Sinkholes have been making the news. What is a sinkhole, where/when can they form? How can I protect my property? What are other benefits or risks of living on karst? Carbonate rocks dissolve slowly, resulting in underground voids that may be completely clogged with soil. Sinkholes form when soil collapses into these voids, often following rain events, etc. The hollow nature of karst means transport from the surface to the water table is rapid. This can result in negative water quality impacts on wells and springs. Karst areas host caves that provide unique habitats and research opportunities.