8 



Indiana University Studies 



signs the lithologic succession of the soHdified strata, as well 

 as the corresponding symbols used to indicate the areal dis- 

 tribution of formations on the map. It was not found con- 

 venient or practical, especially in the case of the thinner 

 members, to show each lithologic unit on the map. It is seen 

 that the bedrock strata which occur in the region are of upper 

 Mississippian and lower Pennsylvanian age, and that these 

 two periods are separated by a disconformity. 



The Mississippian Strata. The Mississippian strata found 

 in the region are confined entirely to the Chester Series, and 

 consist of limestones, shales, and sandstones. Recent work, 

 yet unpublished, on the Chester Series of Indiana has led to 

 a definite naming of the series of formations. This work 

 was done by the writer and J. D. Thompson, of the Empire 

 Gas and Fuel Company, during the summer of 1918. The 

 various formations as they occur in the region here under 

 discussion will be given the names as determined by this 

 latest work on the Chester of Indiana. This work consists 

 mainly in the correlation of the formations with those of 

 Kentucky, following the nomenclature of Butts, of the United 

 States Geological Survey, whose work was published by the 

 Kentucky Survey in 1917. Several new formational names 

 are introduced for the Indiana region, some of which have 

 no representatives in Kentucky. No change has been made 

 in the divisions and nomenclature below the top of that great 

 thickness of limestone known in Indiana as the Mitchell lime- 

 stone, the upper part of which belongs to the Chester and the 

 lower part to the St. Louis. 



The Mitchell Limestone. The Mitchell limestone is really 

 a group of formations, but makes one great lithologic unit 

 very difficult to divide in a mapable way. The upper part in 

 Indiana is equivalent to the Gasper Oolite and the Fredonia 

 Oolite of Kentucky and is Chester in age, while the thicker 

 lower part is the St. Louis limestone. Only the uppermost 

 part outcrops in the ''American Bottoms" region. 



The upper part of the Mitchell limestone is found near 

 the head of Beech Creek valley. It consists of thin layers 

 of compact sub-oolitic limestone, and rises approximately 25 

 feet above the floor of Beech Creek valley, in section 9. To 

 the west the dip carries it beneath the alluvium of the stream. 

 To the east along Beech Creek, in section 10, the Mitchell 



