There are two types of continental margins: passive and active. Passive and active continental margins have different structure and characteristics. Passive continental margins are found near divergent plates and, therefore, tend to exhibit minor seismic or volcanic activity. Passive continental plates are also called Atlantic-type margins. Passive margins have broad continental shelves that reach about 350 kilometers or 220 miles in width and end at a depth of about 140 meters or 460 feet below sea level. The broad shelf extends away from the shore in a slight incline, typically 1.7 meters per kilometer, or 0.1°, or about 9 feet per mile, followed by a steeper drop or plateau break of about 140 meters or 460 feet. Then begins a continental rise that extends about 300 miles further into a deep basin. Features of deep ocean basins include: ocean ridges, abyssal plains, deep trenches, volcanic rock chains.