These seas were inhabited by a variety of creatures, whose remains can be found as fossils and fossil molds in the rocks. Fossil molds are the result of the original fossil material dissolving during dolomitization, which leaves an external and sometimes an internal mold. Fossils identified in the rocks include: crinoids (sea lilies), corals, sponges (stromatoporoids), bryozoans, brachiopods, snails (gastropods), clams (bivalves), nautiloids, and trilobites.
The caves, sinkholes, and other features in the park are prime examples of karst topography. Karst topography forms by the dissolving action of groundwater on carbonate rock. The caves in the park can be classified as either solutional or mechanical, depending on how they formed.