Age:

Devonian

Type designation:

Type section: Orr and Pierce (1973) designated a type section in the center of S½SW¼ sec. 16, T. 18 N., R 7 E., at the falls of Fall Creek in Fall Park at the north edge of Pendleton, Madison County, Indiana (Droste and Shaver, 1986).

History of usage:

The name “Pendleton sandstone” was first used by Cox (1869, p. 7) for a “soft, white sandstone” exposed at Pendleton. The damming of Fall Creek and the mining of the sandstone apparently have obscured the exposure (Droste and Shaver, 1986). Orr and Pierce (1973, p. 326-329) noted that Cox (1869) did not originally designate a type section and they designated a type section (Droste and Shaver, 1986). In their description of the type section, Orr and Pierce (1973) noted 7.6 ft (2.3 m) of the Pendleton Sandstone lying conformably below the Jeffersonville Limestone (Devonian) and disconformably above the Wabash Formation (Silurian) (Droste and Shaver, 1986). The term, at formation rank, had sporadic use in many Indiana reports before the time of Orr and Pierce, who also assigned formation rank. In 1975, the unit was assigned the rank of bed in the Vernon Fork Member of the Jeffersonville Limestone by Droste and Shaver (1975, p. 405-406) (Droste and Shaver, 1986).

Description:

At the type section, the Pendleton Sandstone Bed consists of white and varicolored fine-grained well-sorted calcareous sandstone that is fairly pure but that is partly ferruginous, laminated, and fossiliferous (Orr and Pierce, 1973, p. 328-329; Droste and Shaver, 1986). Early reports refer to a conglomerate in its upper part, but Orr and Pierce suspected that these reports actually referred to blocks of concrete (Droste and Shaver, 1986).

Although Devonian sand is very common, such concentrations of sand as in the Pendleton are rare at the bottom of or within Middle Devonian rocks in central Indiana; the Pendleton concentration grades both vertically and laterally into pale-colored fine-grained to micritic sandy to sparsely sandy and sand-free dolostones (Droste and Shaver, 1986). Pendleton recognition becomes, therefore, very much a subjective matter, and its distribution should be considered as spotty at best and in thicknesses less than that of the type section (Droste and Shaver, 1986).

At its type section the Pendleton disconformably overlies Silurian rocks (Cox, 1869) that were identified as the Mississinewa Shale Member (lower part of the Wabash Formation) by Burger and Patton (1970, p. 129) and simply as the Wabash by Orr and Pierce (1973), who identified reworked Silurian conodonts of Ludlovian age in the Pendleton (Droste and Shaver, 1986). The Pendleton type section, however, is very near the northern limit of distribution of the Geneva Dolomite Member (Jeffersonville Limestone) (Becker, 1974, fig. 14; Droste and Shaver, 1986). Droste and Shaver (1975, fig. 4) considered the Pendleton southward from its type section to be stratigraphically above the Geneva, that is, to be one and the same with sandy basal Vernon Fork rocks where these rocks are high in sand content (Droste and Shaver, 1986). The lower Pendleton contact is a conformable one, therefore, wherever this bed occurs in central Indiana south of Madison County (Droste and Shaver, 1986). The Pendleton is overlain conformably by fine-grained Vernon Fork dolostones that are unnamed at bed rank (Droste and Shaver, 1986). A part of these observations is contrary to the opinions of Orr and Pierce (1973, p. 829), who recommended that the Pendleton be so identified wherever arenaceous carbonate rocks appear at the base of Middle Devonian rocks, whether the base be identified as the Geneva Dolomite Member or the Jeffersonville proper (Droste and Shaver, 1986).

The discussion by Droste and Shaver (1986) suggests questionable status for the Pendleton. Considering its type-section relations and the position assigned by Orr and Pierce (1973) and Droste and Shaver (1975), it is both within the Jeffersonville and at its base (Droste and Shaver, 1986). Because the Geneva is considered to be facies of other lower Jeffersonville rocks, including the Vernon Fork in part, the Pendleton, as defined most lately, may be diachronous at best, if not also totally separated within itself in more than one stratigraphic position (Droste and Shaver, 1986). Droste and Shaver (1986, p. 111) recommended that to assure consistency, short of new definition, the Pendleton should be considered as restricted to areas south and west of the Kankakee and Cincinnati Arches, that is, primarily to the area of Geneva distribution. Otherwise, they felt that confusion with sands as old as earliest Middle Devonian or late Early Devonian in the Illinois and Michigan Basins would result (for example, with the Dutch Creek Sandstone Member and with the Sylvania Sandstone equivalent, which has been identified only tentatively in far northern Indiana).

