3.1 Plate Tectonics Flashcards
What is sedimentary rock?
Rocks that are characterised by their layers. Formed under oceans and lakes. e.g. limestone.
What is metamorphic rock?
Rocks that are formed under extreme heat/pressure. e.g. slate.
What is igneous rock?
Rocks that form when magma cools and hardens. e.g. granite.
What is the core?
The centre of the earth’s structure, with a solid inner and liquid outer.
What is the mantle?
The large layer of the earth. The closer to the core then the more liquid the rock.
What is the crust?
Top layer of earth and the thinnest layer too. It is broken into pieces called plates.
What is the lithosphere?
Another term to describe the upper layer of the earth - the crust and the solid part of the upper mantle.
What is the asthenosphere?
This is the area below the lithosphere - still the upper mantle. The rock here has plastic-like features.
What is SiMa?
Another term for oceanic crust, containing large amounts of Silica and MAgnesium.
What is SiAl?
Another term for continentAL crust. Contains large amounts of Silica and ALuminium.
What is a tectonic plate?
A piece of lithosphere or crust. It is a large slab of rock and moves at slow speeds due to convection currents in the mantle.
What is rheid?
Material in the asthenosphere that, although appearing solid, can behave like a plastic over hundreds of thousands of years.
What is the moho?
The boundary between the crust and the mantle.
What is ridge push?
Intrusion of magma into the spreading ocean ridges propels plates apart.
What is convection drag?
Convection currents on the plastic mantle drag the lithosphere. The heat source is below the oceanic ridges and comes from radioactive decay in the mantle. Involves subduction zones.
What is slab pull?
Cold, dense oceanic lithosphere sinks into subduction zones due to gravity, dragging the rest of the plate with it.
What is continental crust?
Forms the earth’s continents. Made of granite rocks and rich in SiAl.
What are continental shelves and slopes?
Part of the continental crust that forms the earth’s continents, but continues beyond its edges below the sea.
What is oceanic crust?
Much thinner crust, formed of basalt rocks known as SiMa.
What is a convergent boundary?
A destructive boundary where material is being destroyed or subducted due to compression.
What is a divergent boundary?
Where material is being added and plates are moving apart.
What is a conservative boundary?
Where plates are sliding past one another with no material being added to or subducted from either side.
What is a collision boundary?
Where two continental plates meet and subduction has ceased.
What are convection currents?
Heat is formed at the core and released by radioactive decay in the mantle. Heat rises and cools at the crust.
What is subduction?
When the denser oceanic plate is forced under the less dense continental plate. The oceanic plate is absorbed into the mantle and destroyed.
What is orogenesis?
Mountain-building processes.
What is the Benioff zone?
The sloping zone where plates meet and melt and earthquakes occur.
What is an accretionary wedge/prism?
When sediments deposited in the adjacent ocean and trench are scraped up against the leading edge of the continental plate and added to it.
What are anticlines and synclines?
Upfolds and down folds that take place deep in the earth where rock is ‘plastic’.
What is continental drift?
The concept that continents have moved positions.
What are hotspots?
A volcano in a plate above a mantle plume. The plume is a stationary area of high heat flow, and it rises from great depths.
