the is a very beautiful place for life.
the is a very beautiful place for life.
The earth's tectonic plates have fragmented and re-united in a process called a Wilson Cycle. In a million years, the earth's continental configuration will have become unrecognizable again.
Alfred Wegener first gave evidence that the continents may have once comprised a single landmass, which he christened Pangaea. His book was not popular until it was translated into English in the early 20th century. Before then, scientists believed the continents were immobile and that mountains formed not by tectonic upheaval but by contraction of a cooling crust analogous to the wrinkles forming on a dry apple. For a long time Wegener's thesis was dismissed because of his lack of an understanding of a mechanism for driving the continents apart. Evidence for continental mobility, such as the similarity or near identity of fossils found on continents now separated, the seeming continuity of geologic formations on separated continents, geodetic measurements, and the anomalous climate during certain periods on certain continents, indicating a shift of latitude, were explained away by geologists favouring the stability of the lithosphere. Only a few geologists, like Arthur Holmes, fought valiantly for continental drift. But in the 1950's as a result of naval exploration during and after the second world war, an interesting feature of the Atlantic sea floor screamed for an explanation. The magnetic stripes on either side of the mid-Atlantic ridge formed an alternating pattern that was identical on both sides. When it became possible to date these stripes, it became apparent that the stripes farther from the ridge were older than those closer to the ridge. Thus, the sea floor itself was being pushed outward over time, in turn driving the continents farther apart.
does the magma content elements in it?
subduction zone is the region where oceanic plate and continental plate collides, thus, oceanic crust being more dense will subduct under continental crust. Hence, resulting in a deep ocean trench.
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate and sinks into the mantle as the plates converge. Regions where this process occurs are known as subduction zones. Rates of subduction are typically centimetres per year, with the average rate of convergence being approximately two to eight centimetres per year. Plates include both oceanic crust and continental crust. Stable subduction zones involve the oceanic lithosphere of one plate sliding beneath the continental lithosphere or oceanic lithosphere of another plate due to the higher density of the oceanic lithosphere. That is, the subducted lithosphere is always oceanic while the over-riding lithosphere may or may not be oceanic. Subduction zones are sites that have a high rate of volcanism, earthquakes, and mountain building. Orogenesis, or mountain-building, occurs when large pieces of material on the subducting plate (such as island arcs) are pressed into the over-riding plate or when subhorizontal contraction occurs in the over-riding plate. These areas are subject to many earthquakes, which are caused by the interactions between the subducting slab and the mantle, the volcanoes, and (when applicable) the mountain-building related to island arc collisions.
we can say that the Pacific region is an area of high tectonic movement, which in some cases by deslizamineto plates constantly forms earthquakes, also affecting the population, but on the other hand know that these movements indicates that the earth is alive and you can build new structures and new ways in life.
Why does the subducted crust melt when an ocean trench is formed?
What happens when two oceanic plates converge?
here we know about plate tectonics and the movement of these plates.
The layer of the mantle above the asthenosphere plus the entire crust make up a region called the lithosphere. The lithosphere, and therefore, the earth's crust, is not a continuous shell, but is broken into a series of plates that independently "float" upon the asthenosphere, much like a raft on the ocean.
These plates are in constant motion, typically moving a few centimeters a year, and are driven by convection in the mantle. The scientific theory that describes this phenomenon is called plate tectonics.
According to the theory of plate tectonics, the lithosphere is comprised of some seven major plates and several smaller ones. Because these plates are in constant motion, interactions occur where plate boundaries meet.
A convergent (colliding) plate boundary occurs when two plates collide. If the convergent boundary involves two continental plates, the crust is compressed into high mountain ranges such as the Himalayas. If an oceanic plate and a continental plate collide, the oceanic crust (because it is more dense) is subducted under the continental crust. The region where subduction takes place is called a subduction zone and usually results in a deep ocean trench such as the "Mariana Trench" in the western Pacific ocean. The subducted crust melts and the resultant magma can rise to the surface and form a volcano.
A divergent plate boundary occurs when two plates move away from each other. Magma upwelling from the mantle region is forced through the resulting cracks, forming new crust. The mid-ocean ridge in the Atlantic ocean is a region where new crustal material continually forms as plates diverge. Volcanoes can also occur at divergent boundaries. The island of Iceland is an example of such an occurrence.
A third type of plate boundary is the transform boundary. This occurs when two plates slide past one another. This interaction can build up strain in the adjacent crustal regions, resulting in earthquakes when the strain is released. The San Andreas Fault in California is an example of a transform plate boundary.