Mazon Creek fossil hunting in Braidwood, IL

Tully monster fossil mazon creek

Tully monster fossil and model at Chicago Field Museum – photo © Brian Smith on Flickr

Fossil Hunting in Braidwood, Illinois famous Mazon Creek Area

Once in a while, its nice to get out of the city for some decent fishing on a nice day and Braidwood State Fish and Wildlife Area is a solid escape. My trip to the area and Braidwood lake yielded some good weather, decent fishing, hiking, and a few fossils.

Some background: The Mazon Creek area is loaded with Pennsylvanian age fossils, the 300 million year old remnants of the swampy inland ocean that once covered Illinois. These rocks were dug up in the 1960’s when the area used to be a coal strip mine. It has since been turned into a fishing, game, and fossil hunting area. Some common fossils at Mazon Creek are worms, jellyfish, plants and ferns, but rarer concretions will hold small fish, shrimp, spiders, beetles, or even Illinois’ rare state fossil of the Tully Monster.

You need a day permit to collect fossils to state that you know the rules (no digging up plants, only one 5-gallon bucket per person). It’s free and only takes a second to print out, but it seemed unnecessary since nobody was even there to check it or enforce anything. And from what I could see, it is very unlikely that someone could find a 5-gallon-bucket full of fossils in the area.

NOTE: This is about a solo trip I took to Mazon Creek. I later went on 2 more trips with the Lizzadro Museum of Lapidary Art  and again with the Earth Science Club of Illinois to a private dig site. You can read about that trip HERE, and you can check their websites for upcoming trips!

The first stop was at Mazonia State Fish and Wildlife Area as seen on the map below:
View Larger Map
 The DNR website for the area has information on fossil hunting and fishing, so it seemed like a promising area… however despite it being early spring, the lakes are completely overgrown and the only fishing access was via the few boat ramps on the various lakes. Before leaving to the next lake, we scouted around for a fossil dig site to try our luck finding some concretions, but as I said, the area is completely overgrown and any area that was once a ‘dig site’ years ago, now looks more like these photos:
Mazon Creek lake

I have read that the DNR occasionally bulldozes areas of the park for researchers and fossil collectors, but that info is not easily available to a casual day visitor and we had no luck in finding anything other than knee-high brush along a few trails.





Illinois Mazon creek land







The second stop was a more popular dig site on Braidwood Lake. Below is a map of the parking lot and 2 mile walk to the site:

View Larger Map

We brought our fishing poles along and fished the somewhat more open and scenic bank of Braidwood Lake en route to the fossil dig site. We caught several catfish and a few bluegill using nightcrawlers as bait. Despite the area’s fame for fossils, you won’t find any along the way, as it is just as overgrown as the Mazonia area. However, the islands, only accessible by boat, look decent for fossil hunting and fishing.
50 years ago, I’m sure the area was loaded with fossils, but the inactive strip mine turned into a forest over the decades. Here’s some before and after pictures of what the transformation likely looked like:
abandoned coal mine










Mazon Creek fossil area







Those few ridges are all that remains of what was once a vast fossil-collecting area. But despite all, we were able to collect a few concretions and crack them open. I know most people recommend a freeze-thaw method that reveals the fossils inside, but that requires a lot of time and patience, and is not quite as fun as smashing them open with a hammer.

opening mazon creek concretions







Mazon creek fossils unopened








Even the most promising-looking nodules held nothing more than little silver blobs, but there were a few fern leaves and plant stems mixed in, along with something that looked like a tadpole or a shrimp.
My collection continues to grow!

I created a field guide for those who may be interested in fossil hunting Pit 11. You can read more about it in this Chicago Rants post.

And you can buy it in this link here from American Fossil Hunt

I highly recommend it, especially for first-time collectors to the area.
Mazon Creek


  1. That’s pretty cool!

  2. how cool! mind if i share the link to this post?

  3. Sounds like a cool day out, despite the overgrown bits. That Tully monster is AWESOME. maybe one day you’ll find yours. Completely agree on the smashing vs. patience! I used to love smashing bits of limestone together to find fossils as a kid. Maybe I should try it again…

  4. I just moved from New Mexico, which is pretty much a geologist’s dreamland, so I’m really glad to see there’s some good geology in the midwest. Hopefully I’ll find time to make it out there. Thanks for the info!

