Howard Falcon-Lang told the British Association Science Festival in Liverpool the fossil forests are the largest ever found, the BBC reported Tuesday. He said the fossils cover an area the size of Bristol.
The discovery of the first fossil forest in the region along the Illinois, Indiana and Kentucky borders was reported last year. Scientists have since found five more, the report said.
The forests, which date back about 300 million years ago, were buried in vertical sequence during repeated periods of subsidence and flooding. They were discovered during mining operations that now give scientists a unique view of the ancient fossils.
"It's kind of an odd view looking at a forest bottom-up," Falcon-Lang told the BBC. "You can actually see upright tree stumps that are pointed vertically up above your head with the roots coming down."