Item Number: B57
Map Scale: 1:1,000,000

ABSTRACT: Cambrian rocks are present throughout Indiana in the subsurface section. Their identity is based on a study of 121 Indiana test wells which have penetrated pre-Knox strata. Most of the wells are in northern and eastern Indiana. Lateral tracing from tests in adjacent states was used to aid in correlation. The rocks here designated as Cambrian merge indistinguishably with overlying lower Ordovician rocks. The Cambrian rocks have been assigned to the St. Croixan Series and include the Mount Simon Sandstone, the Eau Claire Formation, the Galesville Sandstone, the Ironton Sandstone, the Franconia Formation, and the Davis Formation, along with the lower part of the Knox Dolomite. This study excludes the little understood Knox portion of the Cambrian. The Ironton Sandstone and the Davis Formation as well as the Franconia Formation, which has had only casual understanding before, are recognized for the firsts time in Indiana. The Mount Simon Sandstone is generally a poorly sorted massive sandstone. It is generally grayish red and white and contains thin beds of gray and maroon shales. In places its lower part may contain an arkosic zone. It thins eastward from a thickness of 2,000 feet to 300 feet. The Eau Claire Formation is characterized by siltstone, fine-grained sandstone, shale, and dolomite. Glauconite and feldspar are common constituents. In southern Indiana two oolitic limestone zones also characterize the formation. The Eau Claire thins eastward from a thickness of 1,000 feet to 400 feet. The Galesville Sandstone, present only in northwestern Indiana, is a sandstone composed mostly of fine-to-coarse-grained rounded and frosted quartz grains and attains a maximum thickness of 95 feet. The Ironton Sandstone is found only in northwestern Indiana, ranges from 100 to 150 feet in thickness, and is predominantly medium-grained sandstone, dolomitic sandstone, and dolomite. The Franconia Formation is characterized by glauconitic fine-grained sandstone, siltstone, dolomite, and shale. It attains a maximum thickness of 125 feet in northwestern Indiana and thins to the south and east. The Davis Formation in Indiana, on the basis of faunal evidence and stratigraphic position, includes a carbonate, siltstone, and shale sequence between the base of the Knox and the top of the Eau Claire. The David is believed to be present throughout most of Indiana except the northwestern part and possibly the southwestern part. It ranges from 0 to 220 feet in thickness. Pre-Knox strata in Indiana have potential interest for oil and gas, commercial use for natural gas storage, and disposal of industrial wastes.

Becker, L. E., Hreha, A. J., Dawson, T. A. 1978, Pre-Knox (Cambrian) stratigraphy in Indiana: Indiana Geological Survey Bulletin 57, 72 p., 25 fig., 1 pl.

You may also like:

Keywords: subsurface, stratigraphy, Cambrian, Mount Simon Sandstone, Eau Claire Formation, Potsdam Supergroup, Munising Group, Galesville Sandstone, Ironton Sandstone, Franconia Formation, Davis Formation, Knox Supergroup

Can't find what you're looking for? Feel free to contact us directly:

Publication Sales Office
Indiana Geological and Water Survey
420 N. Walnut St.
Bloomington, IN 47404
812-855-7636 (phone)
812-855-2862 (fax)

IGS Return Policy

All sales are final. Materials may not be returned after they have been accepted by the customer. Any discrepencies in mail orders must be reported to IGWS within 10 days of receipt of order.

The Indiana Geological and Water Survey will refund the purchase price and sales tax of products if returned with the original sales receipt within 10 days of receipt of order. Refunds will be issued with the same method of payment as indicated on the original receipt except for cash purchases, which will be refunded by check. Items must be returned in the same condition as purchased. Refunds on digital products and services are not allowed, except for defective media such as CD-ROMs, flash drives, and so on. The customer is responsible for paying shipping costs to return items.