Continental rocks in the backarc that are landward from the trace of the subduction thrust fault and that are strong enough to support stress accumulation. These rocks are both igneous and dewatered, lithified, consolidated sediments that probably were part of the accretionary wedge. The softer accretionary-wedge rocks are strongly deformed as they accumulate against the backstop. The exact position and dip direction of the backstop is not well determined, and more than one backstop may exist.