* The crust varies in thickness: The Earth's crust isn't uniform. It's thinner under the oceans (oceanic crust, about 3-5 miles) and thicker under continents (continental crust, about 20-30 miles).
* The crust is just a layer: The crust is the outermost layer of the Earth. Beneath it lies the mantle, which extends much deeper (over 1800 miles).
Instead of "miles deep in the crust," consider these terms:
* Crustal thickness: This refers to the actual depth of the crust at a specific location.
* Moho discontinuity: This is the boundary between the crust and the mantle.
Let me know if you have any other questions about the Earth's structure!
