Where In The Oceans Are Biological Communities Thriving Without Sunlight?

Why are oceanic ridges elevated compared to the rest of the seafloor?

Where in the oceans are biological communities thriving without sunlight? … Why are mid ocean ridges elevated compared to the surrounding ocean floor? Because newly formed lithosphere is hotter and therefore less dense than the surrounding rocks. Which of the following is not part of an ophiolite complex?

Why are mid ocean ridges elevated?

At the ridge new crust forms by igneous intrusion and extrusion. … Since hot rocks are in a more expanded state and then contract as they cool (as they spread away from the ridge) the midocean ridges stand up high above the surrounding seafloor. The seafloor depth increases with distance away from the midocean ridges.

What feature of the ocean floor develops where the oceanic lithosphere?

Oceanic lithosphere forms at midocean ridges where hot magma upwells and then cools to form plates as the material moves away from the spreading center. As the plate cools heat flow decreases and the seafloor deepens (Figure 3).

What layer does seafloor spreading occur?

mid-ocean ridge
The mid-ocean ridge is where the seafloor spreading occurs in which tectonic plates—large slabs of Earth’s lithosphere—split apart from each other. Seafloor spreading was proposed by an American geophysicist Harry H. Hess in 1960.

See also what is the main cause of chemical weathering

Are there any places on Earth where the mid oceanic ridges meet the continent?

The place where the Mid-Atlantic Ridge is best visible is at Thingvellir National Park in southwestern Iceland. The continental drift between the North American and Eurasian Plates can be clearly seen in the cracks or faults which traverse the region the largest one Almannagjá being a veritable canyon.

How does the oceanic lithosphere change as it moves away from the mid-ocean ridge?

The oceanic lithosphere thickens as it ages and moves away from the mid-ocean ridge. This thickening occurs by conductive cooling which converts hot asthenosphere into the lithospheric mantle and causes the oceanic lithosphere to become increasingly dense with age.

What is at the center of a mid-ocean ridge?

The material that erupts at spreading centers along the mid-ocean ridge is primarily basalt the most common rock on Earth. Because this spreading occurs on a sphere the rate separation along the mid-ocean ridge varies around the globe.

What is the location for a spreading center?

Spreading centres are found at the crests of oceanic ridges.

Where is a place where continental rifting is occurring today?

We begin with perhaps the best example of a modern continental rift zone – the East African Rift. The East African Rift is a high terrain a broad upwarp of the continent. It is a region of high heat flow and volcanoes of normal faults that bound uplifted blocks of crust and down dropped basins.

How is new ocean floor and oceanic crust formed?

Seafloor spreading occurs at divergent plate boundaries. As tectonic plates slowly move away from each other heat from the mantle’s convection currents makes the crust more plastic and less dense. The less-dense material rises often forming a mountain or elevated area of the seafloor. Eventually the crust cracks.

See also what is the rarest animal in the world 2021

Is the oceanic crust part of the lithosphere?

The lithosphere is the solid outer part of the Earth. The lithosphere includes the brittle upper portion of the mantle and the crust the outermost layers of Earth’s structure. … Oceanic lithosphere is associated with oceanic crust and is slightly denser than continental lithosphere.

Where are ocean trenches formed?

In particular ocean trenches are a feature of convergent plate boundaries where two or more tectonic plates meet. At many convergent plate boundaries dense lithosphere melts or slides beneath less-dense lithosphere in a process called subduction creating a trench.

Where does the ocean floor sink back into the mantle?

Subduction is the process by which the ocean floor sinks beneath a deep-ocean trench and back into the mantle.

What destroys Earth’s crust?

Just as oceanic crust is formed at mid-ocean ridges it is destroyed in subduction zones. Subduction is the important geologic process in which a tectonic plate made of dense lithospheric material melts or falls below a plate made of less-dense lithosphere at a convergent plate boundary.

What is the bottom of the sea called?


The seabed (also known as the seafloor sea floor ocean floor and ocean bottom) is the bottom of the ocean. All floors of the ocean are known as ‘seabeds’.

Where are the oceanic ridges located?

Oceanic ridges are found in every ocean basin and appear to girdle Earth. The ridges rise from depths near 5 km (3 miles) to an essentially uniform depth of about 2.6 km (1.6 miles) and are roughly symmetrical in cross section. They can be thousands of kilometres wide.

Where are the mid ocean ridges?

Mid-ocean ridges occur along divergent plate boundaries where new ocean floor is created as the Earth’s tectonic plates spread apart.

What nation sits on top of the Mid-Atlantic Ridge?


Iceland sits spanning the Mid-Atlantic Ridge tectonic plate boundary which separates the Eurasian and the North American plates. The ridge an underwater mountain chain extends about 16 000 km along the north-south axis of the Atlantic Ocean.

Where and how is oceanic lithosphere formed quizlet?

Oceanic lithosphere is created at divergent boundaries-think of how sea-floor spreading adds rock to the ocean floor. Most divergent boundaries are spreading centers located along the crest of mid-ocean ridges.

What happens to oceanic lithosphere as you move away from a mid-ocean ridge quizlet?

As lithospheric plates move away from midocean ridges they cool and become denser. They eventually become more dense than the underlying hot mantle. After subducted cool dense lithosphere sinks into the mantle under its own weight.

Where does new oceanic lithosphere form quizlet?

The process by which new oceanic lithosphere (seafloor) forms when magma rises to Earth’s surface at mid-ocean ridges and solidifies as older existing sea floor moves away from the ridge.

Where are most of the oceanic trenches located?

the Pacific

Most ocean trenches are in the Pacific. The loss of the earth’s crust at ocean trenches is made up for by seafloor spreading elsewhere which is when tectonic plates are pulling apart. Underwater earthquakes at subduction zones can set off dangerous tsunamis.

See also where do convection currents occur in the earth

Where do divergent boundaries occur?

mid-ocean oceanic ridges
Divergent boundaries are spreading boundaries where new oceanic crust is created to fill in the space as the plates move apart. Most divergent boundaries are located along mid-ocean oceanic ridges (although some are on land).

What is the difference between mid-ocean ridges and rift valleys?

The major difference between different types is what type of plate the divergent boundary is between. If the boundary is found between two continental plates you are left with a rift valley. … If two oceanic plates begin moving away from each other it creates a mid-oceanic ridge.

Scientists explain! “Thriving microscopic life in oceans: they communicate too!”

Leave a Comment