Age Of Ocean Floor Rocks

As the magma and lava cool at seafloor spreading centers whatever magnetic field is present get ingrained into the rock.

Age of ocean floor rocks.

Why is the seafloor so young. Every so often it has occurred over 170 times over the past 100 million years the poles will suddenly switch. This has happened many times throughout earth s history. This image shows the age of rocks on the atlantic ocean seafloor.

Contours of 20 million years are available as a layer that is currently set to invisible. Consider how the age of rocks is related to the shape of the seafloor you saw in step 3. It is due to the process of subduction. 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. The crust overlies the solidified and uppermost layer of the mantle the crust and the solid mantle layer together constitute oceanic lithosphere. When scientists studied the magnetic properties of the. It is called a geomagnetic reversal.

This dataset shows the age of the ocean floor along with the labeled tectonic plates and boundaries. Oceanic crust tends to get colder and denser with age as it spreads off the mid ocean ridges. Examine the color code to understand how the age of rocks changes from the center to the edges of the ocean floor. 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.

Every once in a while the currents in the liquid core which create the earth s magnetic field reverse themselves. 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. 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. 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.

Sea floor age maps have been proven correct by the age dates calculated from hundreds of rock samples gathered from the ocean floor. 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. This sounds old but is actually very young compared to the oldest continental rocks which are 4 billion years old. The oldest oceanic crust is about 260 million years old.

Scientists can determine the age of the seafloor by examining the changing magnetic field of our planet. The ocean plates spread and grow in opposite directions so rocks that are equidistance from the center have the same magnetic polarity and age.