convergent boundary discovered the interfaces that marked the boundary between the crust and mantle.
convergent boundary discovered the interfaces that marked the boundary between the crust and mantle.
who discover the interfaces that mark the boundary between the crust and mantle?
convergent boundary
Na
Na
earth's mantle extends to a depth of 2,890 km, making it the thickest layer of earth. the mantle is divided into upper and lower mantle, which are separated by the transition zone. the lowest part of the mantle next to the core-mantle boundary is known as the d″ ( dee-double-prime) layer. the pressure at the bottom of the mantle is ≈140 gpa (1.4 matm). the mantle is composed of silicate rocks that are rich in iron and magnesium relative to the overlying crust. although solid, the high temperatures within the mantle cause the silicate material to be sufficiently ductile that it can flow on very long timescales. convection of the mantle is expressed at the surface through the motions of tectonic plates. as there is intense and increasing pressure as one travels deeper into the mantle, the lower part of the mantle flows less easily than does the upper mantle (chemical changes within the mantle may also be important). the viscosity of the mantle ranges between 10 and 10 pa·s, depending on depth. in comparison, the viscosity of water is approximately 10 pa·s and that of pitch is 10 pa·s. the source of heat that drives plate tectonics is the primordial heat left over from the planet's formation as well as the radioactive decay of uranium, thorium, and potassium in earth's crust and mantle.
structure of the earth