Ocean floor features

Modeled image of a seamount
The hidden world of seamounts
Documenting the abundance and variety of life on one single seamount, is "like trying to describe a Monet painting from three bristles of a brush."...

Plate tectonics and the ocean floor

The shape of the ocean floor, its bathymetry, is largely a result of a process called plate tectonics. The outer rocky layer of the Earth includes about a dozen large sections called tectonic plates that are arranged like a spherical jig-saw puzzle floating on top of the Earth's hot flowing mantle. Convection currents in the molten mantle cause the plates to slowly move about the Earth a few centimeters each year. Many ocean floor features are a result of the interactions that occur at the edges of these plates.

The shifting plates may collide (converge), move away (diverge) or slide past (transform) each other. As plates converge, one plate may dive under the other causing earthquakes, forming volcanoes, or creating deep ocean trenches such as the Mariana Trench. Where plates are pulled away (diverge) from each other molten magma flows upward between the plates forming mid-ocean ridges, underwater volcanoes, hydrothermal vents, and new ocean floor crust. The Mid-Atlantic Ridge, is an example of this type of plate boundary. Transform boundaries are formed when two plates slide past one another such as on mid-ocean ridges and often cause earthquakes due to zig-zag offsets.

Hot magma blows up into the water before settling to the seafloor. Foreground: Jason remotely-operated vehicle with sampling hoses. Image is about 6-10 feet across in an eruptive area about 100 yards that runs along the summit.
Discovery of a deep ocean volcano
"It was an underwater Fourth of July - a spectacular display of fireworks nearly 4,000 feet deep"...

Marine life and exploration on the ocean floor

Over the last decade, more than 1500 new species have been discovered in the ocean by marine biologists and other ocean scientists. Many of these newly discovered species live deep on the ocean floor in unique habitats dependent on processes resulting from plate movement, underwater volcanoes, and cold water seeps. The discovery of deep ocean hydrothermal vent ecosystems in 1977 forced scientists to redefine living systems on our planet. Considered one of the most important scientific discoveries of the last century, living organisms in this deep, dark, ecosystem rely on chemicals and a process called chemosynthesis as the base of their food web and not on sunlight and photosynthesis as in other previously described ecosystems. Since this discovery, sonar, submarines, satellites, and robots have helped find and explore this type of ecosystem and other deep ocean formations around the globe. With only 5% of the Ocean explored, many more scientific discoveries await our future generations of explorers in this final unknown frontier of our planet Earth.

3-D maps of Heceta Bank made from multibeam sonar data collected in 1998. The image is the northern shoal portion of bank in sidelit bathymetry looking north-northeast in the middle portion of the bank showing details of outcropping geology.
Seeing the sea floor
The first primitive maps of the sea floor came from “soundings” which involved lowering weighted lines into the water...


Helping students understand the connections between plate tectonics, ocean floor bathymetry, diversity of life, and adaptations to the environment can help increase their understanding of the interconnectedness of Earth systems. Utilizing examples of current explorations of the unknown, and almost real-time discoveriesoffsite link can increase the relevance of studying the ocean floor and help increase students' excitement for learning. Ocean science is interdisciplinary and can be incorporated beyond the science classroom, for instance math teachers can use ocean data, graphs, and maps to provide relevance when studying concepts such as integers.

Collection created December 2010.