This is Mazon Monday post #96. What's your favorite Mazon Creek fossil? Tell us at email:[email protected].
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The book "Pennsylvanian Plant Fossils of Illinois" was #6 in the Educational Series published by the Illinois State Geological Survey in 1960. It was written by Charles Collinson (1923 - 2011) and Romayne Skartvedt. The book can be purchased used online or downloaded free from Project Gutenberg.
The main author Charles Collinson also wrote "Guide for Beginning Fossil Hunters", which was #4 in the ISGS's Education Series. He was a paleontologist with the ISGS for the majority of his professional career. In the Foreword, he acknowledges the works of Hirmer, Janssen, Lesquereux, Noe, and Langford, with a full list of references at the end.
This field book is intended to guide beginners in their collection and general classification of plant fossils. It illustrates the plant fossils most commonly found in Illinois and relates them to the plants of which they were a part. A list of publications that will furnish more detailed identification of specimens is included. The book has been prepared in response to numerous inquiries to the Illinois State Geological Survey from amateur collectors.
Information has been drawn from numerous sources. The works of Hirmer, Janssen, Lesquereux, Noé, and Langford have been particularly useful.
We are especially indebted to Dr. Robert M. Kosanke, paleobotanist at the Illinois State Geological Survey, and Dr. Wilson N. Stewart, professor of botany of the University of Illinois, for helpful suggestions and use of their libraries.
The book contains some very nice illustrations and discusses the science of Mazon Creek as it was known in the last 1950's and 1960's. The Pennsylvanian or Coal Age is thought to be 200 million years old (now known to be 307 million years old) with discussions of the low lying swamps of the Mazon Creek area.
Plants that flourished 200 million years ago have made Illinois one of the best known fossil collecting sites in the world. The unusual abundance and preservation of these fossils in the northern part of the state have brought collectors to Illinois from many countries, and prized specimens from that area may be seen in science museums throughout the world.
The remarkable fossils represent plants that lived during the geologic period called the Pennsylvanian or Coal Age and are the result of special geologic conditions that occurred repeatedly during the period.
At the beginning of the Pennsylvanian Period, Illinois was part of a vast lowland that stretched for hundreds of miles to the north, south, and west, and was bordered on the east by highlands. At times much of the plain was swampy and, because the climate was relatively warm and moist, great jungles of fast growing trees, shrubs, and vines covered the landscape. As successive generations of plants lived and died, plant material fell into the swamp waters and, protected there from decay, accumulated.
Frequently during the period, seas spread over the swampy lowlands, submerging the forests and covering 8them with mud. Each submergence lasted only a short time, geologically speaking. When the seas withdrew, the deposits of sand and mud left behind were cut by streams that carried fresh sand and mud from the eastern highlands. The streams eventually became clogged with sediments and when the lowland was again depressed swamp conditions returned and forests grew afresh. Such a cycle of deposition was repeated again and again during Pennsylvanian time, and after burial each layer of plant material gradually lost most of its liquids and gases and was slowly converted into one of the numerous coal beds presently found in Illinois.
There are good drawings of Lepidodendron, Sigillaria, Calamites, and others that are not too different from modern reconstructions.
Reconstruction of Lepidodendron (after Hirmer)
Reconstruction of Sigillaria (after Hirmer)
Reconstruction of Calamites (After Hirmer)
There are useful drawings that show the differences in venation between various species, however due to modern research the names have changed. You'll find similar information in the "ESCONI Keys to Mazon Creek Plants".
Venation of seed fern leaflets, Alethopteris, Odontopteris, Mariopteris, Neuropteris, and Linopteris
The strip line map looks to be from the 1950's with no mention of Pit 11 or I-55. Unfortunately, the majority of the pits are now on private property often as housing developments.
Mazon Creek Strip Mine Area Showing Distribution of Spoil Heaps. The small circular areas represent waste from underground mines.
There is a survey of Illinois Counties with Pennsylvanian fossils, including of course the "Mazon Creek Area". The other counties listed are Bureau, Knox, Mercer, Warren, Fulton, McDonough, and Vermillion, Morgan, and Peoria in the North and Laurence, Saline, Pope, Johnson, Perry, Jackson, and Hamilton in the South.
Near the end, there is a discussion of collecting tools and the handling of specimens. With the hammer listed as the first tool, it should maybe not be surprising that there is no mention of the freeze/thaw method, only how to split a concretion with a hammer.
The most successful way to split an ironstone concretion is to set it on edge, long axis horizontal, on any fairly large rock and strike the upper edge with the hammer. If the concretion is one that developed around a fossil nucleus, it generally will split along the plane of weakness, revealing the fossil. Sometimes one side of the concretion will break off in the middle, in which case the remainder should be tapped firmly but gently on the upper edge until the fossil is completely uncovered. Pieces of the broken half should be glued together neatly with waterproof cement so that the entire specimen can be retained.
There is a small mention about how to wrap concretions in newspaper. There are many old collections that were stored this way.
The usual method of wrapping plant-bearing nodules is to place the end of a sheet of newspaper between the two halves of the nodule, fold the paper over the nodule, and roll it up in the sheet.
The best part of the book is the detailed drawings of specimens, mostly plants, but a few insects.
Ferns
Seed ferns
Aphthoroblattina
Teneopteron
