Inside of a coal mine near the town of Danville in eastern Illinois, it appears that there once existed a very large rainforest – 300-million years ago, that is. Spanning a thousand hectares and preserved by what must have been an incredible earthquake, the hundreds of fossilized plants found in the coal mine bear very little resemblance to today’s American forests.
Giant leaf impressions, large trunks of extinct trees, and tree-sized horsetail plant fossils were found 300 meters below the surface, and geologists have surmised that this ancient forest was once hot, wet, and very humid. The forest would have consisted of a very light upper canopy, with plenty of room for sunlight to enter and nourish the plants below. The trunks found were likely from 12-meter plants that formed a sub-canopy, though some club mosses were over 40 feet tall, judging by the fossilized remains.
Very few insect remains have been found, however it is thought that forest insect and animal life was significantly different – consisting of creatures like dragonflies as big as seagulls, and millipedes around three feet long.
The earthquake that buried this rainforest would have been significant enough to cause the entire section of land to drop below sea level, immediately encasing and preserving the entire ecosystem in mud – since a rapid burial is the only explanation for such extensive and widespread preservation. The fossils themselves look very much like leaf pressings in a scrapbook – just a whole lot bigger.
Not only will this enormous fossilized rainforest provide information about ancient ecosystems and extinct plant species, but it should also help scientists to learn about the formation of coal, which is actually formed by different plants in different settings. The way coal burns depends on its formation processes, so it is suspected that extensive testing will be conducted to see if the coal here has any different properties than coal found in other areas of the country – namely, where there aren’t giant fossilized rainforests overhead.
Want to read more?
Tomorrow: The history of toilet paper!