Tectonics Flashcards
(26 cards)
What are the features of an Oceanic crust?
Very Dense
Thin
Basalt
What are the features of a Continental crust?
Less dense
Thick
Granite
From the Core what are the Earths Layers?
Inner core outer core Lower mantle Upper mantle Crust
What are convection currents?
Convection occurs when particles with a lot of heat energy in a liquid or gas move and take the place of particles with less heat energy. Heat energy is transferred from hot places to cooler places by convection.
How do convection currents drive tectonic plates?
Where convection currents diverge near the Earth’s crust, plates move apart. Where convection currents converge, plates move towards each other.
Where do volcanoes and earthquakes form?
They occur along the boundary where tectonic plates meet.
Name the types of plate boundaries
Divergent < >
Convergent > <
Conservative ^ ^
What are the features of a Divergent plate?
> Plates move away from each other > Can be continental / oceanic > Small shallow earthquakes > Large shield volcanoes > oceanic ridges or islands may form
Examples of islands and ridges made by Divergent boundaries
Iceland
Mid-Atlantic Ridge – Eurasian + N American move apart.
What are the features of Convergent boundaries?
> Plates move towards each other
Only continental plates
Large earthquakes
Huge fold mountains
Examples of fold mountains formed on Convergent- continental - continental boundaries
Rockies
Himalayas – Indian and Eurasian plates collide.
What are the features of a Convergent Oceanic - Continental
> Plates move towards each other
Oceanic continental plates involved
Large earthquakes as the plates collide.
Large composite volcanoes as and lava is forced up under extreme pressures causing explosive eruptions.
Deep sea Ocean trenches (where the oceanic plate is subducted), continental volcanic arcs (chains of volcanoes on land) and volcanic island arcs (chains of volcanoes forming islands in the sea)
Examples of Convergent oceanic - continental plates
Andes mountains (Peru Chile) – Nazca subdued under. S
What are the features of a Convergent oceanic- oceanic boundary?
> Two plates moving towards each other > Both oceanic plates > Large earthquakes as plates collide > Large composite volcanos > Deep sea ocean trenches > Volcanic Island arcs
Examples of Convergent oceanic - oceanic boundary
Pacific plate is subdued below the Philippine plate. S
What are the features of a Conservative boundary
> Plates moving side by side in same or opposite direction
Oceanic and continental plates can be involved
Large earthquakes
Often occurs along ocean ridged
Examples of Conservative boundary
San Andreas fault, California – N American + Pacific.
What are hot spots?
Hot spots are where hot mantle/ magma is rising towards the surface from the core, called a mantle plume.
Where do hot spots occur?
A hot spot develops above the mantle plume and is where the super heated magma will break through the surface in the centre of a plate forming a volcanic island.
How are chains of volcanic islands created?
Hot spots cannot move but the plate above does, this can create a chain of volcanic islands the oldest of which will be extinct as it as it is no longer sitting above the hot spot.
What factors effect an earthquake?
> Location of epicentre > Depth of the focus > Magnitude > Development > Population Density
How do we measure earthquakes?
The Richter scale
Mercalli Scale
What is the Richter scale measured?
The magnitude of an earthquake. It measures the amount of energy released by the shock waves using a piece of equipment called a seismograph.
How is the Mercalli scale measured?
The Mercalli scale measures the strength of an earthquake based on the amount of damage it causes.
