Where Is the Island Arc in a Convergent Boundary

Example Objectives

Describe what a plate is you said it scientists can recognize its edges.
Explain how the plates act up by convection in the Mantle.
Describe the three types of plate boundaries and the features of apiece eccentric of boundary.
Describe how plate tectonics processes jumper cable to changes in Earth's surface features.

Mental lexicon

continental rifting
convergent plate boundary
divergent scale boundary
intraplate activity
island arc
plate
plate boundary
subduction
subduction zone
transmute fault
transform plate boundary

Foundation

The theory of plate tectonic theory explains nigh of the features of Land's surface. Scale architectonics helps us to understand where and why mountains form. Victimization the theory, we get it on where new ocean coldcock will be created and where IT leave be totaled. We know wherefore earthquakes and volcanic eruptions happen where they coiffe. We even privy search for mineralized resources using information well-nig past plate motions. Plate tectonics is the key that unlocks many of the mysteries of our surprising planet.

Earth's Tectonic Plates

The Cold War helped scientists to learn more about our planet. They put together up seismograph networks during the 1950s and early 1960s. The purpose was to determine if other nations were examination atomic bombs. Naturally, at the unvaried time, the seismographs were recording earthquakes.

Earthquake Locations

The scientists realized that the earthquakes were about ordinary in certain areas. In the oceans, they were found along middle-ocean ridges and deep sea trenches. Earthquakes and volcanoes were common all just about the Pacific. They named this region the Pacific Ring of Fire (Chassis below). Earthquakes are also commons in the world's highest mountains, the Himalaya Mountains of Asia. The Mediterranean Sea besides has many earthquakes.

The Ring of Provok that circles the Pacific Ocean is where the most earthquakes and volcanic eruptions take place.

Earthquakes and Home base Boundaries

Earthquakes are used to identify plate boundaries (Figure below). When earthquake locations are fictitious a represent, they outline the plates. The movements of the plates are called photographic plate tectonics.

A map of earthquake epicenters shows that earthquakes are found primarily in lines that run over up the edges of some continents, through the centers of some oceans, and in patches in some land areas.

The lithosphere is divided into a dozen major and several peanut plates. Each plate is named for the continent or ocean basin it contains. Some plates are made of wholly oceanic lithosphere. A fewer are all continental geosphere. But most plates are made of a combination of some.

Scientists have determined the direction that each crustal plate is moving (Build below). Plates move around the World's opencast at a rate of few centimeters a yr. This is about the same rate fingernails grow.

Globe's plates are shown in different colors. Arrows show the guidance the plateful is moving.

How Plates Move

Convection within the Earth's Mickey Mantle causes the plates to move. Mantle bodily is heated above the inwardness. The het up drapery rises up towards the grade-constructed (Figure below). Eastern Samoa the mantelpiece rises it cools. At the show u the substantial moves horizontally departed from a mid-ocean rooftree crest. The material continues to cool. IT sinks chicken out into the mantelpiece at a deep deep-sea trench. The bodily sinks back pour down to the essence. It moves horizontally again, complementary a convection cell.

Plates move for deuce reasons. Upwelling drapery at the mid-ocean ridge pushes plates outward. Low temperature lithosphere sinking into the mantle at a subduction zone pulls the rest of the plate blue with it.

Home base Boundaries

Plate boundaries are where deuce plates meet. Most earth science action takes place at plate boundaries. This activity includes volcanoes, earthquakes, and mountain edifice. The activity occurs as plates interact. How can plates interact? Plates can move away from each other. They sack move toward each other. Finally, they keister slide past each other.

These are the three types of plate boundaries:

Diverging plate boundaries: the two plates move away from each separate.
Convergent plate boundaries: the two plates move towards each other.
Transform plate boundaries: the two plates slip past tense each other.

The features that var. at a plate limit are determined by the direction of plate apparent motion and away the type of crust at the limit.

Divergent Home base Boundaries

Plates move apart at divergent plate boundaries. This put up take plac in the oceans operating room onto land.

Mid-ocean Ridges

Plates move apart at mid-ocean ridges. Lava rises upward, erupts, and cools. After, more lava erupts and pushes the original seafloor outward. This is seafloor spreading. Seafloor spreading forms new oceanic crust. The rising magma causes earthquakes. Most mid-ocean ridges are set deep beneath the sea. The island of Iceland sits right on the Mid-Atlantic ridge (Figure below).

The rift valley in Iceland that is part of the Mid-Atlantic Ridge is seen therein photo.

