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
The Ego and Its Own is certainly true that we must first make a cause our own, egoistic cause, before we can do anything to further it. . . . [W]e are communists out of egoism also, and it is out of egoism that we wish to be human beings, not mere individuals... However, Marx and Engels would later collaborate on a lengthy criticism of Stirner's book in "The German Ideology" (1845, published 1932). The critique is a polemical tirade filled with ad hominem attacks and insults against Stirner (Marx calls him a "petty bourgeois individualist intellectual"). Stirner also had a lasting influence in the