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very folliliferous, showing that life was abundant when it was laid down. 

 The area of outcrop is narrow and intermingles with the western edge of 

 the Knobstone, often capping outliers of the latter. It has no distinct 

 topography outside of tbe fact that sinks occur in it. which never occur in 

 the Knobstone, and rarely in the formation above it. 



Salem Limestone. Superior to the Harrodsburg formation is the 

 famous Salem limestone known as the Oolitic, or Bedford limestone. It is 

 an excellent building stone, and is known as such all over the United 

 States. Typical outcrops of it occur along the valley of Jacks Defeat. 

 The stone is usually massive, with few indications of bedding, varying 

 from a few feet up to eighty and ninety feet in extreme cases. The stone 

 typically is a porous stone composed of nearly pure calcium carbonate. It 

 is made up principally of broken animal remains and several species of 

 Protozoa, among which the main one is Endothyra baileyi. These have all 

 been cemented together in a loose manner. Tbe area of its outcrop is 

 characterized by long, gentle slopes, rounded hills and general undulating 

 topography. 



Mitchell Limestone. The Mitchell limestone is the one that we are 

 mostly concerned with, since practically the entire basin of the Flatwoods 

 region is in this stone. It ranges in thickness from a few feet in its north- 

 ern outcrop to 250 feet in the southern part of the State. The stratigraphy 

 of this formation is rather varied, as there are rarely two successive 

 layers alike. In general it consists of impure limestones and calcareous 

 shales, usually thin. Many layers are very hard, and weather white, 

 sometimes small slabs having the appearance of bleached bone, and on 

 being struck have a metallic ring. Such layers usually have numerous 

 right-angled joint cracks, and are semi-lithographic, breaking wth a sub- 

 concoidal fractiure. The upper members of this formation are usually a 

 beautiful oolitic structure. As a rule the limestone is fossiliferous. The 

 area of the outcrop of the Mitchell limestone extends over a broad plain 

 which narrows to the north and pinches out in Montgomery County. It is 

 essentially a cave-bearing formation, containing some of the most famous 

 caves in the world. Wyandotte and Marengo caves of Crawford County 

 and Mammoth cave of Kentucky are in this stone. The region of its out- 

 crop is pitted with sinks, and underground drainage is a distinct and 

 noticeable feature. Lost River of Orange County is a typical example of 

 an underground stream in the Mitchell area. Hundreds of sinks occur on 

 the borders of the Flatwoods region, where the filled material is relatively 



