Structure of the earth
What is the crust?
The outermost layer of the Earth where we live.
What is plate tectonics?
The theory that explains the movement of the Earth’s lithospheric plates.
What is an island arc?
A chain of volcanic islands that form at oceanic-oceanic subduction zones.
Who is Alfred Wegener?
The scientist who first proposed the idea of continental drift.
What are igneous rocks?
Rocks formed by cooling and solidification of magma or lava.
What is the mantle?
This layer of molten and semi-molten rock lies beneath the crust.
At which type of plate boundary are mid-ocean ridges formed?
A divergent/constructive boundary
A deep underwater trench forms at this type of boundary.
A convergent/subduction boundary
What is Pangaea?
Wegener suggested that all continents were once joined in this supercontinent.
What are sedimentary rocks?
Rocks formed by the accumulation and compaction of sediments.
The Earth’s inner core is mostly made of these two metals.
Iron and Nickel
What is a transform boundary?
This type of plate boundary is where plates slide past each other.
What are andesitic (composite/stratovolcano) volcanoes?
These steep-sided volcanoes are formed from alternating layers of lava and ash, typical at subduction zones.
The matching shapes of continental coastlines, like South America and Africa, and discovery of fossils are evidence for this theory.
Continental Drift
What are metamorphic rocks?
When heat and pressure alter existing rocks, they become this type.
The average thickness of the continental crust is around this many kilometers.
30-40km
The Himalayas formed because of this type of plate collision.
Continental–Continental collision boundary
What are rift valleys?
At divergent boundaries on land, the crust may stretch and create this linear feature.
What is palaeoclimatic (glacial) evidence?
This type of evidence comes from glacial deposits found in now-tropical regions, supporting the idea that continents have moved.
Granite is an intrusive igneous rock. Its extrusive equivalent is this.
Basalt
Convection currents that drive plate tectonics occur in this part of the mantle. What is it called?
The asthenosphere
What is subduction?
The process where one plate sinks beneath another into the mantle.
At transform boundaries, rivers may become displaced sideways. These are called this.
Offset rivers
What is the Mid-Atlantic Ridge?
The discovery of this mid-ocean feature in the Atlantic provided proof for plate movement.
What is lithification?
This process turns sediments into solid rock.