Are elements formed by years of compression under the earths crust?

Answer 1

No.

All elements (since the creation of the Universe) are formed by either combining two lighter elements in to a heavier one (called nuclear fusion) or by splitting a heavy element into 2 (or more) lighter ones (called nuclear fission).

It is believed that at the creation of the Universe mostly hydrogen (and some helium) was present. Hydrogen is by far the most common element. These are the two lightest elements. Inside stars these elements are fused together to form heavier elements. Our very own Sun, for example, fuses hydrogen atoms together to form helium. This process releases energy in the form of heat and light.

A star is able to do this due to the tremendous heat and pressure within it. There are different types of stars, and some have even more staggeringly high pressures inside them allowing them to fuse together and form heavier elements than helium. It is believed that when a star dies, and goes supernova, the tremendous force at this point can fuse and create even heavier elements still. This explains why the heaviest elements are the rarest elements.

So, we have stars to thank for all the elements that exist. The pressures and temperatures within the Earth are just not high enough to fuse atoms together.