Plate tectonic flashcards for quiz
Study for tectonic plate quiz
What is Pangaea and who proposed the idea of it?
Pangaea was a super continent – one giant landmass on Earth that existed hundreds of millions of years ago. Alfred Wegener proposed the idea of Pangaea.
What happens during the process of seafloor spreading?
During seafloor spreading, magma rises up and pushes the tectonic plates away from one another (divergent plate boundary). This creates a chain of underwater volcanic mountains called a mid-ocean ridge. As the magma hardens into new seafloor, it pushes the older seafloor away.
What evidence supported the theory of Pangaea?
Identical fossils of freshwater reptile species were found on either side of the Atlantic Ocean. Additionally, the same coal deposits were found in Europe and North America, and glacial scarring was found on various landmasses. All of these are pieces of evidence that point towards the theory of Pangaea.
Why does the Earth not get larger over time even though new seafloor is created at mid-ocean ridges?
The Earth does not get larger because as new seafloor is created at mid-ocean ridges, crust gets recycled back into the Mantle at convergent plate boundaries through the process of subduction.
What is the name of the theory that the continents have moved slowly over time?
The theory that the continents have moved slowly over time is called Continental Drift.
Explain how the Earth’s layers are layered because of their densities.
The most dense layer is the Inner Core, which is sunk to the middle of the planet. The least dense layer is the Lithosphere, which is floating on top.
How do scientists study the Earth’s deep interior that we can’t reach or that’s too hot or under too much pressure to reach?
Scientists use earthquake (seismic) waves to study Earth’s interior. P-waves move horizontally and S-waves move in an S-shape and cannot travel through liquid (this is how we know about the liquid Outer Core).
How does a convection current form?
Hotter, less dense fluid rises and cooler, denser fluid fills in that space. This creates a cyclical current that repeats as long as heat is continuously applied at the bottom of the fluid.
What are the names of the mechanical layers of the Earth? What is one characteristic of each layer? (hint: what would they ‘shout’ or ‘sing’?)
Lithosphere - the moving tectonic plates
Asthenosphere - plastic flow
Lower Mantle - red hot, convecting rocks
Outer Core - spinning, liquid metal
Inner Core - solid iron
What is the difference between the compositional and mechanical layers of the Earth?
The Compositional layers are how the layers are different chemically and how they are separated by their densities. The Mechanical layers are how the layers move and behave due to their strength and the pressure they are under.
What is a hotspot and how does it form island chains (archipelagos)?
A hotspot is a hot magma plume in Earth’s Mantle. It builds up pressure and erupts occasionally. As the tectonic plate above it moves over the hotspot, new island volcanoes are created. The moving plate takes the island(s) with it, and the hotspot forms a new island.
What types of natural disasters can occur as the Nazca Plate converges with the South American Plate?
As the Nazca Plate converges and subducts under the South American Plate, this causes volcanic eruptions on the edge of the continent, earthquakes, and tsunami.
What is a convergent plate boundary? What are two specific types of convergent plate boundaries?
Tectonic plates move towards each other at a convergent plate boundary. There are continental-continental convergent boundaries and oceanic-continental convergent boundaries.
What are three ways to change the density of a fluid?
You can change the density of a fluid by:
Heating it up
Cooling it down
Adding a solute to it (like salt)
What is the definition and formula for density?
Density is how much ‘stuff’ fits in a ‘space’.
Density = mass / volume
You can remember the formula by a heart.
What are the compositional layers from deepest to the surface?
Core, Mantle, Crust (continental and oceanic)
How do convection currents cause the Earth’s tectonic plates to move?
The convection currents in the Mantle drag the tectonic plates around at the surface of the Earth.
Why are the oldest Hawaiian Island and the oldest Galapagos Island farthest away from one another?
The Hawaiian Islands are on the Pacific tectonic plate, which is moving to the Northwest. As the new islands are created over that hotspot, the older islands get dragged Northwest. The Galapagos Islands are on the Nazca tectonic plate, which is moving to the East. As the new islands here are created over the hotspot, the older islands get dragged East. Therefore, the oldest islands in each chain are farthest from one another.
What is subduction? Where and why does it happen?
Subduction is when the edge of one tectonic plate sinks underneath another tectonic plate. This occurs at convergent boundaries when the tectonic plates are different densities.
What is a divergent plate boundary? What feature is formed when the divergent plate boundary occurs between two oceanic plates?
Tectonic plates move away from each other at a divergent plate boundary. This forms a mid-ocean ridge when the two plates are oceanic.
