Structure of the Earth easily than does the upper mantle (chemical changes within the mantle may also be important). The viscosity of the mantle ranges between 10 and 10 Pa·s, depending on depth. In comparison, the viscosity of water is approximately 10 Pa·s and that of pitch is 10 Pa·s. The source of heat that drives plate tectonics is the primordial heat left over from the planet’s formation as well as the radioactive decay of uranium, thorium, and potassium in Earth’s crust and mantle. The average density of Earth is . Because the average density of surface material is only around , we must
The Theatre and its Double and The Theater of Cruelty, where Artaud expressed the importance of recovering "the notion of a kind of unique language half-way between gesture and thought". The collection is still read, and strongly influenced the directing philosophies of such renowned figures as Peter Brook and The Living Theatre. The Theatre and its Double The Theatre and Its Double ("Le Théâtre et son Double") is a collection of essays by French poet and playwright Antonin Artaud and published in 1938. Artaud intended his work as an attack on theatrical convention and the importance of language of drama, opposing the vitality of the