The layer of Earth you stand on and is only a few miles thick is the crust.

Here's why:

* The Earth's Structure: The Earth is made up of several layers: the crust, the mantle, the outer core, and the inner core.

* The Crust: The crust is the outermost layer, and it's the thinnest. It's composed of solid rock and is divided into two types: oceanic crust (thinner and denser) and continental crust (thicker and less dense).

* Thickness: The crust varies in thickness, but it's generally only a few miles thick, compared to the much thicker mantle and core.

So, when you stand on the Earth's surface, you're standing on the crust.