Contents1 What boundary [] The Cocos Plate in the Pacific Ocean is subducted beneath the Caribbean Plate, just off the western coast of Central America. South America plate, Pacific plate, Antarctic plate, Cocos plate. Unclick all the other layers you've been using, and then click next to . South America plate, Antarctic plate, Eurasia plate, North America plate, Arabia plate, India plate, Australia plate. A series of explosions and ash clouds from the peak between 1914 and 1921 represents the last large volcanic eruption within the lower 48 states prior to Washingtons Mt. Near their boundary, the plates can lock together for centuries, then suddenly let go as a giant earthquake. 20 Million Years Ago Sediment that has accumulated on the continental slope is thrust up into an accretionary wedge, and compression leads to thrusting within the continental plate (Figure \(\PageIndex{7}\)). Pangea began to rift apart along a line between Africa and Asia and between North America and South America at around 200 Ma. The ocean area along southern Asia up to the India plate is also a part of the Australia plate. It runs along the north western coast of the United States and the southern British Columbia coast. By 50 Ma, Australia had separated from Antarctic, and shortly after that, India collided with Asia. Their high-silica magmas produce not only andesite and rhyolite lava flows, but also lots of other volcanic materials such as ash and pumice. And, as at Mt. Half Dome in Yosemite National Park is made of granite that solidified from magma tens of millions of years ago, when a subduction zone extended along the entire west coast. More recent studies of continental matchups and the magnetic ages of ocean-floor rocks have enabled us to reconstruct the history of the break-up of Pangea. North America plate, Africa plate, Australia plate, Arabia plate, India plate, Filipino plate. USGS photo. The Cocos plate was created about 23 million years ago when a larger plate broke into two pieces. Solids and gases are also part of the mix. This beauty is part of the reason that residents and visitors have learned to tolerate, and develop ways to mitigate, the effects of earthquakes, tsunamis and volcanic eruptionsbeasts that are consequences of the same tectonic forces that create the regions beauty. Some parks in the Sierra Nevada Mountains reveal igneous magma chamber rocks that represent the eroded remnants of an ancient subduction zone, when volcanoes similar to those found in the modern Cascade Mountains extended southward all the way through California. Kenai Fjords National Park A map of the ocean floor reveals a deep underwater trench (dark blue line) running along the southern coast of Mexico, defining the boundary between two tectonic plates. Many rift valleys are part of " triple junctions," a type of divergent boundary where three tectonic plates meet at about 120 angles. Photo courtesy of Robert J. Lillie. Plate Tectonics and Our National ParksSite Index, Plate TectonicsThe Unifying Theory of Geology, Tectonic Settings of NPS SitesMaster List, ORCAOregon Caves National Monument, Oregon [, SEKIKings Canyon National Park, California[, YOSEYosemite National Park, California[. When a series of mantle plumes exists beneath a large continent, the resulting rifts may align and lead to the formation of a rift valley (such as the present-day Great Rift Valley in eastern Africa). and Alberta are also a result of continent-continent collisions. Final answer. In 1912 the Katmai region erupted an estimated 7 cubic miles (30 cubic kilometers) of ash and pyroclastic material, roughly 50 times the amount that came out of Washingtons Mt. Transform boundaries where plates slide passed each other. The water rises and melts rock in its path. Introduction The Cocos Plate is a relatively small sized, triangular-shaped oceanic plate located just west of Mexico and the Caribbean. As the mid-ocean ridge separating the Farallon and Pacific Plates entered the subduction zone, the Farallon Plate separated into the Juan de Fuca and Cocos Plates. A continent-continent collision occurs when a continent or large island that has been moved along with subducting oceanic crust collides with another continent (Figure \(\PageIndex{8}\)). (Note that spreading rates are typically double the velocities of the two plates moving away from a ridge.). Lake Clark National Park and Preserve contains an active composite volcano with a profile and recent history reminiscent of Mt. Between 200 and 150 Ma, rifting started between South America and Africa and between North America and Europe, and India moved north toward Asia. Is the Nazca plate convergent or divergent? Three others, Aniakchak National Monument, Katmai National Park, and Lake Clark National Park, are farther inland, along the active volcanic arc. Often it is the older and colder plate that is denser and subducts beneath the younger and hotter plate. For example the Juan de Fuca Plate is actually three separate plates (Gorda, Juan de Fuca, and Explorer) that all move in the same general direction but at slightly different rates. The most famous example of a transform boundary is the San Andreas Fault in California. The rising water melts rock in its path, forming a volcanic arc on the overrriding plate. At an ocean-ocean convergent boundary, one of the plates (oceanic crust and lithospheric mantle) is pushed, or subducted, under the other. This is what has happened in the Sierra Nevada of central and southern California, as represented by the granite-type rocks of Half Dome within Yosemite National Park shown on the California state quarter. Similarly the South American Plate extends across the western part of the southern Atlantic Ocean, while the European and African plates each include part of the eastern Atlantic Ocean. Right image Along these boundaries, earthquakes are common and magma (molten rock) rises from the Earths mantle to the surface, solidifying to create new oceanic crust. A sudden unlocking could produce an earthquake every bit as big as the one that occurred in Alaska in 1964, when a similar subduction zone boundary snap occurred. As they were caught in the vise between the converging Juan de Fuca and North American plates, some of the layers were so contorted that they are now in vertical orientations along the coast. Redoubt, an active volcano in Lake Clark National Park, illustrates how a volcano can pose an unexpected hazard in our modern age