The Mud Caves in Anza-Borrego Desert State Park lie in the Carrizo Badlands along Arroyo Tapiado and form an unusual cave system in soft silt rather than solid rock. Created as water cut passages through thick sediment, they are a type of pseudokarst rather than conventional caves. The area contains at least 22 caves, with some extending about 1,000 feet long and 80 feet high. Their relatively easy access has made them a popular desert destination. Named caves include Big Mud Cave, Chasm Cave with its skylight, and Carey’s Big Mud Cave, the largest cave in the arroyo.