Hypothesis of Continental Drift
What does the hypothesis of continental drift say?
It states that all of the continents had once been joined together and that over time they had moved and spread apart.
What is a mid ocean ridge and what type of boundary does it occur at? How do you know this?
It is a chain of undersea mountains where there is a divergent boundary and we know this because the land plates are moving away from each other and magma is coming up between the plates.
What does the Theory of Plate Tectonics say?
Earth's lithosphere is broken up into distinct plates and the plates are in constant motion.
Name the three types of faults and tell which boundaries they are associated with.
1. Normal faults - Divergent boundary
2. Reverse Faults - Convergent boundary
3. Strike-slip - Transform boundary
How do plate tectonics play a role in the formation of volcanoes?
Volcanoes occur at both converging and diverging boundaries
What types of evidence supported the hypothesis of continental drift?
land features, types of rocks, fossils and climate.
What process occurs on the seafloor that where new spans of rock are being created and why is this important to the Theory of Plate Tectonics.
This is called seafloor spreading. This is where new rock is being created at a divergent boundary and it is important because it is occurring due to convection currents which is what is moving the plates and continents.
What are convection currents? Give an example.
Cyclical movement of fluid driven by temperature differences at the top and bottom. Heating hot water in a pot rises to the top which the cold water sinks. This continually happens creating a cycle.
Give the three types of faults and tell which type of tension is associated with each.
1. Normal - Tension
2. Reverse - compression
3. Strike Slip - Shearing
A volcano forms on the ocean floor at a hot spot. What would happen if volcanic eruptions continued to occur on the ocean floor?
Lava would build up and islands would form.
Give an example of evidence from land features for the hypothesis of continental drift.
1. Mountain ranges near continents' coasts seemed to line up.
2. Coal deposits made millions of years ago where plants survived in warm climates were found in multiple regions that no longer supported that plant life.
What process is occurring at undersea valleys? What do we call this feature and what type of boundary does this occur at? Why is this important to the Theory of Plate Tectonics?
The process is subduction which occurs at an ocean trench in a divergent boundary. It is important because it shows how rocks are being destroyed which is another part that shows how the continents are moving due to convection currents.
What two types of crust are there are Earth and what are the two ways that they differ?
Oceanic crust and continental crust. They are different because continental crust is less dense and almost always thicker than oceanic crust.
What landforms are created by the three fault types
1. Normal (Divergent) - rift valley, fault block mountains.
2. Reverse (Convergent) - anticlines, synclines, folded mountains.
3. Strike Slip (Transform) - Fault line only
What is one way that volcanologists can predict whether or not a volcano will explode?
Sometimes the land swells above a magma chamber showing that a volcano may erupt.
What type of evidence from fossils supported the hypothesis of continental drift? Give an example.
1. Glossopteris (fern) from 20mya was found on 5 continents. Lands had once connected so the fern sora could get to each place.
2. Animal fossils (Mesosaurus-fresh water) found on both South America and Africa. They didn't jump and swim
Is Earth getting bigger or smaller (as we know we can create and destroy crust)?
The rate at which crust is being created or destroyed is the same rate. So Earth is staying the same size.
What are the three types of boundaries and explain how the plates move.
1. Divergent - plates move apart.
2. Convergent - plates move together
3. Transform - Plates slip past each other
What hazards are associated with the three types of faults? Be very specific since one fault has three different options of crust converging.
1. Normal - (Divergent) - earthquake, eruptions, tsunamis
2. Reverse - (Convergent) - earthquake, eruptions for oceanic/oceanic and oceanic/continental but not C/C, tsunami for O/C and O/O
3. Strike Slip - (Transform) - earthquakes
Do you think it's safer to live near one kind of volcano over others? Explain.
Yes, it may be safer to live near a shield volcano since those eruptions are slow and there is more time to evacuate.
What type of evidence from climate supports the hypothesis of continental drift? Give an example.
1. Spitsbergen has fossils of plants that were tropical yet it is now in the Artic Ocean and has freezing climate.
What features are evidence of the Pacific Ocean's maturity?
Subduction zones on many sides.
What are the three different types of convergent boundaries and explain how they move, which plate subducts (if any) and what land features they create.
1. Continental- Continental - plates move together. No plate subducts, creates mountains.
2. Continental- Oceanic - plates move together, Oceanic plate subducts under continental plate, creates volcanoes, trench.
3. Oceanic-Oceanic - plates move together - older/colder plate subducts - creates volcanoes, seamounts, island arcs
On the magnitude scale how much more energy is released by an earthquake that is a magnitude 5 versus a magnitude 6?
32 times more energy.
How are shield volcanoes and lava plateaus similar and different? Give one similarity and one difference.
Both volcanic formations cover large areas. A lava plateau is flatter than a shield volcano.