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
Ida (given name) may refer to: Ida (given name) Ida is a given name occurring independently in several cultures. In Germany, Ida is a female name derived from a Germanic word "id", meaning "labor, work". Alternately, it may be related to the name of the Old Norse goddess "Iðunn". Ida also occurs as an anglicisation of the Irish girl's given name Íde. Ida is a currently popular name in the Nordic countries and is among the top 10 names given to girls born in 2013 in Denmark. It was among the top 20 names for newborn girls in Norway in 2013 and among