Ocean Information: Hydrothermal Vents

Learn about the amazing hydro thermal oceans venting that litter the sea floor. A guide to common problems, disasters, and geography.

Along the volcanic, mid ocean ridge system, far down below the waters, seawater creeps down through cracks in the crust to areas that are very, very hot. The water becomes super heated, it reacts with the rock and absorbs a number of chemicals. The water also becomes more buoyant, which causes it to rise to the sea floor. This, then, is what gives rise to what are known as hydrothermal vents. They are springs or geysers emanating from the ocean floor that put on spectacular displays on a par with any of the thermal activity we can see on land.

The vents occur when two ocean plates pull apart from each other. The gap between them is covered over by erupting lava. The hot fluid mixes with extremely cold water - in the vicinity of just two degrees Celsius - and quickly cools down. The minerals, now cooled, settle around the vent opening and form a chimney like formation.

Hydrothermal vents are more than just ocean floor side shows. They actually serve an important purpose. Through the vents ore is deposited on the sea floor. As the solutions cool and chemical conditions change, the hydrothermal solutions released through the vents rise through the upper levels of oceanic crust, depositing ore in the process. Millions of tons of sulphide ore are, thus, being deposited on the ocean floor in this manner. As man continues to deplete the land supplies of mineral deposits, these stores on the ocean floor may well be utilised for future energy supplies.



The area around hydrothermal vents support a huge variety of life forms. That they thrive in a sunlight free environment is of keen interest to researchers. It was previously believed that nothing could withstand the harsh environment around these vents. The combination of toxic chemicals, high pressures, high temperatures and total darkness was believed to have been too hostile for any living thing. But the discovery of giant tube worms, mussels, shrimps, clams and crabs has surprised the researchers. A whole new area of study has been opened up as they begin to learn about the adaptive abilities of these creatures of the deep. Researchers are still trying to explain how they are able to survive in temperatures of up to 375 degrees Celsius, under 8,300 feet of water and how they manage to appear so quickly after the formation of a new vent. They believe that getting answers to these questions will help mankind in understanding some of the vital factors involved in evolution.

Hydrothermal vents can be found along the crest of mid ocean ridges. They typically form in linear zones that are a few kilometres by a few hundred kilometres wide. They are normally found at depths greater than one mile. The largest vent yet discovered is called the TAG ( Trans Atlantic Geo Traverse). They were first discovered in the late 1970's when researchers for Woods Hole Oceanographic Institute found them along the eastern pacific rise of the Pacific Ocean, not far from the Galapagos Islands. In the twenty years since that first discovery, hydrothermal vents have been found on many other ocean ridges around the world.

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