Geology Chapters 1-4

Front 1

examines the materials composing Earth and seeks to understand the many processes that operate beneath and upon its surface

Back 1

Physical Geology

Front 2

seeks an understanding of the origin of Earth and its development through time

Back 2

Historical Geology

Front 3

dates are placed in their proper sequence or order without knowing their age in years

Back 3

Relative Dating

Front 4

In an undeformed sequence of sedimentary rocks, each layer is older than the one above it and younger than the one beneath it.

Back 4

Law of Superposition

Front 5

Fossil organisms succeed one another in a definite, determinable order.

Back 5

Law of Faunal Succession

Front 6

Geographically widespread,
Easily Recognized, and
Restricted to a specific interval of geologic time.

Back 6

Index Fossils

Front 7

Earth’s four spheres

Back 7

Hydrosphere
Atmosphere
Biosphere
Solid Earth

Front 8

Layers defined by composition

Back 8

Crust
Mantle
Core

Front 9

Layers defined by physical properties

Back 9

Lithosphere
Asthenosphere
Mesosphere
Inner and Outer Core

Front 10

Most prominent feature of continents

Back 10

Mountain belts

Front 11

Most prominent topographic feature on Earth
Composed of igneous rock that has been fractured and uplifted

Back 11

Oceanic ridge system

Front 12

Cooling and solidification of magma (molten rock)
Examples include granite and basalt

Back 12

Igneous rocks

Front 13

Accumulate in layers at Earth’s surface
Sediments are derived from weathering of preexisting rocks

Examples include sandstone and limestone

Back 13

Sedimentary rocks

Front 14

Formed by “changing” preexisting igneous, sedimentary or other metamorphic rocks
Driving forces are increased heat and pressure
Examples include gneiss and marble

Back 14

Metamorphic rocks

Front 15

Evidence used in support of continental drift hypothesis

Back 15

Fit of the continents
Fossil evidence
Rock type and structural similarities
Paleoclimatic evidence

Front 16

proposed by Harry Hess in the early 1960s

Back 16

Seafloor spreading hypothesis

Front 17

Dates when the polarity of Earth’s magnetism changed were determined from

Back 17

lava flows

Front 18

was the most convincing evidence set forth to support the concepts of continental drift and seafloor spreading

Back 18

Paleomagnetism

Front 19

The earth has ______ major lithospheric plates.

Back 19

seven

Front 20

Largest plate is....

Back 20

Pacific Plate

Front 21

Divergent plate boundaries are also known as

Back 21

constructive margins

Front 22

Convergent plate boundaries are also known as

Back 22

destructive margins

Front 23

Tranform fault boundaries are also known as

Back 23

conservative margins

Front 24

Long-lived structures
Some originate at great depth, perhaps at the mantle-core boundary

Back 24

Mantle Plumes

Front 25

Forces that drive plate motion

Back 25

Slab-pull
Ridge-push
Slab suction

Front 26

Basic building blocks of minerals
Over 100 are known (92 naturally occurring)

Back 26

Elements

Front 27

Smallest particles of matter
Retains all the characteristics of an element

Back 27

Atoms

Front 28

A central region called the nucleus consists of...

Back 28

protons and neutrons

Front 29

Negatively charged particles that surround the nucleus
Located in discrete energy levels called shells

Back 29

Electrons

Front 30

Atomic Number =

Back 30

number of protons

Front 31

Atomic Mass =

Back 31

# of protons and # of neutrons

Front 32

Formation of a compound by combining two or more elements

Back 32

Chemical bonding

Front 33

Atoms gain or lose outermost (valence) electrons to form ions
Ionic compounds consist of an orderly arrangement of oppositely charged ions

Back 33

Ionic Bonding

Front 34

Atoms share electrons to achieve electrical neutrality
Generally stronger than ionic bonds
Both ionic and covalent bonds typically occur in the same compound

Back 34

Covalent bonding

Front 35

Valence electrons are free to migrate among atoms
Weaker and less common than other bonds

Back 35

metallic bonding

Front 36

sum of neutrons + protons in an atom

Back 36

Mass number

Front 37

atom that exhibits variation in its mass number

Back 37

Isotope

Front 38

Unstable isotopes emit particles and energy in a process known as

Back 38

radioactive decay

Front 39

Two basic categories of luster

Back 39

metallic and non metallic

Front 40

This test for minerals is generally an unreliable one.

Back 40

Color

Front 41

Color of a mineral in its powdered form

Back 41

Streak

Front 42

Resistance of a mineral to abrasion or scratching

Back 42

Hardness

Front 43

All minerals are compared to a standard scale called the...

