DENVER -- With current dry conditions, it's hard to believe that a tropical rain forest once existed in Colorado, but scientists say it's true and have found more evidence.

Archaeologists have been working the area off Interstate 25, north of Castle Rock, since 1994 and they've been finding ancient leaves. The fossil leaves are a broadleaf variety, some up to 24 inches long, and come from more than 100 species of plants, researchers said.

Then on Sunday, researchers from the Denver Museum of Nature and Science discovered a huge tree.

"Four of us were digging in the quarry, all of us digging out fossil wood and then they all converged together on one gigantic colossal stump," said Kirk Johnson of the Museum of Nature and Science.

Scientists figure the tree's about 6 feet in diameter and 150 feet tall, the kind found in a rain forest.

Scientists say that the crumbling black trunk is proof of what Colorado was like 64 million years ago -- a tropical rainforest that recieved more than 100 inches of rain a year.

The excavation project is funded by the Colorado Department of Transportation, which hopes scientists can remove and study the fossils in the area before a road-widening project , known as T-REX, destroys it.