Show simple item record Gray, Henry H. Jenkins, Robert D. Weidman, Robert M. 2006-08-04T19:44:41Z 2006-08-04T19:44:41Z 1960
dc.identifier.citation 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., 3 pls., 4 figs. en
dc.description Indiana Geological Survey Bulletin 20 en
dc.description.abstract The Huron area is approximately 85 mi. SSW. of Indianapolis and includes approximately 117 sq. mi. of area in the physiographic province known as the Crawford upland. Nearly flat-lying sedimentary rocks of late Mississippian and early Pennsylvanian age underlie the hilltops and slopes, and unconsolidated silts, sands, and gravels, mostly of Pleistocene age, partly fill the major valleys. Exposed rocks of late Mississippian age are assigned to the Blue River, West Baden, and Stephensport groups (new names), in ascending order. Of the Blue River group, which includes 3 formations that consist largely of limestone, only the upper 70 ft. is exposed. The West Baden group is approximately 115 ft. thick and consists of 5 formations which are made up principally of shales but include also some sandstones and limestones. The Stephensport group is approximately 140 ft. thick and consists of almost equal parts of limestones, sandstones, and shales belonging to 5 formations. Between rocks of late Mississippian age and the rocks of early Pennsylvanian age that overlie them is an unconformity that represents a period of erosion of sufficient duration to have beveled the older rocks and then carved into them valleys as much as 100 ft. deep. Statistical analysis of available observations indicates that sandstone deposits in the lower part of the Mansfield formation are not concentrated at the unconformity and that limestone is not more abundant immediately under the unconformity than would be expected from the percentage of limestone in the rocks on which the unconformity was developed, but highly aluminous clays are concentrated at the unconformity, probably as a residual deposit. Rocks of early Pennsylvanian age in the area are assigned to the Mansfield formation, have a maximum exposed thickness of approximately 250 ft. in the SW. corner of the area, and consist of sandstones, shales, and mudstones, and thin and discontinuous beds of coal and clay. The Mansfield formation is divisible into 2 parts, a lower part consisting largely of cross-bedded sandstones and an upper part made up principally of mudrocks and thin-bedded sandstones that have gray shale partings. Coal, crushed limestone, whetstones and grindstones, Fe ore, dimension sandstone, and clay have been produced from the rocks of the area but are no longer of economic importance. The only mineral raw material now produced in quantity is gypsum, which is taken from rocks of middle Mississippian age in underground mines in the western part of the area. en
dc.description.sponsorship Indiana Department of Conservation en
dc.format.extent 7275353 bytes
dc.format.mimetype application/pdf
dc.language.iso en_US en
dc.publisher Indiana Geological Survey en
dc.relation.ispartofseries Bulletin en
dc.relation.ispartofseries 20 en
dc.rights This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License. To view a copy of this license, visit or send a letter to Creative Commons, 543 Howard Street, 5th Floor, San Francisco, California, 94105, USA. en
dc.subject Geology en
dc.subject Stratigraphy en
dc.subject Huron Area en
dc.subject Mississippian en
dc.subject Pennsylvanian en
dc.subject Martin County en
dc.subject Orange County en
dc.subject Indiana en
dc.title Geology of the Huron Area, South-Central Indiana en
dc.type Technical Report en

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