What are the parts of the ocean floor?
What are the parts of the ocean floor?
Features of the ocean floor include the continental shelf and slope, abyssal plain, trenches, seamounts, and the mid-ocean ridge. The ocean floor is rich in resources. Living things on the ocean floor are used for food or medicines.
What is the definition of mid-ocean ridge?
: an elevated region with a central valley on an ocean floor at the boundary between two diverging tectonic plates where new crust forms from upwelling magma.
What are the features of the seafloor that are very deep?
Other significant features of the ocean floor include aseismic ridges, abyssal hills, and seamounts and guyots. The basins also contain a variable amount of sedimentary fill that is thinnest on the ocean ridges and usually thickest near the continental margins.
What discovery about the ocean floor is associated with the seafloor spreading?
If this idea is correct, alternating stripes of normal and reversed polarity should be arranged symmetrically about mid-ocean spreading centers. The discovery of such magnetic stripes provided powerful evidence that sea-floor spreading occurs. The age of the sea-floor also supports sea-floor spreading.
What supports the theory of seafloor spreading?
Abundant evidence supports the major contentions of the seafloor-spreading theory. First, samples of the deep ocean floor show that basaltic oceanic crust and overlying sediment become progressively younger as the mid-ocean ridge is approached, and the sediment cover is thinner near the ridge.
What is the importance of seafloor spreading?
Today it refers to the processes creating new oceanic lithosphere where plates move apart. Seafloor spreading replaces the lithosphere destroyed by subduction, and exerts important influences on Earth’s chemical and biological evolution.
What is the importance of seafloor spreading How does it affect the earth?
Mid-ocean ridges and seafloor spreading can also influence sea levels. As oceanic crust moves away from the shallow mid-ocean ridges, it cools and sinks as it becomes more dense. This increases the volume of the ocean basin and decreases the sea level.
What are 3 types of evidence for seafloor spreading?
Several types of evidence from the oceans supported Hess’s theory of sea-floor spreading-evidence from molten material, magnetic stripes, and drilling samples.
What are the steps in the process of seafloor spreading?
What are the steps in the process of sea floor spreading?
- Magma comes out of the rift valley.
- Magma cools to rock and hardens.
- Rock is pushed away as new rock is formed at MOR.
- Oceanic crust and continental crust meet at the trench.
- Oceanic crust bends down under the continental crust.
- Gravity pulls rock towards mantle.
- Rock melts to mantle.
What are the 4 steps of seafloor spreading?
What are the 4 steps of seafloor spreading?
- Magma comes out of the rift valley.
- Magma cools to rock and hardens.
- Rock is pushed away as new rock is formed at MOR.
- Oceanic crust and continental crust meet at the trench.
- Oceanic crust bends down under the continental crust.
- Gravity pulls rock towards mantle.
- Rock melts to mantle.
What is the first step in seafloor spreading?
A crack forms in oceanic crust. Molten rock rises up through oceanic crust. Molten rock solidifies at the center of the ridge.
What are the types of seafloor spreading?
There are three types of plate-plate interactions based upon relative motion: convergent, where plates collide, divergent, where plates separate, and transform motion, where plates simply slide past each other.
What are the two types of seafloor spreading?
Continued spreading and subduction As new seafloor forms and spreads apart from the mid-ocean ridge it slowly cools over time. Older seafloor is, therefore, colder than new seafloor, and older oceanic basins deeper than new oceanic basins due to isostasy.
What causes seafloor spreading?
Seafloor spreading creates new oceanic crust at a mid-ocean ridge. When this new material reaches the end of the plate and comes into contact with another plate, whether continental or not, a convergent or a transform boundary will occur.
What is a spreading center and what is made at one?
Spreading centers occur where two plates are moving away from each other, and deep cracks are opened through the crust. This lengthening of the crust allows magma from the upper mantle to rise to the surface and cool, commonly forming basalt. An excellent example is the Mid-Atlantic Ridge.
What are the 4 types of plate tectonics?
There are four types of boundaries between tectonic plates that are defined by the movement of the plates: divergent and convergent boundaries, transform fault boundaries, and plate boundary zones.
What are the two types of crust?
Earth’s crust is divided into two types: oceanic crust and continental crust. The transition zone between these two types of crust is sometimes called the Conrad discontinuity. Silicates (mostly compounds made of silicon and oxygen) are the most abundant rocks and minerals in both oceanic and continental crust.
What is another name for tectonic spreading centers?
Plate tectonics, continental drift, spreading centers, subduction zones.
What is the largest tectonic plate?
Pacific Plate
What is the location for a spreading center?
Spreading centres are found at the crests of oceanic ridges. The age of Earth’s oceanic crust can be presented to show the pattern of seafloor spreading at the global scale.
Are earthquakes common or rare near ocean spreading centers?
Mild earthquakes are common at spreading centers. This is the boundary between two continental plates that are being torn apart. A crack in the continental crust allows melted rock to escape to the surface, forming new rock and forcing the plates apart.
What keeps the plate edges from sliding smoothly past each other?
Friction between the plates keeps them from sliding. When the frictional strain is overcome, the ground suddenly snaps along faults and fractures releasing energy as earthquakes.
Are trenches seismically active?
