Why is it that continents are not pulled down (subducted)into the asthenosphere?

Question

why is it that continents are not pulled down (subducted)into the asthenosphere?

this is apart of another question on my worksheet. just this question and im done because i was absent so i have to do this paper! thank ya!

Answer 1

Density contrast is the answer.

The continents are upper part of lithosphere which has lower  density than the Asthenosphere, hence due to buoyancy the continents float.

thnks

Answer 2

The density of continental crust is insufficient to subduct. It is less dense and therefore buoyant compared to oceanic crust it "floats" like a cork on water, continental crust density is about 2.8 g/cm2 and oceanic crust is 3.0 g/cm2.

Answer 3

Basically because of a process known as isostasy.

The continental or granitic crust, sometimes known as the sial (silica aluminium rich) is less dense than the oceanic or basaltic crust, sometimes known as the sima (silicon magnesium rich), and a lot less dense than the asthenosphere.  

Aside from the effects of subduction, the continental crust 'floats' on the basaltic crust and the asthenosphere.  The continental crust is a lot thicker than the oceanic crust as well (50 km thick as against 5), and extends down into the asthenosphere, something like an iceberg; although there area lot of things going on at depth in the continental crust.

So in a way, the continents DO get dragged down into the asthenosphere.