Skip to Main Content
Book Chapter

Cambrian and Ordovician stratigraphy in the Lansing area, northeastern Iowa

Brian J. Witzke
Brian J. Witzke
Iowa Geological Survey, Iowa City, Iowa 52242
Search for other works by this author on:
Robert M. Mckay
Robert M. Mckay
Iowa Geological Survey, Iowa City, Iowa 52242
Search for other works by this author on:
January 01, 1987


The oldest Paleozoic rocks exposed in Iowa are found in the northeastern corner of the state in Allamakee County. Cambrian exposures in the county form part of the classic reference area in the Upper Mississippi Valley for the Upper Cambrian Croixan Series. Overlying dolomites of the Prairie du Chien Group are exposed as bold cliffs in the bluffs along the Mississippi River and its tributaries. Cambrian and Lower Ordovician strata collectively encompass the Sauk Sequence, the first large-scale transgressive-regressive cratonic marine cycle of the Phanerozoic (Sloss, 1963). A major episode of erosion followed deposition of the Sauk Sequence. A widespread unconformity separates Lower and Middle Ordovician strata in the region, marking the boundary between the Sauk Sequence and the succeeding Tippecanoe Sequence.

The most complete sequence of Cambrian and Ordovician strata in northeast Iowa is exposed between Lansing and Church as one ascends from the Mississippi River up the valley of Clear Creek to the crest of Lansing Ridge along Iowa 9 (Fig. 1) 1). Vertical relief along this profile is 630 ft (192 m), and the composite stratigraphic section measured totals 619 ft (189 m). The base of the section begins along Iowa 26 north of the Mississippi River bridge (loc. 1, Fig. 1), and continues through a series of roadcuts and natural exposures in Mount Hosmer Park (loc. 4, Fig. 1). Strata equivalent to the lower half of the section at locality 1 can be seen behind Knopf’s Standard Station

You do not currently have access to this article.
Don't already have an account? Register

Figures & Tables


DNAG, Centennial Field Guides

North-Central Section of the Geological Society of America

Donald L. Biggs
Donald L. Biggs
531 Hayward Avenue Ames, Iowa 50010
Search for other works by this author on:
Geological Society of America
ISBN electronic:
Publication date:
January 01, 1987




A comprehensive resource of eBooks for researchers in the Earth Sciences

This Feature Is Available To Subscribers Only

Sign In or Create an Account

This PDF is available to Subscribers Only

View Article Abstract & Purchase Options

For full access to this pdf, sign in to an existing account, or purchase an annual subscription.

Subscribe Now