Mazon Creek Concretions at Coal City Illinois

Saturday morning early; about five am, we drove south to Coal City Illinois.  We met with some fellow Rock Hounds from ESCONI (Earth Science Club of Northern Illinois) and went to an abandoned tailings pile outside of town, left idle since the coal mines closed in the mid 1960’s.  We had loaded the gear into the van Friday night, before bed, and after a quick breakfast at McDonalds we made the jaunt to look for fossils buried deep in the Frances Creek Shale material on the pile.

It was a warm sunny September morning when we arrived at the site.  There was just enough breeze to keep the mosquitos at bay, and the warm weather had dried the wooded path leading to the mud flats surrounding the protruding mountain-like tailings pile to be explored.  The recent mild weather brought dry conditions to the Illinois clay loam soil, and no boots were needed, as we approached the hundred foot tall, vertically eroded monolith.  It reminded me of the earthier structures of the “Badlands” of South Dakota, as it stood alone as a foreign object amidst the surrounding flatland terrain.

We signed the obligatory insurance waivers and roster of the clip, and carried our buckets and tools towards the inviting mountains containing eons of earth history.  The Tailings pile is what was removed from a long abandoned coal mining operation, which was the founding roots of the small local community namesake.  The mine was closed in the late 1960’s, but the remaining tailings pile of Frances Creek Shale, is what’s left from the spoils removed from the underground tunnels, and abandoned to be used as fill by a local construction company.  As with most excavated materials, the practical use has no regard for the more eccentric historic or scientific treasures which it has protected over the centuries to be found by inquisitive scientists and rock hounds.

The hard clay containing remnants of coal, mining relics, fossilized jellyfish, crustaceans, petrified wood and ferns, perfectly preserved in the smooth, brassy rust colored, oval shaped stone cocoon, waiting to be harvested and explored when opened. While these specimens were formed eons ago; they were brought to the surface and compacted into the piles over many decades, where they lie in wait for us to release them and explore their preserved geological and archeological masterpieces. There is a sense of appealing achievement within; when finding a nodule or specimen after being formed billions of years ago, and being encapsulating as a protective shield from the elements. A plethora of fossils that will need to be frost-thawed to be opened, were retrieved as we dug, excavated and uncovered a number of buckets of material to take home and fill our freezers or wait until we are able to allow nature to frost-thaw them to reveal whatever was found or be discarded.


These treasures were formed while the supercontinents before Pangaea called Rodinia and Gondwana that formed and broke up hundreds of millions of years ago, before the continent of Patagonia Brooke up.  The  pre-atmosphere climate of the era, formed cellulose flora  (plant fiber) vegetation and the crustacean precursor to fauna., which by “intelligent design” or creationism, allows the process of evolution to proceed by giving the environment the first nourishment for the eventual introduction of the beginnings of mammal and animal life, as the seas full of jelly fish, shrimp, crustaceans, cephalopod and insects as they are formed or deformed by the radiation as it penetrates the thin atmosphere.

The sun’s radiation was unfiltered as it warmed and penetrated space to reach the earth, and as we say “Radiation creates a Mutation, and Mutation creates Variation” which are the basic building blocks of every living thing we see today.  In time as the foliage, trees, and all forms of flora and fauna were covered be oceans and seas, carrying and depositing layers of silt, only to eventually recede, and repeat the reforestation of the surface again, every time deepening the solid mass of organic material deposited. Each time sedimentizing the surface under the sand and eroded soils, as the volcanic actions of the mantle and outer core, in conjunction with the oceans and seas continually flooded the surface to be glaciated during the ice ages and form new surfaces and proceed to fossilize, and develop the surface which evolved into what we have today. This would over time fossilize some materials, while compressing the rest into fossil fuels we harvest today. Where it lied until the Teutonic Plates of the continent Pangea were flooded and eventually broke apart, and the globe began to more closely resembles the planet’s surface as we see it today.  But rest assured, we have a role to play as well, as we live on an ever changing planet and someday when this eon of humanity disappears, and we are a part of the next eon, and eventually some time; millions or billions of years from now, we too may be the fossils of someone’s weekend story!

John and Mary Rettler