Drifting Continents
Sea-Floor Spreading
Plate Tectonics
Volcanoes
Challenge
100
The name of the "super continent" that formed where all the continents were joined together.
What is Pangaea?
100
This process adds more crust to the ocean floor while moving older strips of rock outward and away from a mid-ocean ridge.
What is sea-floor spreading?
100
This theory states that Earth's plates are in slow, constant motion, driven by convection currents in the mantle.
What is the theory of plate tectonics?
100
A volcano that is erupting or has shown signs of erupting in the near future is called this.
What is an active volcano?
100
This is the name of lava before it reaches the surface.
What is magma?
200
This is the scientist who first came up with the idea that the Earth's crust was made of separate plates that float slowly around the earth. He/she called the theory "Continental Drift".
Who is Alfred Wegener?
200
This is the technology scientists used in the mid-1900s to map mid-ocean ridges.
What is sonar?
200
This type of plate movement is where earthquakes are most likely to occur.
What is a transform boundary?
200
A long tube where magma moves upward, it extends from the magma chamber up through the top of the volcano.
What is the pipe?
200
Describe the temperature and density of newly formed crust at a mid-ocean ridge.
1) hotter 2) less dense
300
Wegener's hypothesis that all the continents were once joined together in a single landmass and have slowly drifted apart is his theory of:
Continental Drift
300
In sea-floor spreading, molten material rises from the mantle and erupts where?
What is a mid-ocean ridge?
300
When two continental plates diverge from one another, this land form is created.
What is a rift valley?
300
This is a major belt of volcanoes that rim the pacific ocean.
What is the Ring of Fire?
300
Old oceanic crust is more dense than new oceanic crust because it is:
What is colder?
400
Wegener noticed that fossils of certain ancient species were found on continents spaced oceans apart. How did he explain what he observed?
When those animals were living, the continents were together. Later, the continents moved apart with the fossils embedded in them to be scattered around the globe.
400
This is the place where old oceanic crust gets subducted into the mantle to be recycled.
What is a deep-ocean trench?
400
A place where two plates slide next to each other, moving in opposite directions is this type of boundary movement.
What is a transform boundary?
400
The curve of these echo the curve of the deep-ocean trench. Some examples are Japan, New Zealand and the Caribbean.
What is an island arc?
400
What are the three "ingredients" that make up magma?
1) Molten material (silica) 2) gases (oxides) 3) water
500
Wegener used three main pieces of evidence to support his hypothesis of Continental Drift. What are the three pieces of evidence?
1) continents fit like puzzle pieces 2) fossil evidence 3) Climate evidence
500
When two plates converge, what is the biggest factor in deciding which plate will be subducted under the other?
What is density? The denser plate will be pulled down underneath the less dense plate.
500
When two oceanic plates move away from each other, they form this feature.
What is a mid-ocean ridge?
500
This part of magma provides the force that causes it to erupt to the surface.
What is expanding gas trapped in magma?
500
The ocean floor takes around 200 million years to recycle. Describe this process using these words: subduction, mid-ocean ridge, deep-ocean trench, sea-floor spreading.
New sea floor is produced at a mid-ocean ridge. As more sea floor is added, older rock is moved away from the ridge in a process called sea-floor spreading. Eventually, the old rock is subducted into a deep-ocean trench where it recycled, a process that takes around 200 million years.
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