Sinkholes and Blue holes
I’m McKensie Daugherty, your host for on the ocean. We’ve all seen images of sinkholes opening in the middle of busy intersections; a sudden, gaping hole in the Earth swallowing cars in the road. But what causes these holes to form and what can we learn from them? Sinkholes form in regions where the underlying geology is dominated by carbonate rock, such as Florida and the Bahamas. Carbonate rocks are highly susceptible to dissolution by rain, the underlying water table, or by changes in sea level over millennia that carve out underground caves and passageways. Eventually, this erosion may cause the roof of the underground cave to give way, spontaneously engulfing homes, traffic lights, and luxury cars. While we see sinkholes form today, they are not a new phenomenon. Sinkholes have been forming for millions of years. In a marine environment a sink hole, or “blue hole”, will be much deeper than the adjacent seafloor. This drastic change in depth gives marine sinkholes unique characteristics and their color. Sinkholes are often connected to larger subterranean networks through passageways or pores in carbonate rock. Additionally, sinkholes can be protected environments where indicators of climate or landscape use, such as pollen, overwash of sediments and sand from storms, or dead animals, are deposited and archived in sediments. Researchers at Texas A&M exploit the sedimentary archives of both marine and terrestrial sink holes to learn how our climate has changed over Earth’s history, and what additional changes we might expect in an uncertain future. This has been On the Ocean, a program made possible by the Department of Oceanography and a production of KAMU-FM on the campus of Texas A&M University in College Station. For more information and links, please go to ocean.tamu.edu and click “On the Ocean”.
Script Author: Richard Sullivan