Throughout the oceans of the world there exist undersea mountain ranges, known as rift zones – where the movement of tectonic plates is tearing the earth’s crust apart. As the oceanic crust stretches, it thins and is cracked by giant fissures. Magma from deep down, wells up through these cracks and fissures, rushing to fill in the gaps created by the rifting of the plates. When the magma reaches the surface of the oceanic crust, it sometimes oozes out as lava on the ocean floor, creating new oceanic crust as it cools.  Hydrothermal vents were a direct result of the volcanic activity happening under all that ocean water.  Hydrothermal vents are a lot like underwater geysers.  As the water comes into contact with the veins and channels of superheated, molten magma, the sea water is superheated.  The superheated seawater spews out of the holes in the crust, rising quickly above the colder, denser waters of the deep ocean. As the hot and cold waters meet, the minerals suspended in the hot water precipitate out (clump together and drop out) right at the vent opening.  This causes a build-up of minerals, creating unique formations that have come to be called, chimneys. One giant chimney discovered in 1991, reached 15 stories high!

This information gathered from: www.extremescience.com/deep-sea-vents.htm

The above encaustic piece: 8×10, on cradled panel.