[Answer] What is the D" layer?

Answer: A partially molten layer above the outer core at the base of the mantle.

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What is the D" layer? The D ” layer the lowermost portion of the mantle sits just above the molten iron-rich outer core. Seismic observations have revealed a region with an intriguingly complex signature. This relatively thin layer varying around 250 km in thickness may hold the key to understanding how the core and mantle interact. Wed Mar 24 2004 · MONTREAL--Deep within Earth where hellish temperatures and pressures create crystals and structures like none ever seen on the surface a strange undulated layer separates the mantle and the core.... D layer. The lower mantle of the earth between a depth of 600 and 1800 miles (1000 and 2900 kilometers ). The lowest layer of ionized air above the earth occurring in the D region only in the daytime hemisphere; reflects frequencies below about 50 kilohertz and partially absorbs higher-frequency waves. In 1942 the geophysicist Keith Bullen published a paper describing the earth's internal layering in which he used letters to designate various layers from the surface to the core. In this scheme the earth's lower mantle was known as the D layer . Definition of D layer . : a layer within the D region of the ionosphere also : d region. D layer definition the lowest region of the ionosphere characterized by mounting electron and ion density: exists during the day only from about 43 to 50 miles (70 to 80 km) altitude. See more. The core–mantle boundary (CMB in the parlance of solid earth geophysicists) of the Earth lies between the planet's silicate mantl...

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