Rat's Nest Cave

The heritage value of Rat's Nest Cave lies in its remarkable geological formations and its rich collection of paleontological resources.

Rat's Nest Cave was dissolved out of limestone of the Livingstone and Mount Head formations deposited near the end of the Devonian period, roughly 350 million years ago. The Front Ranges of the Rocky Mountains began to rise from these formations approximately 85 million years ago, during the Late Cretaceous Period. The titanic forces that compressed, thrusted, folded, and fractured the rock of the mountains created faults and seams that evolved into underground rivers of groundwater serving a vast subterranean drainage system. The Rat's Nest Cave began as one of these waterways. In time, the volume of the cave expanded as water widened the fracture in the limestone.

The several advances and retreats of the Bow Glacier in the late Quaternary period, 120-12,000 years ago, further shaped the mountain environment. During glacial retreats, massive amounts of water flowed through Rat's Nest Cave, expanding tunnels and imparting to the site much of its distinctive geological form. Roughly 12-13,000 years ago, the Bow Glacier made its final retreat; in its wake, the passages of Rat's Nest Cave slowly emptied of water. The drying of the cave enabled the precipitation of travertine formations created through the interaction of meteoric waters and calcium carbonate, the primary constituent of limestone. The spectacular and varied travertine formations in Rat's Nest Cave imbue the site with a rare kind of beauty.

Following the draining of Rat's Nest Cave, the site became home to a rich variety of animal species. Skeletal remains of dozens of creatures have been discovered in the cave, including paleontological specimens of birds, snakes, fish, and several amphibians. The cave also contains the remains of over 30 mammalian species. The many and varied paleontological resources of the cave exist alongside the diversity of insects, arachnids, and worms that presently inhabit the site. The human presence in the cave has been established by the discovery of prehistoric tools found at the site that date from roughly 3000 years ago. The site also contains a number of pictographs.