Huge underground fossil rainforests discovered in Illinois coal mine.

Illinois landscape, 300 million years ago: Late 19th Century illustration portraying a Carboniferous rainforest
Illinois landscape, 300 million years ago: Late 19th Century illustration portraying a Carboniferous rainforestCourtesy Mark Ryan
Last year, news came out about the discovery of a large fossil forest dating from 300 million years ago in a coal mine located in eastern Illinois. Now, five more prehistoric forests have been identified in the same region.

Central Illinois above the coal mine: The terrain and vegetation today is a far cry from how it looked 300 million years ago.
Central Illinois above the coal mine: The terrain and vegetation today is a far cry from how it looked 300 million years ago.Courtesy Illinois State Geological Survey
The remains of the ancient tropical rainforests cover a tremendous area – 36 square miles – and have been under study by scientists from the Smithsonian, the UK, and the Illinois State Geological Survey. A presentation given at the British Association Science Festival held in Liverpool this week detailed some of the highlights of this incredible find.

"Theses are the largest fossil forests found anywhere in the world at any point in geological time,” said Dr Howard Falcon-Lang a paleobotanist at the University of Bristol.

The prehistoric landscapes existed within only a few million years of each other – a short span geologically speaking – and are found stacked one upon the other. Segments of the forest fossilized in their original vertical position. At places, scientists can trace the original ground cover in well-preserved fossils.

Donning cap lamps, battery packs, and rock hammers Falcon-Lang and his colleagues rode an armored vehicle 250 feet beneath the Herrin coal seam in the Riola and Vermillion Grove coal mine. Once underground, the scientists took an incredible hike through a long-gone prehistoric fossil forest, illuminated only by lights on their caps.

Ancient tree trunk protruding from coal mine ceiling
Ancient tree trunk protruding from coal mine ceilingCourtesy Illinois State Geological Survey
“We walked for miles and miles along pitch-black passages with the fossil forest just above our heads,” Falcon-Lang said. "It's kind of an odd view looking at a forest bottom-up. You can actually see upright tree stumps that are pointed vertically up above your head with the roots coming down; and adjacent to those tree stumps you see all the litter.”

Fallen fossil tree in coal mine: Howard Falcon-Lang (University of Bristol) and John Nelson (Illinois State Geological Survey) mark off the width of a large fossil tree trunk lying just above the contact of the coal bed.
Fallen fossil tree in coal mine: Howard Falcon-Lang (University of Bristol) and John Nelson (Illinois State Geological Survey) mark off the width of a large fossil tree trunk lying just above the contact of the coal bed.Courtesy Illinois State Geological Survey
In some cases toppled trees – complete with crowns – and over 100 feet long were measured lying stretched out in the shale across the ceiling. For paleobotanists it presents a remarkable opportunity to actually stroll through a 300 million year-old ecological system as if taking a walk in the local woods today.

The reason for this unusual preservation is thought to be due to the prehistoric rain forest growing in an estuary near the Royal Center fault in Indiana, which caused the terrain to subside below sea level making it vulnerable to incidents of flooding and abrupt drowning. Geologists suspect earthquakes along the fault are the reason for the subsidence.

The soil that once supported these rainforests was later transformed into coal. Once this coal seam was mined from underground, the base of the fossilized forest was revealed encased in a shale matrix.

These tropical rain forests originally flourished during the Pennsylvania period (known as the Upper Carboniferous in Britain), back when the US Midwest was located near the equator. Forests of giant club moss trees and tree-sized horsetails came and went over a geologically short span of time. At the same time, major shifts in climate were taking place, alternating from cooler temperatures with large planetary ice caps to periods of extreme warming.

The episodes of climatic change coincide with changes in the forest ecology. Close study of the fossil vegetation show that several times the climatic stress pushed the rain forests into extinction, making way for skimpier fern growths to replace them.

Over the next five years Dr. Falcon-Lang’s team will search for reasons why this rainforest extinction took place. Understanding how the first rainforests responded to global warming could help shed light on how climatic change may affect present day rainforests.

Additional photos of the amazing fossil forest can be found here. But if you want to see some of the real thing, visit the coal-mining exhibit at the Museum of Science and Industry in Chicago where an actual slab of the gray roof shale is on display.

