Top 10 Interesting and Fun Facts About the Ocean Floor
1. Features of the Ocean Floor
The ocean floor is where the earth's crust is created and destroyed. Volcanic activity associated with mid-ocean ridges and subduction zones creates many of the most striking and interesting features of the ocean floor.
The continental shelf is the gently sloping rim of the continent where the land mass meets the sea.
The continental slope descends steeply from the continental shelf into the abyssal plain.
About 3,500 to 5,500 m (11,480 to 18,040 feet) below sea level is a vast plain covered with deep sediment, called the abyssal plain.
Below the steep continental slope, sediment may collect to form a gentler slope known as the continental rise.
A river flowing off the land into the sea may carve a deep canyon in the ocean floor.
A long, undersea mountain range runs along the mid-ocean ridge, where two tectonic plates are pulling apart.
A seamount is an underwater volcano that rises 1,000 m (3,280 feet) or more above the surrounding plain.
A guyot is a flat-topped seamount that once rose above the surface of the ocean as a volcanic island.
A deep trough may form at a subduction zone, where one plate plunges beneath another. The ocean floor is destroyed at subduction zones. Deep-sea trenches are about 100 km (62 miles) wide. They may be thousands of metres long.
A curved line of volcanic islands, called an island arc, often forms close to a subduction zone.
2. Major Ridges and Trenches
The major features of the ocean floor form at the boundaries of the plates that make up the earth's crust. Mid-ocean ridges form where two plates are pulling apart. Trenches form at subduction zones, where one plate is plunging beneath another.
Vast undersea mountain ranges form where two tectonic plates are pulling apart.
3. The World's Deepest Sea Trenches
The depth of deep sea trenches is measured from sea level.
Depth in m (feet)
North New Hebrides
4. Smokers (Hydrothermal Vents)
Smokers are tall, chimney-like vents on the ocean floor that belch out clouds of super-heated water. They occur at volcanically active spots on mid-ocean ridges.
Smokers were first discovered in 1977 by a team on board the American submersible, "Alvin".
Smokers are created as water seeps down deep into the sea floor where it is heated by volcanic activity. The heated water then rises back to the surface. "Chimneys" up to 50 m (164 feet) high build up from minerals deposited by the heated water. The heated water rises up the chimney and erupts in tail jets. It can be as hot as 350 degrees Celsius (662 degrees Fahrenheit).
Smokers also support strange life forms that derive energy not from the sun as other life forms on Earth, but from volcanic activity.
5. Ocean Floor Sediment
Close to the coast, sediment consists mainly of mud, sand, and silt washed off the land by rivers. The deep ocean floor is blanketed with ooze (the remains of dead marine plants and animals). The amount of sediment and ooze can help scientists to calculate the age of the ocean floor.
Newly formed Rock
At the mid-ocean ridge, the new volcanic rock of the ocean floor is almost free of sediment.
5 Million Years Later
The rock has moved 500 km (311 miles) from the ridge. Sediment has started to gather in hollows.
10 Million Years Later
The rock has moved 1,000 km (621 miles) from the ridge. It is now covered with a thick blanket of sediment.
6. Mapping and Sampling the Ocean Floor
Early explorations of the ocean floor were made from ships using a lead weight and line to estimate depth. Today, scientists use echo-sounding techniques. They also use special submarines called submersibles, which may have people inside or be entirely robotic, to descend to the very depths of the ocean.
7. Fascinating Ocean Numbers
- A particle of ooze sinks 0.3 to 3 m (1 to 10 feet) per day. At this rate, it would take 25 years for the remains of a dead shrimp to sink from the ocean surface to the floor of a deep-sea trench
- The tube worm, Alvinella pompejana can live on "smoker" walls where the temperature is 105 degrees Celsius (221 degrees Fahrenheit), much higher than any land animal could tolerate
- The Mariana trench could hold 28 Empire State Buildings standing on top of each other
- The oldest parts of the ocean floor are about 200 million years old. The oldest rock found on land are about 3.5 billion years old
8. What Can You Find On the Ocean Floor?
Many useful products are found on or under the ocean floor. They include:
Diamonds are formed in shallow waters off the coasts of Africa and Indonesia. Sand, gravel, and limestone are often found in near-coastal waters. Coal id mined beneath the sea as well as on land. About 20% of oil comes from the ocean floor. Natural gas is found together with oil deposits.
9. The Formation of Oil and Gas on the Ocean Floor
Under certain conditions, oil and gas form from the remains of dead plants and animals that accumulate on the floor of shallow seas. This happens by a three-stage process:
- Dead plants and animals sink down to the floor of the continental shelf. Bacteria break the remains down into organic material
- Sediments of mud and sand washed off the land by rivers form layers of sandstone, covering the organic remains
- Increased pressure from further layers of sandstone and other sedimentary rock turns the organic remains into oil and gas
10. The Highest Seamount and Deepest Submarine Canyon
The highest seamount is near the Tonga trench between Samoa and New Zealand. The deepest submarine canyon is 40 km (25 miles) south of Esperance, Australia.
On land, Mount Everest is the highest mountain, at 8,848 m (29,028 feet) high. The highest seamount is 8, 705 m (28,560 feet) high.
The Grand Canyon is the deepest canyon on land, at 1,676 m (5,499 feet) deep. The deepest submarine canyon sinks down 1,800 m (5,906 feet).
A Last Word
That brings us to the end of our exploration of the wonders and the mysteries of the ocean floor. While most people think of outer space as the final frontier of human exploration, most of the deepest ocean remains unexplored. Who knows what discoveries may yet be made as we develop better technologies for probing into the watery depths of the world's oceans? Perhaps you will be an oceanographer or marine biologist and help make the exciting discoveries of the future!
© 2019 Amanda Littlejohn