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About the Mammoth Site:

Nestled in the Black Hills of South Dakota lies an exceptional active dig site that contains the largest concentration of mammoth remains on Earth. These mammoth remains are preserved in a sinkhole that formed around 140,000 years ago. The original age of these fossils were thought to be around 26,000 years old, but updated dating techniques used by Dr. Sharon Holte and Justin Wylkins in 2018 show the bone bed is actually around 140,000 years old.

Formation of the "Mammoth pit" - Why Ice Age Mammoths are here

The Mammoth Site is a classic "karst" style sink hole. The roof of a porous limestone cavern collapsed, leaving, what cavers would consider a skylight. Paleontologists believe the collapse occurred over 140,000 years ago. At the bottom of the skylight was a spring that turned the hole into a steep sided pond. The ancient pond is approximately 120 by 150 feet across, and bore holes show the pond is at least 65 feet deep.

Mammoths would enter this pond, but due to the steep sides, they often would get trapped and eventually die. Over hundreds of years, sediments accumulated in the pond, entombing the mammoth remains and eventually infilling the pond. Thousands of years later, the hardened mud and bones remained, while the softer Spearfish shale eroded away around it, turning the mud filled sink hole into a hill.

The Discovery

The Mammoth Site was discovered in 1974 by George Hanson while bulldozing the hill for an apartment subdivision. George Hanson brought a bucket of bones home from the site and showed his son, Dan Hanson, who was immediately interested. Dan went to the site, found a mammoth tooth, and realized the site's importance and contacted his paleontology instructor, Dr. Larry Agenbroad. Dr. Agenbroad excavated part of the site and found more mammoths. Eventually, due to its importance, the land owner donated it to a nonprofit organization called the "Mammoth Site."

The entire pond is now enclosed in a large building. It is an active excavation, where paleontologists and volunteers leave many of the remains in situ when possible. Only around 20 feet of the 65 feet deep pond has been excavated. Even though the site is nowhere near being completely excavated, already 61 mammoths (at the time I was there) have been found. The bones of these animals are not truly fossilized since they have not been replaced by minerals. As a result, they are very fragile and need stabilized soon after excavation.

Characteristics of the Ice Age Megafauna

Although entire animals would die and decay in the pond, most remains are not completely articulated. After a trapped mammoth died and rotted, other mammoths would fall in and step through the mud and bones while trying to escape. The stomping motion would push and disarticulate the skeletons in the mud. In fact, profiles of footprints in the thick mud can be seen in the excavated side walls.

As of 2018 there were 58 Colombian mammoths and 3 Wooly mammoths excavated. This is one of the very few, if not only, places where Columbian mammoths and Wooly mammoths are found together. Columbian mammoths are very large mammoths that preferred more temperate regions of North America, while Wooly mammoths are much smaller and lived in the colder regions, mainly in the very Northern United States and throughout Canada. As a result, their ranges normally did not overlap. It is unclear whether both types of mammoths were here at the same time, or if short term swings in climate brought Wooly mammoths here on occasion during separate time intervals.

All of the mammoths are males and most of these males are young adults. To date, no female mammoths have been found. Why all the males? The answer to this question lies in the study of modern elephant behavior. Modern elephants live in matriarchal groups. Young males are sometimes removed from the herd and forced to wonder alone. These isolated males often undertake riskier behaviors than the elephants in the herd. It appears mammoths were also matriarchal, and isolated males would be the ones to roam into this death trap.

Not all of the fossils at Mammoth Springs are mammoths. There have been many other animals found here. These animals include a rare Giant short-faced bear, the American camel, llama, wolves, coyotes, shrub oxen, and a myriad of other smaller mammals, bird, fish, and invertebrates.

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The Mammoth Site also has a small attached museum that holds additional Ice Age relics, including models of frozen mammoths from Siberia and a model of a complete Giant short faced bear skeleton. To be able to walk around the entire ancient pond and peer into such an immense and ongoing excavation is amazing experience for any fossil enthusiast. The Mammoth Site is truly a unique place.

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Location and Hours

The Mammoth Site is located in Hot Springs, SD which is about an hour drive south of the Rapid City Airport.

The Mammoth Site
1800 US 18 Bypass
Hot Springs, SD 57747

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Google Map of the Mammoth Site of Hot Springs, SD

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Hours of Operation:

The Mammoth Site is open year round with visiting hours dependent on the season. General admission is around $10.

Summer months - 8 am to 8 pm.
Spring and Fall - 9 am to 5 pm.
Winter - 9am to 3:30 pm with restricted hours on Sundays.

Check out their website for exact times and fees.

The Tour

After one pays admission, there is a short movie explaining the formation of the mammoth site. Then you are let on a guided tour of the excavation. After the tour, you are free to wonder around and explore the excavation on your own. When done, you leave through a small museum dedicated to Ice Age animals and then the gift shop.

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Recommended Prehistoric Mammal Books:

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Additional Images of the Mammoth Site

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Nearby attractions

The Mammoth Site is nestled in the Black Hills of South Dakota. There are countless activities to do in the immediate area.

A few activities include visiting Mount Rushmore, viewing the Crazy Horse Sculpture, Seeing a Buffalo Herd, Driving the scenic Needle Road, Driving through a Bear Sanctuary, Visiting Deadwood, and Going on a Dinosaur Dig!