Age:

Pennsylvanian

Type designation:

Type section: The Blue Creek Coal Member, named by Gray, Jenkins, and Weidman (1960, p. 25), consists of the coal mined extensively on Coal Mine Ridge at the headwaters of Blue Creek in southeastern Martin County and in northeastern Dubois County, Indiana (Hutchison, 1970; Hutchison and Hasenmueller, 1986). The type section is in an abandoned strip mine in Martin County, SW¼NW¼ sec. 10, T. 1 N., R. 3 W. (Gray, Jenkins, and Weidman, 1960, p. 71-72. See also Jenkins, 1956, p. 30-31.)

Description:

Near the type section the Blue Creek is divided into two benches (Hutchison, 1970; Hutchison and Hasenmueller, 1986). The upper bench, 2.0 ft (0.6 m) thick, is dull banded and slightly fissile to shaly, and the lower bench, 2.8 ft (0.8 m) thick, is bright banded and has blocky to hackly fracture (Hutchison, 1970; Hutchison and Hasenmueller, 1986). The roof of the coal is dark-gray carbonaceous ferruginous shale that is 8.0 ft (2.4 m) thick and is overlain by 6.5 ft (2.0 m) of yellow-brown to light-gray sandstone that is carbonaceous, micaceous, and ferruginous (Hutchison, 1970; Hutchison and Hasenmueller, 1986). The floor is white fire clay at this location. Sandstone overlies the Blue Creek at a few locations (Hutchison, 1970; Hutchison and Hasenmueller, 1986).

The Blue Creek is extremely variable in quality and thickness within short distances (Hutchison, 1970; Hutchison and Hasenmueller, 1986). Near Coal Mine Ridge the coal ranges from less than 1.0 ft (0.3 m) to more than 5.0 ft (1.5 m) in thickness. In places, it is an economically minable coal bed, as described above, but at others it is hardly more coaly than a black fissile shale (Hutchison, 1970; Hutchison and Hasenmueller, 1986). In this area the coal lies some 60 to 80 ft (18 to 24 m) below the top of the Mansfield Formation and about 100 ft (30 m) above the Pinnick Coal Member, or its mapped position (Hutchison and Hasenmueller, 1986).

Distribution: The Blue Creek has been mapped or identified throughout Martin County (Hutchison, 1967), Dubois County (Hutchison, 1964), Daviess County (Hutchison, 1971), and Perry County (Hutchison, 1971) (Hutchison and Hasenmueller, 1986).

Regional Indiana usage:

Illinois Basin (COSUNA 11)
Supergroup: none
Group: Raccoon Creek Group
Formation: Mansfield Formation
Member: Blue Creek Coal Member

Misc/Abandoned Names:

None

Geologic Map Unit Designation:

*mbc

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.

References:

Gray, H. H., Jenkins, R. D., and Weidman, R. M., 1960, Geology of the Huron area, south-central Indiana: Indiana Geological Survey Bulletin 20, 78 p.

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

Hutchison, H. C., 1964, Distribution, structure, and mined areas of coals in Dubois County, Indiana: Indiana Geological Survey Preliminary Coal Map 10, scale 1:126,720.

Hutchison, H. C., 1967, Distribution, structure, and mined areas of coals in Martin County, Indiana: Indiana Geological Survey Preliminary Coal Map 11, scale 1:126,720.

Hutchison, H. C., 1970, Blue Creek Coal Member, in Shaver, R. H., Burger, A. M., Gates, G. R., Gray, H. H., Hutchison, H. C., Keller, S. J., Patton, J. B., Rexroad, C. B., Smith, N. M., Wayne, W. J., and Wier, C. E., Compendium of rock-unit stratigraphy in Indiana: Indiana Geological Survey Bulletin 43, p. 17–18.

Hutchison, H. C., 1971, Distribution, structure, and mined areas of coals in Daviess County, Indiana: Indiana Geological Survey Preliminary Coal Map 15, scale 1:126,720.

Hutchison, H. C., 1971, Distribution, structure, and mined areas of coals in Perry County, Indiana: Indiana Geological Survey Preliminary Coal Map 14, scale 1:126,720.

Hutchison, H. C., and Hasenmueller, W. A., 1986, Blue Creek Coal 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. 16.

Jenkins, R. D., 1956, The geology of the Hillham quadrangle, Martin, Orange, and Dubois Counties, Indiana: Bloomington, Indiana University, master's thesis, 52 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.