Bacteria found deep in the ocean in the volcanic regions of mid-ocean ridges suggest a possible scenario for the beginning of life on earth.
Ocean water seeps into cracks created by sea-floor spreading at the mid-ocean ridges and is heated by magma from inside the earth. Water in these hydrothermal vents reaches temperatures of 375 degrees C and higher and is rich in dissolved minerals. The hot water rises from the vents in geysers and meets cold ocean water, causing minerals to precipitate out of solution as the water cools. In some places compounds of iron and sulfides form "chimneys" on top of the vents. Such an extreme environment seemed unlikely to support life given the conditions of temperature, pressure, and absence of light for photosynthesis.