Geology 100 - Exam 2

Front 1

What is weathering?

Back 1

the process at the earth's surface that breaks down mineral and rocks

Front 2

What is erosion?

Back 2

transport of sediment formed from weathering

Front 3

What are the 2 basic types of weathering?

Back 3

mechanical and chemical

Front 4

What is mechanical weathering?

Back 4

breaks into smaller pieces but doesn't change chemical make-up (eg. freezing water)

Front 5

What is chemical weathering?

Back 5

converts to minerals and rocks stable at earth's surface

Front 6

True or false: all weathering occurs at earth's surface.

Back 6

false

Front 7

What are the different types of mechanical weathering?

Back 7

-frost wedging
-crystal growth
-thermal expansion and contraction
-mechanical exfoliation
-other (plants, abrasion in streams, glaciers, and wind)

Front 8

What is dissolution?

Back 8

-chemical weathering
-solution by water

Front 9

What is oxidation?

Back 9

-chemical weathering
-combine with O2, Fe in silicate minerals

Front 10

What is hydrolysis?

Back 10

-chemical weathering
-Al rich silicates (feldspars) going to clay. *yields soil

Front 11

What affects weathering process speed?

Back 11

-climate (temp and presence of water --the higher the temp and more water, the faster reaction)
-living organisms (acids, burrowing, etc.)
-time (glacial, old/new)
-mineral composition (bonding olivine/quartz)

Front 12

What are products of chemical weathering?

Back 12

-clay minerals (kaolinite, smectite--swelling clay, absorbs water)
-metal ores (bauxite)
-minerals formed function of temp and water present

Front 13

Soils upper surface of regolith (rock) - nature determined by:

Back 13

-parent material
-climate (temp and water)
-topography (location, landforms)
-vegetation
-time

Front 14

What is eluviation?

Back 14

water percolates down soil column, transporting organic material and soluble inorganic matter

Front 15

What is illuviation?

Back 15

materials transported from upper soil horizons are deposited

Front 16

Do limestone and quartz (sandstone) yield a lot of soil?

Back 16

no, very little

Front 17

Talk about CENEX.

Back 17

Washington State mixed its metallic waste in with fertilizer and sold it to farmers who applied it to their crops thru center-pivot irrigation systems

Front 18

Talk about ALCOA.

Back 18

saved $2 million by marketing its smelter waste as road de-icer in the winter and fertilizer in the summer.

Front 19

What is David R. Montgomery's book "Dirt: Erosion of Civilization" about?

Back 19

traces history of major civilizations and ties their decline to abuse of soil

Front 20

What makes up more than half of all sedimentary rocks?

Back 20

mudstones

Front 21

What are detrital sedimentary rocks?

Back 21

rocks formed from pieces of pre-existing rocks or organic debris

Front 22

What are sandstones?

Back 22

usually quartz and feldspars, when cemented can be very hard

Front 23

What is the difference between conglomerates and breccias?

Back 23

-conglomerates- if particles are rounded
-breccias- if particles are angular

Front 24

What is limestone?

Back 24

-inorganic chemical sedimentary rock
-calcite precipitate from water, travertine, or tufa (springs)

Front 25

What are stalactites and stalagmites?

Back 25

cave structures:
-stalactites go down
-stalagmites go up

Front 26

What are biogeneic limestones?

Back 26

-biogeneic chemical sedimentary rock
-CaCO3 shells and external skeletons, formed along shallow coast lines

Front 27

What are biogeneic cherts?

Back 27

-biogeneic chemical sedimentary rock
-silica of raidolara, diatoms, and sponges

Front 28

What is coal?

Back 28

-biogeneic chemical sedimentary rock
-mostly plant remains, buried and compacted in O2 poor environment

Front 29

Name biogeneic chemical sedimentary rock (7).

Back 29

-biogeneic limestones
-biogeneic cherts
-coal
-peat
-lignite
-bituminous
-anthracite

Front 30

What are facies?

Back 30

a body of rock with specified characteristics.[1] Ideally, a facies is a distinctive rock unit that forms under certain conditions of sedimentation, reflecting a particular process or environment.

Front 31

What are the 2 types of sediment?

Back 31

-detrital (most are)
-chemical

Front 32

What is detrital sediment?

Back 32

transported solid fragments weathered from pre-existing igneous, sedimentary, or metamorphic rocks

Front 33

What is chemical sediment?

Back 33

previously discovered either precipitate from solution or ore extracted from water by living organisms

Front 34

What are sedimentary structures (bedding)?

Back 34

arrangement of sediment particles into distinct layers of differing sediment compositions or grain sizes

Front 35

What is graded bedding?

Back 35

single sediment layer in which particle size varies

Front 36

What is cross bedding?

Back 36

sedimentary layered deposited at an angle to the underlying set of beds

Front 37

What are ripple marks?

Back 37

indicate that wind or water currents shaped the particles into a series of shallow curving ridges

Front 38

What is lithification?

Back 38

the conversion of loose sediment into solid sedimentary rock

Front 39

What is metamorphism of rock?

