pedosphere is formed on top of continental crust and chemically reacts through the soil forming process.
what is formed on top of continental crust and chemically reacts through the soil forming process?
pedosphere
earth's lithosphere includes the crust and the uppermost mantle, which constitute the hard and rigid outer layer of the earth. the lithosphere is subdivided into tectonic plates. the uppermost part of the lithosphere that chemically reacts to the atmosphere, hydrosphere, and biosphere through the soil forming process is called the pedosphere. the lithosphere is underlain by the asthenosphere which is the weaker, hotter, and deeper part of the upper mantle. the lithosphere-asthenosphere boundary is defined by a difference in response to stress: the lithosphere remains rigid for very long periods of geologic time in which it deforms elastically and through brittle failure, while the asthenosphere deforms viscously and accommodates strain through plastic deformation.
lithosphere
as explained above, tectonic plates may include continental crust or oceanic crust, and most plates contain both. for example, the african plate includes the continent and parts of the floor of the atlantic and indian oceans. the distinction between oceanic crust and continental crust is based on their modes of formation. oceanic crust is formed at sea-floor spreading centers, and continental crust is formed through arc volcanism and accretion of terranes through tectonic processes, though some of these terranes may contain ophiolite sequences, which are pieces of oceanic crust considered to be part of the continent when they exit the standard cycle of formation and spreading centers and subduction beneath continents. oceanic crust is also denser than continental crust owing to their different compositions. oceanic crust is denser because it has less silicon and more heavier elements ("mafic") than continental crust ("felsic"). as a result of this density stratification, oceanic crust generally lies below sea level (for example most of the pacific plate), while continental crust buoyantly projects above sea level (see the page isostasy for explanation of this principle).
plate tectonics