The Earth's Crust is like the skin of an apple. It is very thin in comparison to the other three layers. The crust is only about 3-5 miles (8 kilometers) thick under the oceans(oceanic crust) and about 25 miles (32 kilometers) thick under the continents (continental crust).
The problem behind your itchy skin might be insufficient vitamin intake. There are a number of vitamins that promote the hydration and healthiness of your skin. A shortage in these could trigger itchiness, dry skin and other skin conditions. Alternatively, an overdose of such vitamins might also lead to itchy skin.
For example, if a person is deficient in the vitamins and minerals that are necessary to make and repair skin, connective tissue, and collagen, he or she will have signs and symptoms related to poor skin healing, excess skin wrinkling or dryness, lack of elasticity, dermatitis, or rashes.