Geography tectonics

• crust is the outer layer of the earth. it is made up of the continental and oceanic plates. it is the thinnest layer
• mantle is made up of semi molten rock called magma temperatures can reach up to 3500 degrees celcius
• outer core is a liquid layer made up of iron and nickel
• inner core is the center and the hottest part of the earth. it can reach over 6000 degrees celcius and is a solid
• tectonic plate is a segment of the earths crust which floats on the mantle
• why plates move- convection currents: the heat from the core causes convection currents to rise and at the mantle the currents separate at the ride. the currents cool and become heavier causing subduction at the trench. convection currents are reheated and the process begins again
• oceanic is younger, denser and can be created and destroyed
• continental is older, cannot be destroyed and less dense
• constructive plate ridge/ volcano: convection currents cause 2 oceanic plates to move apart forming a gap. magma oozes up from the mantle and the lava cools and rises land from either side forming a ridge or a volcano
• deconstructive plate oceanic trench: convection currents cause heavier oceanic place to submerge beneath the lighter continental plate. this is known as subduction. as the oceanic plate is subducted it pulls down the leading edge of the continental plate forming an oceanic trench
• an example of a constructive plate boundary is Mid Atlantic Ridge
• deconstructive plate volcano: the subducted oceanic plate will melt in the mantle creating new lighter magma. the magma will rise and pierce through the lines of weakness of the continental plate forming a volcano
• example of deconstructive plate boundary is Marinas trench, Japan
• collision plate fold mountains: convection currents cause 2 continental plates move towards each other. since neither of the plates can be destroyed erosion occurs. this crumbles rock on either side of the place and the eroded material and marine sediment is uplifted forming a fold mountains
• example of collision plate boundary is the Himalayan Mountains
• conservative plate earthquake: convection currents cause 2 plate to slide past each other. this movement is not smooth. this creates friction and tension which eventually will be released in a jolt creating an earthquake
• example of conservative plate boundary is St Andreas fault, California
• 2 igneous rocks are basalt and granite
• 2 sedimentary rocks are sandstone and limestone
• 2 metamorphic rocks are marble and slate
• 3 rock types are igneous, sedimentary and metamorphic
• formation of basalt: when lava cools on the surface and it cools quite quickly producing less crystals within the structure
• formation of granite: when magma cools slowly underground and forms large crystals and a speckled igneous rock
• formation of sedimentary rocks: small particles of rock or dead animal and plant are deposited under a river or sea. over time layers of rock fragments will accumulate on top of one another. this cause the layers to become cement and compact squeezing out all the moisture of the layers creating a solid rock
• formation of metamorphic rocks: formed under intense heat and pressure creating the rock to change
• global distribution of volcanoes/ earthquakes: occur along long narrow linear belts - encircling the pacific ocean known as the pacific 'ring of fire' and along the coast of the Mediterrean sea and through south Asia and through the Atlantic and Indian ocean
• earthquakes are a series of shocks due to the sudden movement in the earths crust
• focus is the point where an earthquake occurs this is the origin of the seismic activity
• epicenter is the point above the focus where seismic waves are first felt
• a seismograph records shock waves
• magnitude is measured by a seismography by using a richer scale
• liquefaction is when an earthquake shakes wet soil. when water rises on the surface the soild soil turns into liquid mud any buildings resting on it will sink in the mud and collapse
• a tsunami are large waves formed by an underwater earthquake
• volcano is a cone shaped mountain formed by eruptions of magma inside the earth
• supervolcano are eruption which can release 1000 times the amount of a normal volcano and will have global consequences