Lecture 3 - Week 2 - Plate Techtonics

Question 1

Paleomagnetism, matching coastlines, and similar rocks/fossils/etc. in bands across different continents are all evidence for…

Answer 1

Plate Tectonics

Question 2

Why did Plate Tectonics replace the theory of Continental Drift?

Answer 2

Continental drift has no mechanism for continent movement

Question 3

Magnetic minerals lining up with an ancient magnetic field of the Earth in ancient igneous rocks is a demonstration of…

Answer 3

Paleomagnetism

Question 4

The study of magnetic fields recorded in rocks, sediment, and other materials is the study of…

Answer 4

Paleomagnetism

Question 5

Measuring the declination (left/right), and inclination (up/down) in _______ ______ shows…

Answer 5

Igneous rocks. It shows where magnetic
North was, and what latitude the rocks were at, when they formed.

Question 6

Knowing where magnetic North was, and what latitude the rocks were at, when they formed allows us to…

Answer 6

track the movement of continental plates across time.

Question 7

Divergent Boundaries are places where…

Answer 7

New crust is formed through volacanic activity at mid-oceanic ridges. They start as ‘spreading centers’, caused by mantle upwelling.

Question 8

Convergent Boundaries are also called _____________ ______. These are places where…

Answer 8

Subduction zones. This where the denser plate slides under the other plate (e.g. thinner oceanic crust, older crust).

Question 9

Transform Boundaries are mostly found…

Answer 9

At mid oceanic ridges where sections of the ridge move at different paces, and slide past one another.

Question 10

Convergent Boundaries are most likely to create…

Answer 10

Mountain chains, volcanic Island arcs,
earthquakes, and volcanoes

Question 11

An example of a transform boundary is the ___ _______ fault. These boundaries are known to produce….

Answer 11

San Andreas fault. Transform boundaries produce large earthquakes.

Question 12

The Theory of Plate Tectonics states that…

Answer 12

The rigid outer layer of the Earth (lithosphere) is split into large plates that move slowly over time.

Question 13

Who developed the idea of continental drift? When?

Answer 13

Alfred Wegener. 1912.

Question 14

Evidence of Late Paleozoic continental glaciation exists…

Answer 14

In glacial deposits in South America,
Southern Africa, Antarctica and Australia

Question 15

Fossilized reef deposits are early evidence of moving continents because…

Answer 15

The deposits exist outside of where reefs
form today (between 0° and 30°).

Question 16

Evaporite (salt, etc.) deposits are early evidence of moving continents because…

Answer 16

They exist outside of where they form today
(around 30° North and South)

Question 17

What is “declination”?

Answer 17

The difference between the magnetic North Pole vs. the geographic North Pole. (Today: a 7° degree difference)

Question 18

What is “inclination”? How does inclination act at the equator vs. in the arctic?

Answer 18

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.

Question 19

In paleogeography, declination tells us what about the position of the rock/slice of plate when it formed?

Answer 19

Declination gives the apparent direction of the magnetic north pole at the time of magnetization/creation.

Question 20

In paleogeography, inclination tells us what about the position of the rock/slice of plate when it formed?

Answer 20

Inclination gives us the distance between the rock and
pole at the time of magnetization.

Question 21

Ridge push and and slab pull describe what behaviours of slow creep mantle flow?

Answer 21

Ridge push & slab pull

Question 22

Old, cold, more dense ocean crust sinks into the asthenosphere dragging the rest of the plate with it, this is called…

Answer 22

Slab pull

Question 23

Heat and magma push the lithosphere up and apart creating new mid-oceanic ridges, this phenomena is called…

Answer 23

Ridge push

Question 24

_______ crust is higher density, but thinner.

Answer 24

Oceanic

Question 25

____________ crust is lower density, but thicker.

Answer 25

Continental

Question 26

Jeopardy style: An isolated underwater volcanic mountain, resulting from a hot spot mantle plume.

Answer 26

What is a Guyot Formation, and what is it the result of?

Question 27

When was the modern theory of plate tectonics developed?

Answer 27

In the 1960s, as a result of large scale oceanographic research following WW2.

Question 28

Who developed the concept of seafloor spreading?

Answer 28

Harry Hess

Question 29

If a plate is subducting Southwest along the sea floor, what direction will the newest volcano be in from the oldest volcano?

Answer 29

Northeast