ABSTRACT
PLATES AND PLATE MOVEMENT Lithosphère is the relatively brittle outer rock layer, consisting of the crust and upper mantle; it is broken into large slabs known as plates. Convect ion currents circulate within the mantle - because it is heated from below - and the convection cells have horizontal movements over their tops. Plate tectonics are the relative movements of the plates as they are shifted by the underlying mantle flows. Each plate is relatively stable, but disturbances along the plate boundaries cause most geological processes. The formation of igneous, sedimentary and metamorphic rocks, and their subsequent deformation or erosion, can be identified on the cross-section diagram through two plate boundaries.
