How do plate tectonics affect the ocean?
Throughout Earth's history, the global ocean has been modified by plate tectonics. Often, large continents assembled from smaller ones produced more expansive oceans between them. These expansive ocean bodies were subsequently dissected when super-continents rifted and formed smaller oceans out of the formerly vast oceans.
Why is plate tectonics important to geology?
Plate tectonics thus provides “the big picture” of geology; it explains how mountain ranges, earthquakes, volcanoes, shorelines, and other features tend to form where the moving plates interact along their boundaries.
What do we know about the topography of the ocean floor?
First, the topography of the ocean floor was mapped in great detail during and after World War II. It was discovered that the floors of the ocean basins are not flat. A continuous mountain chain circumscribes the globe near the centers of oceans and, in places, the ocean floor descends abruptly into deep-sea trenches.
What layer of the earth do the plates move on?
The plates of crust and stiff mantle (lithosphere) move on the softer mantle layer beneath (asthenosphere). Modified from “Parks and Plates: The Geology of our National Parks, Monuments and Seashores,” by Robert J. Lillie, New York, W. W. Norton and Company, 298 pp., 2005, www.amazon.com/dp/0134905172.
How does the ocean affect plate tectonics?
Changes in tectonic activity that modify the size of ocean basins include. subduction of tectonic plates at ocean trenches at convergent plate boundaries, eruption and formation of large igneous provinces that originate from massive extrusions of lava, oceanic plateaus, hotspot volcanic island chains, etc.
What role did plate tectonics play in the formation of ocean basins?
All of these phenomena can be explained by one theory known as Plate Tectonics. Geological evidence indicates that ocean basins were formed by the drifting apart of large, rigid sections of the Earth's crust called LITHOSPHERIC PLATES which contain the continents (Fig. 1).
Do plate tectonics cause ocean currents?
Plate tectonics causing changes to currents This can affect both global and local patterns of climate and atmosphere-ocean circulation. The position of the continents determines the geometry of the oceans and therefore influences patterns of ocean circulation.
What do ocean plates do?
Most divergent plate boundaries are underwater and form submarine mountain ranges called oceanic spreading ridges. While the process of forming these mountain ranges is volcanic, volcanoes and earthquakes along oceanic spreading ridges are not as violent as they are at convergent plate boundaries.
What happens with ocean basin during plate tectonics occurrence?
As the ocean basin widens the stretched and thinned edges where the two continents used to be joined cool, become denser, and sink below sea level. Wedges of divergent continental margins sediments accumulate on both new continental edges.
What is the importance of ocean basins?
Ocean basins are depocenters for sediment derived from the continents as well as from intrabasinal sources. The rate of aggradation of sediment can be very high, especially in and near active submarine volcanoes.
What are the two main factors of tectonic plates movement?
Tremendous heat and pressure within the earth cause the hot magma to flow in convection currents. These currents cause the movement of the tectonic plates that make up the earth's crust.
What are the ocean currents?
Ocean currents are the continuous, predictable, directional movement of seawater driven by gravity, wind (Coriolis Effect), and water density. Ocean water moves in two directions: horizontally and vertically. Horizontal movements are referred to as currents, while vertical changes are called upwellings or downwellings.
What is most responsible for any movement in the Earth's rock plates?
The force that causes most of the plate movement is thermal convection, where heat from the Earth's interior causes currents of hot rising magma and cooler sinking magma to flow, moving the plates of the crust along with them.
What are oceanic and continental tectonic plates?
Continental crust is composed of granitic rocks which are made up of relatively lightweight minerals such as quartz and feldspar. By contrast, oceanic crust is composed of basaltic rocks, which are much denser and heavier.
What does an oceanic oceanic convergence give rise to?
In ocean-ocean convergence, two oceanic plates converge or collide. The denser plate subducts into the asthenosphere below the convergence zone and forms a trench at the surface.
What is ocean-ocean convergent boundary?
At an ocean-ocean convergent boundary, one of the plates (oceanic crust and lithospheric mantle) is pushed, or subducted, under the other (Figure 4.6. 1). Often it is the older and colder plate that is denser and subducts beneath the younger and warmer plate.
How has plate tectonics revolutionized geology?
Plate tectonics has revolutionized the way we view large features on the surface of the Earth. Earth’s internal processes were previously thought to operate in a vertical fashion, with continents, oceans, and mountain ranges bobbing up and down, without much sideways movement. But the acceptance of continental drift and other evidence for large lateral motions changed all that. Now it’s understood that Earth’s internal processes can move large plates of Earth’s outer shell great horizontal distances. Plate tectonics thus provides “the big picture” of geology; it explains how mountain ranges, earthquakes, volcanoes, shorelines, and other features tend to form where the moving plates interact along their boundaries.
What is the big picture of tectonics?
Plate tectonics thus provides “the big picture” of geology; it explains how mountain ranges, earthquakes, volcanoes, shorelines, and other features tend to form where the moving plates interact along their boundaries.
What are the continents?
The continents are blocks of thick crust that are passengers on the tops of large tectonic plates (lithosphere) that move over a softer part of Earth’s mantle (asthenosphere). Earthquakes, mountain building and volcanic activity occur mostly at the boundaries of the moving plates.
What is the supercontinent that is made of thick crust?
Blocks of thick continental crust fit together nicely along the edges of their shelves to form the supercontinent called Pangea.
What are the three observations of earthquakes?
First, earthquakes are not scattered throughout the oceans, but instead are confined to narrow, rather continuous bands. The narrow zones of earthquakes outline the boundaries of moving plates.
How deep do seismic waves travel?
Finally, seismic waves slow down as they travel through a zone about 100 to 400 miles (150 to 700 kilometers) deep, a sign that there is a relatively soft layer within Earth’s mantle. This last observation is the “Rosetta Stone” for plate tectonic theory. It provides a means by which continents can drift apart.
Why did geologists use seismographs?
Second, a network of seismographs was installed around the world in the early 1960s, to detect nuclear tests during the Cold War. As a result geologists could more precisely locate earthquakes and map the speed of seismic waves passing through various regions of the Earth.
How does the global ocean change?
Global or eustatic sea level can change as the result of changes in the number, size, and shape of ocean basins. Throughout Earth's history, the global ocean has been modified by plate tectonics. Often, large continents assembled from smaller ones produced more expansive oceans between them.
What are the oceans made of?
Plate Tectonics and Sea Level Change. Today, the Earth’s ocean is made up of the large Pacific, Atlantic, Indian, and Arctic Oceans. These bodies of water were not always in their current shape and configuration.