and why monitoring volcanic activity is so important (see photo below). The southern boundary is a mid-oceanic ridge, the Galapagos Rise. Off the Pacific coast, the Cocos plate is subducted beneath both the North American and Caribbean plates, which are separated by a sinistral transcurrent boundary. That the Atlantic Ocean rift may have occurred in approximately the same place during two separate events several hundred million years apart is probably no coincidence. Now you should see color coded lines that are the plate boundaries, and the names of Earth's major plates. Credit: Photo Courtesy of Robert J. Lillie. Rainier in Washington, Mt. Spreading rates vary considerably, from 2 cm/y to 6 cm/y in the Atlantic, to between 12 cm/y and 20 cm/y in the Pacific. Rather, it flowed underground to a vent 6 miles (10 kilometers) away! Find the boundary between the North American and Cocos plates. Novarupta Lava Dome 40 Million Years Ago The Cocos Ridge (CR), which formed when the Cocos Plate drifted over the Galapagos Hotspot (Walther, 2003) , is a bathymetric high reaching about 2 km above the surrounding seafloor and stretching about 2000 km long and 200-300 km wide across the Cocos Plate . The Pacific Plate is almost entirely oceanic, but it does include the part of California west of the San Andreas Fault. Igneous, sedimentary, and metamorphic rocks are all found in abundance. There is commonly an ocean trench along the boundary. Near the western edge of the continent, the Juan de Fuca Plate plunges downward and some of the layers of hard crust and ocean sediments are scraped off the top and squeezed upward as the Olympic Mountains and other coastal ranges. New Guinea and the northern parts of New Zealand are part of the Australia plate. Examples of ocean-ocean convergent zones are subduction of the Pacific Plate beneath the North America Plate south of Alaska (Aleutian Islands) and beneath the Philippine Plate west of the Philippines, subduction of the India Plate beneath the Eurasian Plate south of Indonesia, and subduction of the Atlantic Plate beneath the Caribbean Plate (see Figure \(\PageIndex{1}\)). The magma, which is lighter than the surrounding mantle material, rises through the mantle and the overlying oceanic crust to the ocean floor where it creates a chain of volcanic islands known as an island arc. Subduction zones occur when one or both of the tectonic plates are composed of oceanic crust. Explain why the Nootka Fault is a transform fault, and show the relative sense of motion along the fault with two small arrows. Elias National Park Effects of the 1964 earthquake are quite spectacular in the park; the coastline dropped so much that in places it lies submerged beneath about 8 feet (2.5meters) of water. Over time, the San Andreas boundary has grown longer as the Farallon Plate split into two separate platesthe Juan de Fuca Plate on the north, and the Cocos Plate on the south. This plate moves north and slightly west towards the Caribbean plate and the North America plate. Photo courtesy of Robert J. Lillie. It formed millions of years ago when the Farallon Plate split into the Cocos Plate and the Nazca Plate.. CC BY. The northern boundary of the Cocos Plate is the Middle America Trench. The Coast Range (accretionary wedge), Great Valley (forearc basin), and Sierra Nevada (volcanic arc) still reflect the subduction zone topography. The North American plate is moving to the west-southwest at about 2.3 cm (~1 inch) per year driven by the spreading center that created the Atlantic Ocean, the Mid Atlantic Ridge. Mazama, Aniakchak no longer holds a large lake because the caldera wall is breached. When rifting of Pangea started at approximately 200 Ma, the fissuring was along a different line from the line of the earlier collision. St. Helens in 1980. The Pacific plate is subducting beneath the Philippine Sea plate to the east while the west/northwestern part of the Philippine Sea plate is subducting beneath the continental Eurasian plate. . Download the official NPS app before your next visit, Accretionary WedgeCoast Ranges [3 parks], Accretionary WedgeSouthern Alaska [1park]. Subduction zones form where a plate with thinner (less-buoyant) oceanic crust descends beneath a plate with thicker (more-buoyant) continental crust. Likewise, individual volcanic eruptions may add only a thin layer to the surface. Finally, using a highlighter or colored pencil, label as many of the boundaries as you can as divergent, convergent, or transform. What plate boundary shows the collision of two plates? On Dec. 15, 1989 a jet with 244 passengers and crew was en route from Amsterdam to Anchorage. What type of plate boundary is the Cocos Plate? Some transform faults connect continental parts of plates. . Rainier in Mt. The initial magma formed as mantle rock melts beneath a subduction zone has low silica (basalt) composition. The subducted lithosphere descends into the hot mantle at a relatively shallow angle close to the subduction zone, but at steeper angles farther down (up to about 45). Garibaldi to Lassen Peak, coincides with the north-to-south extent of the subducting plate boundary. This plate is moving north east towards the Arabia and Eurasia plates. We think that the Explorer Plate is also moving east, but we dont know the rate, and there is evidence that it is slower than the JDF Plate. A small piece of California, including . This plate includes all of North America, Greenland, the eastern most part of Russia, northern Japan, and the northwestern part of the Atlantic ocean. Mount Rainier is a 14,000 foot (4,300 meter) volcano in the Cascade Range developed above the place where the subducting Juan de Fuca Plate reaches sufficient depth to release hot fluids into the overriding North American Plate. Western Mexico, where the young and small Rivera Plate and the adjacent large Cocos Plate are subducting beneath the North American Plate, is a unique Some of the resulting magma makes it all the way to the surface and forms Mount Rainier, Mount Hood, Mount Shasta and other spectacular volcanoes of the Cascade Range. What type of boundary is the Philippine plate? Copalis River, Washington Left image Mazama, Aniakchak spewed lava across its caldera floor for centuries after its collapse. The same forces that shift the land so dramatically also gradually build spectacular landscapes like the coastlines of the Pacific Northwest.
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