Geo Final Flashcards
1
Q
weathering
A
the way a rock falls apart
- creates sediment
2
Q
rock
A
an aggregate of minerals
3
Q
mineral
A
naturally occurring substance composed of a specific ration of chemical elements arranged in a specific crystalline structure
4
Q
2 types of weathering
A
- physical
2. chemical
5
Q
importance of w to weathering
A
- w is a polar molec
- w expands by 9% when it freezes
- w is common on eth in all 3 phases
- universal solvent
- if it is not a part of the chem rxn, it provides a place for one
6
Q
sedimentary rocks
A
rocks that form as the result of: 1. weathering 2. erosion 3. transport deposition 5. precipitation 6. lithification
7
Q
erosion
A
how sediment is set in motion
8
Q
transport
A
the way sediment moves once it is in motion
9
Q
deposition
A
the way sediment stops moving
10
Q
4 forces that cause weathering erosion, transport, and deposition:
A
- moving w
- moving air
- moving ice
- gravity
11
Q
precipitation
A
a form of deposition that happens when new mineral crystals form from elements in solution
12
Q
lithification
A
the transformation of loose sediment into solid srock
13
Q
how is lithification accomplished (2)
A
- compacting
- cementing
14
Q
porosity
A
the space btwn sediment grains
15
Q
permeability
A
a measure of how well connected the pores are
16
Q
cementing sediment
A
sediment is cemented to form a solid rock when w infiltrates into the pores and ppttn creates new minerals in the pores that bind the sedi together
17
Q
clastic sedi rocks
A
rocks made up of clasts or rock fragments
18
Q
threshold velocity
A
the speed of w necessary to move a grain of a certain size (erosion)
19
Q
clay minerals (2)
A
flat silicate minerals that have:
- a shape like a piece of paper
- an electrical charge
20
Q
are clay minerals easy to erode?
A
no because they stick together because of their charge
21
Q
sorting
A
the range of rock sizes
22
Q
well sorted
A
a narrow range of sizes
23
Q
poorly sorted
A
a wide range of sizes
24
Q
sphericity
A
the shape of a grain (high/low)
25
roundness
the surface of a grain (round/angular)
26
composition
minerology of the grains in a rock
27
do mafic or felsic minerals weather faster?
mafic
28
work is done to sediment by (4)
1. moving w
2. moving ice
3. moving air
4. gravity
29
source area
the point of origin for sedi
30
inertia
the tendency of a moving object to stay in motion; ensures transport continues over time and distance
31
as sedi moves from high to low (4)
1. grain size dec
2. sorting improves
3. sphericity inc
4. roundness improves
32
work increases with (2)
time and distance
33
moving from high to low, larger grains (2)
1. are left behind b/c they are harder to move
| 2. break apart to become more smaller grains
34
how does composition change going from high to low?
becomes simpler as heavier mafic grains are left behind, or they weather and disappear
35
what is the least mature rock?
breccia
36
what is the most mature rock?
claystone
37
3 common types of sandstone
1. lithic
2. arkosic
3. quartz
38
sedimentary structure
a physical feature, most commonly a layer, because of a preferred arrangement of grains
39
why is a layer/bed (injection feature) important?
reps a unique env of deposition, and maybe weathering, erosion, and transport
40
why is the bottom contact of a layer important?
where and when the unique env started
41
why is the top contact of a layer important?
where and when the unique env ended
42
horiz bedding
a layer of sedi that is has parallel upper and lower contacts parallel to the eths surface
43
internal structure of a horiz bed
uniform
44
how is a uniform layer created?
fine sedi in suspension sinks to the bottom
45
graded bedding texture
not uniform
46
normal graded bedding
grain size decs from lower to the upper contact
47
how is normal graded bedding created
over time w velocity dec'd
48
reverse graded bedding
grain size inc from lower to upper contact
49
what is reverse bedding a result of (2)?
processes after deposition
50
kinetic sieving
little things fall through large as things are shaken
51
dispersive pressures
big ones rise above (mosh pit)
52
cross bedding
layers of sedi that are inclined at an angle to eths surface
53
what does cross bedding indicate?
flow in 1 direction
54
how does cross bedding form (2)?
