Coastal caves and karst of the Puerto Rican Islands

Abstract

Puerto Rico, in addition to numerous associated smaller islands and cays, forms a complex archipelago exhibiting a wide range of coastal geomorphologies influenced by the interaction of regional tectonics, lithology and sea level fluctuations. Coastal landforms in this setting also display the influences of multiple karst and pseudokarst processes. Expressions of coastal karst in this setting include caves formed by littoral erosion (sea caves), cliff retreat (talus caves and fissure caves) dissolution from processes associated with a freshwater lens (flank margin caves), coastal karren and dissolution pipes. The effects of a combination of Quaternary glacioeustatics and tectonic uplift are illustrated by multiple distinct cave horizons, or discrete elevations associated with past sea-level stillstands, ranging from 0 to more than 40 m above mean sea level (msl). While systematic research into the speleogenesis, biospeleology and archaeology of coastal caves and karst of the Puerto Rican islands has historically been sporadic in its geographic coverage and limited in its scope, recent efforts focusing on these fascinating landforms have revealed an expansive inventory of over 400 coastal cave sites to date with significant modern shoreline and paleoshoreline karst areas remaining to be studied.