A Changing Climate - A Changing Scene
Color layers exposed in the slopes
before you mark fossil soils which were
formed during the Oligocene and Eocene
Epochs. They contain evidence of life
here between 37 and 23 million years ago.
Thirty-five Million Years Ago
A warm climated with ample rain produced open
woodland. The Saber-toothed Cat, Dinictis, prowled
the woods along with the nearly elephant-size
Twanothere, a large land mammal of the Eocene.
Thirty Million Years Ago
During the Oligocene the climate became drier and
cooler, restricting the woodland to stream banks. But
between streams, low plants grew among scattered
trees. Here lived the tiny deer-like Leptomeryx,
and numerous land snails, and land toirtoises.
Twenty-three Million Years Ago
By ths time the climate was even cooler and drier,
and trees were absent except near streams. Low
shrubs, wildflowers and grass has formed the first
North American prairie. Burrowing beavers,
Palaeocaster, lived there, much in the style of
today's prairie dogs.
At the bases of some of the buttes you can see
a yellow fossil soil below a red fossil soil. Both are
discussed at the Yellow Mounds Exhibit a mile west
on the Loop Road. In all, eighty-seven fossil soils
have been distinguished.