- fast moving w from the river enters the lake/ocean and stops
- the sedi is deposited
55
ripple bedding (2)
consists of linear ridges of sedi of diff lengths
| - either symmetrical or asymmetrical
56
internal structure of an asymmetrical ripple
cross beds all facing 1 direction
57
internal structure of a symmetrical ripple
cross beds facing in two opposite direction
58
where does ripple bedding form?
shallow turbulent w moving in 1 or 2 directions with an abundant supply of sand moving as bedload
59
bedload
sedi that is rolling, sliding, or bouncing along the bottom
60
massive bedding (2)
1. uniformly mixed
| 2. poorly sorted
61
how was deposition in massive bedding?
very rapid, due to a sudden drop in w velocity before it could be sorted
62
how do chem sedi rocks form?
when a new mineral pptts from elements/molecs in solution
63
coral reef
long, linear ridge found in a shallow marine setting; limestone
64
formation of reef
calcite remains of marine orgs accumulate on the sea floor
65
conditions of reef formation (4)
- warm w (over 20 deg)
- w w/ normal salinity
- w that is clean and clear so sunlight can penetrate + filter feeding orgs are not harmed
- w that is circulating so that enough O is available
66
formation of dolomite
alteration product of limestone, forms when a change in mineralogy occurs in the ocean (Mg)
67
coal
partially preserved terrestrial plant remains
68
oil/gas//hydrocarbons
partially preserved remains of aquatic plants/algae
69
formation of oil/gas conditions (3)
1. O is absent
2. clastic sedi deposition is slow
3. w circulation is minimal
70
source rock (4)
1. rock where oil is made
2. often black shale
3. high porosity
4. low permeability
71
reservoir rock (4)
1. where oil is stored
2. often lime or sandstone
3. high porosity
4. high permeability
72
cap rock (4)
1. what stops the oil
2. often a salt
3. low porosity
4. low permeability
73
fossils
the remains of plants and animals partially preserved in the geological record
74
geological record includes (4)
1. rock
2. sedi
3. soil
4. ice (glaciers)
75
most fossils are (2)
shells + bones
76
trace fossils
evidence for the presence of plants of animals; burrows, footprints, etc.
77
4 causes of sea level change
1. ice ages (formation/melting)
2. plate tectonics (growth/movement changes the size of the oceans)
3. thermal expansion of the ocean as it heats up
4. local variations in geology (sedi)
78
typical coast (3)
- shallow w sandy beach
- coral reef further offshore
- deepw mud well offshore
79
what happens to deposits as w rises?
shift toward shore
80
unconformity
a surface that reps where something is missing in the geological record
81
what type of rock are in our coastal ranges?
igneous
82
what type of rock makes up the rockies?
sedi
83
metamorphic rocks
rocks that form when a pre-existing rock is altered by heat and pres w/ no sig melting
84
the 2 physical forces that can change a rock
1. pres
| 2. stress
85
pres (3)
- forces are = in all directions
- changes volume and density
- does not change shape
86
stress (3)
- forces not =ly applied in all directions
- change in shape
- does not change volume or density
87
compressive stress
un= forces directed inward results in upward oval
88
tensional stress
un= forces directed outward results in horiz oval
89
shear stress
forces moving side-by-side result in slanted ovals
90
metamorphism is caused by (4)
- heat
- pres
- stress
- w
91
strain
how a rock responds to pres/stress; change in shape
92
3 types of strain
1. elastic (retains)
2. plastic (deformed)
3. brittle (broken)
93
3 factors that affect metamorphism
1. heat (minerals)
2. w (superheated)
3. composition of original rock
94
what happens to a rock during metamorphism (6)?
1. some original minerals will disappear
2. new minerals form
3. mineral crystals get larger/combine
4. density of rock inc
5. some original structures (horiz bedding) disappear
6. new structures (foliations) form
95
4 common meta rocks
1. slate
2. phyllite
3. schist
4. gneiss
96
meta formation
beginning w/ shale and inc temp/pres/depth - slate, phyllite, schist, gneiss
97
low grade meta rock
slate
98
high grade meta rock
gneiss
99
types of metamorphism (4)
1. regional (high heat/pres)
2. dynamic (low heat/high pres)
3. contact (high heat/low pres)
4. hydrothermal metamorphism/metasomatism (heat, pres, w)
100
craton
a very old, very stable mass of mostly meta rock that makes up the interior of all continents
101
what is an example of an exposed craton
the Canadian Shield
102
facies
a collection of rocks and minerals and their features (structure) that rep a particular env
103
metamorphic facies
a set of meta rocks and minerals that rep the heat and pres in a particular meta env
104
geological time main principles (4)
1. uniformitarianism
2. catastrophism
3. actualism
105
uniformitarianism (2)
- the eth formed by way of slow consistent forces that have always been the same
- suggests the eth is very old
106
catastrophism (2)
- eth formed due to catastrophic events
| - eth not very old
107
actualism
eth formed and will probably continue to form as a result of slow consistent processes periodically interrupted by catastrophic events
108
superposition
sequence: oldest rocks on the bottom and youngest on the top
109
original horizontality
rock layer that is tilted or folded was originally deposited as a horiz layer
110
lateral continuity
rock formations that are found at diff locations were once part of the same continuous formation
111
inclusions
a rock formation inside another is always older
112
cross-cutting relationships
a rock that cuts across another is always younger
113
fossil succession (3)
- oldest fossils are simple
- newer fossils are more complex
- fossils + the life forms they depict get more complex w/ time
114
relative (2)
- comparison of diff events/features
| - determine which is older and which is younger
115
absolute
determination of the age of an event/feature in yrs
116
isotope
an atom that has diff #s of neutrons and therefore diff masses
117
stable isotope
does not decay
118
radiogenic isotope
decays/changes
119
half-life
the time it takes for 1/2 the parent isotopes to become daughter isotopes (ratios tell ages)
120
non-conformity
separates 2 diff and incompatible rock types
121
disconformity
separates 2 similar rock formation that have diff ages based on isotopes/fossils
122
angular unconformity
separates 2 rock formations that have diff orientations
123
when do folds and faults occur?
