Lithosphere for silicate rocks, and formula_4 is the age of the given part of the lithosphere. The age is often equal to L/V, where L is the distance from the spreading centre of mid-oceanic ridge, and V is velocity of the lithospheric plate. Oceanic lithosphere is less dense than asthenosphere for a few tens of millions of years but after this becomes increasingly denser than asthenosphere. This is because the chemically differentiated oceanic crust is lighter than asthenosphere, but thermal contraction of the mantle lithosphere makes it more dense than the asthenosphere. The gravitational instability of mature oceanic lithosphere has the
Common name or coinages; such names generally are difficult for laymen to learn, remember, and pronounce and so, in such books as field guides, biologists commonly publish lists of coined common names. Many examples of such common names simply are attempts to translate the Latinised name into English or some other vernacular. Such translation may be confusing in itself, or confusingly inaccurate, for example, "gratiosus" does not mean "gracile" and "gracilis" does not mean "graceful". The practice of coining common names has long been discouraged; de Candolle's "Laws of Botanical Nomenclature", 1868, the non-binding recommendations that form the basis of the modern