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World's Largest Fossil Forest, and One of the Oldest
solitas writes in with news from last week of the discovery of a fossilized forest in Illinois. The forest was found in the ceiling of a working coal mine, 250 feet below the surface. It was drowned 300 million years ago in an earthquake, its discoverers speculate — here is a graphic of its formation. Geologists are excited because the huge fossilized forest, over 25 square miles in extent, preserves trees and other plants upright, as they grew.
Ordinary subsidence of the crust can do that (e.g., the modern Mississippi Delta continues to subside and slowly bury old swampland forests in sediment), but sudden drops due to earthquakes are well-known too. An excellent example is Reelfoot Lake in Tennessee, which was formed (or at least enhanced) due to ground shifts related to the 1812 New Madrid earthquake -- this was not far from Illinois.
Burial of trees happens all the time. Sites with fossil forests are known from all over the world. But having them exposed in a roof of a coal seam is quite cool, even though that isn't unknown either (e.g., in the area near Price, Utah -- some of the seams even have dinosaur footprints in their roof in addition to tree stumps).
The original article being referred to is in the latest issue of the journal Geology, but you have to be a subscriber to view it.
From the summary, which you obviously didn't read:
>>>Geologists are excited because the huge fossilized forest, over 25 square miles in extent, preserves trees and other plants upright, as they grew.
Hi,
One of the authors here (Scott Elrick - geologist from the Illinois State Geological Survey). I would be happy to answer questions from folks... or at least try!
I can start by giving a basic overview of the discovery, what we found, and how it is important (to paleobotanists that is).
The location of the fossils is just to the south and west of Danville, IL, itself about 30 miles to the east of the University of Illinois, Urbana-Champaign (say hi to HAL when you come to visit). The forest was found directly above the Herrin coal seam in the Riola and Vermillion Grove coal mines, owned by Black Beauty coal (a subsidiary of Peabody Energy). The mines cover approximately 15 square miles and the study area was about 4 square miles... actually 1000 hectares. (I'm rounding up the square miles)
Okay, so what's so cool? If you are a geologist and read the headlines that have been popping up about the story, you may have scoffed and shook your head saying, "What do they mean largest fossil forest? A coal seam is nothing but the fossil remnants of a fossil forest. And a coal seam like the Colchester coal extended from Pennsylvania all the way to Oklahoma!" And you are correct! (This is my first exposure to the modern day media... and its been an eye opener! Give them credit, they do a pretty god job overall)
What is 'largest' about this fossil forest story is that it is the largest STUDY of a mostly entact fossil forest. Specifically one that is looking at the ecology of that forest. The largest study before this that looked at the overall ecology was about 25 hectares.. say about 1/10th of a square mile. So this study is an order of magnitude greater. The meat of the matter here is that we had an opportunity to examine a fossil forest at just a wonderfully huge scale and as a result were able to see subtle changes in the make-up of the forest as we walked the multiple miles of passageways in the mine.
The analogy is that previous studies were like blindfolded people examining an elephant. Each person has a wonderfully detailed and accurate description of his or her patch of the elephant, and when they compare notes a decent group consensus exists as to what the elephant probably looks like... but nobody has a chance to see the whole elephant. Our study is where we get to step back from the elephant a bit and take a pretty good peak under the blindfold at the whole animal. (I wont go so far as to say we are able to clearly see the whole thing as that is stretching the analogy. The point being it is an important and exciting step forward, but not necessarily a monstrous revelation!)
A couple of things to highlight.
First, the part that I find the coolest about work like this. In much of geologic science (field aspects more so), geologists look at vast spreads of time in small geographic slices. For example, standing at the rim of the Grand Canyon and peering across to the other side, your eye takes in millions of years of geologic time... but you are only able to see a thin 'slice' of each unit in profile. What does a particular rock unit look like 500 feet into the side of the canyon walls? The only way to find out is to drill a hole and take a core sample.
Geologic research, or in this case paleontological research, in an underground mine such as these coal mines is orthogonal to the norm above! At these mines, looking up at preserved trees and ferns in the mine ceiling, we were looking at single slice of time, a T(0) event, over a huge (relatively speaking) geographic area. That means that we were able to get a snapshot in time look at the forrest landscape of 300 million years ago. It's the 'worms eye' view of a fossil forest.
I should point out that the 'discovery' of this fossil forest was a gradual process. One of the responsibilities of the Illinois State Geological Survey is to try to understand the geology of the state of Illinois... and for us in the coal section that means coworker John Nelson and I (also one of the aut
Indeed. So far as I understand Christianity, this is the fundamental message. We are all sinners and nothing but. Salvation is gained through faith alone.
"The question of whether a computer can think is no more interesting than that of whether a submarine can swim" -EWD
Yeah, the fifteen minutes will probably run out any moment now!
Peabody Energy (owners of the coal mines) was extremely accommodating of our work in the mine. As they mined the coal, they exposed more and more roof shale for us to examine... and yes they kept on mining. We were able to easily go around their operations and stay out of their way.
I'm afraid you are correct in that it is something you look at, record and describe to the best of your ability and then take out the best samples you can. That's one of the reasons we try to visit the mines on a regular basis. To see what's going on geologically! Fortunately, you can go see a bit of this fossil forest today at the museum of science and industry in Chicago. When they remodeled their coal mining exhibit a few years ago (6 or 7 I think) Riola mine donated a big slab of shale containing plant fossils for display.
We did find a few pieces of a Eurypterid, a fossil 'sea-scorpian' but this was a plant dominated fossil assemblage and thats where we spent the majority of our time!
Good question about the state of the fossils. As you will be able to see from the pictures we post on Friday, most of the plants show up as carbonized impressions on the shale. Some of the plant material actually transforms all the way to coal if it was thick enough to begin with.