Seafloor Spreading Age Of Rocks

The ocean plates spread and grow in opposite directions so rocks that are equidistance from the center have the same magnetic polarity and age.

Seafloor spreading age of rocks. As the magma and lava cool at seafloor spreading centers whatever magnetic field is present get ingrained into the rock. The magnetism of mid ocean ridges helped scientists first identify the process of seafloor spreading in the early 20th century. As upwelling of magma continues the plates continue to diverge a process known as seafloor spreading 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. The oldest sediments so far recovered by a variety of methods including coring dredging and deep sea drilling date only to the jurassic period not exceeding about 200 million years in age.

Spreading rate is the rate at which an ocean basin widens due to seafloor spreading. Basalt the once molten rock that makes up most new oceanic crust is a fairly magnetic substance and scientists began using magnetometers to measure the magnetism of the ocean floor in the 1950s what they discovered was that the magnetism of the ocean floor around. This is how scientists determine the age of the seafloor. Rocks on either side of the crest of oceanic ridges having equidistant locations from the crest were found to have similarities both in terms of their constituents their age and magnetic orientation.

These age data also allow the rate of seafloor spreading to be determined and they show that rates. Examine the color code to understand how the age of rocks changes from the center to the edges of the ocean floor. When the lava solidifies at the ridges to form the new seafloor radioactive elements coming from the mantle are trapped in it. These plates float atop an underlying rock layer called the asthenosphere.

Every so often it has occurred over 170 times over the past 100 million years the poles will suddenly switch. Measurements of the thickness of marine sediments and absolute age determinations of such bottom material have provided additional evidence for seafloor spreading. Evidence for seafloor spreading nature of oceanic rocks around mid ocean ridges. Consider how the age of rocks is related to the shape of the seafloor you saw in step 3.

Hydrothermal vents are common at spreading centers. To confirm the ages obtained with magnetic records and get an absolute age of the seafloor scientists use the radioactive dating technique. This image shows the age of rocks on the atlantic ocean seafloor. On the other hand the newest thinnest crust is located near the center of the mid ocean ridge the actual site of seafloor spreading.

Tuzo wilson combined the continental drift and seafloor spreading hypotheses to propose the theory of plate tectonics. Radiometric age dating and fossil ages. Older rocks will be found farther away from the spreading zone while younger rocks will be found nearer to the spreading zone. Tuzo said that earth s crust or lithosphere was divided into large rigid pieces called plates.