The Geology Of Wind Cave

As humans, we are constantly trying to understand the world around us As humans, we are constantly trying to understand the world around us. Wind Cave is one of many geological wonders found on the Earth.

The passages of Wind Cave are found within the Pahasapa Limestone. Fossils tell us the origins of the limestone, which is a sedimentary rock.

When marine organisms died, their bodies collected on the sea floor. The limestone was created when warm, shallow seas covered the land approximately 350 million years ago. Coral Fossil When marine organisms died, their bodies collected on the sea floor. Brachiopod Fossils

With time and pressure, the shells and other sediment were compacted together and solidified, thus creating the limestone.

Uplifting pressures in the Black Hills area created cracks in the limestone.

Acid rich water entered those cracks and began to dissolve very early cave passageways.

About 65 million years ago, the collision of tectonic plates west of today’s Black Hills area caused more buckling and bulging in the earth’s crust.

This uplift created a dome shaped area that we call the Black Hills today.

That uplifting created more cracks in the limestone That uplifting created more cracks in the limestone. Acid rich water filled these cracks and began dissolving…

…and enlarging them. As the water table dropped, the cave passageways...

…and rooms that we see in Wind Cave today were revealed.

The water that formed the cave began to slowly drain from the cave about 40 million years ago.

Currently, the water level is about 450 feet below the surface, an area called the Lakes.

Geologists believe that the unique formation found in Wind Cave called boxwork, predates the cave.

Internal pressures cracked the limestone Internal pressures cracked the limestone. These cracks were later filled with calcite.

Over time, the boxwork was exposed as the more easily dissolved surrounding limestone weathered away.

While boxwork is abundant in Wind Cave, it is rarely found in other caves.

Map of Wind Cave Passages. Besides the unusual boxwork formation, Wind Cave is also one of the longest and most complex caves in the world! Map of Wind Cave Passages. Over 124 miles long.

Over the years, Wind Cave has undergone many geological changes; however, water continues to seep into the cave. As it does, the water leaves behind formations such as popcorn and frostwork.

As the processes shaping the cave continue, we also continue our quest to understand the vast, incredible world beneath our feet.