Plate tectonic theory
What is the name of the theory that explains how Earth's plates move?
Plate tectonic theory
What is the outermost layer of the Earth?
Crust
Which type of plate boundary occurs when two plates move apart?
Divergent
What was the name of the supercontinent that existed about 300 million years ago?
Pangea
Which property determines whether a material sinks or floats?
Density
Approximately how many major tectonic plates make up Earth's surface?
7
What layer is the thickest?
Mantle
Which type of boundary forms when two plates collide?
Who proposed the theory of continental drift?
Alfred Wegener
Hot mantle material is less dense, so what does it do?
Rises
What do tectonic plates float on?
Asthensophere/ Upper mantle
Which layer is made mostly of liquid iron and nickel?
Outer core
Which type of boundary forms when plates slide past one another?
Transform
Name one piece of evidence Wegener used to support continental drift.
Matching fossils, rock types, mountain ranges or continental shapes
What is the circular movement of mantle material called?
Convection current
What causes tectonic plates to move?
Convection currents in the mantle
Which layer is the hottest and most dense?
Inner core
Which type of boundary is most commonly associated with volcanic island arcs?
Convergent: oceanic-oceanic
Which two continents fit together like puzzle pieces?
South America and Africa
Which type of crust is more dense: oceanic or continental?
Oceanic crust
What is the name of the rigid layer made up of the crust and upper mantle?
Lithosphere
In which layer do convection currents occur?
Mantle/ Asthensosphere
At which boundary type is new oceanic crust created?
Divergent
Why was Wegener's continental drift hypothesis originally rejected?
He couldn't explain how continents moved
Why does colder mantle material sink?
Becomes denser