MINEOLA LIMESTONE. 17 



and generally containing many crinoid stems. Fossils are rare; 

 Atrypa reticularis is sometimes found. Its total thickness in this 

 county is probably about 15 feet. It is extensively used in 

 Montgomery County (where it is better developed) for chimney 

 fire-places. It probably belongs to a division of the Upper 

 Silurian system." 1 



Number 8 given in the section and the crinoidal limestone 

 are part of the Mineola. 



Lithology. — The Mineola is rather heterogeneous in composi- 

 tion. One of its typical phases is a highly crystalline, crinoidal 

 limestone, almost white in color, which weathers readily to a 

 crumbly condition. This phase might easily be mistaken for 

 ordinary Burlington limestone, though it weathers much more 

 rapidly than Burlington. It contains large numbers of crinoid 

 stems and in many places numerous crinoid heads from which the 

 outer parts of the plates have been exfoliated. Near Rensselaer, 

 in Ralls County, crinoid heads in good condition were found in 

 this bed. 



Another phase, about as common as the crinoidal, is made 

 up of a yellowish to pinkish gray limestone, which contains 

 large numbers of small irregular cavities produced by the solu- 

 tion of fossils. In most places the limestone is sandy. A fenes- 

 telloid bryozoan, Cyclotrypa communis Ulrich, is abundant, but 

 other fossils are rare. 



A brown limestone flecked with specks of white occurs 

 rarely. It contains few impurities and the white specks are of 

 calcite. The rock is abundantly fossiliferous. 



In some places the lowest member is a very sandy, pinkish 

 to yellowish limestone, that grades towards sandstone, and is 

 abundantly fossiliferous. It ordinarily occurs in shallow erosion 

 depressions in the older rocks. 



The various phases are never present in one section and they 

 seem to have been contemporaneous deposits, the lithologic 

 differences being due to variations in sedimentation. 



Distribution and Relationships.— The Mineola limestone oc- 

 curs in Callaway, Montgomery, Warren, St. Charles, Lincoln, 

 Ralls and Pike counties. It exists only as erosion remnants and 

 though its east-west extent is more than 100 miles and its north- 

 south extent 60 miles or more, it probably covers a total area of 

 less than 500 square miles. Only rarely is any patch of the forma- 



'Geol. Surv. Mo., 1855-71, pp. 47-48. 



