Bethany Ostlund 4 th Grade . The Ocean Floor. The Ocean Floor. Imagine flying around the world. Below is a land filled with mountains, plains and deep canyons. Now, picture this area about seven miles under the ocean.
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Imagine flying around the world. Below is a land filled with mountains, plains and deep canyons. Now, picture this area about seven miles under the ocean.
Under water there are also numerous hills, slopes and very deep canyons as you can see from the ocean floor map on the slide before.
The sea bottom is divided into three areas:
* The continental shelf
* The continental slope
* The ocean floor
The Continental Shelf
Surrounds all continents
Relatively shallow when compared to the other regions of the ocean
Extends to the continental slope
The Continental Slope
A steep drop off that leads toward the deep bottom of the ocean
Canyons cut through many areas of the continental slope.
The Ocean Floor
Much of the deep ocean floor is covered in basins
Many mountain ranges spread across the ocean floor
There are deep ocean trenches that are found in areas of volcanic activity
This is a diagram of where the continental shelf, continental slope and the ocean floor are in relation to each other and the coast of continents.
What causes the mountain ranges, canyons, and deep sea trenches on the ocean floor?
This is the movement of Earth's outer layer which causes mountains to push higher and oceans to grow wider.
Seafloor Spreading causes the deep ocean trenches to develop on the ocean floor.
In the following diagram there is evidence of seafloor spreading by showing the ages of the ocean floor.
The red colors are the youngest parts of the seafloor, where fresh new crust is formed as lava seeps up from the deep interior of the Earth at spreading ridges.
The green colors are the spreading ridges, older crust, that moves away from the ridge as new crust is formed.
The blue colors are the oldest regions of the seafloor. They are either next to continents, or are near areas on Earth where seduction is taking place.
The deepest ocean trench is the Marianas Trench in the South Pacific Ocean, it is more than 35,000 feet, or almost 6.6 miles deep.
What is going on at the Marianas trench?
The oceanic plate or in this case the fast-moving pacific plate, plunges downward toward the mantle, while the continental plate or the Philippine Plate, rides up over the top. The forces driving the two plates together are really intense, so the underlying oceanic plate creates a trench where it drags the edge of the continental crust down as it descends underneath.
This is an example diagram of how the two plates at the Marianas trench are interacting with each other.
One of the fastest spreading areas of the ocean is the:
Eastern Pacific Rise
A mountain range on the floor of the South Pacific Ocean, roughly paralleling the western coast of South America.
The main portion of the rise lies generally about 2,000 mi off the coast, and it lies about 6,000–9,000 ft above the surrounding seafloor. The East Pacific Rise has a generally smooth and flattish surface, and it drops sharply away at the sides.
Next students we are going to take a virtual field trip exploring the East Pacific Rise. Information about our trip is on the following website:
Virtual Field Trip
For any questions about the ocean try these websites:
Window into the Universe