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
Iced Earth introduced the Something Wicked Saga, which was later expanded upon on 2007's "", and 2008's "". Iced Earth have also released several albums written around a theme. 2001's "Horror Show" was largely based on horror literature and films, 2004's "The Glorious Burden" was inspired by history and war, while 2011's "Dystopia" centered around dystopian themes in literature and film. Iced Earth Iced Earth is an American heavy metal band from Tampa, Florida. It was formed in 1984 under the name The Rose, then Purgatory by guitarist and main songwriter Jon Schaffer and original drummer Greg Seymour. Iced Earth released their