Tar Springs Formation,
Type section and description: The Tick Ridge Sandstone Member was named by Gray (1978, p. 8) for Tick Ridge, a physiographic feature 3 miles (4 km) south of Taswell in Crawford County, Ind. A section about 2 miles (3 km) north of Taswell, first described by Malott (1925, p. 129), was designated as the type section. At that place the member is 85 feet (26 m) thick.
The Tick Ridge Sandstone Member is recognized only on the outcrop and only where the sandstone is sufficiently thick and massive to be topographically prominent so as to form steep slopes and overhanging cliffs. The sandstone is commonly cross stratified and in many places weathers to fretted surfaces. Its maximum observed thickness is 90 feet (27 m) at Spruce Pine Bluff, just east of Taswell as a practical matter, the member is not differentiated where the sandstone is less than 30 feet (10 m) or so in thickness. Lateral transition from the sandstone into shale that contains thin limestone interbeds is remarkably abrupt, so that definition of the lateral extent of the member presents little difficulty.
In Malott's (1925) original study of the upper Chesterian rocks in Indiana, he identified this lenticular massive sandstone as the Tar Springs Sandstone. Over the years, however, the concept of this term became diffused (see discussion of boundary problems under "Tar Springs Formation"), so that it became necessary to make a distinction between the more extensive and lithologically varied formation and the local sandstone bodies within it (Gray, 1978) for clarity, therefore, Malott's original Tar Springs Sandstone became Gray's Tick Ridge Sandstone Member.
The Tick Ridge Sandstone Member is prominent only near Taswell in Crawford County and Branchville in Perry County. The name has not been applied in the subsurface, although numerous similar sandstone bodies are known within the Tar Springs Formation (Willman and others, 1975, p. 158-159).