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 Public and its Problems what he saw as argumentation on the part of Lippman that was particularly doctrinaire and absolutist in its judgements, and saw his own philosophical pragmatism as a means by which a more accurate and realistic conception of what the public and democracy was capable of it, and its limitations. Dewey begins his argument by distinguishing between the "state," represented by elected lawmakers, and the "public," the diffuse, often incoherent body of citizens who elect the state. The public is called into being when ordinary citizens experience the negative externalities (or consequences) of exchanges beyond their control (such as market or