The Earth is comprised of many plates that float on the hot magma in the mantle layer. They are constantly moving but its so slow we can't feel it. A long time ago, all the land on Earth was connected in one big continent named Pangaea. As the plates have moved the land has separated forming the continents.
When plates come together they cause friction between them. This causes the plates to push up forming a mountain. This was how the Himalayan mountains were formed.
Diamond have C-C bonds, so we do not expect difference in electronegativity since only are C atoms. In diamond the bonds are covalent as is expected for bonds between atoms with small difference in electronegativity (<1.7).
