Chapter 3 - Plate Tectonics Flashcards
What is tectonics?
It is the study of large-scale movement and deformation of earth’s outer layers.
What is plate tectonics?
A theory that explains tectonic movement through the existence of rigid “plates” of rock over a weaker, more plastic layer in the earth’s upper mantle.
What is the curie temperature?
The temperature below which a magnetic mineral stays magnetic. If it above the curie point it loses its magnetism.
What is the basis for the study of paleomagnetism?
As a magma cools it forms iron-bearing minerals which are magnetic and tend to line up in the same direction (like a compass).
What is sea floor spreading?
It is the parting of sea floor rocks at ocean ridges. This phenomenon led to magnetic bands with differing polarities on the ocean floor due to the shift in polar north throughout the earth’s history.
How is age distributed on the sea floor?
Oldest sea floor further away from the oceanic ridge, youngest is nearest.
What age are the oldest rocks recovered from the sea floor?
200 million years old
What is the polar wander curve?
When the directions and latitudes of many rocks of various ages from one continent are determined and plotted on a map, it appears that the magnetic poles have meandered far over the surface of the earth.
When is an object under stress?
When force is being applied to it.
What is known as compressive stress?
When the object is being compressed or squeezed.
What is known as tensile stress?
When stress is stretching and object or pulling it apart (sea floor spreading).
What is known as shearing stress?
It is stress that causes parts of an object to move in different directions.
What does strain mean?
It is deformation resulting from stress.
What happens in elastic deformation?
The amount of deformation is proportional to the stress applied.
What happens once the elastic limit is met?
The material would go through a phase of plastic deformation
