Karst features such as springs, losing streams, sinkholes and caves are common. The limestone provides numerous sinkholes and caverns. The Valley of Virginia is a region of karst, with many sinkholes and caverns. Potholes and sinkholes can damage human settlements. The park landscape features natural streams, sinkholes, caves and fissures. There are many caves, sinkholes and underground streams. Natural firebreaks include exposed limestone cliffs and solution sinkholes. Secret Beach also features remote cenotes, sinkholes, and caves. This area is also riddled with ravines and sinkholes. It is also known for its karst sinkholes in the north-eastern section of the park. Many live underground in marine and freshwater caves, sinkholes, or stream beds. It is characterized by underground drainage systems with sinkholes and caves. The park also features caves, sinkholes, and bluffs overlooking the lake. The landscape includes many caves, sinkholes, springs, and streams. Some sinkholes form in thick layers of homogenous limestone.