Breezy Hill Limestone Member
Nelson, W.J., 2020, Pennsylvanian Subsystem in Illinois: Illinois State Geological Survey Bulletin (in press).
Edited and figures drafted by Jennifer M. Obrad.
Pierce and Courtier (1938, p. 33–35) gave the name Breezy Hill limestone member (of Cherokee shale) to “gray, impure, concretionary to nodular limestone” that occurs a short distance beneath the Fort Scott (now Mulky) Coal in southeastern Kansas.
The name refers to a hill just southwest of Mulberry, close to the Missouri border in Crawford County, Kansas.
Usage of the term Breezy Hill in the Midcontinent has remained stable. Inden (1968) introduced the unit into Illinois in a thesis; the first published usage here was by Nance (1970).
No published stratotype exists.
A neostratotype (principal reference section) is in the west bank of Morris Creek, NW¼ NE¼ NW¼ NW¼ of sec. 33, T 44 N, R 27 W, Henry County, Missouri.
Gentile and Thompson (2004, p. A-131).
A reference section in Illinois is proposed in the south bank of Vermilion River ¼ mi (400 m) west of Rt. 178 at Lowell; SE¼ SW¼ sec. 8, T 32 N, R 2 E, LaSalle County (Figure 4-42).
Smith et al. (1970, p. 24–25); Trask (1987, p. 224–225).
According to Pierce and Courtier (1938, chart, p. 18), the Breezy Hill Member lies directly below the underclay of the Fort Scott (Mulky) Coal and approximately 80 ft (24 m) above the Bevier Coal. Later authors followed this usage in Kansas (Howe 1956; Zeller 1968; Heckel 2013). Likewise, in Missouri, the Breezy Hill resides directly below the Mulky underclay and is separated from the Bevier Coal by a thick succession of shale and sandstone now called the Lagonda Formation (Howe and Koenig 1961; Gentile and Thompson 2004). The Breezy Hill has not been recognized in Iowa (Ravn et al. 1984; Pope 2012).
The limestone identified as Breezy Hill in Illinois resides at the same position as the Breezy Hill of Kansas and Missouri and therefore is accepted in the present report. The Breezy Hill should not be confused with fossiliferous limestone that is locally present near the base of the Lagonda Member.
Extent and thickness
In Illinois, the Breezy Hill is discontinuous and rarely exceeds about 1 ft (30 cm) thick. Reported occurrences are in northern and western Illinois, including Fulton, LaSalle, and Peoria Counties. Inden (1968) reported two outcrops of bedded to massive limestone as thick as 9 ft (2.7 m), both overlying channels filled with Pleasantview Sandstone. The Breezy Hill may occur more widely (albeit sporadically) in the basin but has been given scant attention. In a core from Edwards County in southern Illinois (Figure 4-28), the Breezy Hill is argillaceous, nodular, micritic, unfossiliferous limestone about 0.6 ft (18 cm) thick.
According to Nance (1970), the Breezy Hill in western Illinois is thin, silty, nodular limestone that lies directly below underclay of the Houchin Creek Coal. Polished sections revealed “micritic patches and filaments” interpreted as algal in origin. Smith et al. (1970, p. 22, 24–25) described Breezy Hill as “light greenish gray, sandy, clayey, massive” at a locality in LaSalle County. Trask (1987) replicated Smith et al. (1970), and Inden (1968) provided more detailed information based on a thin-section study. In Illinois, the Breezy Hill is dominantly micrite (lime mudstone), containing ≤3% fossil fragments, ≤1% pellets, and <1% intraclasts. Some samples contained trace amounts of quartz silt, detrital phosphate, and bitumen. The micrite is partly to thoroughly recrystallized. A single sample contained 20% fossil fragments (predominantly algae).
No detailed information is available. The unit commonly consists of lenses or nodules of limestone in a claystone matrix, yielding a highly irregular interface.
Well log characteristics
No logs that illustrate this unit are known.
