At 4,000 miles long and 30–40 miles wide, the East African Rift (EAR) system is one of the geologic wonders of the world.

the interaction of the Earth's mantle with other major reservoirs (continental crust, core), and the estimation of the bulk composition of major Earth reservoirs, to more localized aspects of melt ...

Extraction of the continental crust has left the Earth's mantle depleted ... implying that much remains unknown about the processes that affect the composition and evolution of the Earth's mantle.

But its composition can also be inferred from basaltic rocks in the oceanic or continental crust, or from chunks of mantle rock that were caught up in the crust. A compositionally heterogeneous ...