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1.4.2 Earth's Mantle
mantle2ultrabasic compositionultramafic rocks
Upper Mantle and Transition Zone
lithosphere
low velocity zone (LVZ)asthenosphere
transition zone2424243
ssss1 Major layers and seismic (p‐wave) velocity changes within Earth; showing details of upper mantle layers. Colors are as for ssss1.
ssss1 World map showing the distribution of major plates separated by boundary segments that end in triple junctions.
Source: From USGS.
The lower mantle (mesosphere)
lower mantlemesosphere3224Dlayer
1.4.3 Earth's core
coreGutenberg discontinuitycore–mantle boundary (CMB)outer core
Lehman discontinuityinner core
In this section, we have discussed the major layers of the geosphere, their composition, and their mechanical properties. This model of a layered geosphere provides us with a spatial context in which to visualize where the processes that generate earth materials occur. In the following sections we will examine the ways in which all parts of the geosphere interact to produce global tectonics. The ongoing story of global‐scale tectonics is one of the most fascinating tales of scientific discovery in the last century and new discoveries continue to be made in this one.