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 Do Not Ask What Good We Do Do Not Ask What Good We Do: Inside the U.S. House of Representatives is a 2012 book by the author Robert Draper and published by Free Press. It details the activities of Republicans and Democrats in the United States House of Representatives and the Senate during the first term of Barack Obama's presidency. The book was republished under the title When the Tea Party Came to Town. In order to research the activities and politics within the House of Representatives, Draper "embedded with new and senior House members" that had been elected in