Task 2 - term 1 Flashcards
1
Q
Continental drift
A
- proposed by alfred wegner in 1912
- suggested that continents were once joined together as a supercontinent called “pangea”
- over millions of years, continents drifted apart to current position
2
Q
Seafloor spreading
A
- harry hess discovered seafloor spreading in 1965
- seafloor spreading occurs at divergent boundaries where new crust if formed when tectonic plates move away from each other
- magma rises through the cracks and then solidifies into oceanic ridges, pushing away older rock
3
Q
Fossils
A
- wegner proposed that organisms of the fossils found on different continents were unable to swim across oceans
- Pangea should have been connected when they were alive
4
Q
Whats a key observation about continental drift?
A
Africa and South America fit together.
5
Q
Volcanoes on convergent boundary
A
- formed when 2 tectonic plates move towards each other
- denser oceanic crust sinks beneath the thick continental crust
- oceanic crust sinks into the mantle melting it to create magma
- magma solidifies and forms into volcanic arc
6
Q
Volcanoes on divergent boundaries
A
- formed when 2 tectonic plates move away from each other
- magma rises to fill up space, solidifies and turns into a volcano
7
Q
Convergent boundary
A
- occur when two tectonic plates move towards each other
land,land: collision zone - mountain ranges
ocean,land: subduction - oceanic trenches, volcanic arcs
ocean,ocean: subduction - oceanic trenches, island arcs
8
Q
Divergent boundary
A
- occur when two tectonic plates move away from each other creating a rift
land-land: rift valley, inland seas, volcanoes
ocean-ocean: oceanic ridges
9
Q
Transform boundary
A
- occurs where two tectonic plates slide past each other in opposite directions
land-land, ocean-land, ocean-ocean: faults, fault lines, earthquakes
10
Q
Subduction zone
A
- occurs at convergent plate boundary
- involves either continental-oceanic or oceanic-oceanic crust
- denser crust is pushed downwards into mantle
- volcanic arcs, island arcs and oceanic trenches formed
11
Q
Collision zone
A
- occur at convergent plate boundary
- involve continental-continental crust
- both crust have similar density, push each other upwards
12
Q
Volcanic stages
A
- active: currently or recently erupting
- dormant: has not erupted recently; expected in future
- extinct: has not erupted in human history
13
Q
Earthquakes properties
A
- focus: point inside the earth where energy is first released
- epicentre: point on earth’s surface directly above the focus
14
Q
Hotspots
A
- cause volcanoes when extremely hot magma oushes through thinner parts of the crust
- under a hotspot is large active magma chamber
- plate moves, volcanoes move, allowing new volcano to form at the hotspot
15
Q
Type of volcanoes
A
oceanic-oceanic: underwater volcano
continental-oceanic: volcanic arc
continental-continental: volcano
