Sea Floor Spreading Age Evidence

Measurements of the thickness of marine sediments and absolute age determinations of such bottom material have provided additional evidence for seafloor spreading.

Sea floor spreading age evidence. Spreading rate is the rate at which an ocean basin widens due to seafloor spreading. 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. Chapter 1 section 4. 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.

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 rate at which new oceanic lithosphere is added to each tectonic plate on either side of a mid ocean ridge is the spreading half rate and is equal to half of the spreading rate. As the magma and lava cool at seafloor spreading centers whatever magnetic field is present get ingrained into the rock. These age data also allow the rate of seafloor spreading to be determined and they show that rates.

When scientists studied the magnetic properties of the. 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. 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. Every once in a while the currents in the liquid core which create the earth s magnetic field reverse themselves.

This evidence was from the investigations of the molten material seafloor drilling radiometric age dating and fossil ages and the magnetic stripes. The ocean plates spread and grow in opposite directions so rocks that are equidistance from the center have the same magnetic polarity and age. Sea floor age maps have been proven correct by the age dates calculated from hundreds of rock samples gathered from the ocean floor. Every so often it has occurred over 170 times over the past 100 million years the poles will suddenly switch.

Evidence for seafloor spreading nature of oceanic rocks around mid ocean ridges. Eruptions of molten material magnetic stripes in the rock of the ocean floor and the ages of the rocks themselves. Harry hess s hypothesis about seafloor spreading had collected several pieces of evidence to support the theory. This has happened many times throughout earth s history.

Spreading rates determine if the ridge is fast intermediate or slow. It is called a geomagnetic reversal. Scientists can determine the age of the seafloor by examining the changing magnetic field of our planet. The magnetism of mid ocean ridges helped scientists first identify the process of seafloor spreading in the early 20th century.