Back 39

process by which temperature, pressure, and chemical reactions deep within the earth alters the mineral content and structure of pre-existing rock with melting it
-usually round 1,000's of meters below earth's surface and seen only when uplift and erosion have stripped away overlying rocks

Front 40

Where are rocks and minerals most stable?

Back 40

in the environment in which they form

Front 41

Rather than melting under increased heat and pressure to form magmas, metamorphism involves a transformation in the ________ ________.

Back 41

solid state

Front 42

Clays formed at earth's surface on heating will _______________________.

Back 42

recrystalize to form new minerals

Front 43

True or false: Quartz will change size and shpae but remain quartz.

Back 43

true

Front 44

What is geothermal gradient?

Back 44

heat increases within depths of earth

Front 45

Does pressure increase or decrease with depth?

Back 45

increase

Front 46

What are the 2 types of pressure?

Back 46

-lithostatic (directional)
-confining

Front 47

What does directed pressure produce?

Back 47

foliation or parallelism of mineral grains

Front 48

What do circulating fluids do?

Back 48

-provide medium for movement of ions within rock
-contribute foreign ions to metamorphic reactions

Front 49

Describe contact metamorphism.

Back 49

-caused by migrating magma- local effect
-heat of magmas
-hot circulating fluids
-pressure is not a significant factor
-aureole - cm/m around dike, km batholith

Front 50

Describe regional metamorphism.

Back 50

-thousands of km2
-buried metamorphism - 10 km nonfoliated, Gulf Coast area
-dynamothermal metamophism - at core of most major mountains, typically foliated

Front 51

What is hydrothermal metamorphism?

Back 51

chemical alteration by hot water- ocean ridges olivine to serpentine

Front 52

What is fault metamorphism?

Back 52

friction yielding heat and directed pressure. cold faults/ warm<-- if ground water circulates through

Front 53

What is shock metamorphism?

Back 53

meteorite, very high temp and pressures, unique mineral. stishovite

Front 54

What is pyrometamorphism?

Back 54

lightning or burning coal

Front 55

Name 4 foliated metamorphic rocks.

Back 55

-slate
-phyllite
-schist
-gneiss
(increase heat and pressure as you go down)

Front 56

Name 3 nonfoliated metamorphic rocks.

Back 56

-marble
-quartzite
-hornfels
(contact with hot magma)

Front 57

Describe nonfoliated metamorphic rock.

Back 57

-no directional pressure
-deep burial or heat from magma
-marble from pure limestone and dolomites
-quartzite from pure quartz sandstones, very hard with quartz cement
-hornfels- heat drives off mineral bond water in shales, slates or...

Front 58

What is low metamorphic grade?

Back 58

can still identify rock

Front 59

What is high metamorphic grade?

Back 59

have lost all of their original structures

Front 60

True or false: One million years is virtually instantaneous in geologic time.

Back 60

true

Front 61

What is relative dating?

Back 61

-comparing layers (older layers = older)

Front 62

What is numerical dating?

Back 62

absolute dating

Front 63

What is uniformitarianism?

Back 63

present is the key to the past, have to consider how earth has evolved

Front 64

What is horizontally/ super-position?

Back 64

most sediment deposited from water is horizontal, so rocks on top are younger

Front 65

What is inclusion?

Back 65

fragments of rocks in a rock must be older

Front 66

What are unconformities?

Back 66

rock layers don't match but you know bottom is old

Front 67

What are the different types of relative dating?

Back 67

-uniformitarianism
-horizontally/super-position
-cross-cutting

Front 68

Describe numerical age - isotope.

Back 68

-radioactive isotopes- parent to daughter resulting in new element
-know that daughter element was not present in original mineral
-rate of decay- different
-isotopes more accurate for igneous rock
-age of rock/rate of decay- may be difficult if weathering
-although scores of isotopes only a few are useful for dating
-C-14 - 100-70,000 years

Front 69

What is fission track dating?

Back 69

-numerical technique
-decay particle leaves track in mineral - crystal, count tracks

Front 70

What is dendrochronology?

Back 70

-numerical technique
-tree rings

Front 71

What are varves?

Back 71

-can be used for numerical dating
-paired layers of sediment in lakes

Front 72

What are lichen?

Back 72

-can be used for numerical dating
-size of lichen related to age

Front 73

True or false: There are not distinct patterns representing droughts, fires, etc. shown in tree rings that can be correlated from tree to tree

Back 73

false

Front 74

What are the 2 types of isotopic numerical dating?

Back 74

-dating of rocks
-dating of organic matter

Front 75

What are the 3 types of other numercial dating?

Back 75

-botanical growth rates
-geologic processes
-nuclear processes

Front 76

What are the 2 types of botanical growth rates for numerical dating?

Back 76

-lichenometry
-dendrochronology

Front 77

What is the type of geological process for numerical dating?

Back 77

varve chronology

Front 78

What are the 2 types of nuclear processes for numerical dating?

Back 78

-fission track
-surface exposure (cosmogenic isotope)