Geology of Puerto Rico

The geological structure of the island is oriented east-west. It can is often conveniently divided into three geographical regions:

the karst belt
the mountainous area
the discontinuous coastal plains which include buried karst with no visible solution feature

However, if you look at a slightly more detailed map, it becomes mor complicated. There is a central volcanic cordillera with insoluble rocks without caves. Then there are two belts, to the north and to the south, with limestone overlying the volcanic rocks. Finally, there is a narrow belt of coastal plans on both sides and on the western coast. The Northern Karst is the by far the biggest karst area of Puerto Rico, and is separated into five catchment areas. The Southern Karst is much smaller and separated into numerous small karst areas. The term Carso Norteño (Northern Karst) is widely used to describe the large northern karst area. The term Southern Karst seems to be uncommon, nevertheless we use it as a descriptive name for the karst areas in the southern side of the mountains.

The limestone regions of Puerto Rico cover about 27% of the island's surface. Most of this is in the north of the country where all the large caves are found. The caves are not particularly long but many have large river passages. The large guano deposits are the source of histoplasmosis amongst cavers. The deepest and the longest cave is Sistema del Rio Encantado - VR=344 m and L=21,770 m [2020].

Cueva de Empalme is a 1,000 m long show cave, sometimes also called Rio Camuy Cave. But its most common name is Showcave Cueva Clara.