ASBOG Flashcards
1
Q
Offset
A
The horizontal component of displacement measured perpendicular to the strike of the disrupted unit.
2
Q
Reverse Fault
A
A dip-slip fault in which the hanging wall has moved up relative to the footwall. The dip of the fault is between 45 and 90 degrees.
3
Q
Rule of V’s
A
The outcrop pattern of a formation as it crosses a valley forms a V shape (as viewed on a map). The V points in the direction that the formation underlies the valley.
4
Q
Strike Separation
A
The horizontal distance between a stratigraphic unit offset by a fault, measured along the strike of the fault. It is an apparent displacement.
5
Q
Strike-slip Fault
A
The horizontal distance between a stratigraphic unit offset by a fault, measured along the strike of the fault. It is an apparent displacement.
6
Q
Throw
A
The amount of vertical displacement on a fault, also, the vertical component of net slip.
7
Q
Thrust Fault
A
A reverse fault in which the fault plane dips less than 45 degrees.
8
Q
Type Locality
A
The place where a geologic feature (such as a fossil species) was first recognized and described. It contains the type section.
9
Q
Type Section
A
The originally described strata that constitutes a stratigraphic unit to which other parts of the unit may be compared. It is preferable to describe the location where the unit attains its maximum thickness and where the top and bottom unit are exposed.
10
Q
Unconformity
A
A gap in the geologic record; an interruption in the depositional sequence that implies uplift and erosion have removed part of the geologic record or non-deposition has occurred.
11
Q
Cenozoic
A
Present - 65 m.y.a | Quaternary (Age of Man) & Tertiary (Age of Mammals)
12
Q
Mesozoic
A
65 - 248 m.y.a | Cretaceous, Jurassic & Triassic (Age of Reptiles)
13
Q
Paleozoic
A
248 - 543 m.y.a | Permian - Mississippian (Age of Amphibians), Devonian & Silurian (Age of Fish), Ordovician & Cambrian (Age of Invertebrates)
14
Q
Precambrian
A
543 - 4200? m.y.a
15
Q
Law of Superposition
A
The oldest layer is on the bottom and the youngest layer is on the top. Assumes that the layers have not been overturned during deformation. Applies to any layered rock sequence.
16
Q
Yardang
A
A long, jagged, sharp-edged ridge between troughs, oriented with the direction of the prevailing winds, in an arid region which is underlain by relatively weak materials
17
Q
Ventifacts
A
Stones that have been abraded by the wind on at least one side so they are polished or faceted. They are usually only found in a unique environment of no vegetation, strong wind and plentiful sand.
18
Q
Pedestal Rocks
A
Commonly called balanced rocks, these formations are a results of a combination of wind and water erosion (deflation) in an area where there are resistant rocks capping weaker more easily eroded rocks.
19
Q
Blowout
A
A depression caused by deflation in an area where either migrating dunes exist or a small break develops in the surficial integrity of a stabilized windblown deposit or in some cases the underlying material is composed of a poorly to non-indurated material.
20
Q
Desert Pavement
A
Sometimes called desert armor, is a name applied to the relatively flat residual surface of closely-packed, wind polished stones. This type of condition is the result of the removal of the fine-grained particles by wind and sheetwash. Often these remaining stones are somewhat cemented in place.
21
Q
Ripples and ridges
A
Small-scale features that are usually found on the surfaces of sand deposits resulting from the flow of wind or water over the surface. The shape of the ripple mark can be an indicator of the direction of flow of the wind or water or of the depositional environment.
22
Q
Sand shadows and sand drifts
A
These two features are similar in that both form as a result of an obstruction in the path of migrating sands. The sand shadow forms behind the obstruction where the velocity of the wind declines causing the sand to drop. Sand drifts develop in the lee (downward side) of a gap where the velocity of the wind declines after passing through the gap.
23
Q
Dunes
A
Sand that is piled up as a result of transportation by the wind of sand sized particles. Often found in back beach areas or desert climates where the topography is relatively flat and the surface sand is dry. Most dunes are composed of a well-sorted sand.
