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
Riley (given name) Riley (given name) Riley is a unisex given name, which first appeared as "Raghallach", which was originated on a man who died in the Battle of Clontarf. Its source gives its meaning as "valiant". Riley in the United States is mostly a girl's name. In 2017, it was the twenty-fifth most popular girl's name, and the 253rd most popular boy's name. The opposite is true for the UK, where it is primarily a boy's name, being the fortieth most popular name given to baby boys in 2016. Riley is also a popular surname. The surname's first variant is Ó Raghallaigh