THE BARITE DEPOSITS OF MISSOURI 17 



It consists predominantly of dolomite, calcareous dolomite, shale, 

 conglomerate, and some sandy, glauconitic dolomite. The shale, 

 sandy dolomite, and conglomerate predominate in the lower part 

 of the formation (the Davis shale of Buckley's report), but are 

 interbedded with dolomite and calcareous dolomite. The char- 

 acter of the upper part is shown by the following partial section 

 taken at the bluff on Big River near its junction with Mineral 

 Fork: 



PARTIAL SECTION OF THE ELVINS FOEMATION, BEGINNING AT THE TOP 



Dolomite, yellowish, fine-grained, finely porous, rather mot- 

 tled, thick bedded ; weathers into angular blocks 3 or 5 

 feet square and 1 foot thick 4 ft. 



Dolomite, mottled gray, contains numerous fragments of 

 quartz and some crystals of calcite, thick-bedded; weath- 

 ers into very large blocks 4 ft. 



Dolomite, light to dark gray, fine-grained, has nodular struc- 

 ture and fine, wavy bedding planes; weathers into beds 

 from 1 inch to 1 foot thick 11 ft. 



Dolomite, light gray, very fine-grained, nodular, platy, thin- 

 bedded 6 ft. 



Dolomite, light gray, fine-grained, massive, contains fragments 



of calcite an inch or more across 2 ft. 



Dolomite, light colored, thin-bedded, platy, contains irregular 



fragments of calcite 1 ft. 6 in. 



Dolomite, light gray, medium to fine-grained 3 ft. 6 in. 



Dolomite, light gray, very dense, hard, contains small amount 

 of pyrite, upper part contains masses of calcite; shows 

 bedding planes; weathers to elongated angular fragments 

 on a flat surface ; would probably weather platy 9 ft. 6 in. 



Dolomite, yellowish-gray, medium to fine-grained, slightly 

 porous, contains crystals of calcite; weathers into blocks 

 1 foot or more square 3 ft. 



Dolomite, gray, shaly, fucoidal, fine-grained ; weathers rapidly 



and forms re-entrants 4 ft. 



Dolomite, dark gray, massive, medium-grained 3 ft. 



Dolomite, gray, mottled, fine-grained ; weathers to a thick bed 



in angular blocks 1 foot square 1 ft. 9 in. 



Dolomite, gray, weathers to a buff color, very dense; shows 

 suggestions of thin bedding; shows fucoids in abundance, 

 weathering taking place around them 3 ft. 3 in. 



Dolomite, gray, shaly, medium to fine-grained, very tough, 

 some beds slightly porous; weathers to irregular shaped 

 fragments an inch or two in diameter; middle parts 

 weather platy 6 ft. 



