Chapter 1

Question 1

1. What is geology, and what is the difference between physical and historical geology?

Answer 1

a. Geology- What is it?
i. Scientific study of the Earth and its major systems.
b. Subdivisions
i. Physicial Geology- Study of Earth’s compisition, structure, and the processes that shape it
ii. Historical Geology- Study of Earth’s history and history of life.

Question 2

GEOLOGY- Why Study It?

Answer 2

• Acquiring Knowledge Needed To:
- Obtain natural resources
- Assess and avoid natural hazards
- Prevent or correct environmental damage
• Expanded Awareness of:
- How beautiful and complex Earth is
- How much our survival depends upon understanding how Earth works

Question 3

THE SCIENTIFIC METHOD

Answer 3

• A systematic, logical way of studying how nature works
• Data is gathered which poses questions
• Hypothesis:
- an attempt to explain the data
- often, more than one is proposed
- tests are devised to find which , if any, are true
• theory: a hypothesis that has tested true
• high probability of being valid

Question 4

Atmosphere

Answer 4

Gaseous envelope surrounding Earth

• 78% Nitrogen, 21% Oxygen, and 1% Argon, carbon dioxide, and others

Question 5

EARTH’S MAJOR COMPONENTS

Answer 5

• Geosphere: from the Earth’s surface to its center
• Subdivisions:
• Crust: outermost and thinnest part of Earth. Two types exist
• Continental: thicker, variable thickness, and granitic average composition
• Oceanic: thinner, more uniform in thickness, and basaltic composition
• Mantle: most of Earth’s volume and mass. Denser rock than crust
• Core: molten outer core, and solid inner core. Iron and nickel composition
• Hydrosphere: All of Earth’s water
• 97% is in the oceans
• Atmosphere: Gaseous envelope surrounding Earth
• 78% Nitrogen, 21% Oxygen, and 1% Argon, carbon dioxide, and others
• Biosphere: All life on Earth

Question 6

• Hydrosphere

Answer 6

: All of Earth’s water

• 97% is in the oceans

Question 7

• Geosphere

Answer 7

from the Earth’s surface to its center
• Subdivisions:
• Crust: outermost and thinnest part of Earth. Two types exist
• Continental: thicker, variable thickness, and granitic average composition
• Oceanic: thinner, more uniform in thickness, and basaltic composition
• Mantle: most of Earth’s volume and mass. Denser rock than crust
• Core: molten outer core, and solid inner core. Iron and nickel composition

Question 8

• Biosphere

Answer 8

All life on Earth

Question 9

DYNAMIC RELATIONSHIP BETWEEN COMPONENTS

Answer 9

• the Earth’s major components exist in “dynamic equilibrium” (changing balance)
• a change in any one results in a change in all the others.
• Not necessarily of the same magnitude

Question 10

• continental shelves

Answer 10

(below sea level): shallow sea

Question 11

• continental slopes

Answer 11

(below sea level): steeper slope that connects shallow sea to deep sea

Question 12

• oceanic ridges

Answer 12

undersea mountain range extending through all the oceans

Question 13

• transform faults

Answer 13

fractures that cut across a ridge at 90 degree shifting it right or left

Question 14

• abyssal plains

Answer 14

flat parts of deep ocean

Question 15

• volcanic island arcs

Answer 15

curving chains of volcanic islands that are next to a trench

Question 16

• Geologic Time

Answer 16

vast spans of time ranging from thousands to billions of years
• Implications:
- most of Earth’s features can be explained by observable processes acting over geologic time spans according to natural laws
- often called “the principle of uniformitarianism” “The present is the key to the past.”

Question 17

• The Rock Cycle

Answer 17

continual transformation of rocks from one type to another.

• Caused by internal (underground) and external (surface) processes

Question 18

• igneous

Answer 18

formed when melted rock (magma) cools and solidifies.

Question 19

• Sedimentary

Answer 19

formed when rocks weather and erode into sediment then becomes new rock

Question 20

• Metamorphic

Answer 20

formed when rocks recrystallize without melting, due to heat and pressure deep underground

Question 21

The Hydrologic Cycle

Answer 21

continuous transfer of water from one repository to another. For example, from sea to the air, then from the air to the land, and then back to the sea

• primary water source= oceans
• primary energy source= sun
• cycle of evaporation, condensation, precipitation, infiltration, and runoff
• effect on the Earth’s surface: most erosion, and most sediment and sedimentary rock is due to the water cycle.

Question 22

• Plate Tectonics

Answer 22

motion and interaction of rigid, interlocking plate-like segments of Earth.
• Plate interaction causes deformation (bending and breaking)
• This results in tectonic (Earth building) activity such as:
- earthquakes
- volcanism
- mountain formation (orogensis)

Question 23

• Lithosphere:

Answer 23

• crust + uppermost mantle joined as a single rigid unit
• average thickness= 100 km (62 mi)
• this is what “plates” are made of

Question 24

• asthenosphere

Answer 24

• highly deformable (plastic) upper mantle

- allows plates to move

Question 25

• Divergent:

Answer 25

- as two plates pull apart and move away from one another - as they diverge, magma intrudes into cracks and forms new lithosphere - almost all occur along the central part (axis) of oceanic ridges - earthquakes and volcanic activity occur here

Question 26

• convergent:

Answer 26

- two plates collide and one is forced down under the other into the mantle where it is “recycled” - this causes quakes and violent volcanic activity - deep ocean trenches mark where one plate slips under the other - volcanic island arcs and continental volcanic arcs form next to them - when two continental plates collide, a great mountain range is formed

Question 27

• transform:

Answer 27

- two plates are sliding past one another along a transform fault - there is neither creation nor destruction of lithosphere - quakes and deformation occur - features on opposite sides of the boundary are offset