GEOLOGY

Detailed explanation-1: -Very little of the sea floor is older than 150 million years. This is because the oldest sea floor is subducted under other plates and replaces by new surfaces. The tectonic plates are constantly in motion and new surfaces are always being created.

Detailed explanation-2: -Why are there no oceanic rocks older than 200 million years? Oceanic crust is eventually destroyed in subduction zones. Although oceanic crust has been forming on Earth for over 4 billion years, all of the sea floor older than about 200 million years has been recycled by plate tectonics.

Detailed explanation-3: -The ocean floor is the ultimate recycling center. While the Earth’s continental crust can exist for billions of years, movement of tectonic plates causes subduction, which is when the ocean crust is shoved down into the molten mantle. So the ocean floor rarely lasts longer than 200 million years.

Detailed explanation-4: -The oldest large-scale oceanic crust is in the west Pacific and north-west Atlantic-both are about up to 180-200 million years old. However, parts of the eastern Mediterranean Sea could be remnants of the much older Tethys Ocean, at about 270 and up to 340 million years old.