Hostile Worlds Flashcards
Mantle properties
Thickest layer Viscous Temp range from 5000°c (core) & 1300°c (crust) Liquid magma
Crust properties
Outer layer
Very thin
Thickness between 6 - 70km
Two types:
Oceanic
ContinentalOuter core properties
Semi solid & liquid
Largely iron
Magnetism spins around inner core
Contributes to 1/5 earth’s heat
Inner core properties
Solid
Made of iron
Temp can reach to 5500°c
Dense
What is plate tectonics?
Theory
Earth’s outer layer is made up of:
crustal plates,
which have moved throughout Earth’s history.
What is plate tectonics also known as?
Continental drift
Evidence that plates have always been moving:
Similar fossils-different continents
Rock pattern layers-different continents; joined/close together
Continents shape fit like jigsaw
Why do plates move ?
Convection cells created •when magma heated •from the core=rises •top=cools •creating circulation •moving the plates
Two types of plate- describe
Oceanic: heavy, v dense —thin
Continental: lighter, less dense —thick
What is a plate boundary ?
The point where:
•two or more plates meet
aka
•plate margin
or
•boundaryConstructive plate
Plates pulled apart •bc of convection currents in the mantle •gap created = magma rises to fill gap •magma cools = new oceanic crust •become new island or volcanoes
Example of oceanic plate:
Mid- Atlantic Ridge , Iceland
Destructive plate boundary ?
Oceanic + continental = collide •oceanic — sinks bc heavy & dense •it melts bc of heat from the mantle + pressure & friction •continental — not melt bc less dense •ascends form
As well as the destructive plate boundary causing volcanoes to form, what else does it cause to happen ?
Earthquake
Example of destructive plate boundary
Mt St Helens
