Rock layers in Badlands National Park contain fossils that show a dramatic cooling and drying of global climate over millions of years. The oldest rock layers contain marine fossils, roughly 70 million years old, from when this area was underwater. Although dinosaurs lived during this time, they did not live in this area. Younger layers show evidence of cooler and drier climates. The most recent layers reveal animals and plants from an open shrubland. Today, rock layers are stripped away by erosion, exposing new fossils within these bands of time.


Sharps Formation
28 to 30 million years ago
Sediments of the Sharps Formation preserve evidence of a cool and dry shrubland.

Rockyford Ash
30 million years ago
This thick layer of volcanic ash forms the bottom layer of the Sharps formation.

Brule Formation
30 to 34 million years ago
Open woodlands preserved In the Brule Formation were direr and cooler than those in the Chadron Formation. In some areas water was hard to find.

Chadron Formation
34 to 37 million years ago
Sediments carried by streams and rivers flowing from the Black Hills created this formation. These sediments were deposited in a hot and humid forest flood plain.

Yellow Mounds
67 to



75 million years ago
After the sea drained away, the black ocean mud was exposed to surface weathering. The upper layers of this mud developed into a yellow soil called Yellow Mounds.

Pierre Shale
67 to 75 million years ago
This formation first began to form 75 million years ago when a shallow sea covered this area.


Oreodont

Leptauchenia

28 to 32 million years ago

Nimravid

Nimravus

30 to 32 million years ago

Three-toed Horse

Mesohippus

30 to 37 million years ago

Dog

Hesperocyon

28 to 37 million years ago

Titanothere

Brontops

34 to 37 million years ago

Alligator

Alligator

34 to 37 million years ago

Ammonite

Placenticeras

67 to 75 million years ago

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Show me all markers in:  Wall, SD  |  Jackson County  |  57790  |  South Dakota  |  United States of America

What a Find!
Under the Sea
Titanic Discovery
See Ya Later, Alligator
Off to the Races
A 75-Million-Year Walk
Fight for Survival
Dying to Become a Fossil
It's a Dog's Life
Reading the Rocks

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