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
Ashton (given name) Ashton (given name) Ashton is a given name derived from an English surname derived from a place name meaning "ash tree town." The name is in use for both boys and girls in the United States. Ashton was used far more often on American females from years 1986–1997. The popularity for girls was from the Terri Garber character "Ashton Main" on 1985's North and South (miniseries). Since Ashton Kutcher's debut on television and film in the late 1990s, the name is now in favor more for boys, as it was always before 1986. Ashton was the 124th most popular name