Collie Ridge Trail

The Collie Ridge Trail explores the upland karst terrain above Mammoth Cave, a landscape defined by the same soluble limestone bedrock that created the cave system below. The loop climbs through a mixed oak-hickory and eastern red cedar forest, passing numerous sinkholes — circular depressions formed when cave roofs collapse or surface drainage dissolves a funnel through the limestone. The sinkholes range in size from shallow bowls a few feet across to dramatic pits ten meters deep, and their interior microclimates support shade-tolerant ferns, hepatica, and bloodroot in spring. The karst topography here overlies the Mammoth Cave system at depths ranging from 50 to 200 feet, and the sinkholes serve as direct recharge points, funneling surface water directly into the cave's active hydrology. The trail passes through stands of old-growth eastern red cedar, a species that colonized abandoned farmland throughout this region after European settlement and has persisted due to the thin rocky soils and drought-prone karst terrain that discourage competition from faster-growing hardwoods. Barred owls are commonly heard at dawn and dusk, and the ridge provides habitat for the American woodcock, which performs its spectacular aerial courtship display in forest openings in early spring.