Geographic area Rifting

A branching home plate boundary can also occur within a chaste. This is named continent-wide rifting (Figure below). Magma rises beneath the continent. The impudence thins, breaks, and then splits apart. This first gear produces a rift valley. The Geographic region Rupture is a rift vale. Eastern Africa is splitting away from the African chaste. One of these days, American Samoa the continental crust breaks apart, oceanic crust will manikin. This is how the Atlantic Ocean formed when Pangaea broke up.

The Arabian, Indian, and African plates are rifting apart, forming the Great Rift Valley in Africa. The Dead Oversea fills the rift with seawater.

Convergent Home base Boundaries

A convergent home plate limit forms where two plates collide. That hit can happen between a celibate and unlimited crust, between two unlimited plates, surgery 'tween 2 continents. Oceanic crust is always destroyed in these collisions.

Sea-Continent Convergence

Oceanic crust may strike a continent. The oceanic plate is denser, so it undergoes subduction. This means that the oceanic plate sinks beneath the continent. This occurs at an ocean trench (Figure below). Subduction zones are where subduction takes place.

As you would expect, where plates collide there are lots of intense earthquakes and volcanic eruptions. The subducting oceanic plate melts as IT reenters the mantle. The magma rises and erupts. This creates a volcanic chain of mountain neighbouring the coast of the continent. This straddle is called a volcanic arc. The Andes Mountains, along the western edge of South America, are a mountain arc (Figure below).

Subduction of an Oceanic plate beneath a continental plate forms a line of volcanoes known as a continental arc and causes earthquakes.

A relief map of South America shows the trench Rebecca West of the continent. The Andes Mountains line the northwestern edge of South America.

Sea-Ocean Convergence

Two oceanic plates may collide. In this case, the experienced plate is denser. This plate subducts beneath the younger plate. As the subducting plate is pushed deeper into the mantle, it melts. The magma this creates rises and erupts. This forms a telephone line of volcanoes, known as an island spark (Figure below). Japanese Archipelago, Indonesia, the Philippine Islands, and the Aleut Islands of Alaska are examples of island arcs (Figure below).

A convergent shell boundary subduction geographical zone between two plates of oceanic lithosphere. Melting of the subducting plate causes volcanic bodily function and earthquakes.

The Aleutian Islands that border southern Alaska are an island bow. In that overwinter image from space, the volcanoes are mossy with snow.

Continent-Continent Convergence

Continental geosphere is low in density and very thick. Continental lithosphere cannot subduct. So when two continental plates collide, they just smash together, just like if you put your hands on two sides of a sheet of paper and bring your hands together. The material has nowhere to go but sprouted (Figure below)! Earthquakes and metamorphic rocks result from the tremendous forces of the collision. But the crust is as well thick for magma to bring fort direct, so there are no volcanoes.

When two plates of geographic area cheekiness collide, the material pushes upward, forming a high mountain range. The remnants of subducted oceanic crust persist below the continental convergence zone.

Mountain Building

Continent-continent convergence creates some of the macrocosm's largest mountains ranges. The Himalayas (Figure below)are the world's tallest mountains. They are forming as 2 continents jar. The Appalachian Mountains are the remnants of a larger mountain range. This range formed from continent-continent collisions in the fourth dimension of Pangaea.

The Karakoram Range is part of the Himalaya Mountains Mountains. K2, the second highest gobs the world, is over 28,000 feet. The number and meridian of mountains is impressive.

Transform Plate Boundaries

Two plates may slide past each other in opposite directions. This is called a transform scale boundary. These plate boundaries experience massive earthquakes. The world's world-class known transform mistake is the San Andreas Fault in California (Figure below). At this fault, the Pacific and North American plates bray ult each else. Transform plateful boundaries are most shared as offsets along mid-sea ridges.

Transform home boundaries are distinguishable from the other two types. At branching home plate boundaries, new oceanic crust is club-shaped. At convergent boundaries, old oceanic crust is destroyed. But at translate dental plate boundaries, crust is not created or destroyed.

The reddish line is the San Andreas Fault. On the far left is the Pacific Plateful, which is moving northeastern. On the right is the North American Plate, which is moving southwest. The cause of the plates is relative to apiece other.

Earth's Dynamical Opencast

Informed where plate boundaries are helps explain the locations of landforms and types of geologic activity. The activity can be current or used.

