Ocean floor

Underwater mountain formed by erupting volcanoes

• island

• mid-ocean ridge

• continental shelf

• trench

A steep-sided valley at the center of a mid-ocean ridge

• island

• continental slope

• rift

• continental shelf

A flat area of the ocean floor covered with sand , mud and plant or animal remains

• continental rise

• rift

• island

• abyssal plains

A mountain that breaks through the surface of the water

• rift

• island

• ridge

• continental shelf

A steep drop-off from the continental shelf that plunges to depth of 2 1/4 miles

• continental rise

• continental shelf

• island

• continental slope