KASKASKIA GROUP— CARBONIFEROUS SYSTEM. 73 



CHAPTER XXXI. 



KASKASKIA GROUP. 



§ 154. Dr. Geo. G. and B. F. Shumakd were acquainted with this Group, in 

 Kentucky, Indiana, Illinois, Missouri, and Arkansas, in 1852, but did not name it. 

 In 1856 Hall named it, from Kaskaskia, Illinois, and more fully defined it in 1858. 

 In 1866 Prof. Worthen called it the Chester Group, because he had proposed 

 the name in 1853, and had so informed Prof. Hall while acting as his assistant in 

 1855 ; but the latter published the information, and instead of using the name 

 Chester used Kaskaskia. Chester is the shortest and best name, but Kaskaskia 

 has priority of publication. At the typical locality it consists of a compact, arena- 

 ceous, and coarse-textured limestone, with shaly partings, in the lower part, heavy- 

 bedded sandstone and limestone, with shaly partings, in the central part, followed 

 by a mass of green shale, succeeded by heavy-bedded limestone. The thickness at 

 Chester is 198 feet, at Huntsville, Alabama, 635 feet, on the southern line of 

 Tennessee 720 feet, at the northern line 400 feet, and in Indiana 300 feet. It 

 forms a belt surrounding the Illinois and Indiana Coal-basin, exists upon the western 

 and south-western border of the Appalachian Coal-basin, and upon the eastern bor- 

 der of the Missouri and Arkansas Coal-basin. It consists everywhere of fossiliferous 

 limestones and sandstones, and is followed by rocks unconformable with it. 



§ 155. The fossils having the greatest distribution and most characteristic are 

 Acrocrinus shumardi, Agassizocrinus conicus, Hydreionocrinus depressus, Pentremites 

 godoni, P. stdcatus, P. cervinus, P. obesus, P. piriformis, Pterotocrinus capitalis, 

 Talarocrinus comigerus, Zeacrinus maniformis, Athyris sublamellosa, A. subquadrata, 

 Spirifera increbescens, Spiriferina spinosa, Euomphalus planidorsatus, and Temnocheilns 



spectabih. 



» 



CHAPTER XXXII. 



CARBONIFEROUS SYSTEM. 



§ 156. This system is divided into the Carboniferous Conglomerate, Coal 

 Measures, and Permian Group. The Carboniferous Conglomerate rests uncou- 

 formably upon the Subcarboniferous rocks, and forms a belt around all the coal- 

 basins. It is a massive sandstone or conglomerate, almost nonfossiliferous, except 

 the occasional presence of Stigmaria, Catamites, and Lepidodendron. In Indiana the 

 thickness is about 200 feet, in Illinois about 300 feet, in Kentucky 500 feet, in 

 Ohio 200 feet, in Michigan 100 feet, in Pennsylvania 1,500 feet, in Virginia 1,000 

 feet, and in Nova Scotia, where it is called the Millstone grit, 6,000 feet. The 

 pebbles are well rounded, showing the fragments of rock were rolled for a long 

 time on the beaches by the action of the winds and waves, before they were 

 cemented into rock. A similar conglomerate separates the Subcarboniferous and 

 Coal Measures in Europe, where it is called the Millstone Grit. It bears the marks 

 everywhere of a shore-line deposit that surrounded the basins of internal seas. It 

 does not underlie the whole of the Coal Measures— the central parts of the basins 

 are free from it, as is shown by artesian boring. 



