Mazon Creek Fossils by Mary Fairchild

In all North America, the Mazon Creek flora has the largest number of species and greatest taxonomic diversity of any Moscovian Pennsylvanian period assemblage.  More than 200 species have been documented, of which the majority are fern and seed fern foliage. 

Jack Wittry

 

 

Mazon Creek was originally discovered by Joseph Evans in the late 1800s and later went on to be explored by famous amateurs George Langford and Francis Tully. The first specimens found along the banks of the Mazon River were plants, a few freshwater clams and crustacea.  George Langford, Curator of Fossil Plants, established a large collection at the Field Museum.  Of the vast array of unique specimens found here, some are still undecided as to where to even place them in the animal kingdom.  One in particular happens to be our own Illinois State Fossil, a strange wormlike "Tully monster" named after its collector, Francis Tully.   

 

It would be “the amateurs” who would soon fill the Field Museum with thousands of specimens, many rare and unique.  Their working relationship with the museum staff was initiated by the late staff scientist Dr. Eugene Stanley Richardson, Jr. who was the Curator of Vertebrate Paleontology at the Field Museum of Natural History in Chicago.  Richardson had been the leader in exploring the fossil animals that were being discovered in the 1950s and 1960s amongst the coal mining operations southwest of the Mazon River.  Before he passed away in 1983, he had recorded thousands of fossils for a projected book. 

 

In 1967, Dr. Eugene Richardson and Dr. Ralph Gordon Johnson , University of Chicago professor, organized a National Science Foundation study.  After systematically collecting at Pit 11 they discovered that the area unveiled "marine" fossils compared to more terrestrial forms found to the northeast.  There was now a division made between the marine fossils (Essex fauna) and freshwater association (Braidwood fauna).  In the following years, students would find many species of worms, crustaceans, and fish.  

 

As a graduate student under Richardson and Johnson, Charles W. Shabica was to find out how Mazon Creek fauna lived and died.  Detailed stratigraphic sampling combined with fossil census sampling by Gordon C. Baird allowed for the division of the Mazon Creek biota into several deltaic associations.  The data showed a distinct regional boundary between esturine (Essex) and freshwater and terrestrial (Braidwood) faunal assemblages paralelling the ancient shoreline.  

 

Gordon C. Baird, professor of geology at State University of New York at Fedonia, in his article Mazon Creek Census writes, Looming above the cornfields, an hour’s drive southwest of Chicago, are gray, cone-shaped hills which may catch the traveler’s eye as he motors along Interstate Highway 55.  These hills, notable for their drabness and symmetry, are evidence of a system of abandoned coal mines that extends both across and under 40 square miles of Will, Grundy, Livingstone, and Kankakee Counties...To the paleontologist...these mined-out areas...contain abundant fossils, including forms that are both unusual and spectacular. [Field Museum of Natural History Bulletin; Sept. 1978]  Gordon Baird did undergraduate education at Earlham College which introduced him to the famous Mazon Creek formation.

 

Gene Richardson had a tremendous workforce on his side as the amateur collectors that were allowed access into Pit 11 would anxiously await to share thier rare finds at the annual open house at the Field Museum.  Later, when Peabody sold pit 11 to Commonwealth Edison for the construction of a nuclear power-generating station, some collecting areas were lost. Area around the reactor cooling pond was leased, however, to the State of Illinois as a conservation area for fishing and fossil collecting. 

 

Mazon Creek fossils occur within ironstone concretions.  The animal and plant fossils here belong to the Pennsylvanian Period which is also called the “coal age” as extensive coastal swamps during this age developed and peat deposits formed that later turned into coal.  Do to their rapid burial, many organisms were buried alive creating incredibly well-preserved specimens.  The concretions were buried in layers of shale that were stripped away during coal mining.  Most of them ended up in spoil piles. 

 

The concretions are placed in water-filled buckets during the cold months of the year to allow the gentle freezing and thawing to split them open.  This technique was first introduced by late fellow amateur collector and ESCONI member Larry Osterburger.  It would be “the amateurs” who would soon fill the Field Museum with thousands of specimens, many rare and unique.  Their working relationship with the museum staff was initiated by the late staff scientist Eugene S. Richardson.  For many of us, when we are able to engage a considerable amount of time in an activity or research there is a sense of pride in being able to share that with others both amateur and professional alike. 

 

 

The 1997 Richardson's Guide to the Fossil and Fauna of Mazon Creek  by Charles W. Shabica and Andrew A. Hay, was dedicated to the late Eugene Richardson who founded the Mazon Creek Project  in the 1960s.  It was a program sponsored by Northeastern Illinois University whose main goal was to keep the Mazonia-Braidwood Conservation Area open for collecting by scientists, school children, scout groups, visitors from other states and others.  It was also an attempt to encourage more communication between paleontologists and amateur collectors.

 

Mazon Creek Fossils hold a special place in paleontological record.  Because conditions of life, of death, and of burial were unusually propitious, we find a more complete record of plant and animal populations than in most other fossil occurances....I suppose that these elegant fossils have been collected...for centuries... But we have no inkling of any collections made by the Indians.  The tradition that continues to the present has begun in the mid-ninteenth century, when there were already established towns and farms in the Illinois valley..." 

Eugene Richardson

As the cover of his book The Mazon Creek Fossil Flora [pictured above]accurately describes, Jack Wittry is a "prolific collector"  with a long standing interest in the taxonomy of the Mazon Creek flora.  He has been welcomed to the Illinois State Museum, The Field Museum and The Smithsonian Institute to study and consult upon collections from this locality.  His 2006 book is a welcomed and well-awaited update of the fossil flora of the Mazon Creek region of Illinois.  

 

One way to get more involved in understanding or collecting Mazon Creek fossils is to join a local rock club like ESCONI which has been very involved in Mazon Creek since it's beginnings.  Stop in at their general meeting the second Friday of each month at 8pm at the College of Du Page or check out their annual show in March.   

   

Comments

[rc helicopter]

Impressive blog! -Arron