Earth's mantle and core

Earth's core and mantle were identified as distinct layers based on earthquake wave behavior, suggesting the core is liquid and mainly nickel-iron in a 1-9 ratio. The mantle is composed of rocky material. The two layers are separated by the Gutenberg discontinuity.
 Beno Gutenberg USA 1914 Earth's mantle and core

Earth's core and mantle were identified as distinct layers based on earthquake wave behavior, suggesting the core is liquid and mainly nickel-iron in a 1-9 ratio. The mantle is composed of rocky material. The two layers are separated by the Gutenberg discontinuity.