Cypress Sandstone

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Lithostratigraphy: Pope Megagroup >>West Baden Group >>Cypress Sandstone
Chronostratigraphy: Paleozoic Erathem >>Mississippian Subsystem >>Chesterian Series >>Gasperian Stage
Allostratigraphy: Kaskaskia Sequence

Primary source

Willman, H. B., Elwood Atherton, T. C. Buschbach, Charles Collinson, John C. Frye, M. E. Hopkins, Jerry A. Lineback, and Jack A. Simon, 1975, Handbook of Illinois Stratigraphy: Illinois State Geological Survey Bulletin 95, 261 p.

Contributing author(s)

Elwood Atherton, Charles Collinson, and Jerry A. Lineback


Original description

Cypress Sandstone (Engelmann, 1863, p. 189-190).


Named for Cypress Creek, Union County.

Other names

The name Ruma, now abandoned, was given to equivalent strata in Randolph County (S. Weller, 1913).


Type section

Type location

The type section of the Cypress Sandstone is in bluffs along the creek about 6 miles southeast of Anna (T12 and 13S-1E).

Type author(s)

Type status

Reference section

Reference location

Reference author(s)

Reference status

Stratigraphic relationships

Extent and thickness

The Cypress and the Tar Springs Sandstone are the thickest and most persistent sandstone formations of the Chesterian Series. In the central part of southern Illinois, the Cypress is generally well over 100 feet thick, and it reaches 200 feet thick (fig. M-37). It thins outward from that area, and it is only 20-30 feet thick near the outcrops in southern Randolph County.


The Cypress Sandstone varies from thick bodies of sandstone to shale and sandy shale interbedded with some thin beds of sandstone. The massive sandstone in the Cypress is white to light gray, fine to medium grained, angular, and generally friable. It makes up about half of the formation and typically is in a single body at the base of the formation. Some wells encounter two sandstone bodies, usually in the lower part of the formation, and others, mostly in the north and southwest but sporadically elsewhere, encounter only shale. Typically the upper part of the Cypress is more shaly than the lower, and commonly 5-30 feet of shale or sandy shale occurs at the top. Locally a few thin beds of sandstone lie immediately below the overlying Beech Creek Limestone. Sandstone beds near the top are generally cemented with calcite or dolomite. The shale in the Cypress is largely dark greenish gray, but some of the top beds are green, and a moderately persistent bed of red shale occurs about 10 feet below the top of the formation. In Randolph County in western Illinois, where the Cypress is almost entirely shale, the formation includes a considerable proportion of red and green shale. Beds of gray or green siltstone are present in the upper part of the Cypress, and a thin, dark green, quartzitic siltstone occurs near the top. Coal beds a few inches thick are sporadically present near the top of the Cypress, especially near its southern limit. The base of the Cypress and, to a lesser extent, surfaces in the middle part of the formation tend to parallel underlying structure more closely than they do the overlying Beech Creek Limestone, which suggests slight warping during Cypress time.




Well log characteristics


Plant fossils, including Lepidodendron trunks, are present in the Cypress.

Age and correlation

Environments of deposition

Economic importance

“Weiler”, “Kirkwood”, “Carlyle”, “Bellair 900” and “Lindley” are informal names applied to producing zones in the Cypress Sandstone.



ENGELMANN, HENRY, 1863, On the Lower Carboniferous System as developed in southern Illinois: St. Louis Academy of Science Transactions, v. 2, part 1, p. 188-190.
WELLER, STUART, 1913, Stratigraphy of the Chester Group in southwestern Illinois: Illinois Academy of Science Transactions, v. 6, p. 118-129.

ISGS Codes

Stratigraphic Code Geo Unit Designation