THE PENNSYLVANIAN PERIOD. 



563 





Section 



in Northern Texas. 1 



Names of Formations. 



Thickness 

 in Feet. 



Charac teristics . 





f Albany division 



0-1180 



840 



800-930 



950-3700 

 1000 



Thick beds of limestone, generally 



separated by shaly layers. 

 Shales, with thin beds of limestone 



1 



Cisco division 



o3 

 £ ■ 



Canvon division 



sandstone, conglomerate and coal. 

 Limestone and shale with local beds of 





Straw division 



sandstone and conglomerate; no coal. 

 Sandstone and shale; no coal. 



Pm 



Millsap division. . 



Blue and black shale interstratified with 





Ordovician? 



occasional limestone and sandstone 

 strata. 



Section in West-Central Colorado. 2 



Names of Formations. 



Thickness 

 in Feet. 



Characteristics. 



Jura-Trias 



Unconformity. 



Maroon conglomerate 



Faunal break . 3 



Weber limestone. . 

 Unconformity. 



2 '£, •{ Leadville limestone. 



B.&1 



Silurian. 



2500 



2000 



100-550 



400-525 



Conglomerate and sandstone in heavy 

 beds; material is derived chiefly from 

 the Archean, but some of the con- 

 glomerate contains limestone pebbles 

 derived from the Mississippian beds; 

 occasional thin beds of fossiliferous 

 limestone. 



Quartzose conglomerate, grit and sand- 

 stone, with varying amounts of 

 pebbles derived from the Weber and 

 Leadville formations, sometimes form- 

 ing the bulk of the deposit; thin 

 interbedded layers of fossiliferous 

 limestone. 



Dark gray to black shale, with limestone 

 beds carrying black chert. 



The upper third massive, blue and 

 cavernous; lower two thirds bedded 

 gray to brown; dark cherts. 



Rocks faulted and somewhat folded. 



Cummins, Geol. Surv. of Texas, 2d Ann. Rept., pp. 361-375. 

 2 Eldridge, Anthracite-Crested Butte (Colo.) folio, U. S. Geol. Surv. 



Girty, Professional Paper No. 16, pp. 258-267. 



