hard, with conchoidal fracture 



Covered 



Soft white massive sandstone, with soft greenish concretions 



Soft, red, thin-bedded, and shaly sandstones 



Siliceous limestone, porous 



Soft, red, thin-bedded, and shaly sandstones 



Bottom. 

 Total, (about) 



40 



42 



40 

 20 

 50 

 6 

 20 

 30 

 400 

 20 



870 



At remaining points, though taken in less detail, the sections still 

 show the general features of the series: 

 Section of Jurassic heds exposed near Ralston CreeJc. — William H. Holmes. 



No. 



Nature of strata. 



Top. 

 Variegated shales, mostly argillaceous, with thin beds of limestones 



and sandstones 



White sandstones 



Variegated shales, mostly argillaceous 



Thin red sandstones and arenaceous shales 



Cherty limestone 



Red sandy shales 



Bottom. 

 Total, (about) 



Thickness 

 in feet. 



270 

 30 

 40 



200 

 20 



100 



660 



