However, walking is an excellent long-term weight-loss exercise. You can easily walk thousands of miles over decades, because walking has a very low injury risk. How many calories you burn on a one-mile walk depends on your speed and weight.
The thickest layer of the Earth. The Earth can be divided into four main layers: the solid crust on the outside, the mantle, the outer core and the inner core. Out of them, the mantle is the thickest layer, while the crust is the thinnest layer. Artistic depiction of the Earthâs structure. Image via Victoria Museum.
The Mantle. Sitting on top of the outer core, we find the mantle. This layer is by far the thickest layer of Earth, about 1,800 miles thick! It also makes up about 85% of Earth's volume. Like the core, the mantle contains mostly iron, but in the form of silicate rocks. You might be surprised to learn that this rock actually moves like a fluid, similar to how silly putty moves.