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
What (ITS utility) What (ITS utility) What (typed as in the prompt) was a small information utility available in the Incompatible Timesharing System. It could provide information about incoming email, bus schedule on the MIT campus, executable source files or answer the user in a humorous manner. was written in the MIDAS assembly language. It can still be used on some of the ITS instances maintained across the web. The last traceable edit of the source code was by Ken L. Harrenstien on 16 May 1988. Without arguments would print information about inbox status: With the argument bus it would print out information