![]() ![]() 24 E., the stratigraphic position of the shale is occupied by a breccia composed of angular limestone fragments. In most localities in Miami County the Sniabar Limestone Member is composed of two distinct limestone beds separated by a thin bed of shale. The conglomerate was probably derived from erosion of the Critzer Limestone Member, as it occurs at approximately the same stratigraphic position. ![]() Insoluble residues of the conglomerate have a high percentage of oolitic and oomoldic chert. 23 E., abundant hematite pebbles are found in a conglomerate composed of limestone phenoclasts in a calcareous matrix at or near the base of the Member. 24 E., it is oolitic at the top and contains chert in the lower part. It is the most lithologically variable unit in the lower part of the Kansas City Group. Sniabar Limestone Member-The Sniabar Limestone Member (Jewett, 1932) is a medium- to coarse-grained, medium- to thick-bedded limestone with an average thickness of about 6 feet. 24 E.), where it consists of 0.4 foot of dusky-yellow, unfossiliferous sandy shale. It is exposed at the location mentioned above in the description of the Critzer (SE SE sec. Mound City Shale Member-The Mound City Shale Member (Jewett, 1932) occurs only locally in Miami County. 24 E., where it is composed of 1.0 foot of light olive-gray, medium-grained, cherty limestone with abundant crinoid remains and some bryozoans. ![]() (Based on data from surface outcrops and from well logs in files of State Geological Survey of Kansas.)Ĭritzer limestone Member-The Critzer Limestone Member (Jewett, 1932) was observed at only a few localities in Miami County. The local relief on this surface is probably the result of an initial irregularity at the time of deposition and subsequent regional movement of the rocks.įigure 3-Structural contour map on the base of ther Kansas City Group in Miami County, Kansas. Structural contours drawn at the base of the Hertha (base of the Kansas City Group) show an irregular surface (Fig. In most localities it has a thickness of about 8 feet, but averages slightly more in the subsurface. The Hertha is poorly exposed where it crops out along the valleys in the southeastern part of the county. The Hertha Limestone (Adams, et al., 1903) comprises in ascending order: the Critzer Limestone Member and the Mound City Shale Member, which are exposed only locally, and the Sniabar Limestone Member, which is the most persistent member of the Hertha in Miami County. Study of the sandstone indicates that it consists of a number of separate lenses, which were probably deposited by streams flowing across a surface of low relief (D.A. This sandstone is termed the "Knobtown" by drillers in the area. This is predominantly of continental origin and is composed of olive-gray to grayish-orange sandy shale with thin, nodular limestone beds occurring locally.Ī series of fine-grained, cross-bedded sandstone lenses ranging in thickness from 0 to 25 feet occurs in the upper part of the Tacket Formation at varying distances below the overlying Hertha Limestone. Only about 25 feet of the upper shale member of the Tacket Formation is exposed in Miami County. It is a slope-forming unit, but it is poorly exposed along its outcrop in valleys in the southeastern part of the county. ![]() The Formation has an average thickness of 120 feet. It is composed of three units, which are, in ascending order, a lower shale member, a middle limestone member, and an upper shale member. The Tacket Formation (Jewett, et al., 1965) is the oldest outcropping formation in Miami County (Pl. Descriptions of measured sections are at the end of the report. Geology-Stratigraphy of Outcropping RocksĬorrelation of units discussed in this report on the basis of measured sections is shown on Plate 3. ![]()
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