56 



Pleistocene (no rock 'outcrop), the Coal Measures, the. lower Carboniferous 

 or Mississippian, .tlie- Devonian, the Silurian, and :theOrdivician or lower 

 Silurian/ All of ' these are found in the territory; of this drainage area; 

 and of "the twenty -five 'or more formations as subdivisions of the above- 

 named periods "there are at least eighteen of these found as surface out- 

 crops in this area. These formations may be listed as follows: Merom 

 Sandstone:— A massive 'coavae-grained sandstone lying unconformably on 

 the coal measures. It furnishes glass-sand and some building stone. 

 Mansfield Sandstone, the basal member of the coal measures, is a medium 

 to coarse-grained stone. It is quarried for building purposes and for whet- 

 stones and grindstones. Coal.— This area is just in the edge of the Indiana 

 coal field. The coal is, therefore, very thin-bedded and is mined only by 

 drifting. Shales. — The shales of the coal measures are in many places 

 from 25 to 40 feet in thickness, and are of value in the manufacture of 

 cement, paving brick and sewer tile. Associated with these shales in 

 Martin, Greene, Lawrence and Orange counties are considerable deposits 

 or iron ore ; there are also beds of fireclay underlying the coal. Huron. — 

 This consists of a series of thin bedded limestones separated ' from each 

 other by shales and sandstones. MitcheU Limestone consists of massive 

 compact layers of dark blue and gray limestone with interbedded impure 

 fossiliferous limestone, shales and chert. Salem Oolitic Limestone. — The 

 massive fine-grained stone so well known as a building and ornamental 

 stone. Harrodsburg Limestone. — A very fossiliferous limestone, and also 

 contains great numbers of geodes and chert in the lower members. Knob- 

 stone. — A series of shales and sandstones reaching a thickness of more 

 than 500 feet. This formation has its western outcrop in the eastern half 

 of Monroe and Lawrence and extends to the east as the surface stone for 

 many miles. To the present time biit little use has been made of this 

 group, but it is growing to be of economic importance. New Albany Shale. 

 — A persistent underlying brown to black shale at the top of the Devonian 

 System. It is rich in bitumen and when kindled will burn. The lamin- 

 ated structure and joints are shown in the illustration. Hamilton Group. — 

 The Sellersburg and Silver Creek limestones. The former is a white to 

 gray limestone, rather thin bedded but persistent, stretching from the Falls 

 of the Ohio, north through Clark, Scott, Jefferson, .Jennings and Decatur 

 counties. The Silver Creek lies beneath the Sellersburg. It ranges in 

 thickness from 15 to IG feet in the Silver Creek region to 5 or G feet In the 

 vicinity of Lexington, in Scott County, and disappears altogether us a per- 