24
Q
Barchan Dune
A
Crescent-shaped, tails to leeward, rarely vegetated
25
Parabolic Dune
Crescent-shaped, tails to windward often associated with some vegetative cover.
26
Transverse Dune
perpendicular to the wind, exhibits the traditional gentle windward slope and the steep slip face nearing the angle of repose. Both the Barchan and Parabolic dunes are a variety of transverse dune.
27
longitudinal or Seif Dune
Parallel to the wind, thought to develop in area in which the prevailing wind caused the dunes to lengthen in the direction of the wind but the dune height increases due to the cross winds during periods of irregular wind flow.
28
Whaleback or sand levees
Very large hill or ridge of sand elongated parallel to the prevailing wind. In general whalebacks do not migrate and can be over 100 miles long, a couple of miles wide and 150 feet high.
29
Undulations
similar to a whaleback but smaller
30
Sandsheets
extensive flat areas covered with a coarse-grained sand that does not form dunes, but typically are covered with ripple marks
31
Alpine Glaciation
Found in the mountainous areas particularly in the Rockies and the Cordilleran Ranges
32
Continental Glaciation
What covered much of the central and northern U.S. during the Ice Ages
33
Conditions for a Glacier
1. Large accumulation or mass of ice and snow
2. Must be located principally on land
3. Must be formed by the compaction and recrystalization of snow
4. Must be evidence of past or present movement
5. Remains from year to year
34
Cirque
Horseshoe-shaped hollow high on a mountainside that was created by the erosive action at the head of a glacier
35
Tarn
Small deep lake formed in a cirque basin
36
Glacial Polish
Smooth surface produced on bedrock by abrasion by the movement of a glacier
37
Striations
Lines scraped into the bedrock by rocks being carried along at the base of the glacier. Lines generally indicate the direction of glacier movement. Larger rocks create grooves or grooved rock that can be as big as a valley.
38
Glacial Trough (U-shaped Valley)
Steep-sided valley that extends down from the cirque in which glacial action has widened and deepened an existing valley
39
Glacial Steps or Stairway
Series of cross-valley steps extending down from the cirque which are characterized by a relatively flat floor or with a slight up-valley slope broken by steeper sections steepening down valley.
40
Paternoster Lakes
A series or chains of lakes occupying the glacial steps.
41
Hanging Valley
U-shaped glacial tributary valley truncated by a deeper U-Shaped glacial main valley leaving a valley whose mouth is relatively high on the main valley wall. The discordance is due to the greater erosive power of the main glacier
42
Arete
Jagged sharp sawtooth-like ridge that results form the growth of cirques on opposite sides of a mountain ridge by alpine glaciation.
43
Col
Narrow sharp-edged pass or sag between cirque head and side walls along an arete.
44
Horn
A jagged sharp peak at the high point in an arete which has been sculpted by the erosional action of three or more cirques. This pyramidal feature is the remainder of the original mountain summit in a region modified by alpine glaciation.
45
Monuments (tinds)
A horn that has been isolated by the lateral intersection of cirques.
46
Truncated or faceted Spur
Ridge, which once protruded into a pre-glacial valley, that has been truncated by the abrasion of glacial action as it straightened the valley. This feature characteristically has an inverted V-shaped face.
47
Fjords, fiards (fjards)
Submerged glacial trough or valley at its seaward end resulting from the raising of sea level as the glaciers melted. The fiard is a shallower and shorter, but often broader, feature than the fjord.
48
Trough Lakes
Similar to fjords in that they consist of a long glacial trough and contain water but are found above sea level.
49
Moraine
Mound or ridge composed of accumulated glacial drift or till deposited directly by the glacier. Moraines are composed of a heterogeneous collection of unsorted and unstratified clay, silt, sand, gravel and boulders.
50
End (terminal) Moraine
An arcuate moraine that has been deposited at the terminus of the glacier, marking the furthest progression of the glaciation. Older terminal moraines that are not the maximum extent of glaciation are typically destroyed by the subsequent glacial advances incorporation the older moraine material with the younger. Younger glaciations which do not exceed the maximum extent will deposit a series of moraine deposits called recessional moraines which are created during a temporary hiatus in the retreat of the glaciers.
