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.
Poor blood circulation, especially on the legs, can cause the skin to itch without rash. Poor blood circulation can cause dry skin which can result to itchy skin. Iron deficiency. Iron is needed in the production of red blood cells, and when there is low red blood cell count, and then blood circulation is not as efficient as it should be.