Chapter 3

Question 1

Who came up with the Continental drift theory?

Answer 1

Alfred Wegner

Question 2

Continental drift theory

How long ago would this have occurred?

Answer 2

Theory suggesting that all of Earth’s land had once been joined together into a single super-continent surrounded by an ocean

• pangaea: the landmass
• panthalassa: the surrounding ocean

-200 million years ago

Question 3

What is the centrifugal theory?

Answer 3

Theory that believed the continents were slung toward the equator on the spinning Earth by a centrifugal effect
- inertia coupled with tidal drag on the continents (from the combined effects of the sun and moon) would account for the drifting continents

Question 4

Is earth’s mantle a solid?

Answer 4

no it reacts to earthquakes, so it is a deformable mass

Question 5

Seismic waves

Answer 5

low frequency waves generated during earth quakes

Question 6

What are the types of seismic waves?

Answer 6

Surface waves: move along earth’s surface and the main reason for damage from earthquakes

Body waves: less dramatic, but very useful for analyzing earth’s interior surface

Question 7

Types of Body waves?

Answer 7

P wave (primary wave): a compressional wave similar in behavior to a sound wave

S wave (secondary wave): a shear wave like that seen in a rope shaken side to side

Question 8

Seismograpgh

Answer 8

instrument that senses and records earthquakes

Question 9

Shadow zone

Answer 9

a wide band from which S waves were absent, would be found on the side of the Earth opposite the location of an earthquake
-existence of liquid core and shadow zone 1914, seismographic analysis

Question 10

Mantle

Answer 10

core boundary

Question 11

Crust

Answer 11

thin, relatively lightweight outermost layer

• oceanic crust: thin and mostly basait
• continental crust: granite

Question 12

Mantle

Answer 12

beneath the crust, compose of 68% Earth’s mass and 83% volume

Question 13

Core

Answer 13

intermost layer

-31.5% earth’s mass, 16% of its volume

Question 14

Physical layers of the Earth

Answer 14

Lithosphere
Asthenosphere
Lower mantle
Core

Question 15

Lithosphere

Answer 15

earth’s cool rigid outer layer

-Continental and oceanic crusts

Question 16

Asthenosphere

Answer 16

hot, partially melted, slowly flowing layer of upper mantle

Question 17

Lower mantle

Answer 17

extends to the core

• similar composition to the asthenosphere
• hotter but due to rapidly increasing pressure the mantle below the asthenosphere does not melt

Question 18

Core

Answer 18

Two parts:

• outer layer dense viscous liquid
• inner layer solid

Question 19

William Thomson

Answer 19

Lord Kelvin
Earth is 80 million yrs old
-based on the rate at which the planet would have cooled from an original molten mass
*drying fruit model: earth shrunk as it cooled

Question 20

Radioactive decay

Answer 20

though most atoms are stable and do not change some forms of elements are unstable and give off heat when their nuclei break apart (decay)

• radioactive particles ejected in process
• released heat that contributed to Earth’s melting of the original mass

Question 21

Conduction

Answer 21

Internal heat journeys toward the surface

Question 22

Convection

Answer 22

heat that arises in the asthenosphere and mantle

- occurs when a fluid or semisolid is heated, expands, and becomes less dense and rises

Question 23

James Hutton

Answer 23

Uniformitarianism: all of Earth’s geological features and history could be explained by process identical to today’s and these processes must have been at work for a long time
- did not believe in the bibles concept of creation