APPENDIX. 



Section in Eastern Wyoming. 1 



565 



Names of Formations. 



Thickness 

 in Feet. 



Characteristics. 



Sb\ 



Alluvium. 



1-30 



Gravel, sand, and silt. 



<y 



J g \ Arikaree formation. 



700 + 

 30-40 



2. White sand and soft sandstone, with pipy 



concretions; non-marine. 

 1. Gray sandstone and conglomerate. 



Brule formation. 



250 



Flesh-colored sandy clay, with lenses of sand- 

 stone: non-marine. 



Chadron formation. 



Unconformity ~^~~ 

 Graneros formation 

 (Colorado) . 



Green, maroon, and pink sandy clay and gray 

 sandstone; non-marine. 



Gray flaky shale, with concretions and massive 

 sandstone near top; non-marine. 



Dakota sandstone. 



Unconformity ^~~~ 

 Morrison clay. 

 (May be Lotoer Cre- 

 taceous.) 



250-300 



100 



Massive buff, gray, and reddish sandstone and 

 quartzite, with thin beds of clay and shale; 

 non-marine. 



Clays of various colors, with a thin bed of 

 limestone; probably non-marine. 



Sundance formation 



200 



Buff sandstone, with interbedded clays near 

 top; marine 



J f 



Spearfish sandstone. 

 ("Red beds," possi- 

 bly Permian.) 



450 



Dark reddish-brown, medium-grained, thin- 

 bedded; limestone beds, and thin sheets of 

 gypsum in lower parts; salt lake deposits. 



Minnekahta lime- 

 stone. 



20 



Gray to purplish, thin-bedded. 



Opeche formation. 



60 



Bright-red, thin bedded sandstone, with red, 

 flaky shale; marine. 





o o 



PL O 



Hartville formation. 



Unconformity -~ 



Guernsey formation. 



Unconformity ^>~~~ 



Whalen group and 

 intrusive granite. 



650 



150 



3. Massive gray limestone, some beds cherty; 



occasional beds of white, gray, buff, and 



red sandstone. 

 2. Red shale and gray limestone. 

 1. Red quartzite streaked with white. 



Conglomeratic quartzite, with sandstone and 

 gray limestone above. 



Quartzite, schist, siliceous limestone, and 

 gneiss. Masses and dikes of intrusive gra- 

 nitic rocks. 



Strata horizontal or with gentle dips. 



> Smith, W. S. T., Hartville, Wyo., folio, U. S. Geol. Surv. 

 2 Proterozoic given as Algonkian in folio. 



