A site on the bluffs just north of Fults , overlooking the Bottoms is known as Saltpetre Cave and took its name from the quantities of bat guano mined there for potassium nitrate which was used in the local manufacture of black powder by the French at Fort de Chartres and later inhabitants . This cave , cut into the side of the bluffs , and an excellent defensive position , was one of the last refuges for Native Americans in the region . It was a popular site in the area for rappelling and hiking , until access to it was restricted in the aftermath of the Great Flood of 1993 and several accidents at the site
Great Flood of 1993
Great Flood of 1993
Fults, Illinois