"Illuminating Darkness" is the theme of the Ravalli County Museum's Montana Cave Exploration exhibit. The display, in a portion of the second floor main exhibit hall, includes maps of some of the 400 natural caves that have been explored in Montana. The exhibit opens at 6 p.m. Thursday, March 15.

Museum Director Tamar Stanley said the deepest limestone cave in the continental U.S. is in Montana. A map of the Tears of the Turtle cave is one of the hand-drawn displays, created by "cavers" of the Northern Rocky Mountain Grotto group.

Kids (and adults) will be able crawl through some openings that mimic passages of some of the caves. There is information about caving gear, ecology of the underground, stalagtites and stalagmites, bats and plants and water. Mike McEachern and others will be at the Thursday Opening Reception to talk about the exploration. They will also mention how the caves are fragile ecosystems, with strict rules for those who enter.

The exhibit will be in place through the summer at the Hamilton museum on South 3rd Street.