51
Lateral Moraine
Linear moraine located along the edge of a valley glacier and composed of materials deposited on the glacier from the valley walls.
52
Medial Moraine
Linear moraine paralleling the valley walls which occurs when two valley glaciers merge joining the two inside lateral moraines from the two or more tributaries as they flow into the more major drainage.
53
Valley Train
Long, narrow deposit of outwash (sand and gravel), deposited by glacial meltwater, which begins at the end moraine and extends downvalley.
54
Lacustrine Plains
Plain that has formed by the filling of a lake with lake sediments and alluvium which has been deposited along the margin of the glacier. Characterized by very flat valley bottoms in hilly terrain.
55
Knob and Basin topography
Also called knob-and-kettle topography, a hummocky landscape consisting of knolls or mounds of glacial drift in an area also interspersed with basins or kettles. The basins often contain water.
56
Ice-scoured plain
Assemblage of erosional landforms on exposed bedrock resulting from the flow of an ice cap. Exhibits many of the same surficial features as are found in area of alpine glaciation such as striations, grooves and polished surfaces, as well as the development of roche moutonnees or mammillated surfaces
57
Roche Moutonnee
An elongated bedrock knob which is oriented parallel to the direction of glacial flow and has a smooth rounded upstream end and usually a steep rough downstream end where the glacier plucked out the rock as it moved away.
58
Streamlined Topography (mammillated surface)
Series of smooth rounded erosional rock mounds alternating with parallel valleys resulting from the smoothing off of a mountainous region by the ice cap.
59
Arcuate terminal moraine
Similar to that found in alpine glaciation
60
Till Plain
Also called ground moraine, deposition by an ice cap of glacial till forming a relatively flat to undulating surface which covers an extensive area and buries the pre glacial topography
61
Drift
Refers to all rock and associated material that has been carried by and deposited by a glacier, glacial ice, or water running from a glacier. This term is a general term and includes all those deposits that can be further described by the terms till, stratified till, and deposits of glacio-fluvial, glacio-lacustrine, glacio-eolian, and glacio-marine origin.
62
Till
An unsorted, unstratified glacial deposit composed of heterogeneous mixture of clay, silt, sand, gravel, and boulders. It is usually unconsolidated and deposited directly by glacier without having been reworked by meltwater.
63
Ground Moraine
Often used interchangeable with till plain. Can be composed of both the material contained within the glacier as well as that being moved along at its base.
64
End Moraine (continental)
The end moraines found at the maximum extent of a continental glaciation are similar to those found in alpine glaciation through tend to be much more extensive and often have less steep slopes,occasionally making it difficult to distinguish between the ground moraine and the end moraine materials.
65
Swell and Swale Topography
Till rich in clay may result in a gently undulating surface which often is also found in areas that have had multiple glaciations.
66
Drumlin
An elongated ellipsoidal feature which can be composed of a wide variety of till materials ranging from clays to relatively large rock fragments, some even have a bedrock core. These streamlined hills are usually clustered and are relatively near the terminal or recessional moraines. Many are thought to be formed by the flow of the ice around an obstacle which deposits the soil and rock materials when the stress is released after having passed the obstruction.
67
Outwash Plain
Broad plain composed of outwash, stratified debris that is carried by meltwater streams both in front of and beyond the terminal or end moraine. The outwash plain is typically comprised of coarser grained materials closer to the terminus of the glacier grading to finer material with increased distance.
68
Esker
Serpentine shaped deposits developed as the load carried by the streams flowing beneath, within and above the glacier, once it has become stagnant is dropped. They are stratified and have the appearance of inverted stream channels, often with branching and may join the outwash plain at the glacier margin
69
Kettle
Depression in the postglacial terrain formed by the melting of large stagnant ice block allowing the settlement of the overlying glacial drift. In some areas the outwash plains are pitted with many kettles. This could result from the stagnation of a laterally extensive sheet of ice with varying thickness.
70
Kame and Kame Terrace
Small hummock or terrace of ice-contact drift that has resulted from the deposition of sediment either in crevasses at the surface of the glacier, on the irregular surface of stagnant glaciers, or often from streams flowing at the edge of the glacier along the contact of ice with the valley wall. The materials are typically stratified and contain poorly sorted sands and gravel.
