 The trough is the deepest point in the Caribbean Sea and forms part of the tectonic boundary between the North American Plate and the Caribbean Plate.The Cayman Rise extends from southeastern Cuba along the northern margin of the Cayman Trough toward Costa Rica and resulted from Paleocene to Eocene island arc formation with associated volcanism along an extinct subduction zone.The islands are formed of marine limestone and dolomite that was uplifted during the late Miocene epoch.