The Mammoth Site
Location: Hot Springs, Fall River County, South Dakota
Time: 25,300-26,000 years ago, during the Quaternary period
About this Famous Find: The Mammoth Site in Hot Springs, South Dakota, preserves the remains of a Late Pleistocene biota in sinkhole sediments. Evidence indicates that a cavern collapsed at the site about 26,000 years ago and artesian-fed spring waters filled the basin. The resulting steep-sided pond, estimated to have been originally about 120 by 150 feet across, attracted and trapped local wildlife, with many creatures being buried and preserved in the accumulating sediments. Sediments and animal remains continued to fill the pond for the next 350 to 700 years.
Mammal remains are dominated by the bones of Columbian mammoths. The remains of more than 50 individuals have been found, making the site the world's largest primary accumulation (i.e., the bones were not transported by water, etc., to the location) of mammoth fossils. Evidence of three woolly mammoths have also been discovered, making this the only site where the two species have been found together. Other mammals found at the site include camel, llama, short-faced bear, wolf, coyote, and prairie dog. Other taxonomic groups represented in the sinkhole sediments include plants (angiosperms, gymnosperms, ferns, mosses, and algae), mollusks (thousands of shells have been recovered), insects, fish, amphibians, and birds.
The site was discovered in 1974 by construction workers building a new subdivision. With the discovery of a skull and tusks, local citizens banded together to protect the site. Their work led to the construction of the museum at the site and it's designation as a National Natural Landmark in 1980. The Mammoth Site is a non-profit organization which engages volunteers to help with continuing excavations each year.