This is Mazon Monday post #84. What's your favorite Mazon Creek fossil? Tell us at email:[email protected].
-----------------------------------------------------
During the ESCONI Sale back in October, a member noticed a booklet called "A Guide to the Coal Fossils of Chowder Flats, Morris, Illinois". It was written by Robert J. Reich in 1982, who was advisor to the Botany Learning Club at the Milwaukee Area Technical College. If anyone has information about Mr. Reich or the Botany Learning Club, please send it along, as unfortunately, there doesn't seem to be anything about Mr. Reich or the Botany Learning Club available online. The ESCONI library has a few copies available to be lent to ESCONI members.
There isn't much available about the Chowder Flats locality, which is now a housing development. While some of the introductory material is a little dated and has been revised with additional scientific evidence in the years since, this booklet contains a wealth of historical and scientific information.
There are numerous maps of the area, including a detailed layout of the Chowder Flats locality with frequency of fossil specimens, both plant and animal.
Except for using a hammer to open concretions, the advice on collecting, namely logging and numbering specimens is very good... most of us (included myself) should follow these guidelines.
4. Collecting Concretion Fossils.
Concretions are greatly variable in size ranging from about 3/4 inch in diameter to several inches across. Their shapes are also very variable. They may be round, oblong, oval, or long and narrow. They are usually rusty yellow-brown on the surface, but the surface color is caused by oxidation from exposure.
Collect a few concretions and squeeze each one between your fingers to determine if it is hard or if it crumbles. Perhaps only surface layers will fall away leaving a hard interior nodule. This structure should be struck on the thin edge, with the hammer, to cause a split along any surface bearing a fossil. Usually, the rock will split along the weak zone surface of the fossil. Very brittle stones should be discarded. Please use safety glasses when hammering rocks.
If a whitish feature is observed inside the stone, or if other colors drastically different than the normal ground color are observed in streaks, lines, or other shapes keep the stone for later examination. Sometimes, even weak smudge-like structures, upon cleaning, will reveal rare shrimp, polychaetes, jellyfish, fishes, etc. Of course, spectacular fern leaves, stems, etc. are frequently encountered.
Reassemble good specimens and wrap or rubber-band them and place them in a bag. Add a tag with the hill number from which the concretions were collected.
Try not to mix concretions from two or more hills in the same bag. Use a new bag for each new hill. Always place an identification tag in each bag. See the maps on pages 12-13 for hill numbers.
Sometimes fossil stems and large pieces of fossil wood will be found that are not in concretions. Keep a lookout for such prizes.
Pack your bags carefully one on top of the other, into your pail or backpack. Try not to mix specimens from different hills.
Don't carry more weight than you can manage comfortably.
If you wish, you may take bags of unopened concretions home for opening later. You can increase your fossil collection greatly in this way.
Jot notes in your field notebook concerning bag numbers and hills of origin, etc. Include in your field notes interesting bits of information about opened concretions and their contents. These notes are often quite helpful later, when working with the specimens.
5. Preparing Your Fossil Collection at Home.
1. Cleaning: Remove loose scale from concretions into a paper bag for disposal. Don't wash scale down a drain, you'll clog the pipes. Hose your specimens in the garden or alley. Use a bucket of water to scrub the specimens. A scrub brush is fine for outer surfaces of large concretions. A toothbrush is good for small concretions, or fossil surfaces.
2. Drying: Allow the specimens to dry in old cardboard beer-box flats, fossil surfaces upward.
3. Numbering: Assign a number to each specimen. Write the number on two small pieces of paper and glue one on the outside of each half.
4. Notebooks: Obtain a notebook about 5 x 7 inches, with a hard cover. Keep careful notes on each specimen.
5. Storage: The simplest method of storage is in cotton-lined shirt boxes which can be purchased from gift departments in most department stores. Basement or closet shelves are good places to stack these boxes. The more ardent collector may wish to provide wooden drawers or steel drawers in more elaborate cabinets.
6. Identification: Various books are available for identifying Pennsylvanian concretion fossils. A brief list of important titles is found in the bibliography at the end of this paper.
There are lists of the plant and animal fossils that could be found... it's very extensive. How amazing that many Pit 11 species were found, including the Tully Monster! From the lists, Chowder Flats was a very rich fossil locality!
ALPHABETICAL LIST OF PLANT FOSSILS OF CHOWDER FLATS
Alethopteris
Annularia
Aspidiopsis
Asterophyllites
Calamites
Codonospermum
Codenotheca
"Cones"
Cordaicarpus
Cordaiphyllum
Cordaites
Crosiers (Ferns) (Spiropteris)
Crossetheca
Cyclopteris
Equisetites
"Ferns" (Various)
Lepidodendron
Lepidophyllum
Lepidostrobophyllum
Lepidostrobus
Linopteris
Mariopteris
Neuropteris
"Nedes" (Stem)
Odontopteris
Pecopteris
Roots
Sarcotesta
Scars (Leaf)
Seeds (Assorted)
Sigillaria
Sphenophyllum
Sphenopteris
Sperangites
Stems (Asserted)
Stigmaria
Wood (Asserted)
CaulopterisALPHABETICAL LIST OF ANIMAL FOSSILS OF CHOWDER FLATS
Acanthotelsen stimpsoni
Anthracomedusa turnbullii
Beletelsen magister
Centipede
Clams
Cyclus americanus
Cyzicus sp.
Esconites zelus
Essexella ascherae
"Fishes"
Flea Shrimp
Gastrepeds (Shails)
Horseshee Crab
Hydroids
Hydrozoans
Insects
Insect Wings
Lamproy?
Leech?
Medusae
Millipedes
Mite?
Octomedusa pieckerum
Ostraced
Plain Worm
Polychaetes
Scallops
Sea Cucumbers
Shark Teeth
Shrimps
Shail
Spirerbis
Tully Monster
Worm Borings
Worms
There are many good drawings of both plant and animal species.
The author uses the data collected to propose a paleoecological setting for the site. That setting is a section of river and banks upstream of a delta that thought to extend into a bay. Presently, the land based plants and animals are referred to as the Braidwood biota, while downstream in the bay, there is the Essex biota. Like Pit 11, there were elements of both in Chowder Flats.
10. The Paleoecology of the Chowder Flats Area
In part 3 of this paper, the rationale was described for the study of individual hills (ridges) through careful use of a numbering system and notations of collections. In section 8, each hill is described in terms of its fossil flora and fauna. The frequency study in section 9 is basic to gaining some insight into the ecological setting of the area when the organisms were living.
A static view is presented, deliberately avoiding the extensive time span involved, and the obvious changes which had occurred at the site. Ecological succession was probably active in the Pennsylvanian coal forests as it is in present day forests. A probable sequence is suggested,based upon the distribution of fossil remains at the site. From this data, a hypothetical setting is reconstructed. See page 45. The fossil materials have been vertically disrupted, destroying stratigraphic sequence and obliterating evidences of successional changes of coal forest vegetation.
The known structure of coal forest trees and other vegetation suggests a possible sequence of development of vegetation on a site such as Chowder Flats, from open water to drier, upland situations. A bold attempt to depict this "succession of vegetation" is shown on page 46.
Tides influence the marine community as shown on page 47.
