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
Call of Cthulhu: Dark Corners of the Earth of "Call of Cthulhu: Dark Corners of the Earth" was a commercial bomb, with sales slightly above 5,000 units by the end of 2005. Eurogamer's Kristan Reed called it among "the most disappointing" commercial performances of an Xbox game that year, and noted that it had been released "right in the thick of a busy release period to zero fanfare." "Call of Cthulhu: Dark Corners of the Earth" received generally favorable reviews, but was also often criticized for being buggy and inaccessible for many players because of its high difficulty. GameSpy ranked it as the tenth best game of E3