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
Do Not Ask What Good We Do the 2010 election. A majority of those he spoke with and listened to were Republicans, especially among the 87 new legislators. The title of the book, "Do Not Ask What Good We Do", is taken from a sentence in a letter from Fisher Ames to Thomas Dwight, dated May 30, 1796: "Do not ask what good we do : that is not a fair question, in these days of faction." The prologue to the book details how, on the night of Obama's inauguration, a group of around 15 Republican Representatives and Senators met in the Caucus Room, a "high-end D.C.