b1 - features associated with plate tectonics
What is Plate Tectonics?
The processes and landforms associated with movements within the lithosphere and asthenosphere.
In basic terms, the earth's crust (lithosphere) is broken up into tectonic plates which float on a liquid mantle beneath and move due to convection currents producing features such as volcanoes, earthquakes, rift valleys and ocean trenches at plate boundaries.
There are 4 main types of plate boundary including: convergent, divergent, subduction and transform - the type of boundary influences the features and events which occur.
These pages are a good introduction:
http://www.bbc.co.uk/schools/gcsebitesize/geography/natural_hazards/tectonic_plates_rev1.shtml
For a more academic background to the theories read through these USGS pages:
http://pubs.usgs.gov/gip/dynamic/dynamic.html
This video explains the main processes
The processes and landforms associated with movements within the lithosphere and asthenosphere.
In basic terms, the earth's crust (lithosphere) is broken up into tectonic plates which float on a liquid mantle beneath and move due to convection currents producing features such as volcanoes, earthquakes, rift valleys and ocean trenches at plate boundaries.
There are 4 main types of plate boundary including: convergent, divergent, subduction and transform - the type of boundary influences the features and events which occur.
These pages are a good introduction:
http://www.bbc.co.uk/schools/gcsebitesize/geography/natural_hazards/tectonic_plates_rev1.shtml
For a more academic background to the theories read through these USGS pages:
http://pubs.usgs.gov/gip/dynamic/dynamic.html
This video explains the main processes
Earth Structure
The earth has distinct layers including:
For a more detailed description of each layer, read through these pages:
http://geomaps.wr.usgs.gov/parks/pltec/
- Centrosphere = the central or inner part of the earth
- Mesosphere = also known as the mantle, it lies just below the earth's crust
- Asthenosphere = the ductile part of the earth just below the lithosphere, including the upper mantle
- Lithosphere = the outer solid part of the earth, including the crust and uppermost mantle
For a more detailed description of each layer, read through these pages:
http://geomaps.wr.usgs.gov/parks/pltec/
Geology
All rocks are produced via the continuous processes of volcanism, erosion and deposition
Igneous = rocks such as Granite (below the surface) and Basalt (on the surface) formed from cooled magma
Sedimentary = rocks formed by the deposition of layers of eroded 'sediments' under various conditions eg. Limestone, Sandstone and Shale
Metamorphic = sedimentary or igneous rocks altered under intense heat or pressure eg. Marble and Slate
Read through these pages for more detailed information:
http://www.edu.pe.ca/southernkings/rockcycle.htm
Igneous = rocks such as Granite (below the surface) and Basalt (on the surface) formed from cooled magma
Sedimentary = rocks formed by the deposition of layers of eroded 'sediments' under various conditions eg. Limestone, Sandstone and Shale
Metamorphic = sedimentary or igneous rocks altered under intense heat or pressure eg. Marble and Slate
Read through these pages for more detailed information:
http://www.edu.pe.ca/southernkings/rockcycle.htm
Plates and plate boundaries
The earth's crust is divided into tectonic plates, there are two main types of plate - continental and oceanic
Continental plates are between 20-80 km thick and relatively less dense
Oceanic plates are thinner, around 10 km thick and relatively dense
Plate Boundaries
For more detailed explanation check out this USGS page
http://pubs.usgs.gov/gip/dynamic/understanding.html
Convergent = two plates move towards each other, continental vs continental plates produce Fold Mountains eg. the Himalayas. Where oceanic vs continental plates, Subduction Zones are formed (see below)
Subduction = oceanic vs continental plates move towards each other, due to the difference in density, the more dense oceanic plate sinks and is forced beneath the less dense continental plate, this produces extra magma where the oceanic plate melts causing volcanoes to form eg. Cascade Volcanic Arc, North America
Divergent = two plates move away from each other, continental vs continental plates produce Rift Valleys eg. East African Rift Valley. Where oceanic vs oceanic plates Oceanic Ridges form eg. Mid-Atlantic Ridge. Volcanoes commonly form where faults allow magma to rise to the surface.
