Type locality: Doherty, Droste, and Shaver (1975) used the name “Grover Ditch Member” for the lower dolostone and evaporate rocks of the Detroit River Formation that are partly exposed in the Woodburn Quarry of May Stone and Sand, Inc., and that were cored in Indiana Geological Survey drill hole 188 (Indiana Geological Survey Petroleum Database Management System [PDMS] No. 133650 and Core File No. 452) in the NE¼ sec. 23, T. 31 N., R. 14 E., Allen County, Indiana (Droste and Shaver, 1986). The name was taken from the drainage ditch that empties into the Maumee River alongside the quarry (Doherty, Droste, and Shaver, 1975, p. 24-25; Droste and Shaver, 1986).
The Grover Ditch consists of light-colored fine-grained dolostone, cryptocrystalline anhydrite, and coarsely crystalline and fibrous gypsum (Doherty, Droste, and Shaver, 1975; Droste and Shaver, 1986). The basal most rocks consist of gray fine-grained sandy dolostone (Doherty, Droste, and Shaver, 1975; Droste and Shaver, 1986). Above these basal rocks that average 10 to 15 ft (3.0 to 4.6 m) in thickness, yellowish laminated to thick-bedded dolomitic mudstones are interbedded with massive dolomitic mudstones (Droste and Shaver, 1986). Brecciation and interbedded anhydrite and gypsum are common in this interval (Droste and Shaver, 1986). Some thick sections show repeated sedimentary cycles consisting in ascending order of (1) dark-yellowish-brown laminated dolomitic mudstone, (2) pale-yellowish-brown massive dolomitic mudstone, (3) pale-blue anhydrite and white gypsum, and (4) light-gray massive dolomitic mudstone (Droste and Shaver, 1986). As many as 12 to 15 of these 5-foot (1.5-m) cyclothems have been noted in LaPorte and Steuben Counties (Doherty, Droste, and Shaver, 1975; Droste and Shaver, 1986).
The Grover Ditch Member rests unconformably on the Wabash Formation of Silurian age and is generally overlain conformably by other Detroit River rocks assigned to the Milan Center Dolomite Member (Droste and Shaver, 1986). In some places, however, the Traverse Formation (Middle Devonian) overlies the Grover Ditch in an unconformable, overlapping relationship (Droste and Shaver, 1986).
The Grover Ditch represents a restricted marine environment and therefore mostly lacks faunas useful for interregional correlation (Droste and Shaver, 1986). Nevertheless, the oldest Devonian conodonts described by Orr (1971, p. 15) in his northern Indiana study come from the Grover Ditch and indicate a middle Eifelian age (early Erian, North American standard) (Droste and Shaver, 1986). Also, in accord with evidence and principles discussed in the Detroit River Web page, these general correlations may be stated: Geneva Dolomite Member of the Jeffersonville Limestone, southern Indiana; lower parts of the Grand Tower Limestone, Illinois, and of the Lucas Formation, Michigan; Lucas Formation, Ohio; and the Moorehouse Member and the lowest part of the Seneca Member of the Onondaga Formation, New York (Droste and Shaver, 1986).
Regional Indiana usage:
Kankakee Arch (COSUNA 14)
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.)
COSUNA areas and numbers that approximate regional bedrock outcrop patterns and major structural featuers in Indiana.
Major tectonic features that affect bedrock geology in Indiana.
Droste, J. B., and Shaver, R. H., 1986, Grover Ditch 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. 54-55.
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.
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 (email@example.com)Date last revised: October 24, 2017