摘要: It is well known that the solid Earth wholly covered by a thin rock layer called crust. The Earth’s crust made up of two parts. One oceanic and other continental Oceanic occupies about 60% remaining 40% surface. generally believed to form at ridges cooling solidification basaltic magma forms from mantle convection. However, origin has not yet been clearly elucidated. Today, most researchers have come think separated throughout history. there remains wide range opinions on processes its formation.