Phytokarst on aragonitic calcarenitic eolianite limestone (North Point Peninsula, San Salvador Island, Bahamas) 1 (16136840257)

Description:

Summary[edit] Description: Phytokarst on aragonitic calcarenitic eolianite limestone at a shoreline outcrop along the western side of North Point Peninsula, northeastern San Salvador Island, eastern Bahamas. Several categories of karst (dissolutional features in soluble rocks such as limestone) exist on islands in the Bahamas. Common small-scale karst features include phytokarst and solution tubes. Large-scale karst features include flank margin caves, pit caves, banana holes, lake drains, and blue holes. The irregular, sharp-edged, small-scale karst shown above is phytokarst. It is developed on many exposed limestone surfaces in the Bahamas. Synonyms for phytokarst include “epikarst” and “biokarst” and “eogenetic karren”. Phytokarst is the result of several inorganic and biologic processes. These include preferential cementation of otherwise nonlithified young limestones by sea spray, differential dissolution by slightly acidic rainwater, cyanobacterial & algal boring activities, and physical abrasion by gastropod radular scraping. As examples of the latter, note the small, dark-colored Echinolittorina tuberculata common pricklywinkle snail near the lower left & the small, light-colored Tectarius muricatus beaded periwinkle snail at center right. The snails use their mineralized radulas to scrape away and consume biofilms on the rocks. This is one type of bioerosion. Stratigraphy: North Point Member, Rice Bay Formation, Holocene. Date: 12 June 2008, 16:58. Source: Phytokarst on aragonitic calcarenitic eolianite limestone (North Point Peninsula, San Salvador Island, Bahamas) 1. Author: James St. John.