Relative to the ocean floors, the continents are?

Question

a. much younger
b. about the same age
c. much older
d. any of the above, depending on the ocean and continent

Answer 1

c) much older

The oldest oceanic crust is about 200 million years old. Continental crust is billions of years old (most from 2 - 4 billion years old)

I've included a couple of excerpts from Wikipedia to help explain why:


Oceanic crust generally does not last longer than 200 million years. It is continuously being created at oceanic ridges. At these ridges, hot magma rises into the crust and cools, pushing the crust apart at the ridge. The continuous formation of new oceanic crust pushes the older crust away from the mid-ocean ridge.
The oceanic crust subducts toward the mantle at what are known as convergent boundaries. These boundaries can exist between two oceanic plates or between an oceanic and a continental plate. At oceanic plate-continental plate boundaries, the oceanic plate always subducts because the continental crust is less dense. The subduction process is why oceanic crust lasts a maximum of 200 million years.


As a consequence of the density difference, when active margins of continental crust meet oceanic crust in subduction zones, the oceanic crust is typically subducted back into the mantle. Because of its relative low density, continental crust is only rarely subducted or re-cycled back into the mantle (for instance, where continental crustal blocks collide and overthicken, causing deep melting). For this reason the oldest rocks on Earth are within the cratons or cores of the continents, rather than in repeatedly recycled oceanic crust; the oldest continental rock is the Acasta Gneiss at 4.01 Ga, while the oldest oceanic crust is of Jurassic age.

It is a matter of debate whether the amount of continental crust has been increasing, decreasing, or remaining constant over geological time. One model indicates that at prior to 3.7 Bya continental crust constituted less than 10% of the present amount. By 3.0 Bya the amount was about 25% and following a period of rapid crustal evolution it was about 60% of the current amount by 2.6 Bya

(Bya means billion years ago)

Answer 2

Hey Thisbrit, I know! The answer is C, much older. Seafloor is constantly being created at mid-oceanic ridges and destroyed in subduction zones. The oldest oceanic crust is about 180 million years old while the oldest continental crust is almost 4 billion years old.

Answer 3

properly.. there is likewise the techtonic plates. and its unlike sometime the sea ended up there and then day after on the instant.. enhance!! there is land. i'm no longer one hundred% optimistic if the scientists be attentive to. i might say "A."

Answer 4

d, I suppose.

But maybe younger since the earth was more water at first. . .who knows?