Athro, Limited Gubik Field Trip Section 20 Cretaceous

Plants in Cretaceous Sediments at base of Skull Cliff

This horizon in the Cretaceous sandstone is covered with plant fossils. Specifically, these look like fossilized bits of trees - large branches and small logs.

Logjam

A possible modern analog for this accumulation can be seen in this log jam in a river in West Virginia. This suggests that channel and overbank deposits might be a suitable depositional setting to consider for the Cretaceous rocks at the base of Skull Cliff.

Plant lag in Permian Channel

Here is an older fossil example: This is plant debris found as a lag at the base of a channel in Permian non-marine rocks.

Log at base of Permian channel fill

In the center of this picture is a coalified log in situ at the base of a sandy channel fill in a Permian non-marine fluvial deposit.