✅3.1.5.2 - Plate Tectonics Flashcards
Describe the crust:
The thin layer of the outer shell that we live on, 5-10km thick beneath oceans and 70km thick beneath continents, lithosphere
Describe oceanic plates:
An occasionally broken layer of basaltic rocks known as sima - silicon and magnesium
Describe continental plates:
Bodies of mainly granite rocks, known as sial - silicon and aluminium
What is the lithosphere?
The crust and upper mantle, where tectonic plates are formed
How thick is the mantle?
2900km
What is the asthenosphere?
A layer of soft, plastic like rock that carries the lithosphere
How hot is the core?
5000 degrees C
What are intrusive rocks?
Rocks formed by the cooling of molten Magma, that crystallises and solidifies slowly below the surface. Forms coarse grained igneous rocks. Vertical dykes and inclined sills may form within.
What are extrusive rocks?
Lava that is in contact with the air or sea. It cools, crystallises and solidifies much quicker than Magma that is still underground. Fine grained rocks with small crystals.
What is gravitational sliding?
The movement of tectonic plates under the influence of gravity
What is ridge push?
Gravity acting on the weight of the lithosphere near the ridge pushes the older part of the plate in front.
What is slab pull?
The lithosphere sinks into the mantle under its own weight following subduction, helping to ‘pull’ the rest of the plate with it.
What events and landforms occur at Constructive boundaries?
Volcanoes
Mid ocean ridges
Rift valleys
What events and landforms occur at Destructive boundaries?
Powerful earthquakes
Volcanoes
Fold Mountains
Ocean trenches
What events and landforms occur at Collision boundaries?
Powerful earthquakes
Fold Mountains