REVIEWS 



Ordovician 



Preliminary Report on the Deposits of Manganese Ore in the Batesville 



District, Arkansas. By Hugh D. Miser. Bulletin 715-G, 



United States Geological Survey, Government Printing Office, 



Washington, B.C., 1920. Pp. 93-124 (32), pis. 3, figs. 4, 



bibliography, tables, and analyses. 



The Batesville manganese district is in the southern part of the 



Ozark region, in Independence, Sharp, Izard, and Stone counties, in 



north-central Arkansas. The deposits have been worked intermittently 



since 1849. They lie in a region of rough topography but of no great 



relief. In the manganese-bearing areas the following formations are 



exposed : 



Age Formation 



Mississippian Boone shert 



f Cason shale 

 I Fernvale limestone 

 Kimmswick limestone 

 Plattin limestone 

 Joachim limestone 

 St. Peter sandstone 



The Cherty Fernvale limestone is the principal source of manganese 

 ore. Its weathering leaves cherty nodules and sticky residual clay, 

 varying in color from yellow to red. The overlying thin Cason shale 

 bears phosphate, here as pebbles almost an inch in diameter, there as 

 shell fragments or grains; such phosphate deposits have, however, not 

 been extensively worked. The only fossils in the formation are flattened 

 "buttons" of supposedly algal origin, composed of calcium or manganese 

 carbonates; the "buttons" may occur in great quantity in the residual 

 clay, as at the Cason mine. 



Structurally the beds are almost flat-lying; a general doming of the 

 region has given them a gentle dip southward, upon which are super- 

 imposed several minor flexures. There are seven small normal faults, 

 with a throw not exceeding 400 feet. An uncomformity separates Mis- 

 sissippian and Ordovician beds and four others occur in the Ordovician 

 sequence. 



SOI 



