Type section: The Cranberry Marsh Member was named by Doheny, Droste, and Shaver (1975, p. 32-33) for pertinent rocks that were cored in the Northern Public Service Co. August Taelman No. 1 well in eastern LaPorte County, Indiana (NE¼ sec. 16, T. 36 N., R. 1 W.), and that were assigned as the upper member to the Detroit River Formation (Droste and Shaver, 1986).
The Cranberry Marsh consists of a series of interbedded gray to dark-brown lithographic to sublithographic limestone, dolostone, and evaporate rocks (Droste and Shaver, 1986). Some dolomitic grainstones and packstones are included, but micritic texture is a dominating character for this upper member of the Detroit River Formation (Droste and Shaver, 1986). Brecciated intervals, shaly partings, and thin lamination are other features of note (Droste and Shaver, 1986). As much as 30 ft (9 m) of massive gypsum is found in the lowest part of this member in eastern LaPorte County and western St. Joseph County (Droste and Shaver, 1986).
The Cranberry Marsh conformably overlies the Milan Center Dolomite Member of the Detroit River Formation, probably in a partial facies relation (Droste and Shaver, 1986). Where the Milan Center is absent from parts of northeastern Indiana, the Cranberry Marsh overlies the Grover Ditch Member, probably conformably (Droste and Shaver, 1986). The Cranberry Marsh is overlain unconformably by the Traverse Formation (Middle Devonian) in an updip overlapped, truncated manner (Droste and Shaver, 1986).
No index fossils are known from the Milan Center, but the presumably isochronous Tioga Bentonite Bed is found in the Milan Center in part of the distribution of the member (Droste and Shaver, 1986). Therefore, much of what is said elsewhere about correlation of the upper parts of the Detroit River and of the Grover Ditch applies to the Cranberry Marsh (Droste and Shaver, 1986). (See articles on the Detroit River and the Grover Ditch.)
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 features in Indiana.
Major tectonic features that affect bedrock geology in Indiana.
Droste, J. B., and Shaver, R. H., 1986, Cranberry Marsh 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. 32–33.
Ells, G. D., 1958, Notes on the Devonian-Silurian in the subsurface of southwest Michigan: Michigan Geological Survey Progress Report 18, 55 p.
Gardner, W. C., 1974, Middle Devonian stratigraphy and depositional environments in the Michigan Basin: Michigan Basin Geological Society Special Paper 1, 138 p.
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.
Meents, W. F., and Swann, D. H., 1965, Grand Tower Limestone (Devonian) of southern Illinois: Illinois State Geological Survey Circular 389, 34 p.
Rooney, L. F., 1965, Gypsum deposits in northern Indiana: Society of Mining Engineers of American Institute of Mining, Metallurgical and Petroleum Engineers Transactions, v. 232, p. 268–273.
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 (firstname.lastname@example.org)Date last revised: June 27, 2017