Ever increasing pressures on our natural environment necessitate measures to detect and ameliorate problems of contamination, construction and overuse, before they become critical. This is particularly the case in our national parks and monuments where the tide of visitors is continually growing. the underground resource of natural caverns is especially vulnerable to damage, due to its fragile features, rare and delicate biota, open communication with groundwater, and its invisibility beneath the ground surface. It is important that we be able to recognize the existence of a cavern system prior to the planning of roads and facilities that may encroach upon or introduce waste and hazardous materials into the underground system.