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 Dog and Its Reflection down as it is crossing a stream and sees its own reflection in the water. Taking it for another dog carrying something better, it opens its mouth to bark at the "other" and in doing so drops what it was carrying. The story became incorporated into mediaeval animal lore. The Aberdeen Bestiary, written and illuminated in England around 1200, asserts that 'If a dog swims across a river carrying a piece of meat or anything of that sort in its mouth, and sees its shadow, it opens its mouth and in hastening to seize the other piece of meat, it