Why is oceanic crust thinner than continental crust?

[SeannyBoi71]

Hi, I am doing a geophysics assignment and had some confusion. Basically I want to know why oceanic crust is so much thinner than continental crust. My friend has told me it's because there is less weight on top of it because the ocean water is not very dense, causing the mantle to rise up higher in that area. Doesn't seem right to me. Can someone please clarify?

 

[Evo]

Hi, I am doing a geophysics assignment and had some confusion. Basically I want to know why oceanic crust is so much thinner than continental crust. My friend has told me it's because there is less weight on top of it because the ocean water is not very dense, causing the mantle to rise up higher in that area. Doesn't seem right to me. Can someone please clarify?

Your friend is wrong. What does your textbook say about the crust? What research have you done and what have you found?

I just googled it and got the answers in less than .05 seconds. Try doing a search and if you still have specific questions, please ask. It's always good to look first yourself.

 

[Ophiolite]

Questions you might wish to ask yourself would include:
how do the compositions of oceanic and continental crust differ
how do the ages of the two differ
how do the formation mechanisms of the two differ
what does my forum name mean

 

[phinds]

... I just googled it and got the answers in less than .05 seconds ...

Oh, Evo, there you go again expecting people to actually do at least some trivial amount of research THEMSELVES before asking questions here. SUCH high expectations for today's youth.

 

[LudusRex]

There are a few factors that contribute to the difference in thickness between oceanic crust and continental crust. One of the main reasons is the composition of the two types of crust. Oceanic crust is primarily made up of basalt, which is denser and more compact than the granite that makes up continental crust. This means that oceanic crust is able to support less weight on top of it compared to continental crust.

Additionally, the process of seafloor spreading plays a role in the thickness of oceanic crust. As molten magma rises up from the mantle and cools at the mid-ocean ridges, it forms new oceanic crust. This crust is constantly being pushed away from the ridges by the movement of the tectonic plates, causing it to become thinner and older as it moves away from the ridge. On the other hand, continental crust is not formed in the same way and is not constantly being pushed away, allowing it to remain thicker over time.

It is also important to consider the density of the underlying mantle. The oceanic crust sits on top of the mantle, which is less dense than the crust itself. This allows the oceanic crust to sink deeper into the mantle, making it thinner compared to the continental crust which is sitting on top of a denser mantle.

In summary, the difference in composition, formation process, and underlying density all contribute to the thinner nature of oceanic crust compared to continental crust. While the weight of the ocean water may play a small role, it is not the main factor in this difference. I hope this helps to clarify any confusion you may have had.