This has happened many times throughout earth s history.
Ages of rocks on the ocean floor.
The magnetism of mid ocean ridges helped scientists first identify the process of seafloor spreading in the early 20th century.
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.
Consider how the age of rocks is related to the shape of the seafloor you saw in step 3.
Other cratons in south africa australia and asia have continental rocks that are 3 billion years old.
Scientists collected rock samples from the sea floor.
This dataset shows the age of the ocean floor along with the labeled tectonic plates and boundaries.
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 image shows the age of rocks on the atlantic ocean seafloor.
The sedimentary rocks are uplifted and tilted.
The ocean plates spread and grow in opposite directions so rocks that are equidistance from the center have the same magnetic polarity and age.
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.
Every once in a while the currents in the liquid core which create the earth s magnetic field reverse themselves.
Every so often it has occurred over 170 times over the past 100 million years the poles will suddenly switch.
Contours of 20 million years are available as a layer that is currently set to invisible.
Examine the color code to understand how the age of rocks changes from the center to the edges of the ocean floor.
It is found in the mediterranean sea and is a remnant of an ancient ocean that is disappearing between africa and europe.
Scientists can determine the age of the seafloor by examining the changing magnetic field of our planet.
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.
The age of rocks in the ocean crust depends on where the rocks are collected.
The relative age of a rock then is its age in comparison with other rocks.
As the magma and lava cool at seafloor spreading centers whatever magnetic field is present get ingrained into the rock.
A series of sedimentary beds was deposited on an ocean floor.
When scientists studied the magnetic properties of the.
They found out that rock samples that were closer to mid ocean.
Sea floor age maps have been proven correct by the age dates calculated from hundreds of rock samples gathered from the ocean floor.
The oldest seafloor is comparatively very young approximately 280 million years old.
The sediments hardened into sedimentary rock.
