How was the Mariana Trench formed?
Sometimes a piece of the ocean floor (called a plate) will form a crack, and one side of the crack will sink beneath the other side. As the sinking side falls into the Earths mantle below, it pulls the rest of its plate with it. The ocean floor deepens along this crack. The sinking seafloor grinds against the other side of the crack and tears pieces off to be carried down into the Earth. The overall result is a long, deep trench that marks the location of the initial crack. We call such features subduction zones or oceanic trenches. This process is how the Mariana Trench formed. What is the highest rift valley? This is a tricky question, partly because the word “highest” can have several definitions in the context of ocean floor geology, and partly because of the complexity of seafloor spreading processes. If you define “highest” as the shallowest water depth at which a rift valley or spreading center exists, the winner would be the Mid Atlantic Ridge (MAR). Some of the underwater moun