4. Ocean floor
What are the various features on the ocean floor and what causes them?
CONTINENTAL MARGIN
Not all of the ocean floor is the same. You may not know but actually, the ocean floor is all very different. These different parts and characteristics are known as the ocean bathymetry and the shape of the ocean floor is known as the topography. A lot of things occur more under the ocean, then they do on land. For example the ocean floor has higher mountains, and lower valleys than land. The ocean also has more earthquakes and volcanoes. However, the Earth's crust under the ocean is much thinner than the crust under the land. You probably already know that where the land and the ocean meets is known as the shoreline, but you might not know that that's considered average sea level. The content technically goes on for a little while under the ocean, but when it ends, thats called the continental margin. This consists of a continental shelf, slope, and rise.
Not all of the ocean floor is the same. You may not know but actually, the ocean floor is all very different. These different parts and characteristics are known as the ocean bathymetry and the shape of the ocean floor is known as the topography. A lot of things occur more under the ocean, then they do on land. For example the ocean floor has higher mountains, and lower valleys than land. The ocean also has more earthquakes and volcanoes. However, the Earth's crust under the ocean is much thinner than the crust under the land. You probably already know that where the land and the ocean meets is known as the shoreline, but you might not know that that's considered average sea level. The content technically goes on for a little while under the ocean, but when it ends, thats called the continental margin. This consists of a continental shelf, slope, and rise.
As you can see, the brown part of this diagram is still considered the continent. The continental shelf is usually where people swim when they go to the beach. It fades VERY slowly, and the horizontal measurement varies depending on the ocean. For example, the Atlantic ocean's continental shelf lasts for about 200 kilometers. The arctic lasts for over 1,200 kilometers and Florida has almost no continental shelf. The continental slope and rise are basically what separates the ocean floor and the continent's floor. The continental shelf is simply formed from land of the continent. The continental slope and rise, however, is made of small pieces of broken down rocks, animals, plants, etc. How do these pieces get there you may be asking, well they travel by things called turbidity currents. These are very powerful currents that are like avalanches underwater.
SUBMARINE CANYONS
When you go to the beach, you may think that you are completely safe staying on the continental shelf, but in some places, the continental shelf is split. This split is called a submarine canyon. This is basically a deep canyon that runs right through the continental shelf.
SUBMARINE CANYONS
When you go to the beach, you may think that you are completely safe staying on the continental shelf, but in some places, the continental shelf is split. This split is called a submarine canyon. This is basically a deep canyon that runs right through the continental shelf.
These can be extremely dangerous because they can be more than 2000 meters, which is more than the grand canyon! Oceanographers have different theories on how these are formed, but they mainly think that turbidity currents or earthquakes are responsible.
ABYSSAL PLAINS
You probably already know that a plain is a large flat piece of land, and that is no difference in the ocean. Abyssal plains are directly after the continental slope and rise. These plains consist of thick layers of mud, sand, and the remains of tiny organisms. These things mixed up make a substance thats called ooze, which makes life on the abyssal planes very rare.
All abyssal plains differ in size, so they are larger in the Atlantic and Indian oceans, and smaller in the Pacific ocean. Oceanographers have 2 main threes on why this is.
1. Earth's major rivers (Mississippi, Congo, Nile, Amazon, Ganges, and Indus) flow into the Atlantic and Indian Oceans, depositing different sediments, which cause the abyssal plains to stretch farther.
2. The pacific ocean includes many large cracks, that trap all the sediments that have been moved to that area.
1. Earth's major rivers (Mississippi, Congo, Nile, Amazon, Ganges, and Indus) flow into the Atlantic and Indian Oceans, depositing different sediments, which cause the abyssal plains to stretch farther.
2. The pacific ocean includes many large cracks, that trap all the sediments that have been moved to that area.
SEAMOUNTS AND GUYOTS
Seamounts are pretty explanatory because the definition is in the word! Obviously SEA means the ocean and MOUNTS stands for mountains, meaning mountains at sea. However, that's not all they are. They are in fact volcanic mountains that rise very high above the ocean (at least 1000 meters). Some of these mountains are known as volcanic islands, like the Hawaiian Islands. Not all seamounts are shaped the same, however. Scientists have noticed some seamounts are flat at the top instead of rounded. They've noticed so many that they decided to give them a separate name: guyots. How are these formed, you may be wondering. Well, over time, the top of the seamounts are eroded and they become flat peeked seamounts/guyots. The following picture is an example of the process.
TRENCHES
How deep is the ocean? Well, thats a good question! No one truly knows the depth of the ocean, but oceanographers have discovered the deepest parts of the ocean, and they are known as trenches. These are long narrow slivers of the ocean floor that are usually more than 11,000 meters deep.Trenches are usually formed by moving plate tectonics.
(The picture bellow is a very minor example of what a trench looks like. They are usually deeper and thinner)
(The picture bellow is a very minor example of what a trench looks like. They are usually deeper and thinner)
Some particular oceans have more trenches than others, such as the Pacific ocean. It also includes the worlds deepest point on Earth and is known as Challenger Deep. This trench is more than 11,000 meters deep! (an example bellow)
MID-OCEAN RIDGES
Mid ocean ridges are simply underwater mountain ranges. These underwater mountains are formed by molten materials comes out of the Earth and into the ocean. This hot substance cools and forms a new crust.
REEFS
Reefs are larger bits of limestone rocks surrounding volcanic islands. Reefs support a lot of life, and are usually only found in tropical water (the fish can't survive cold water). Because there is so much life, reefs aren't that deep because they need to have sunlight to harden the limestone (usually stay around 55 meter deep). Just like anything else, there are different kinds of reefs, called fringing reefs, barrier reefs,and atoll reef.
FRINGING REEFS-
These are coral reefs around a volcanic island that touch the shoreline. These are less than 30 meter s and up to several hundred meters long.
BRRIER REEFS
These are exactly the same as fringing reefs, but they are separated from the volcanic island by shallow water (called lagoon) . These are usually bigger than a fringing reef and the island it surrounds is usually not as big because it has sunk a little. This particular reef has more plants and animals than all the others.
ATOLL-
An atoll is something that surrounds a volcanic island that has been worn away and sank beneath the ocean surface.
As you can see, the ocean floor has various different forms that were all caused by various different things. The following is a picture of all the ocean floor's features together.