Earth's Interior
Convection Currents and the Mantle
Continental Drift
Sea-floor Spreading
Plate Tectonics
100

What is the difference between destructive and constructive forces?

Destructive forces wear away Earth's features (like erosion) and constructive forces build up mountains and landmasses.

100
What type of heat transfer moves heat through empty space or air by waves?
Radiation
100

Which scientist came up with the idea of continental drift?

Alfred Wegener

100

Describe the density of oceanic crust vs. continental crust.

Oceanic crust is more dense than continental.

100
What is a transform boundary? What happens at this boundary type?
Plates slip past each other in opposite directions at a transform boundary. Earthquakes occur frequently here.
200

What happens to temperature and pressure as you travel closer to Earth's core?

After about 20 m deep, temperature and pressure increase as you get closer to Earth's core.

200
Which type of heat transfer occurs when a spoon gets hot when it is placed in a cup of hot chocolate?
Conduction
200
All landmasses were originally connected into a supercontinent called what?
Pangaea
200
What is the mid-ocean ridge?
It is the longest mountain range in the world, and happens to be underwater. New crust is formed in the middle of the ridge.
200
What is a divergent boundary? Where do these occur when 2 oceanic plate meet? What occurs when 2 continental plates meet?
At a divergent boundary, 2 plates move apart. In the ocean this happens at the mid-ocean ridge, where sea-floor spreading occurs. At 2 continental plates, a rift valley is formed.
300

How do geologists know about Earth's interior?

Geologists indirectly study the speed and path of seismic waves produced by earthquakes.

300
Where do convection currents occur inside the Earth? (which layer)
Asthenosphere
300
Why did other scientists originally reject Wegener's continental drift theory?
Although he had evidence of continental drift, he could not explain what force caused the landmasses to move.
300
Explain how new crust is formed during sea-floor spreading.
Molten material rises from the mantle and erupts. The molten material spreads out and pushes older rock to both sides. Molten material cools and forms a strip of new solid rock in the middle.
300
What is a convergent boundary?
A convergent boundary is where two plates come together.
400

Describe the lithosphere.

The lithosphere is the top layer made of crust and rigid upper part of mantle. Tectonic plates are part of the lithosphere.

400
What types of substances can have convection currents?
Fluids (liquid or gas)
400
What is the theory of continental drift?
The continents were once joined as a single landmass. Over time, the continents have slowly moved apart to their present day locations.
400
Explain what happens at deep-ocean trenches.
Old crust that has been pushed to both sides gets subducted at the trenches. Oceanic crust is more dense, so it gets pulled under continental crust. As it sinks deeper, the oceanic crust melts and returns to part of the molten asthenosphere.
400
What happens when 2 continental plates meet at a convergent boundary?
Mountains form.
500

Describe Earth's layers from the middle to the outside.

Inner core- solid ball of iron and nickel. Outer core- liquid/molten iron and nickel. Lower mantle- hot, solid material Asthenosphere- thick ilquid layer where convection currents take place. Lithosphere- made up of crust and rigid upper part of mantle. Crust- rocky surface of the earth; 2 types- continental and oceanic.

500
Explain what temperature and density have to do with convection currents.
As a substance is heated, particles spread out, making it less dense. The hot substance rises. Once it is farther away from the heat source, it begins to cool. When the temperature goes down, the particles get closer together. This makes the substance more dense, so it sinks.
500
EXPLAIN three pieces of evidence that Wegener used to support his continental drift theory.
Landforms- Rock types and mountain ranges on different continents match up. For example, coal fields in Europe are the same as coal fields in North America. Wegener also noticed that the edges of the continents match up like puzzle pieces (Africa & South America). Fossils- Wegener found that the same reptile fossils were in places now separated by oceans, but those reptile could not have swum across the ocean. This made him think that the continents were once joined. He found similar evidence when the same fern fossils were found in rocks in Africa, South America, Australia, India, and Antarctica. Climate and glaciers- Wegener found evidence of tropical plants in areas that have a very cold climate today. He also found grooves caused by glaciers in areas that are very warm today.
500
EXPLAIN 3 pieces of evidence for Harry Hess' sea-floor spreading theory.
Molten material- scientists took underwater pictures of rocks at the mid-ocean ridge. They look like pillows! These types of rocks only form when molten material hardens quickly after erupting underwater. Magnetic Stripes- When molten material cools, iron bits in the rock point toward Earth’s magnetic north. Every so often, Earth’s magnetic poles shift, which means the iron bits point in the opposite direction. This has formed magnetic stripes on the ocean floor as new rock has hardened. The pattern is the same on both sides of the mid-ocean ridge. Scientists inferred that rock that hardens at the same time has the same magnetic memory. Drilling Samples- Scientists drilled into the ocean floor and brought up samples of rock. They determined the age of the rocks and found that the farther away from the ridge, the older the rocks are. The youngest rocks were always in the center.
500
What happens when an oceanic plate meets a continental plate at a convergent boundary?
The oceanic plate gets subducted under the continental plate because it is more dense.
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