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
Civilization and Its Discontents Civilization and Its Discontents Civilization and Its Discontents is a book by Sigmund Freud, the founder of psychoanalysis. It was written in 1929 and first published in German in 1930 as "Das Unbehagen in der Kultur" ("The Uneasiness in Civilization"). Exploring what Freud sees as the important clash between the desire for individuality and the expectations of society, the book is considered one of Freud's most important and widely read works, and one of the most influential and studied books in the field of modern psychology. Freud enumerates what he sees as the fundamental tensions between civilization and the individual.