When an oceanic plate and a continental plate meet, the continental plate will remain the up plate because it is the less dense of the two, and the oceanic plate will be subducted. As in the previous case, the edges of the plates will be deformed, and there will be a trench. Volcanos again form on the up plate, this time on the edge of the continent. As the oceanic plate plunges underneath the continental plate, shallow, intermediate and deep focus earthquakes generated by the descending plate rack the continent. The upper layers of the descending oceanic plate will be scraped and welded onto the continent in an accretionary wedge.  Finally, the edge of the continent, being compressed by the action of the oceanic plate, will be deformed by faults and folds forming marginal mountain chains on the edge of the continent.

The Andes, a marginal mountain range in South America, are an excellent example of such a mountain range. The trench is clearly visible as the very dark blue line oceanward of the continent, on the margin of the Pacific plate.