Little Salt Spring is an archaeological and paleontological site in North Port, Florida. The site has been owned by the University of Miami since 1980 with research performed there by the university's Rosenstiel School of Marine and Atmospheric Science. It is located directly off Price Boulevard between US 41 and Interstate 75 adjacent to Heron Creek Middle School in the North Port, Florida. History In 2013, the University of Miami began considering selling the site to Sarasota County, Florida, due to funding being cut towards maintaining the site and its facilities. On July 10, 1979, the site was added to the National Register of Historic Places. Little Salt Spring is a feature of the karst topography of Florida, specifically an example of a sinkhole. It is classified as a third magnitude spring. The numerous deep vents at the bottom of the sinkhole feed oxygen-depleted groundwater into it, producing an anoxic environment below a depth of about . This fosters the preservation of Paleo-Indian and early Archaic artifacts and ecofacts, as well as fossil bones of the extinct megafauna once found in Florida. Originally it was thought that Little Salt Spring was a shallow freshwater pond, but in the 1950s SCUBA divers discovered that it was a true sinkhole extending downward over , similar to the cenotes of the Yucatán Peninsula (another karst region). The actual depth of the surface pond is with a central shaft dropping vertically to an inverted cone with a maximum determined depth at the outer edges of . There are ledges around the wall of the cenote at below the present water level. Prehistoric human use The water level in the spring has varied over time. Twelve to thirteen thousand years ago the ocean level was about 100 meters (more than 300 feet) lower than at present, drawing down the water table in Florida, and the water level in Little Salt Spring was lower than at present. The basin around the spring and a slough extending away from it are filled with moist, soft peat. Hundreds of burials dating from 5,200 to 6,800 years ago have been found in the slough. As has happened in other wetland burials in Florida, such as at the Windover Archaeological Site, brain matter survived in many of the skulls. In the 1970s the overturned shell of an extinct giant land tortoise was found on the ledge. A wooden stake had