  5. I hope you join ESCONI so you can go on the next trip because you will find 1-2 buckets of fossils! Also, there are many people to talk with during the day who are also searching the same site – fun and informative.

    • chicagoranter says:

      im considering it, but i know i just missed a trip out there last weekend, but i will keep an eye out for ones later in the summer!

  6. I too am irritated at the small area available to collect fossils. In all that land they let it become overgrown and don’t seem to recognize the value of the fossils below. Short sighted to say the least. I remember when I was a kid and went fossil hunting with Mr. Tully, the place looked like the moon. There is no need to have all that vegetation.
    It is truely sad the plants that can and will grow back are considered more important than the fossils that are irreplaceable. Mr. Tully would be appalled.

    • chicagoranter says:

      thanks for the comment Nina, I really wish I got to see how it was back in the day. Ive read about people taking home bucketloads of concretions just in an hour of walking the dirt path. But it really does look like a forest as if there was never even a coal mine

      • Well back in the day there were no paths. It was totally open and clear of most vegetation. It is true that just walking along looking down yielded many many fossil concretions. And so many had wonderful fossils. I went last weekend and in the area that the map shows as the correct place to be, I found only one very small concretion that did indeed have a fossil. Sad but true.

        • chicagoranter says:

          The second map I posted shows the area where I found about 20 concretions. It was a small open area and was very hard to get to, lots of climbing and roughing it in the hills. Only found 4 decent plant fossils though. I’m hoping for a really snowy winter, hopefully the melt will uncover a few, and I’ll try again in the early spring before it gets too overgrown. Also, if you look around the area on google earth, there are a few bare hills. I think most of them are on private property, but maybe something worth looking into if you’re up to being sneaky about it! What was the one concretion of you found last weekend?

  7. When I was in 5th grade.. I went on a fossil hunting trip with my class to this location. At that time.. It still looked like a strip mine. There were nodules EVERYWHERE!!! I found a couple ferns and a jellyfish. And there was another student who found a trilobite. A couple years ago. I returned to this site. And it has indeed changed drastically. They do in fact plow an area in the spring for hunting. But after searching for several hours. I found nothing. I have since been told that there are still piles of rock in the area that take some walking to reach. That are still fossil rich. I intend to go back soon and see if I can locate them.

    • chicagoranter says:

      Good luck! follow up if you do end up going, I’m curious to hear. I’m aware that they plow certain areas ever year, but I’ve been unable to find them!

      • Matthew Ewert says:

        I also remember going as a kid and thought we took a boat somewhere on the site to find fossils. Does that sound right?

        • chicagoranter says:

          100% correct, in the middle of the big cooling lake there is a giant spill pile that you can only access by boat. There are also areas of the South Unit that you can only get to by boat as well. I actually recently bought a kayak so hopefully I’ll be able to get to these spots soon!


  1. […] nodules. The area is so overgrown! Here's a blog post about my trip and details about the area: Mazon Creek fossil hunting in Braidwood, IL-Chicago Rants Has anybody had more luck in this area? I know I'm not in the wrong spot, as this is one of the […]

  2. […] reading this blog post about fossil digging in Braidwood, IL, I took a look on the map and realized there would be enough outdoor attractions nearby to make a […]

  3. […] might remember my post about fossil hunting in Mazon Creek near Braidwood, IL at the Mazonia State Fish and Wildlife Area. It’s a preserve on the […]

  4. […] be trying out a few new things to compile my Chicago Summer Bucketlist, like a guided trip to Mazon Creek and attending the Learn to Row Day with the Lincoln Park Boat Club. A full list will be up soon, […]


    Mazon Creek fossil hunting in Braidwood, IL-Chicago Rants — Chicago Rants

  6. […] can read about my previous adventures to Mazon Creek in the posts below: Mazon Creek Fossil Hunting in Braidwood, IL Fishing the Mazon River in Morris, […]

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