The Sauk Sequence contains the rocks bounded unconformably below by Precambrian rocks and above by rocks of the Chazyan Stage in the Middle Ordovician Series. In Indiana Sauk rocks range from just less than 1,500 feet to more than 6,000 feet in thickness, are at least early Dresbachian in age at the base and as young as Whiterockian in age at the top, and are divided into two supergroups. The siliciclastic rocks of the Potsdam Supergroup (below) grade into the younger carbonate rocks of the Knox Supergroup (above). The Potsdam Supergroup in Indiana ranges from less than 1,000 feet to more than 3,000 feet in thickness and contains the Mount Simon Sandstone below and the Munising Group above. In northern Indiana the Munising Group contains in ascending order the Eau Claire Formation, the Galesville Sandstone, the Ironton Sandstone, and the Franconia Formation. The Galesville, Ironton, and Franconia formations grade southward through the Davis Formation of the Munising Group into the carbonate rocks of the Knox Supergroup. In southern Indiana the oldest unit of the Munising Group, the Eau Claire Formation, is directly overlain with a gradational contact by the carbonate rocks of the Knox Supergroup. These facies relationships indicate a Dresbachian and Franconian age for the Potsdam rocks in northern Indiana and only a Dresbachian age in southern Indiana.

Droste, J. B., and Patton, J. B., 1985, Lithostratigraphy of the Sauk Sequence in Indiana: Indiana Geological Survey Occasional Paper 47, 24 p., 18 figs., 2 app.

You may also like:

Keywords: Potsdam Supergroup, Munising Group, Galesville Sandstone, Ironton Sandstone, Franconia Formation, Davis Formation, stratigraphy, Knox Supergroup, Eau Claire Formation, Mt. Simon Sandstone

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.