The Mammoth Site
In Hot Springs, South Dakota, a construction crew in 1974 was leveling ground for a housing development when they uncovered bones. Not just any bones - massive femurs and tusks belonging to Columbian mammoths. The development stopped. Excavation began. What emerged was a prehistoric death trap: a sinkhole fed by warm springs where mammoths came to drink and couldn't escape. The steep, slippery walls trapped them. Over thousands of years, 61 mammoths died here - all young males, apparently the demographic most likely to take risks for warm water in winter. The Mammoth Site is now an active paleontological dig where visitors watch scientists uncover Ice Age bones in real time. It's one of the largest concentrations of mammoth remains in the world, preserved exactly where they fell, still being excavated after 50 years.
The Trap
About 26,000 years ago, a sinkhole formed over a warm spring. The spring kept the water temperature constant year-round - inviting to thirsty animals during cold South Dakota winters. Mammoths came to drink. The sinkhole's sides were steep and covered with slippery mud; animals that entered couldn't climb out. They drowned or starved. Their bodies sank into the sediment and were preserved. The warm water created an ideal fossilization environment - bones remained articulated, some with soft tissue traces. When the spring eventually dried up, the sinkhole filled with sediment, sealing the mammoth remains until a bulldozer broke through the surface in 1974.
The Discovery
George Hanson was grading land for a housing subdivision when his bulldozer hit bone. He recognized it as important and stopped work. Local amateur paleontologists confirmed the significance: mammoth bones, possibly multiple animals. The developer, Phil Anderson, donated the site to a nonprofit foundation rather than continue building. A steel building was erected over the sinkhole to protect the remains. Excavation began in 1975 and has never stopped. The decision to preserve the site in place - rather than removing bones to a museum - was unusual and prescient. The Mammoth Site became both museum and active dig, a living laboratory.
The Mammoths
The site contains remains of at least 61 Columbian mammoths - the species that lived on the Great Plains, larger than woolly mammoths. All identified individuals are male, mostly young adults. Scientists theorize that young males, less cautious than older animals or females with calves, were more likely to approach the dangerous sinkhole. The bones are largely articulated, meaning skeletons remained connected, indicating the animals died quickly and weren't scavenged. Some tusks are over 10 feet long. The site also contains remains of giant short-faced bears, camels, llamas, and wolves - a cross-section of Ice Age fauna.
The Excavation
Excavation at the Mammoth Site is ongoing - one of the longest continuous paleontological digs in history. The sinkhole is enormous, and only about 20% has been excavated. New bones appear constantly. Visitors can watch paleontologists working with dental picks and brushes, carefully exposing bones that have been buried for 26,000 years. Summer programs allow visitors to participate in controlled excavations. The exposed bones are left in place where possible, creating a tableau of Ice Age death. The site is both museum and research facility, with scientists publishing new findings regularly.
Visiting the Mammoth Site
The Mammoth Site is located at 1800 US-18 Bypass in Hot Springs, South Dakota. The site is open year-round; hours vary seasonally. Admission is charged. Guided tours of the excavation floor are offered throughout the day. The museum includes exhibits on mammoth biology, Ice Age climate, and the site's history. Summer programs offer hands-on excavation experiences. Hot Springs also offers Evans Plunge, a natural warm-water swimming pool, and is a gateway to Wind Cave National Park. Rapid City Regional Airport is 60 miles north. The Black Hills region offers extensive tourism opportunities. Allow at least two hours for the Mammoth Site.
From the Air
Located at 43.43°N, 103.48°W in Hot Springs, South Dakota, in the southern Black Hills. From altitude, Hot Springs appears as a small town in a valley, surrounded by the forested hills of the Black Hills region. The Mammoth Site's distinctive building is visible on the town's western edge. Wind Cave National Park is 10 miles north. The Black Hills rise to the north and west; the Great Plains spread to the east. Rapid City Regional Airport is 60 miles north. The terrain transitions from forested hills to open prairie, the edge of the Rocky Mountain system.