A tectonic plate is any of the large, thin, relatively rigid plates that move relative to one another on the outer surface of the Earth (Figure 1). See also plate tectonics.

 

Accretionary wedge

An accretionary wedge consists of sediments, the top layer of material on a tectonic plate, that accumulate and deform where oceanic and continental plates collide (Fig 2). These sediments are scraped off the top of the downgoing oceanic crustal plate and are appended to the edge of the continental plate.