Tick Ridge Sandstone Member



Type designation:

Type section: 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, Indiana (Gray, 1986). A section about 2 miles (3 km) north of Taswell, first described by Malott (1925, p. 129), was designated as the type section.


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 (Gray, 1986). The sandstone is commonly cross stratified and in many places weathers to fretted surfaces (Gray, 1986). At the type section in Crawford County the member is 85 ft (26 m) thick (Gray, 1986). Its maximum observed thickness is 90 ft (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 ft (10 m) or so in thickness (Gray, 1986). 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 (Gray, 1986).

In Malott's (1925) original study of the upper Chesterian rocks in Indiana, he identified this lenticular massive sandstone as the Tar Springs Sandstone (Gray, 1986). 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 (Gray, 1986).

Distribution: 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 (Atherton and others, 1975, p. 158-159; Gray, 1986).

Regional Indiana usage:

Misc/Abandoned Names:


Geologic Map Unit Designation:


Note: Hansen (1991, p. 52) in Suggestions to authors of the reports of the United States Geological Survey noted that letter symbols for map units are considered to be unique to each geologic map and that adjacent maps do not necessarily need to use the same symbols for the same map unit. Therefore, map unit abbreviations in the Indiana Geologic Names Information System should be regarded simply as recommendations.

COSUNA areas and regional terminology

Names for geologic units vary across Indiana. The Midwestern Basin and Arches Region COSUNA chart (Shaver, 1984) was developed to strategically document such variations in terminology. The geologic map (below left) is derived from this chart and provides an index to the five defined COSUNA regions in Indiana. The regions are generally based on regional bedrock outcrop patterns and major structural features in Indiana. (Click the maps below to view more detailed maps of COSUNA regions and major structural features in Indiana.)

Map showing the COSUNA areas (heavy black line) that approximate regional bedrock outcrop patterns and major structural features in Indiana, and the COSUNA numbers (large bold font) for these areas. The COSUNA boundaries are limited to state and county boundaries that facilitate coding.

COSUNA areas and numbers that approximate regional bedrock outcrop patterns and major structural features in Indiana.

Map showing major tectonic features that affect bedrock geology in Indiana.

Major tectonic features that affect bedrock geology in Indiana.


Atherton, Elwood, Collinson, Charles, and Lineback, J. A., 1975, Mississippian System, in Willman, H. B., Atherton, Elwood, Buschbach, T. C., Collinson, Charles, Frye, J. C., Hopkins, M. E., Lineback, J. A., and Simon, J. A., Handbook of Illinois stratigraphy: Illinois State Geological Survey Bulletin 95, p. 123-163.

Gray, H. H., 1978, Buffalo Wallow Group upper Chesterian (Mississippian) of southern Indiana: Indiana Geological Survey Occasional Paper 25, 28 p.

Gray, H. H., 1986, Tick Ridge Sandstone Member, in Shaver, R. H., Ault, C. H., Burger, A. M., Carr, D. D., Droste, J. B., Eggert, D. L., Gray, H. H., Harper, Denver, Hasenmueller, N. R., Hasenmueller, W. A., Horowitz, A. S., Hutchison, H. C., Keith, B. D., Keller, S. J., Patton, J. B., Rexroad, C. B., and Wier, C. E., Compendium of Paleozoic rock-unit stratigraphy in Indiana–a revision: Indiana Geological Survey Bulletin 59, p. 153-154.

Hansen, W. R., 1991, Suggestions to authors of the reports of the United States Geological Survey (7th ed.): Washington, D.C., U.S. Geological Survey, 289 p.

Malott, C. A., 1925, The upper Chester of Indiana: Indiana Academy of Science Proceedings, v. 34, p. 103-132.

Shaver, R. H., coordinator, 1984, Midwestern basin and arches region–correlation of stratigraphic units in North America (COSUNA): American Association of Petroleum Geologists Correlation Chart Series.

For additional information contact:

Nancy Hasenmueller (hasenmue@indiana.edu)
Date last revised: June 6, 2017

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