In Kansas, the Breezy Hill contains brachiopods and foraminifera, including fusulinids (Howe 1956) and sparse conodonts (Heckel 2013). Nearly all the bioclasts examined by Inden (1968) were algal stromatolites, genus undetermined. One thin section revealed ostracods and a single gastropod.
Age and correlation
Fusulinids and conodonts are reported to occur in Kansas but have not been studied. Correlatives outside the Illinois and Midcontinent Basins have not been identified.
Environments of deposition
The Breezy Hill carries a marine fauna in the Midcontinent and is regarded as the transgressive to highstand portion of a minor cyclothem. In places, the upper part of the limestone is “heavily pedogenized” (Heckel 2013). Inden (1968) interpreted the Breezy Hill of Illinois as deposits of freshwater lakes or ponds on a delta plain or floodplain. The rock texture, presence of algae and peloids, virtual absence of other fossils, and association with underclay support this interpretation. Nance (1970) concurred. Inden (1968) envisioned a regional transition from freshwater in Illinois through brackish or marginal marine in Missouri to fully marine in Kansas and Oklahoma. Heckel (2013, text figure 7) charted the Breezy Hill as a minor marine incursion.
- Gentile, R.J., and T.L. Thompson, 2004, Paleozoic succession in Missouri, Part 5, Pennsylvanian Subsystem, Volume A, Morrowan strata through Cherokee Group: Missouri Geological Survey, Report of Investigations 70, 241 p. and correlation chart.
- Heckel, P.H., 2013, Pennsylvanian stratigraphy of Northern Midcontinent Shelf and biostratigraphic correlation of cyclothems: Stratigraphy, v. 10, nos. 1–2, p. 3–39.
- Howe, W.B., 1956, Stratigraphy of pre-Marmaton (Cherokee) rocks in southeastern Kansas: Kansas Geological Survey, Bulletin 123, 132 p.
- Howe, W.B., and J.W. Koenig, 1961, The stratigraphic succession in Missouri: Missouri Geological Survey and Water Resources, v. 40, 2nd Series, 183 p. and chart.
- Inden, R.F., 1968, Petrographic analysis and environmental interpretation of the Breezy Hill Limestone in Illinois, Missouri, Kansas, and Oklahoma: Urbana, University of Illinois, M.S. thesis, 65 p.
- Nance, R.B., 1970, Limestones and phosphatic rocks from the Summum and Liverpool cyclothems in western Illinois: Illinois State Geological Survey, Guidebook Series 8, p. 75–83.
- Pierce, W.G., and W.H. Courtier, 1938, Geology and coal resources of the southeastern Kansas coal field: Kansas Geological Survey, Bulletin 24, 122 p.
- Pope, J.P., 2012, Description of Pennsylvanian units, revision of stratigraphic nomenclature, and reclassification of the Morrowan, Atokan, Desmoinesian, Missourian, and Virgilian stages in Iowa: Iowa Geological and Water Survey, Special Report Series No. 5, 140 p.
- Ravn, R.L., J.W. Swade, M.R. Howes, J.L. Gregory, R.R. Anderson, and P.E. Van Dorpe, 1984, Stratigraphy of the Cherokee Group and revision of Pennsylvanian stratigraphic nomenclature in Iowa: Iowa Geological Survey, Technical Information Series No. 12, 76 p.
- Smith, W.H., R.B. Nance, M.E. Hopkins, R.G. Johnson, and C.W. Shabica, eds., 1970, Depositional environments in parts of the Carbondale Formation—western and northern Illinois: Francis Creek Shale and associated strata and Mazon Creek biota: Illinois State Geological Survey, Guidebook Series No. 8, 125 p.
- Trask, C.B., 1987, Cyclothems in the Carbondale Formation (Pennsylvanian, Desmoinesian Series) of La Salle County, Illinois: Geological Society of America, Centennial Field Guide, Vol. 3, North-Central Section, p. 221–226.
- Zeller, D.E., ed., 1968, The stratigraphic succession in Kansas: Kansas Geological Survey, Bulletin 189, 81 p., 1 pl.
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