Age Of Ocean Floor Rocks

Sea floor age maps have been proven correct by the age dates calculated from hundreds of rock samples gathered from the ocean floor.

Age of ocean floor rocks.

These age data also allow the rate of seafloor spreading to be determined and they show that rates vary from about 0 1 cm 0 04 inch per year to 17 cm 6 7 inches per year. As the magma and lava cool at seafloor spreading centers whatever magnetic field is present get ingrained into the rock. Why is the seafloor so young. Shortly after the conclusion of world war ii sonar equipped vessels crisscrossed the oceans collecting ocean depth profiles of the seafloor beneath them.

The survey data was used to create three dimensional relief maps of the ocean floor and by 1953 american oceanic cartographer marie tharp had created the first of several maps that revealed the presence of an underwater mountain range. This has happened many times throughout earth s history. More proof for sea floor spreading comes from seismic studies indicating that earthquakes occur along the rift valley of a midoceanic ridge and the cross cutting fractures that offset it. Oceanic crust tends to get colder and denser with age as it spreads off the mid ocean ridges.

It is believed that continental rocks formed 3 billion years ago however the sediments samples from the ocean floor are found to be not exceeding 200 million years old. The ocean plates spread and grow in opposite directions so rocks that are equidistance from the center have the same magnetic polarity and age. 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. This image shows the age of rocks on the atlantic ocean seafloor.

It is called a geomagnetic reversal. Contours of 20 million years are available as a layer that is currently set to invisible. Samples collected from the ocean floor show that the age of oceanic crust increases with distance from the spreading centre important evidence in favour of this process. It gets so dense that it sinks in the.

It is due to the process of subduction. When scientists studied the magnetic properties of the. Consider how the age of rocks is related to the shape of the seafloor you saw in step 3. The crust overlies the solidified and uppermost layer of the mantle the crust and the solid mantle layer together constitute oceanic lithosphere.

Examine the color code to understand how the age of rocks changes from the center to the edges of the ocean floor. Every once in a while the currents in the liquid core which create the earth s magnetic field reverse themselves. Scientists can determine the age of the seafloor by examining the changing magnetic field of our planet. The data is from four companion digital models of the age age uncertainty spreading rates and spreading asymmetries of the world s ocean basins.

By the use of radiometric age dating and studying fossil ages it was also found out the rocks of the sea floor age is younger than the continental rocks. This sounds old but is actually very young compared to the oldest continental rocks which are 4 billion years old.