The bottom of the ocean has features as varied as those on land. Huge plains spread out across the ocean floor, and long moutain chains rise toward the surface. Volcanoes erupt from the ocean bottom, and deep valleys cut through the floor. In the early 1960s, a theory called sea-floor spreading provided some explanation. According to the theory, the sea floor itself moves, carrying the continents along. Circulating movements deep within the earth's mantle make the sea floor move. The circulating movements carry melted rock up to the mid-ocean ridges and force it into the central valleys of the ridges. As the melted rock cools and hardens, it forms new sea floor and pushes the old floor and the continents away from the ridges.
Fact file
A hot vent is a chimey-like structure on the ocean floor that discharges hot, mineral-rich water. Scientists first observed hot vents in 1977, in the Galapagos Rift, a region on the floor of the Pacific Ocean.
resources: Tell me what (Chancellor Press)
image 1: https://muraljoe.com/wp-content/uploads/edd/2015/06/UW3.jpg
image 2: https://upload.wikimedia.org/wikipedia/commons/thumb/a/aa/Champagne_vent_white_smokers.jpg/1200px-Champagne_vent_white_smokers.jpg
