Lecture 3 - Week 2 - Plate Techtonics Flashcards
Paleomagnetism, matching coastlines, and similar rocks/fossils/etc. in bands across different continents are all evidence for…
Plate Tectonics
Why did Plate Tectonics replace the theory of Continental Drift?
Continental drift has no mechanism for continent movement
Magnetic minerals lining up with an ancient magnetic field of the Earth in ancient igneous rocks is a demonstration of…
Paleomagnetism
The study of magnetic fields recorded in rocks, sediment, and other materials is the study of…
Paleomagnetism
Measuring the declination (left/right), and inclination (up/down) in _______ ______ shows…
Igneous rocks. It shows where magnetic
North was, and what latitude the rocks were at, when they formed.
Knowing where magnetic North was, and what latitude the rocks were at, when they formed allows us to…
track the movement of continental plates across time.
Divergent Boundaries are places where…
New crust is formed through volacanic activity at mid-oceanic ridges. They start as ‘spreading centers’, caused by mantle upwelling.
Convergent Boundaries are also called _____________ ______. These are places where…
Subduction zones. This where the denser plate slides under the other plate (e.g. thinner oceanic crust, older crust).
Transform Boundaries are mostly found…
At mid oceanic ridges where sections of the ridge move at different paces, and slide past one another.
Convergent Boundaries are most likely to create…
Mountain chains, volcanic Island arcs,
earthquakes, and volcanoes
An example of a transform boundary is the ___ _______ fault. These boundaries are known to produce….
San Andreas fault. Transform boundaries produce large earthquakes.
The Theory of Plate Tectonics states that…
The rigid outer layer of the Earth (lithosphere) is split into large plates that move slowly over time.
Who developed the idea of continental drift? When?
Alfred Wegener. 1912.
Evidence of Late Paleozoic continental glaciation exists…
In glacial deposits in South America,
Southern Africa, Antarctica and Australia
Fossilized reef deposits are early evidence of moving continents because…
The deposits exist outside of where reefs
form today (between 0° and 30°).
Evaporite (salt, etc.) deposits are early evidence of moving continents because…
They exist outside of where they form today
(around 30° North and South)
What is “declination”?
The difference between the magnetic North Pole vs. the geographic North Pole. (Today: a 7° degree difference)
What is “inclination”? How does inclination act at the equator vs. in the arctic?
The dip of a magnetized needle in line towards the magnetic north. There is no pull “downwards” into the Earth by magnetic lines at the equator, the magnetic lines pull into the Earth’s core is greatest at the Poles.
In paleogeography, declination tells us what about the position of the rock/slice of plate when it formed?
Declination gives the apparent direction of the magnetic north pole at the time of magnetization/creation.
In paleogeography, inclination tells us what about the position of the rock/slice of plate when it formed?
Inclination gives us the distance between the rock and
pole at the time of magnetization.
Ridge push and and slab pull describe what behaviours of slow creep mantle flow?
Ridge push & slab pull
Old, cold, more dense ocean crust sinks into the asthenosphere dragging the rest of the plate with it, this is called…
Slab pull
Heat and magma push the lithosphere up and apart creating new mid-oceanic ridges, this phenomena is called…
Ridge push
_______ crust is higher density, but thinner.
Oceanic
____________ crust is lower density, but thicker.
Continental
Jeopardy style: An isolated underwater volcanic mountain, resulting from a hot spot mantle plume.
What is a Guyot Formation, and what is it the result of?
When was the modern theory of plate tectonics developed?
In the 1960s, as a result of large scale oceanographic research following WW2.
Who developed the concept of seafloor spreading?
Harry Hess
If a plate is subducting Southwest along the sea floor, what direction will the newest volcano be in from the oldest volcano?
Northeast
