Plate Tectonics

When continental and oceanic plates converge, the scenario is a predictable one. Due to its greater density, the oceanic plate easily subducts below the edge of the continental plate. Again subduction of the oceanic plate leads to volcano formation, but in this setting, the chain of volcanoes forms on the continental crust. This volcanic mountain chain, known as a volcanic arc, is usually several hundred miles inland from the plate margin. The Andes Mountains of South America and the Cascade Mountains of North America are examples of volcanic arcs formed by subduction along a continental-oceanic convergent margin. Continental-oceanic convergence may form a prominent trench, but not always. No continental-oceanic divergent margins exist today. As you can imagine, they are unlikely to form and would quickly become oceanic-oceanic divergent margins as sea floor spreading occurred.