Plate Tectonics and Tectonic Flashcards Preview

freshmen year > Plate Tectonics and Tectonic > Flashcards

Flashcards in Plate Tectonics and Tectonic Deck (25):
1

Who developed the continental drift hypothesis? When?

Alfred Wegener
1912

2

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

3

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

4

Why didn't scientists accept the idea of Cd initially?

could not explain how continents moved

5

With additional evidence collected in the 1960s the Cd hypothesis led to the _______ ________ theory

plate tectonics

6

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

7

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

8

Minerals present in the igneous rock _______ act like a _______ pointing to the north magnetic pole.

basalt, compass

9

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

10

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

11

_________ 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

12

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

13

Why don't the continents fits together exactly toay?

Erosion

14

What plates are colliding to form the Himalayas?

India and Eurasia

15

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

16

What are the 3 places that volcanoes occur? Which of these has the most explosive eruptions?

Subduction zones
hot spots
rift eruptions

17

Describe the 3 shapes of volcanoes

shield
cinder
composite

18

What determines the explosiveness of a volcano?

Amount of Silica and Disowed Gas

19

What is pyroclastic material?

pulverized rock, dust, ash and gas cloud

20

A _________ wave travels the fastest through any material. .How des it move?

P (primary)
Push- Pull (compression)

21

A _____ wave only travels through solids. How does it move?

S (secondary)
Side to side

22

What wave travels up and down on the surface?

L (love)

23

The point where an earthquake occurs is called the ________. An ________ is the point on the surface above this place.

focus- (origin)
Epicenter

24

A _______ records an earthquake and creates a _____. How many are needed to find the epicenter of an earthquake? ____

seismograph, seismogram 3,

25

What 2 scale are used to measure earthquakes?

Richter- 31 x energy (1-10)
Mercalli- (1 to 12) - Damage