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.
Vitamin B6 deficiency symptoms for instance, can cause depression and dermatitis. Not getting enough B5 can give you a nice case of acne. Vitamin B2 deficiency symptoms in adults can include cracked lips or sores in mouth corners, photo sensitivity, eyes that itch or burn, and a swollen tongue in its mild state. Those are just the mild effects however. As your vitamin B2 deficiency worsens, so does how effectively your body decides to let you know.