Modoc Rock Shelter, a sandstone bluff, sheltered Native American groups beginning shortly after the Ice Age and continuing for almost 8000 years. Periodic floods from the Mississippi River and nearby Barbeau Creek buried abandoned camps and created 25 feet of layered archaeological deposits. Excavations uncovered well-preserved hearths, tools, and food remains, including animal bones, shells, and plant remains, which archaeologists, botanists, zoologists, and geologists studied to trace changes in Native American environment and culture through time. Finds included projectile points fastened to shafts and thrown with a spear thrower, a deer bone perforator used to punch holes in hide and other materials, freshwater mussel shells used for food and sometimes for spoons and scrapers, a bannerstone of banded slate used as a weight on a spear thrower, pitted cobbles used to make stone tools and crack and grind seeds, and flaked-chert preforms later modified into projectile points and other tools. Archaeologists from the Illinois State Museum and the University of Chicago excavated there in the 1950s, and the Museum and the University of Wisconsin-Milwaukee carried out additional work in the 1980s.