Plate Tectonics and Tectonic Flashcards
Who developed the continental drift hypothesis? When?
Alfred Wegener
1912
Describe the idea of continental drift. What is the name of the supercontinent?
Continents were once joined together in a giant land massed alled Pangaea. They are drifting apart
What 5 pieces of evidence supported CD?
Coastlines match fossils match rock formations match glacier striations match ancient climate evidence does not match current location
Why didn’t scientists accept the idea of Cd initially?
could not explain how continents moved
With additional evidence collected in the 1960s the Cd hypothesis led to the _______ ________ theory
plate tectonics
The Earth’s surface is broken into rigid, moving plates.. These plates can be ______ km thick. They make up the _______ which is composed of the crust and upper mantle. This layer floats on the _______ which is a hot, weak, flexible sone.
100, lithosphere, asthenosphere
other evidence for plate tectonics include _______ and ______ which occur on plate boundaries. Where do most of these occur?
earthquakes, volcanoes
Ring of fire- pacific subduction zones
Minerals present in the igneous rock _______ act like a _______ pointing to the north magnetic pole.
basalt, compass
Describe the pattern of magnetic reversal on the ocean floor around a spreading center.
Alternating bonds of rock with magnetic minerals pointing north and south- N and S reverse with the banding
Sea floor spreading occurs at _______. Where are the newest rocks in the ocean? ________ What happens to the age of rock as distance from a spreading center increases? ______ Where is crust destroyed and returned to the mantle? _______
mid ocean ridge, close to ridge, gets older, subduction zone- deep sea trench
_________ currents in the asthenosphere are the main cause of plate movement. What causes these currents? When currents rise plate move ______. When currents sink, plates move ________
mantle convection, apart, together
What is a hot spot? What are two in the United States?
An area of volcanic activity from a stationary plume. Hawaii-O Yellowstone- C
Why don’t the continents fits together exactly toay?
Erosion
What plates are colliding to form the Himalayas?
India and Eurasia
Name the five boundary types, their plate movement, features/results, and examples.
Transform- slide past, EQ’s and Faults, San Andreas
Divergent- apart, ridge and Rift Valley, mid Atlantic ridge, east pacific ridge
Collision- together, EQ’s and folded mountains, Himalayans, alps,Appalachian
Convergent- Ocean to Ocean- together trench Island Arc, Japan, Philippines
Convergent- Ocean to Continent- together, trench volcanic arc, Andes, cascades
