Great Bahama Bank

Source: Modified Copernicus Sentinel data (2024) / Google Earth Engine

The varying colors and curves are the result of geological processes and ocean creatures. The shallow bank quickly drops off into a deep, dark region known as the “Tongue of the Ocean.” The bank itself is composed of white carbonate sand and limestone, mainly from the skeletal fragments of corals. The Great Bahama Bank was dry land during past ice ages. When it was exposed to the atmosphere, the limestone bank was subjected to chemical weathering, that created karst structures, resulting in the structures visible now here and famous so-called blue holes.

Later, the area got slowly submerged as sea levels rose. Today, the bank is covered by water, though it can be as shallow as two meters deep. The wave-shaped ripples in the images are sand on the seafloor. Sand and seagrass are present in different quantities and at different depths, which gives the image a range of blues and greens.

Researchers at UZH are investigating genetic diversity of such habitats with the help of Earth Observation satellite images and ground measurements to examine the evolution of the coral reefs.