The first difference between the two layers comes in the composition of the rocks.
Sea floor and continental crust age differecne.
This difference in relative density causes oceanic plates to subduct beneath the more buoyant continental plates.
Difference between oceanic and continental crust.
The oldest oceanic crust is about 260 million years old.
The difference in density has an impact on isostacy of crust floating on the semi fluid upper mantle asthenosphere with continental crust about 2 7g cm 3 rising or floating above oceanic crust about 3 5 g cm 3.
Continental crust also consists of the shallow seabed close to shores called continental shelves.
The average density of ocean plates is approximately 200 pounds per cubic foot while continental crust ranges between about 162 and and 172 pounds per cubic foot.
It is due to the process of subduction.
Continental shelf 300 feet continental slope 300 10 000 feet abyssal plain 10 000 feet abyssal hill 3 000 feet up from the abyssal plain seamount 6 000 feet.
As ocean crust descends toward the hot mantle it melts and becomes recycled into the mantle.
The continental crust is by far the older of the two types of crust.
The following features are shown at example depths to scale though each feature has a considerable range at which it may occur.
The continental crust has a density of about 2 6 g cm3 which helps the continents of the world to stay in one place.
This sounds old but is actually very young compared to the oldest continental rocks which are 4 billion years old.
The oceanic crust is mainly made out of dark basalt rocks that are rich in minerals and.
The difference between oceanic and continental crust rock material is the density and explains why the oceanic crust is beneath the ocean s surface while continental crust can rise into the earth s atmosphere in the form of mountain peaks.
This graphic shows several ocean floor features on a scale from 0 35 000 feet below sea level.
Because of this correlation between age and subduction potential very little ocean floor is older than 125 million years and almost none of it is older than 200 million years.
Therefore seafloor dating isn t that useful for studying plate motions beyond the cretaceous.
Why is the seafloor so young.
Hess went on to say that as the ocean crust spreads and cools over millions of years it becomes denser and eventually sinks down into oceanic trenches or subduction zones a long way from where it forms at the mid ocean ridge crest.
It gets so dense that it sinks in the.
Unlike oceanic crust that has young geological rock continents can have rocks up to 4 billion years old.
