The Earths crust is approximately 650 km deep.
This is because the size of the earth is relative stable or constant. Geologic activities do not actually changes earth size as a whole, but rather reshapes and resizes its landforms and continents. All that happen is just a recycling process whenever the earths crust seperates at divergence a boundary its being consumed somewhere else at a convergence boundary. And so on and on it goes, by this the earths overall size is maintained.
The amount of crust present on Earth always stays the same. The amount of crust descending into the mantle is balanced by the amount of crust formed at mid-ocean ridges.
The sudden vibration in the plates inside the crust causes the earths crust to rise & fall.
mantle
The earth's crust is not stress
half of earths layer
continental crust
crust
The earth's crust is generally solid.
The crust is the thinnest part on the Earth.
crust
the crust and the core