Correlations:

Although some reports (for example, Hall, 1879, p. 60, and Ells, 1958, p. 16), partly on the basis of faunal evidence, correlated the Pendleton with Lower Devonian rocks of New York (Schoharie Grit) and Michigan (Garden Island Formation), some other reports have not (Droste and Shaver, 1986). For example, Sutton (1944) correlated the Pendleton with basal Jeffersonville and Geneva rocks, that is, with what has been called the Dutch Creek Sandstone Member (Droste and Shaver, 1986); Orr and Pierce (1973) agreed; Fagerstrom (1971, p. 69) doubted that the Pendleton fauna permitted precise correlation; and as already noted Droste and Shaver assigned the Pendleton a position mostly within the Jeffersonville and above the Geneva (middle Eifelian) (Droste and Shaver, 1986).

Because sand is so common within or at the base of several Middle Devonian rock units, whether or not these units are basalmost in the local Devonian section, many of the older reports of Pendleton and Pendleton-correlative rocks must be individually appraised (Droste and Shaver, 1986).

Regional Indiana usage:

Illinois Basin (COSUNA 11)
Supergroup: none
Group: Muscatatuck Group
Formation: Jeffersonville Limestone
Member: Vernon Fork Member
Bed: Pendleton Sandstone Bed
Illinois Basin Margin (COSUNA 12)
Supergroup: none
Group: Muscatatuck Group
Formation: Jeffersonville Limestone
Member: Vernon Fork Member
Bed: Pendleton Sandstone Bed
Cincinnati Arch (COSUNA 13)
Supergroup: none
Group: Muscatatuck Group
Formation: Jeffersonville Limestone
Member: Vernon Fork Member
Bed: Pendleton Sandstone Bed
Kankakee Arch (COSUNA 14)
Supergroup: none
Group: Muscatatuck Group
Formation: Jeffersonville Limestone
Member: Vernon Fork Member
Bed: Pendleton Sandstone Bed

Misc/Abandoned Names:

None

Geologic Map Unit Designation:

Djp

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:

Becker, L. E., 1974, Silurian and Devonian rocks in Indiana southwest of the Cincinnati Arch: Indiana Geological Survey Bulletin 50, 83 p.

Burger, A. M., and Patton, J. B., 1970, Pendleton Sandstone, 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. 129–130.

Cox, E. T., 1869, Introduction, in Cox, E. T., First annual report of the geological survey of Indiana, made during the year 1869: Indianapolis, Indiana, p. 5–11.

Droste, J. B., and Shaver, R. H., 1975, The Jeffersonville Limestone (Middle Devonian) of Indiana—stratigraphy, sedimentation, and relation to Silurian reef-bearing rocks: American Association of Petroleum Geologists Bulletin, v. 59, p. 393–412.

Droste, J. B., and Shaver, R. H., 1986, Pendleton Sandstone Bed, 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. 110–111.

Ells, G. D., 1958, Notes on the Devonian-Silurian in the subsurface of southwest Michigan: Michigan Geological Survey Progress Report 18, 55 p.

Fagerstrom, J. A., 1971, Brachiopods of the Detroit River Group (Devonian) from southwestern Ontario and adjacent areas of Michigan and Ohio: Canada Geological Survey Bulletin 204, 112 p.

Hall, James, 1879, Footnote [Correlation of the Pendleton Sandstone]: Indiana Geological Survey Annual Reports 8, 9, and 10, p. 60.

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.

Orr, R. W., and Pierce, W. H., 1973, The type section of the Pendleton Sandstone: Indiana Academy of Science Proceedings, v. 82, p. 326–334.

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.

Sutton, A. H., 1944, The Devonian System in Indiana, in Symposium on Devonian stratigraphy: Illinois State Geological Survey Bulletin 68, p. 162–173.