Geology

• Metamorphic rocks are formed from the transformation of existing rocks through heat and pressure.
• a extrusive rock is formed when lava quickly cools above the earth's crust
• Intrusive rocks are formed by magma that cools and solidifies beneath the Earth's surface.
• lava is molten rock ABOVE the crust
• Magma is molten rock that is UNDER the earth's crust
• Subduction is when one tectonic plate is forced under another because of their difference in density
• transform plate boundary - two plates move past each other horizontally in different directions
• divergent plate boundary - when two plates move away from each other
• Convergent plate boundary - when two plates move towards eachother
• Mountain ranges are formed when tectonic plates collide. each plate has a similar density, forcing the earth up instead of subducting
• The epicentre of an earthquake is the point on the earth's surface directly above the focus
• The focus of an earthquake: The point beneath the earth's surface where the earthquake originated
• A fault is is a fracture between two rocks that allows movement between the rocks to occur. Earthquakes often start on fault lines.
• Tsunamis are caused by earthquakes that occur under the ocean floor. Tectonic plates converge and the difference in plate elevation displaces water, sending rippling effects from the epicentre
• Volcanic/Island arcs are large chains of volcanoes formed by plate subduction. The subducted plate melts when entering the mantle, creating magma. The magma rises to the surface and forms volcanoes along the plate boundary
• Ocean trenches are formed when subduction causes the lithosphere to bend creating a V-shaped depression in the crust
• P waves are longitudinal waves that travel fast through the earth. They can travel in solids, liquids and gases.
• S waves are transverse waves that can travel through the earth. They can travel through solids only.
• surface waves are the slowest moving wave, only able to travel on the earth's surface
• A hotspot is a place in the mantle where magma is hotter. The heat melts the crust above, creating weak spots where magma plumes can rise and create volcanoes.
• The lithosphere is the rigid outer layer of the Earth, consisting of the crust and the upper part of the mantle
• The asthenosphere is the semi-solid layer of mantle below the lithosphere that facilitates tectonic plate movement