How are trenches formed? This process makes trenches dynamic geological features—they account for a significant part of Earth’s seismic activity—and are frequently the site of large earthquakes, including some of the largest earthquakes on record.
Why are earthquakes associated with rifts?
The majority of deep crustal earthquakes occur along the rift margins in regions that have cooler, thicker crust. We believe the deep crustal earthquakes represent either the relative motion of rift zones with respect to adjacent stable regions or the propagation of rifting into stable regions.
Is rifting always successful?
However, the rifting does not always continue up to its end, and many rifts become inactive before their oceanization remaining “rifted basins” and not continental margins. Conversely, a “successful” rift is indeed made up by the conjugate continental passive margins of an oceanic domain.
Do rifts cause earthquakes?
As the lithosphere is not ductile, stretching takes place by the formation of a series of asymmetric normal faults. As with any movement within a fault system, strain build up can occur that when released can result in devastating earthquakes. Thus, earthquakes are common in rift zones.
How are rifts formed?
A rift valley is formed on a divergent plate boundary, a crustal extension or spreading apart of the surface, which is subsequently further deepened by the forces of erosion. On Earth, rifts can occur at all elevations, from the sea floor to plateaus and mountain ranges in continental crust or in oceanic crust.
In which two places do divergent boundaries occur?
Divergent boundaries are typified in the oceanic lithosphere by the rifts of the oceanic ridge system, including the Mid-Atlantic Ridge and the East Pacific Rise, and in the continental lithosphere by rift valleys such as the famous East African Great Rift Valley.
What do divergent boundaries create?
Divergent boundaries occur along spreading centers where plates are moving apart and new crust is created by magma pushing up from the mantle. Picture two giant conveyor belts, facing each other but slowly moving in opposite directions as they transport newly formed oceanic crust away from the ridge crest.
What is an ocean rift?
In geology, a rift is a linear zone where the lithosphere is being pulled apart and is an example of extensional tectonics. Major rifts occur along the central axis of most mid-ocean ridges, where new oceanic crust and lithosphere is created along a divergent boundary between two tectonic plates.
What’s the definition of mid-ocean ridge?
What do the side slits represent?
The side slits stand for where subduction has occurred and the ocean floor has sunk in. Also, the space under the paper stands for the oceanic crust of the Earth.
What process happens at the two side slits represent?
Side slits are the resultant of subduction, a geological process wherein a tectonic plate moves under another plate. A side slit is basically the place where the process of subduction occurred. In addition, the subducting plate is the one that goes under the other plate, which is called the overriding plate.
Where is the famous seafloor spreading site?
mid-ocean ridge
What is the first step of seafloor spreading?
What are three pieces of evidence for seafloor spreading?
Several types of evidence supported Hess’s theory of sea-floor spreading: eruptions of molten material, magnetic stripes in the rock of the ocean floor, and the ages of the rocks themselves.
What is the best description of seafloor spreading?
Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge.
What is the process that continually adds new crust?
This process, called sea-floor spreading, continually adds new material to the ocean floor. Scientists have found strange rocks shaped like pillows in the central valley of mid-ocean ridges. Such rocks can form only if molten material hardens quickly after erupting under water.
What are 2 pieces of evidence that support seafloor spreading?
Look at Figure 19 to see the process of sea-floor spreading. Several types of evidence from the oceans supported Hess’s theory of sea-floor spreading-evidence from molten material, magnetic stripes, and drilling samples. This evidence also led sci- entists to look again at Wegener’s theory of continental drift.
What happens old seafloor?
What happens to old oceanic crust as new molten material rises from the mantle? It is recycled back into the mantle through the process of subduction. The process of subduction also plays a role in the new molten material rising from the mantle (see page 132).
What is it called when new rock forms on the seafloor?
Igneous rock is formed by the cooling and crystallization of molten magma at volcanoes and mid-ocean ridges, where new crust is generated.
Which crust is thicker but with less density?
Oceanic crust
Which crust is thicker?
Earth’s crust is generally divided into older, thicker continental crust and younger, denser oceanic crust. The dynamic geology of Earth’s crust is informed by plate tectonics.
What causes the formation of new seafloor?
Explanation: Seafloor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge.At a spreading center, basaltic magma rises up the fractures and cools on the ocean floor to form new seabed.
How is seafloor destroyed?
Framework Integration: Themes: Patterns of change: over time, new sea-floor is created by the upwelling of magma at mid-ocean spreading centers; old ocean floor is destroyed by subduction at deep sea trenches. Life Science: animals found at hot-water vents on the ocean floor.
Where is seafloor destroyed?
You are correct that the seafloor is destroyed at subduction zones, but it is simultaneously being created at mid-ocean ridges. see figure 1 . Figure 1: Seafloor spreading at a mid-ocean ridge(where new crust is being created) and it’s destruction at a subduction zone.
Which boundary is seafloor destroyed?
COnvergent Boundary
What causes tectonic plates to move?
The heat from radioactive processes within the planet’s interior causes the plates to move, sometimes toward and sometimes away from each other. This movement is called plate motion, or tectonic shift.
What are three causes of plate movement?
In this lesson, we explore the causes of plate movement, including thermal convection, ridge push and slab pull. Students will learn how these processes complement each other and form a theory for tectonic plate movement.