There is a convergent boundary on the west side of the United States. At a convergent boundary, two plates collide, and the denser plate is subducted. Volcanoes and earthquakes are common as a result of pressure and friction. There is also a transform boundary forming the San Andreas Fault which is between an oceanic plate subducting under a continental plate. 3.
8. How does hornfels form? Rock contacts with magma and bakes rock. 9. Know that the type of metamorphic rock relates to how much heat and pressure the rock was exposed to.
What do earthquake swarms indicate? (page 94, para 2 to page 95) Earthquake swarms indicate that new fractures were forming. Swarms can be used as an early indication that magma from a storage zone is being injected into the rifts were these new fractures are happening. 3. What is "summit deflation"?
Due to high temperatures in the mantle of around 3000 degrees centigrade, this oceanic crusts melts and then rises due to the convection currents in the aesthenosphere . As it joins with trapped seawater and sediment, it melts the overlying continental crust, and the magma plumes rise to the surface. They contain more silica so are more viscous, which plugs up the volcano, meaning pressure build up. This is why these volcanoes are so explosive. Another type of plate boundary are constructive, which is the margin between two diverging plates where new magma
Evidence of sea floor spreading can be found in the Atlantic, where it is believed that the North American and Eurasian plates are moving apart at a constructive plate margin. New land has been created due to the magma rising through a rift and cooling quickly on the surface, also creating a ridge of volcanoes called the Mid-Atlantic ridge. The
These include.... * The eruption had left destruction in its wake, it created a ‘Pyroclastic Flow’ or ‘Nuée ardente’ (Glowing Cloud). This is a cloud of volcanic debris, made up of solid, semi solid and hot, expanding gases. The cloud behaves like a liquid, flowing down the slope of the volcano. It can reach up to and above 100Km/h and so destroys everything in its path. The pyroclastic flow from Mt.
'The extent to which volcanic processes represent hazards depends on where and when they occur.' Discuss this statement. Volcanic processes become a hazard when they impact upon the human and built environments, killing and injuring people, burying and collapsing buildings, destroying infrastructure and bringing agricultural activities to a halt. Volcanic hazards are influenced by several factors including location, time and frequency of eruptions, and the materials ejected. It is the viscosity of magma that largely determines the nature and power of an eruption and the resultant severity of the hazard.
After subsidence a depression with steep fault scarp sides i.e. a rift valley is formed. It is trapped in position by later pressure. Theory 2: Compressional forces a) Layers of rocks are subjected to compression forces. b) Faults develop and the outer blocks move upwards.
He suggested that at the centre of oceans, molten material would rise from the Earth’s mantle, causing new sea floor to be created, pushing the ocean floor. He also suggested that there were ocean trenches where old sea floor would then go back into the mantle, and molten. He found that these ocean trenches, the deepest parts of the ocean, were very near continental plates. Hess theorized that the action of the sea floor spreading caused continents to move apart and so this being evidence for continental drift, showing why it happened. The evidence of sea floor spreading was further supported by Vine and Drummond, who studied the magnetic pattern of the sea floor.
This type of volcano can be recognized by its broad, gentle slopping shape. The lava dome that composes a shield volcano is usually built over a period of time. When this type of volcano erupts it often involves a flow after flow of lava. An example of shield volcano is Mauna Kea, which along with Mauna Loa forms the large island of Hawaii. The largest shield volcano in the solar system is Olympus Mons, on the planet mars.