when a rock is subjected to stress which changes its shape
124
anticline
fold upward
125
syncline
fold downward
126
what type of stress is a symmetrical fold caused by?
compressive
127
what type of stress is a, asymmetrical fold caused by?
shear
128
does tensional stress cause folding?
no
129
what type of stress causes a reverse fault?
compressive
130
what type of stress causes a normal fault?
tensional
131
what type of stress causes a strike slip fault?
shear
132
groundw
water held underground in the soil or in pores and crevices in rock
133
w table
the surface that separates the saturated zone (all pores full of w)
from the non-saturated zone
134
is the water table always flat?
no; waves w/ the ground
135
what happens when too much ground is removed (2)?
1. w table is lowered
| 2. sometimes even the ground is lowered
136
fossil w
w deposited in the ground during past conditions (limited resource)
137
eg. of a Canadian aquifer
Ogallala aquifer (rockies)
138
Hadean Eon (2)
- 4/65-4.0 bya
| - any rocks formed were recycled b/c the eth was very hot
139
Archean Eon (3)
- 4.0-2.5 bya
- solid mafic crust started to form as the eth cooled (oceanic)
- eventually cc formed (small, fast moving)
140
Proterozoic Eon (6)
- 2.5bya-570 mya
- cont to cool
- oceanic crust thickens
- cp's inc in size as more felsic minerals form and the smaller plates join together (fewer, larger, more slow moving plates)
- O starts to appear in sig [] in the atmos
- large stable land masses + O-rich atmos = abundant complex life
141
Paleozoic Era (3)
- 570-250 mya
- 3 orogenies/mountain building episodes in eastern NA due to plate convergence (sedi)
- along now NA, then a passive plate margin existed
142
Mesozoic Era (2)
- 250-65mya
- plate convergence (op vs cp) along the W coast of NA (mtns created separated and new sources of sedi)
- later, mtn building shifted E b/c of the subducting op @ a shallower angle, which created a wider mtn belt in the W coast (inc volcanism)
143
Cenozoic Era (2)
- 65mya-today
| - plate margin on W coast of NA went from being mostly c vs o convergent, to one that includes transform and divergence
144
eg. of transform margin
S Cali
145
eg. of divergence
N BC
146
egs. of convergence (3)
- N Cali
- Oregon
- Washington
147
last ice age was caused by (5)
1. presence of large land masses at high latitudes
2. separation of cold polar ocean w from warm equit w's
3. formation of Isthmus of Panama
4. red CO2 in the atmos
5. changes in the amount of solar rad received by eth
148
Isthmus of Panama (3)
- land bridge that connects N and S America
- deflected warm E/W ocean currents at the eqt N
- created the Gulf Stream in the atlantic o, which provided snow to glaciers of NA
149
what does a reduction of CO2 do to the atmos?
supports colder temps
150
what is CO2 red caused by?
plate tectonics and the uplift of the Himalaya mtns (shifted monsoon; inc'd weathering; removed CO2)
151
what changes the amount of solar rad received by eth (3)?
- changes in the size of eths orbit around the sun
- changes in the tilt of the eths axis
- changes in the wobble of the eths axis
152
Milankovitch cycle
a sig change in the amount of solar rad hitting eth that occurs about every 96,000 yrs
153
5 hazards along the sea-to-sky?
1. earthquakes
2. steep mtn slopes (mass wasting)
3. volcanism (weak volcanic rock prone to failure btwn eruptions)
4. extreme weather (ppttn = lubrication)
5. old glacial deposits (stranded sedi)
154
4 forms of mass wasting
1. falls
2. slides
3. flows
4. creep
155
coastal flooding
strong sustained winds blowing from the o to the land will generate larger, more freq waves
156
storm surge
w trapped against the shoreline results in a temp inc in sea lvl
157
what causes coastal flooding?
storm surge
158
what is an eg. of coastal flowing?
gulf of Mexico
