These trees are most likely evidence from a geological period when area was wetter and cooler than today.

For greater geologic detail, see the articles on the various geological periods.

The Cryogenian is a geological period, from 850 million years ago to 63 5mya.

He published many research papers on various geological periods.

One is the presence of rocks from many different geological periods near the earth's surface.

They believe it will take nineteen geological periods to breed her match.

It's named for the Silurian geological period because of rocks found there.

Thus, deposits formed in different geological period would have various lead isotope signature.

This made it the first new geological period declared in 120 years.

Information may be related to geological periods or estimated dates.