Examples of regional metamorphic rocks include schist and gneiss. Thermal metamorphic rocks, also known as contact metamorphic rocks, are formed by extreme heat along with quite a bit of pressure. The pressure pushes the molten rock against the Earth's surface, causing it to recrystallize. Examples of thermal metamorphic rocks are marble and sandstone
J. Subbiondo © 2004The CrustThe outer layer of the Earth is called the crust. It is made up of rock that floated to the surface when the Earth was formed. It is not a continuous layer, but is made up of large masses called tectonic plates.These plates drift slowly across the Earth's surface (tectonic means moving).The movement of these plates creates mountains and valleys.At weak points in the crust, it causes volcanic eruptions. And when plates bump into each other, earthquakes occur -- emitting shock waves or vibrations called seismic waves. The crust is the Earth's coldest layer.
GCSE Geography Explain the process which leads to the development of one landform at a destructive plate boundary (6 marks). A destructive plate margin is an area where two plates are moving towards each other. The point where the two plates meet is called the subduction zone, where one plate is forced down under the other into the mantle. The subducted plate is cooler and denser than the surrounding mantle and gravity pulls it down. Along the coast of south America, the Nazca plate is moving towards the south American plate.
The crust is made up of two types, the oceanic crust and the continental crust. The oceanic is thinner as its thickness is around 5 – 10 km whereas the continental crust is around 35 to even 70km in mountain areas. The oceanic crust has a higher density than the continental as it is made up of basalt whereas the continental crust is made up of granite which is less dense compared to basalt rock. Due to this difference in densities in magma between the oceanic crust and the continental crust, the continents stay in their places, and both crusts are able to float on the magma. The continental crust floats much more freely on the magma.
Alfred could not explain how the huge masses of land could have moved so far. The major means for the lithospheric plates to float on the asthenosphere comes from the process of convection in the mantle of the Earth. Heat from the outer core rises in the mantle and “melts” the upper part, which is called the asthenosphere. The plates of the lithosphere move in three main ways. There are divergent boundaries where the plates are moving away from each other and new land is formed as magma is released from inside the mantle.
------------------------------------------------- Submarine earthquake From Wikipedia, the free encyclopedia Tectonic plate boundaries, showing the plate movement direction and magnitude of motion. Tectonic plate boundaries Convergent plate boundary trench formation and dynamics Convergent plate boundary: Mariana trench Plate Tectonics Transform plate boundary: San Andreas Fault Divergent plate boundary: Mid-Atlantic Ridge Divergent plate boundary: Mid-Atlantic Ridge A submarine, undersea, or underwater earthquake is an earthquakethat occurs underwater at the bottom of a body of water, especially anocean. They are the leading cause of tsunamis. The magnitude can be measured scientifically by the use of either the Richter scale or the Mercalli scale. [1] Understanding plate tectonics helps to explain the cause of submarine earthquakes.
These are boundaries where the plats move towards each other but 1 plate travels underneath (subduction). The less dense oceanic plate is the plate that subsides under the denser continental plate. The oceanic plate with melt as it falls to the asthenosphere creating a mantle plume where we expect to see a strombolian (cone) volcano. These volcanoes are typically tall cone shaped volcanoes. They are as such because they lava is andesitic/rhyolitic which means the lava contains 55%+ silica content.
Plate tectonics was first suggested as a theory by the geologist Alfred Wegener in 1915 when he proposed the concept of continental drift. Back in the geological past, what is now South America, Africa, Australasia and Antarctica fitted together into a supercontinent known as Gondwanaland; with North America, Europe and Asia fitting into another supercontinent known as Laurasia. (OCR AS/A2 Geology, Mugglestone et al, 2008). These were once believed to be joined to form one major central global landmass known as Pangaea (Introducing Geology, Graham Park). But now due to the global distribution of these major plates it has been proposed by Wegener and his successors that convection currents in the mantle are the cause of the movement of plates.
(USGS) There are two types of faults called dip-slip faults and strike-slip faults. Dip-slip faults occur when vertical displacement takes place and strike-slip faults happens when there is horizontal displacement. (Chapter 3&4 Powerpoint) Haiti is located in the western part of the island of Hispaniola and is situated between Puerto Rico and Cuba as seen in the picture to the right. (USGS) On January 12th 2010 at 4:53 p.m., an earthquake with a magnitude of 7.0 occurred 16 miles west of Port-au-Prince, Haiti’s capital. The earthquake was said to be felt in areas of Aruba, Cuba, Jamaica, Puerto Rico, Turks and Caicos, Venezuela, Bahamas, US Virgin
This is founded on dissimilarities in mechanical properties and in the procedure for the transfer of heat. Theoretically, the lithosphere is cooler and harder, while the Asthenosphere is hotter and flows more easily. The key principle of tectonic movement is that the lithosphere exists as separate and distinct tectonic plates, which ride on the fluid-like Asthenosphere. The geological position where two plates rendezvous is called a plate boundary. Plate boundaries are routinely affiliated with geological events such as earthquakes and are responsible for geological enrichment by conceiving topographic characteristics such as hills, volcanoes, mid-ocean ridges, and oceanic trenches.