Transform = two plates slide past one another, typically with a stick-slip motion - this produces seismic activity and earthquakes
Continental plates are between 20-80 km thick and relatively less dense
Oceanic plates are thinner, around 10 km thick and relatively dense
Plate Boundaries
For more detailed explanation check out this USGS page
http://pubs.usgs.gov/gip/dynamic/understanding.html
Convergent = two plates move towards each other, continental vs continental plates produce Fold Mountains eg. the Himalayas. Where oceanic vs continental plates, Subduction Zones are formed (see below)
Subduction = oceanic vs continental plates move towards each other, due to the difference in density, the more dense oceanic plate sinks and is forced beneath the less dense continental plate, this produces extra magma where the oceanic plate melts causing volcanoes to form eg. Cascade Volcanic Arc, North America
Divergent = two plates move away from each other, continental vs continental plates produce Rift Valleys eg. East African Rift Valley. Where oceanic vs oceanic plates Oceanic Ridges form eg. Mid-Atlantic Ridge. Volcanoes commonly form where faults allow magma to rise to the surface.
Transform = two plates slide past one another, typically with a stick-slip motion - this produces seismic activity and earthquakes
To see how this has shaped our oceans and continents, watch this animation which shows how plates are continually reshaped, produced and destroyed
hot Spots
In addition to plate boundaries, tectonic activity can occur over 'hot spots'. These are super heated areas of magma within the mantle which cause magma to break through the crust eg. Hawaiian Islands in the middle of the Pacific plate.
For more information and examples explore these pages:
http://pubs.usgs.gov/gip/dynamic/hotspots.html#anchor19620979
http://hvo.wr.usgs.gov/volcanoes/
For more information and examples explore these pages:
http://pubs.usgs.gov/gip/dynamic/hotspots.html#anchor19620979
http://hvo.wr.usgs.gov/volcanoes/
Volcanoes
There are 3 main types of volcano:
This is a detailed introduction
http://pubs.usgs.gov/gip/volc/types.html
Shield = found at constructive, divergent margins, produced by flows of fluid lava which forms gently sloping, low profile cones
For more details read through these pages:
http://vulcan.wr.usgs.gov/Glossary/ShieldVolcano/description_shield_volcano.html
Composite = found at destructive, convergent margins, produced by layers of viscous lava and ash which form steep sloped, tall cones
For more detail and examples explore these pages:
http://vulcan.wr.usgs.gov/Glossary/StratoVolcano/description_composite_volcano.html
Cinder = found close to subduction zones, these are simply produced by layer upon layer of cooled 'blobs' or lava to form a circular or oval cone
http://vulcan.wr.usgs.gov/Glossary/CinderCone/description_cinder_cone.html
This is a detailed introduction
http://pubs.usgs.gov/gip/volc/types.html
Shield = found at constructive, divergent margins, produced by flows of fluid lava which forms gently sloping, low profile cones
For more details read through these pages:
http://vulcan.wr.usgs.gov/Glossary/ShieldVolcano/description_shield_volcano.html
Composite = found at destructive, convergent margins, produced by layers of viscous lava and ash which form steep sloped, tall cones
For more detail and examples explore these pages:
http://vulcan.wr.usgs.gov/Glossary/StratoVolcano/description_composite_volcano.html
Cinder = found close to subduction zones, these are simply produced by layer upon layer of cooled 'blobs' or lava to form a circular or oval cone
http://vulcan.wr.usgs.gov/Glossary/CinderCone/description_cinder_cone.html
tectonic features and processes
Folding and faulting occur due to plate movements and produce a variety of features depending upon the type of movement
This page is brilliant, so I won't even attempt to explain...
http://www.physicalgeography.net/fundamentals/10l.html
This page is brilliant, so I won't even attempt to explain...
http://www.physicalgeography.net/fundamentals/10l.html
Earthquakes
Earthquakes can occur wherever there is plate movement, associated with any type of plate boundary. They can also be caused by compression and rebound of the crust associated with melting glaciers and dam construction.
The associated hazards will be discussed in the next section, but explore these pages to get a general overview of the processes and terminology.
http://geography-site.co.uk/pages/physical/earth/cause.html
This is a great video explaining the processes involved in earthquakes
The associated hazards will be discussed in the next section, but explore these pages to get a general overview of the processes and terminology.
http://geography-site.co.uk/pages/physical/earth/cause.html
This is a great video explaining the processes involved in earthquakes