Page 1: Overview
Mazon Creek Pit 11
City: Braceville, IL
Timeline: Mid-Pennsylvanian epoch of the Carboniferous period, approximately 300 million years ago.
Unique for: Soft-bodied animal and plant material that do not normally fossilize.
Terrain and land: The Mazonia State Fish and Wildlife area is 2,640 acres of publicly accessible land is open for fossil collecting from March 1 to September 30. It was a coal strip mine until the early 70’s, and has now been reclaimed by nature, and repurposed, into an outdoor recreation area. It is known for great year-round fishing, seasonal deer hunting, and seasonal fossil collecting.
The Adventure
Here we venture to an old coal strip mine in Northeastern Illinois, where we follow in the footsteps of thousands of amateur and professional paleontologists before us, to hunt for concretions in this midwestern forest and grassland. This is one of very few, if not the only, area where one can find a Tully Monster, Illinois’ elusive state fossil. It is named after Mr. Francis Tully, an amateur collector, who first found the creature in 1958. He avidly collected the coal mine for fossils during its production days, and often brought his finds to Chicago’s famous Field Museum for research and identification. The bizarre creature challenged identification and became one of paleontologists’ favorite puzzle. As recently as 2016, new research claims it to be a vertebrate.
Collectors travel to Mazon Creek to find this prized jewel for their collection. But they are rare. Even the most skilled collectors take years to find their first. It gets more difficult each year with the new forest growth. These days, most prospectors leave with a bagful of concretions that will yield the common jellyfish, various plant and fern material, and the very occasional shrimp or insect. But the chosen few will find a Tully.
The Mazonia-Braidwood State Fish and Wildlife area terrain
The land is scarred by decades of coal mining, leaving behind deep, cavernous lakes and steep mounds of old coal spoil piles.
Despite the name, there is no creek here. The Mazon River runs north and west of the public collecting area known as Pit 11, but its few and isolated fossil deposits lie on private land.
Page 2: History
History of Mazon Creek and the Braidwood Coal mines
Braidwood, Illinois was a small prarie town first discovered coal in the 1860’s, the first times, surely by accident, while digging a water well. Landowners at the time hit a rich, thick seam of coal, less than 100 feet below the surface, and was the Midwest’s first taste, of what would become a massive industry in Northwest Illinois.
The earliest method of extracting coal was longwall mining, in which deep shafts led to the coal bed, that was then extracted horizontally, leaving pillars or rock and coal intact to support the mine roof. Shaft mines were used in the area from the 1870’s followed by strip mines in the 1920’s.
At one point, Northeastern Illinois was considered to be producing the greatest coal deposits in the country.
In 1999, the Illinois Department of Natural Resources purchased the southern portion of Pit 11 from Commonweath Edison, adding an additional 1,662 acres to the Mazonia State Fish and Wildlife area for $7 million dollars.
As this book is published in 2018, Commonweathe Edison owns restricted land near the nuclear power plant, as well as Braidwood Lake, used as its cooling pond. The lake is open and accessible to the public for recreation and fishing throughout the year.
Page 3: Paleo history
The Carboniferous Period
Between 350 to 290 million years ago in earth’s history lies the Carboniferous Period. The planet was extremely rich with forest, plant, and animal life, and North America was covered by vast tropical swamp forests. Plants and animals during this time were just fully becoming accostomed to land, primarily dominated by amphibians and seedless plants. The intense amount of plant growth during the Carboniferous period absorbed much of the carbon dioxide out of the atmosphere, and oxygen levels were higher than any other time in earth’s history. A great number of insects and arthropods evolve. The very first reptiles began to appear as well.
The decayed forests and vegetation are attributed to the beginning of coal and the Carboniferous Period is largely responsible for the recent past, and fading present, industry of coal mining.
The preservation of Mazon Creek fossils is largely attributed to the theory that this relatively small (just a few dozen square miles today) was formerly a basin of sorts, where a large river met an ancient sea. It is often compared to where the Mississippi River meets the Gulf of Mexico, a large and constant stream of constantly-deposited sediment. Any creatures and plants that got caught or happened to die of natural causes in its wake, settled on the bottom to become instantly encased in a forever tomb.
Page 4: Collecting
The Collecting
Now we journey into the woods on an unmarked trail, over rolling hills of a long-abandonded coal strip mine. To the unsuspecting, it is a beautiful wildlife area, rich with deep fish-filled lakes and wild game native the midwest, and seasonally open for hunting, fishing, and fossil collecting. But to the miner and naturalist, this is scarred and harvested land that, after several decades, is just healing over.
To collect Mazon Creek is no easy task. There are thousands of acres of overgrown land to hike and collect across to find the isolated pockets of these famous fossiliferous concretions.
There are two types of Mazon Creek concretions, the Braidwood biotia, mostly terrestrial fossils in the North pits (Pit #’s 1-10), then the Essex biotia (Pit #11), which has some plant material, but many more marine fossils, like jellyfish, worms, and the infamous Tully Monster. Pits 1-10 are, for the most part, inaccessible.These pits have been sold off and repurposed into private hunting and recreation clubs, campgrounds, and unfortunately, housting developments. Pit 11, the largest and most well-known remains open to the public, and these few thousand acres have no shortage of productive concretions.
Fossil collecting is permitted here from March 1-September 30 each year. The area is popular for duck and deer hunting the rest of the year, and fossil collecting is closed, not that you would want to find yourself foraging around in the underbrush amongst loaded rifles.
Page 5: Torino Hill
Tornio Hill
The largest and most tempting collecting land mass lies in the middle of Braidwood Lake, the massive cooling lake for Exelon Corporation’s nuclear power plant.
Torino Hill is named after a small, decrepit, and eventually abandonded mining town that once resided nearby. Occassionaly, one can find old mining equipment here, railroad stakes, mule horseshoes and the like, which are equally excellent finds as it represents the lands more recent, but very past history.
The small mountain is only accessible by motorized boat, and boasts the best exposed collecting area in the park. Those lucky enough to get access, are rewarded with steep ravines with regular rain washout that brings concretions to the surface.
The quality here varies, it is mostly marine, and yeilds a less than 5% fossil preservation rate, so it is best only to take the most promosing of nodules.
Page 6: Closing
The Lagerstätte that lies
Mazon Creek is my favorite, but least glamorous of sites documented in this book. Collecting fossils here requires much determination, and even more patience. The act of collecting is no easy task, even early in the spring, the area gets very overgrown, and riddled with ticks.And in the end, you leave with a bucket of heavy rocks that require the patience of the aforementioned freeze/thaw process. It is a cycle that takes weeks, even months.
Regardless, these fossils rank among the rarest, and best-preserved soft-bodied specimens in the world. The word Lagerstätte is referred to in the paleontology community as a site that holds extraordinary flora and fauna diversity. Literally, the word translates to ‘place of storage,’ but sometimes referred to as “mother loade.’
Some may call the area ‘picked over’ and ‘not what it used to be,’ but reader, I assure you, there are many treasures still to be found in these foothills.
