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
Logan (given name) Logan (given name) The given name Logan is derived from the Scottish surname "Logan", which is in turn derived from a place name. The likely origin of this surname is a place located near Auchinleck, in Ayrshire. The place name is derived from the Scottish Gaelic "lagan", which is a diminutive of "lag", which in turn means "hollow". The given name is borne by males and females. The given name was the 17th most popular name for baby boys born in the United States in 2007 and was the 455th most popular name for baby girls born there in 2007.