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 Earth's crust is an extremely thin layer of rock that makes up the outermost solid shell of our planet. In relative terms, it's thickness is like that of the skin of an apple. It amounts to less than half of 1 percent of the planet's total mass but plays a vital role in most of Earth's natural cycles. The crust can be thicker than 80 kilometers in some spots and less than one kilometer thick in others. Underneath it lies the mantle, a layer of silicate rock approximately 2700 kilometers thick. The mantle accounts for the bulk of the Earth.