The layer of Earth you stand on is called the crust. It's the outermost layer and is indeed only a few miles thick.

Here's a bit more detail:

* Continental crust: This is the thicker part of the crust, making up the landmasses. It's typically 20-30 miles thick.

* Oceanic crust: This is the thinner part of the crust, forming the ocean floor. It's usually only 3-5 miles thick.

So, the exact thickness of the crust you stand on depends on whether you're on land or in the ocean.