Thursday, September 14, 2023

Fossils of the Upper Ordovician Platteville Formation in the Upper Midwest USA: An Overview

I'm not really in the business of plugging books, but I *have* gotten one recently that those of you who read this blog for the Ordovician posts may find interesting (if you haven't already come across it). The book is "Fossils of the Upper Ordovician Platteville Formation in the Upper Midwest USA: An Overview" by Dennis Kolata, Illinois State Geological Survey emeritus (and also one of the authors on a volume on the Deicke K-bentonite). I was tipped off to it by member "connorp" on The Fossil Forum during my quest to identify what turned out to be Zittelloceras.

The Platteville of Illinois and southern Wisconsin isn't *exactly* the same as in Minnesota (the strata are thicker and the fossils are better preserved than what we see in the Twin Cities), but anyone looking for information or comparative photos for Minnesota Platteville fossils is going to find plenty in the book to consider. The book is also useful for identifying fossils in the overlying rocks (e.g., the Decorah Shale), because many of the genera are the same. Several graphics clarify the correlation of different Platteville divisions across the area where the formation was deposited.

The text, organized by broad taxonomic group, is technical. Each species is given a diagnosis, followed by remarks about aspects such as notable features or distinguishing it from other species, and then its stratigraphic and geographic distribution. This is not unlike the various group-focused articles in Sloan (1987), but unlike the small black-and-white figures in the 1987 book, Kolata's book is filled with gorgeous color plates featuring large photos of every species. (The one quibble I have is that scaling is given by numbers, e.g., "x1.5", instead of scale bars, but I can certainly use them either way!) For anyone who is interested in the fossils but is not versed in the details of invertebrate anatomy, or anyone just looking to identify a particular find, these plates are invaluable.

If you'd like to find out more about this volume, the Illinois State Geological Survey bookstore is online here. The book can also be found on Amazon. It is 316 pages and costs $60.00.


Kolata, D. R. 2021. Fossils of the Upper Ordovician Platteville Formation in the upper Midwest USA: an overview. Illinois State Geological Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, Champaign, Illinois. Bulletin 108.

Sloan, R. E., editor. 1987. Middle and Late Ordovician lithostratigraphy and biostratigraphy of the Upper Mississippi Valley. Minnesota Geological Survey, St. Paul, Minnesota. Report of Investigations 35.

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