Crust (geology) crustal rocks formed before 2.5 billion years ago are located in cratons. Such old continental crust and the underlying mantle asthenosphere are less dense than elsewhere in Earth and so are not readily destroyed by subduction. Formation of new continental crust is linked to periods of intense orogeny; these periods coincide with the formation of the supercontinents such as Rodinia, Pangaea and Gondwana. The crust forms in part by aggregation of island arcs including granite and metamorphic fold belts, and it is preserved in part by depletion of the underlying mantle to form buoyant lithospheric mantle. A theoretical protoplanet named
Spencer (given name) Spencer (given name) Spencer is a given name of British origin, meaning "steward" or "administrator". It is a shortened form of the English word "dispenser", which derives from Anglo-French "dispensour", from Old French "dispenseor", from Latin "dispensatorem", the agent noun of "dispensare", meaning "to disperse, administer, and distribute (by weight)". The name originated as the surname Spencer, but later gradually came to be used as a given name as well. From its origin as a surname, it has been given to both males and females, but it has historically been more common as a name for males. According to the