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
What on Earth! Pindal in December 1963, with the working title "Automation", with the intention of showing how "in spite of appearances, man is the master in the automated world." The working title would become "Martians", before the final title "What on Earth!" was chosen. Drew was brought in to work on the film in 1965 and 1966, with Brittain assigned to write narration. Pindal's original idea of "man as the master" is not reflected in the final version of the film, and NFB archivist and blogger Albert Ohayon believes Brittain may have been responsible for this key change. "What on Earth!" was