Age Of Oldest Rocks On Ocean Floor

The oldest ocean floor is located near the continents next to a subduction zone.

Age of oldest rocks on ocean floor.

The crust overlies the solidified and uppermost layer of the mantle the crust and the solid mantle layer together constitute oceanic lithosphere. In 1990 after 20 years of searching geologists found the oldest oceanic rocks by drilling into the seafloor of the western pacific. Examine the color code to understand how the age of rocks changes from the center to the edges of the ocean floor. The data is from four companion digital models of the age age uncertainty spreading rates and spreading asymmetries of the world s ocean basins.

There are rocks on every continent that are 3 to 4 billion years old. Every so often it has occurred over 170 times over the past 100 million years the poles will suddenly switch. Oceanic crust is the uppermost layer of the oceanic portion of a tectonic plate it is composed of the upper oceanic crust with pillow lavas and a dike complex and the lower oceanic crust composed of troctolite gabbro and ultramafic cumulates. As the magma and lava cool at seafloor spreading centers whatever magnetic field is present get ingrained into the rock.

Why are there no oceanic rocks older than 200 million years. The ocean plates spread and grow in opposite directions so rocks that are equidistance from the center have the same magnetic polarity and age. These rocks turned out to be about 200 million years old only. Consider how the age of rocks is related to the shape of the seafloor you saw in step 3.