Illinois State Geological Survey story
University of Bristol story
BBC website story
Coal-mining info
More about the Carboniferous period

Your Comments, Thoughts, Questions, Ideas

Martha's picture
Martha says:

I think this is an amazing discovery! How exciting!

posted on Tue, 09/23/2008 - 8:18am
Anonymous's picture
Anonymous says:


posted on Tue, 01/20/2009 - 3:00pm
irule12345's picture
irule12345 says:

this providen a lot of information. it was intersesing for me because i am into science and weather a lot. if oyu are doing a report, i reccomend this information

posted on Fri, 03/13/2009 - 4:34pm
Joan Stuchner's picture
Joan Stuchner says:

God created the earth in six periods of time, then rested in the seventh period of time. (That's right, 'Yom' didn't mean 'day' way back when) This amazing find is an awe inspiring example of God's science.

posted on Sat, 10/17/2009 - 4:51pm
Dale's picture
Dale says:

The word "yom" is not easily translated into English. It CAN mean "period of time," as you suggest, but it CAN also mean a 24 hr period of time.

In any case, I don't argue about the difference. Since I wasn't there, all I can say definitively is "I believe in God the Father, almighty creator of heaven and earth." I'll leave the details of His creative power in the hands/mind of God.


posted on Thu, 05/05/2011 - 7:33am
Sakiq's picture
Sakiq says:

I can't believe that they found a FOSSILIZED RAINFOREST around 200 feet underground!!! It is really cool that they did and that it is preserved really good!!

posted on Tue, 11/24/2009 - 2:45pm
Nirmala Ayyar's picture
Nirmala Ayyar says:

There is a fossil forest in the outskirts of Chennai. I have not personally seen it, but it is a tourist attraction for people visiting the Vajra Kali Temple. It is said the area was frozen into stone during the Kali's fight with Vajrasura due to her curse

posted on Wed, 09/01/2010 - 3:46am
Anonymous's picture
Anonymous says:

Guys do you really have to get all "Holier than thou" about EVERYTHING? I mean, this is a cool scientific discovery, it doesn't argue any points about religion that weren't already clear to the logical and educated.

Let's just leave it at "Cool" because that is quite simply what it is. Take the religion out of it already, ignorance is enough a problem in our world without people like you proselytizing at any given chance, even when it doesn't call for it.

posted on Wed, 01/11/2012 - 4:14pm
Anonymous's picture
Anonymous says:

not 300 billion about 10,oo0 years old do your math in the holy bible

posted on Wed, 03/07/2012 - 11:35pm
brad's picture
brad says:

These trees settled at the tops of this coal bed during the flood of Noah. Notice there is no bark on them? Logs float right? the flood didn't go away in 40 days. It was months before the ark rested upon the mount. Huge and I mean huge log mats were floating and being blown around by winds on the seas. They rubbed and banged against each other...all the bark leaves and stuff from them settled. (Coal) then the trees became waterlogged and sank. The water currents covered them up with sediment. Hundreds of feet of it. Took less than a year. Turned to rock soon after. Just like at Mount Saint Helens. A catastophic worldwide event

posted on Tue, 05/08/2012 - 8:28am
mdr's picture
mdr says:

Well, right off the bat your claim that there is no bark on the trees is untrue, many of the fossil trees have bark on them (Here’s proof and more here). Also, if, as you say, huge log mats were being buffeted by the sea winds, then you could reasonably expect to find a whole lot of fossilized forests like these not just over coal beds but covering all sorts of different terrain – mountaintops, lake bottoms, drowned villages, etc. But that’s not the case. Lastly, your equating the effects of the eruption of Mount St. Helens with that of a mythical worldwide flood is puzzling. Mount St. Helens' 1980 eruption was hardly a worldwide catastrophe. In fact, it was only a regional one. And compared to many other volcanic eruptions, a minor event. Please explain what you mean.

posted on Wed, 05/09/2012 - 2:52pm

Post new comment

The content of this field is kept private and will not be shown publicly.
  • Allowed HTML tags: <a> <h3> <h4> <em> <i> <strong> <b> <span> <ul> <ol> <li> <blockquote> <object> <embed> <param> <sub> <sup>
  • Lines and paragraphs break automatically.
  • You may embed videos from the following providers vimeo, youtube. Just add the video URL to your textarea in the place where you would like the video to appear, i.e.
  • Web page addresses and e-mail addresses turn into links automatically.
  • Images can be added to this post.

More information about formatting options