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.
Getting plenty of vitamin C on a daily basis helps prevent vitamin C deficiency, which can lead to scurvy. Scurvy is a health condition that can cause fatigue, inflammation of the gums, bleeding gums, impaired collagen synthesis, joint pain, depression, loose teeth and poor wound healing.