Back 43

Mohs scale of hardness

Front 44

Fluorite, Halite, and Calcite all exhibit perfect

Back 44

cleavage

Front 45

Absence of cleavage when a mineral is broken

Back 45

Fracture

Front 46

Nearly ____ minerals have been named

Back 46

4000

Front 47

____ and ____ are the most abundant elements in the Earth's crust.

Back 47

Oxygen and Silicon

Front 48

Most important mineral group
Comprise most rock-forming minerals
Very abundant due to large % of silicon and oxygen in Earth’s crust

Back 48

Silicates

Front 49

Fundamental building block of all silicates is the

Back 49

Silicon-oxygen tetrahedron

Front 50

Most common mineral group

Back 50

Feldspar group

Front 51

________ (potassium feldspar) and _________ (sodium and calcium feldspar) are the two most common members

Back 51

Orthoclase and Plagioclase

Front 52

Only common silicate composed entirely of oxygen and silicon
Hard and resistant to weathering
Conchoidal fracture
Often forms hexagonal crystals

Back 52

Quartz (light silicate)

Front 53

Common member of the mica family
Excellent cleavage in one direction
Produces the “glimmering” brilliance often seen in beach sand

Back 53

Muscovite

Front 54

_____ minerals all have a sheet or layered structure
Most originate as products of chemical weathering

Back 54

Clay

Front 55

High temperature Fe-Mg silicates
Individual tetrahedra linked together by iron and magnesium ions
Forms small, rounded crystals with no cleavage

Back 55

Olivine group

Front 56

Single chain structures involving iron and magnesium
Two distinctive cleavages at nearly 90 degrees
Augite is the most common mineral in the group

Back 56

Pyroxene group

Front 57

Double chain structures involving a variety of ions
Two perfect cleavages exhibiting angles of 124 and 56 degrees
Hornblende is the most common mineral in the group

Back 57

amphibole group

Front 58

extrusive, or volcanic rocks

Back 58

Rocks formed from lava

Front 59

intrusive, or plutonic rocks

Back 59

Rocks formed from magma at depth

Front 60

Magma consists of three components

Back 60

Liquid portion = melt
Solids, if any, are silicate minerals
Volatiles = dissolved gases in the melt, including water vapor (H2O), carbon dioxide (CO2), and sulfur dioxide (SO2)

Front 61

Slow rate = fewer but larger crystals
Fast rate = many small crystals
Very fast rate forms glass

Back 61

Rate of cooling

Front 62

Rapid rate of cooling
Microscopic crystals
May contain vesicles (holes from gas bubbles)

Back 62

Aphanitic (fine-grained) texture

Front 63

Slow cooling
Large, visible crystals

Back 63

Phaneritic (coarse-grained) texture

Front 64

Minerals form at different temperatures
Large crystals (phenocrysts) are embedded in a matrix of smaller crystals (groundmass)

Back 64

Porphyritic texture

Front 65

Very rapid cooling of lava
Resulting rock is called obsidian

Back 65

Glassy texture

Front 66

Fragmental appearance produced by violent volcanic eruptions
Often appear more similar to sedimentary rocks

Back 66

Pyroclastic texture

Front 67

Most common extrusive igneous rock

Back 67

Basalt

Front 68

Separation of a melt from earlier formed crystals

Back 68

Magmatic differentiation

Front 69

Changing a magma’s composition by the incorporation of surrounding rock bodies into a magma

Back 69

Assimilation

Front 70

Two chemically distinct magmas may produce a composition quite different from either original magma

Back 70

Magma mixing

Front 71

Incomplete melting of rocks is known as

Back 71

partial melting

Front 72

Igneous rocks that form when molten rock solidifies at the SURFACE are classified as

Back 72

extrusive

Front 73

Igneous rocks that are formed at depth are

Back 73

intrusive

Front 74

basic building blocks or silicate minerals....

Back 74

silicon-oxygen tetrahedra

Front 75

3 Factors contribute to the textures of igneous rocks

Back 75

1. The rate at which magma cools
2. Amount of silica present
3. amount of dissolved gas in the magma

Front 76

Igneous rocks that form at the surface or as small masses within the upper curst where cooling is relatively rapid possess a very fine-grained texture termed ______.

Back 76

Aphanitic

Front 77

When large masses of magma slowly solidify far below the surface, they form igneous rocks that exhibit a coarse-grained texture described as ______.

Back 77

Phaneritic

Front 78

Granitic magma is rich in...

Back 78

silica

Front 79

Basaltic magma is low in...

Back 79

silica