568 



APPENDIX. 

 Section in Central Montana. 1 



Names of Formations. 



Thickness 

 in Feet. 



Characteristics. 





Alluvium. 



0-50 + 



o 



CD a) 



£ 8 



Glacial drift. 

 Unconformity ^^^ 



I 



Smith River beds. 



Unconformity —^ 



Livingston for- 

 mation. 



^~ Unconformity—- 



Laramie forma- 

 tion. 



0-100 + 



0-800 



3300 



900-1050 



Clay, sand, conglomerate, and tuff; vertebrate 

 remains: non-marine. 



Dark-brown tufaceous sandstone, with local 

 beds of conglomerate, shale, limestone, and 

 pyroclastic materials. Estuarine or lacus- 

 trine conditions, followed by land conditions, 

 and then by marine. 



Light-gray or yellow sandstone; shale-beds in 

 upper portion; workable seams of coal; plant 

 remains and brackish-water shells. 



s « 



Montana forma- 

 tion. 



Colorado forma- 

 tion. 



Dakota forma- 

 tion. 



2800-3500 



4. Lead-gray arenaceous shale, with thin beds 



of sandstone; marine. 

 3. Calcareous shale with limestone concretions 



and interbedded sandstones; marine. 

 2. Black bituminous shale. 

 1. Quartzite; sandy shale below and conglom- 

 erate at base; fresh-water fossils in limestone 

 near top; fluvatile or lake deposits. 



g .2 \ Ellis formation. 



3 GO 



90-120 



Arenaceous limestone and shale; marine. 



Quadrant forma- 

 tion. 



1400 



5. Alternating beds of limestone and sand- 

 stone. 



4. Green shale with interbedded limestones. 



3. Limestone with sandstone beds. 



2. Green shale with interbedded limestones, 

 often oolitic. 



1. Red clay with yellow lumps. 



All shallow-water, marine deposits 



Madison limestone 



1025 



Massive and white above, thin-bedded, dark 

 gray below. 



>*A Monarch 



Q °3 I 



forma 



tion. 



165 



Chocolate-brown, granular limestone. 



1 Weed, Little Belt Mts. (Mont.) folio, U. S. Geol. Surv. Combination of the sections there given. 

 Ellis formation classed as Jura-Trias in the folio. What is here marked Yellowstone series is given 

 as Yellowstone formation, Belt series as Belt formation, Barker series as Barker formation, and Proter- 

 ozoic as Algonkian. 



