Geology Driving Tour
Geologists measure changes in the earth along a geologic time scale extending 4.6 billion years. The time line to the left will help you understand when the various rock formations in the area were deposited. Geologic time lines are expressed in geologic eras and periods. A period is a smaller time frame within an era.
The earth is constantly changing. While some geologic changes can be observed, most occur very slowly and are imperceptible during a human lifetime. Because of this, geologists use the rock record to explain the complex geologic history of our planet. Studying rock types and layers provides insight into the geologic, climatic and biologic changes that have occurred on the earth.
On this driving tour you will examine the rock record of Wind Cave National Park. Please note that the stops are presented in the most convenient driving order, not in geologic order. Because of this, please check off the stops on the geologic time line as you visit them.
Geologic History of The Black Hills
During the Paleozoic Era, this area was a basin covered by a shallow sea that, over millions of years, deposited a thick blanket of sediments over the Precambrian igneous and metamorphic rocks. Then, about 70 million years ago, the earth's crust began to uplift into a dome. This uplift may have occurred when tectonic plates collided, forming the Rocky Mountains. As the force of the colliding plates increased, the Eastern plate rippled and formed the dome shaped Black Hills. Erosion eventually carried away many sediments in the central area of the hills, exposing the Precambrian rocks. Many of these stages of development can be readily seen in the park.
Did You Know?
Fire is an important factor in protecting the prairie. Historically, fires burned across the prairie every 4 to 7 years. Fires burn the small trees that would otherwise march across the prairie and turn the grasslands to forest.