Core–mantle boundary Core–mantle boundary The core–mantle boundary (CMB in the parlance of solid earth geophysicists) of the Earth lies between the planet's silicate mantle and its liquid iron-nickel outer core. This boundary is located at approximately 2891 km (1796 mi) depth beneath the Earth's surface. The boundary is observed via the discontinuity in seismic wave velocities at that depth due to the differences between the acoustic impedances of the solid mantle and the molten outer core. P-wave velocities are much slower in the outer core than in the deep mantle while S-waves do not exist at all in the liquid portion of
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.