Yr9 Geology and Plate Tectonics Flashcards
What are the two types of tectonic plates
Oceanic Plates which are in the ocean and a much thinner (over 6km) but also denser.
Continental Plates - Which are far thicker (30 - 60km) but not as dense
What causes earthquakes
Earthquakes occur across plate boundaries called fault lines. When 2 tectonic plates slide along each other, rock can be bent without breaking which creates a lot of pressure. The release of that pressure (when the rock snaps) is an earthquake.
What are the three types of plate boundaries?
Divergent boundaries where plates move away from each other and magma erupts to create new crust. These boundaries can result in ridges and volcanoes
Convergent boundaries where plates move towards each other and crust is destroyed or driven downward. These boundaries can result in ocean trenches and mountains
Transform or Translational boundaries where crust is neither created nor destroyed and the plates are sliding sideway in relation to each other. These faults often cause earthquakes.
What is Folding
Folding is the process of rock bending and crumpling without breaking and it is caused by the huge forces generated beneath the earth
What are synclines and anticlines?
A fold that bends upwards is called an anticline whereas a fold that bends downwards is called a syncline
P waves vs S waves vs L Waves
Pressure waves are longitudinal, fast and travel through the earth. Shear waves are transverse and travel through the earth but only through solids. Since they travel through the earth they are called body waves. Love waves only go on the surface of earth and cause the most damage though they are the slowest wave
How do volcanoes form
Volcanoes form at divergent plate boundaries. Here the plates move away from each other causing magma to erupt in a vent or fissure
3 Types of Cone Volcanoes
Shield Cones - Are low domes made from very fluid lava. They are unlikely to erupt though gases can escape easily
Cinder Cones - Steeper pointed shape. Made mostly of rock, ash and cinders formed after an eruption (pyroclastic materials)
Composite Cones - Most common volcano. Steep slopes made from lava and pyroclastic material
Continental Drift
The movement of continents due to convection currents in the mantle
Which part of the earth’s crust is solid and made mostly of iron?
inner Core
How do tsunami waves get higher?
Tsunami waves get higher because the top of the wave travels faster than the bottom when the bottom hits the shore.