Active Plate Margins

Western North America has volcanoes and earthquakes. Mountains line the region. California, with its volcanoes and earthquakes, is an important part with of the Peaceable Ring of Fire. This is the boundary between the North American and Ocean Plates.

Resistless Plate Margins

Mountain ranges also line the eastern edge of Northwards US. Just there are no quick volcanoes operating theater earthquakes. Where did those mountains come from? These mountains formed at a convergent home boundary when Pangaea came together. About 200 million years ago these mountains were similar to the Himalayas today (Figure beneath)! There were also earthquakes.

The E. B. White Mountains in New Hampshire are part of the Appalachian province. The mountains are only around 6,000 feet high.

The Supercontinent Cycle

Scientists intend that Pangea was non the first supercontinent. There were others earlier it. The continents are now moving together. This is because of subduction around the Pacific Ocean. Eventually, the Pacific bequeath disappear and a new supercontinent will take form. This won't be for hundreds of millions of years. The creation and dissolution of a supercontinent takes place about all 500 million years.

Intraplate Activity

Most geological activity takes place at plate boundaries. But some activity does not. A good deal of this intraplate activity is institute at live spots. Hotspot volcanoes form equally plumes of hot magma upgrade from deep in the mantelpiece.

Hotspots in the Oceans

A range of volcanoes forms as an oceanic photographic plate moves over a hotspot. This is how it happens. A volcano forms over the hotspot. Since the plate is moving, the volcano moves off of the hot spot. When the hotspot erupts once more, a sunrise vent forms over it. This volcano is in line with the basic. Over meter, there is a draw of volcanoes. The youngest is directly above the hot spot. The oldest is the far away (Figure below).

This view of the Hawaiian islands shows the youngest islands in the southeast and the oldest in the northwest. Kilauea volcano, which makes up the southeastern side of the Big Island of Hawaii, is located above the Hawaiian hot spot.

The Hawaii-Emperor chain of mountains of volcanoes formed o'er the Hawaiian Hotspot. The Hawaiian Islands lancet-shaped last. Kilauea volcano is currently erupting. Information technology is over the hot spot. The Emperor Seamounts are so old they no longer pass on above sea stage. The oldest of the Emperor Seamounts is about to subduct into the Aleutian trench off of Last Frontier. Geologists use hotspot chains to tell the direction and the speed a plate is moving.

Yellowstone Lake lies at the center of a giant caldera. This fix in the terra firma was created by enormous eruptions at the Yellowstone hotspot. The hotspot lies beneath Yellowstone National Park.

Hotspots Beneath Continents

Hot spots are also found under the geographic region crust. Since information technology is more touchy for magma to make it through the thick crust, they are a great deal less communal. One exception is the Yellowstone hotspot (Figure above). This hotspot is rattling active. In the past, the hotspot produced enormous volcanic eruptions. Now its activity is best seen in the region's famous geysers.

Lesson Drumhead

Convection in the mantle drives the movement of the plates of lithosphere ended the Earth's surface. Modern body of water crust forms at the ridge and pushes the older seafloor away from the ridge horizontally.
Plates interact at three other types of plate boundaries: divergent, convergent and transform fault boundaries, where most of the Terra firma's geologic activity takes place.
These processes acting over long-wool periods of time are causative the geographic features we see.

Moral Review Questions

Call up

1. Name the three types of plate boundaries? Which has volcanoes? Which has earthquakes? Which has mountain building?

Apply Concepts

2. Describe convection. How does this work to create plate boundaries?

Think Critically

3. Make some generalizations about which types of plate boundaries have volcanoes and which have earthquakes. Could you look at a shell boundary and decide what geological activeness there would represent?

4. Wherefore is continental crust thicker than oceanic crust? Why is oceanic crust relatively thin?

Points to Consider

On the map in Public figure to a higher place, the arrows show the directions that the plates are going. The Atlantic has a mid-ocean ridge, where seafloor spreading is attractive spot. The Pacific Ocean has many deep oceangoing trenches, where subduction is taking lay. What is the future of the Atlantic plate? What is the future of the Pacific scale?
Using your hands and words, explicate to someone how plate plate tectonic theory works. Live trustworthy you describe how continents drift you bet seafloor spreading provides a mechanism for continental movement.
Now that you have intercourse about crustal plate plate tectonics, where do you think would make up a safe place to live if you wanted to avoid unstable eruptions and earthquakes?

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Where Is the Island Arc in a Convergent Boundary

Source: https://www.sites.google.com/site/earthscienceinmaine/theory-of-plate-tectonics