71
Condition of Karst Development
1. A soluble rock, preferably limestone, at or near the surface.
2. A dense rock, highly jointed and thin-bedded.
3. Entrenched valleys below uplands underlain by soluble and well jointed rocks.
4. Region of moderate to abundant rainfall.
72
Terra Rosa
Red clayey soil found mantling the ground surface and extending into joints or fractures resulting from surface or near surface solution, usually found on moderate to gentle slopes
73
Lapies
Grooved or fluted surface resulting from the solution of limestone at or near the surface in an area of high relief. The grooves range in width from a few millimeters to more than a meter in width and commonly results in knifelike ridges.
74
Sinkholes
Circular depression that is commonly funnel-shaped and can be a few feet up to a hundred feet in diameter. Most commonly observed feature of karst terrain.
75
Doline (sinkhole)
Solution of the rock beneath the rock.
76
Collapse Sink (sinkhole)
Collapse of the rock over an underground cavity
77
Compound sinkholes
Form as sinkholes enlarge and combine with adjoining sinkholes.
78
Sinkhole ponds or Karst Lakes
Pond or lake resulting from the clogging by clay of a doline sinkhole that perches water above the water table.
79
Swallow Holes
Hole in the bottom of a sinkhole which allows surface water runoff or streams to flow into the subsurface cavities
80
Karst Window
Hole in the ground in which one can observe an underground stream flowing from one cavern to another. A hole in a cavern which breaks the surface
81
Uvala
Elongated karst window that has occurred by the collapse of a extensive portion of a subsurface waterway, Can extend from 100 feet to a mile or more
82
Polje
Sinkhole formed by solutional modification of the rock (similarly to a doline) in a previously faulted or folded structure. This can be up to 30 miles or more in length
83
Solution-subsidence Trough
Non-tectonic feature, up to 10 miles in length, resulting from concurrent subsidence and solution along joints or faults
84
Sinkhole or Karst Plain
Limestone plain exhibiting sieve-like characteristics resulting from numerous sinkholes intercepting any surface water and diverting them to subsurface channels
85
Sinking Creeks
Any surface creek or stream which disappears underground in karst terrain/ many disappear in a swallow hole
86
Sink
Point at which sinking creeks end, often an observable swallow hole
87
Blind Valley
Valley that ends at a swallow hole due to a prolonged period of upstream erosion above the sinkhole
Solution valley or karst valley - a transitional feature between surface and subsurface drainage in an area of clastic rocks. A special type of blind valley
88
Natural Tunnels and Bridges
Features produced by the underground flow of water in karst terrain, when the tunnel sections collapse leaving only small segments, bridges are formed
89
Hum
Isolated hill remnants due to erosion by solution in karst terrain
90
Cavern
Larger caves that may extend in any direction, have one or several levels, and are created by solution of limestone along joints and bedding planes
91
Travertine
Deposit of calcium carbonate precipitate that can be found in limestone caverns coating the cavern walls, floors and ceilings
92
Dripstone
The travertine deposits that result from the calcium carbonate-rich water dripping from the ceiling of a cave or cavern. Stalactites are the downward protrusion of these deposits and stalagmites are the upward. protrusion.
93
Helictite
An irregular twig-like deposit forms in a cavern where there is not enough water to form drips but the surface remains damp or the water comes from tiny hole or tube within the deposit and the water flow out the end.
94
Law of Initial Horizontality
Assumes that the sequence of layers was deposited horizontally or nearly so, with the oldest layer on the bottom and youngest on top.
95
Faunal and Floral Evolutionary Changes
May be determined from the position of the fossil in the stratigraphic sequence.
96
Cross-cutting relationships
Useful in determining relative ages. If cross-cutting relationships exist, the feature that is cut is older than the feature that cuts across it. Rocks can be cut by intrusion, faulting, unconformities, or replacement minerals.
97
Correlation of units by Physical Continuity
Strata are generally continuous unless eroded, interrupted by faulting, truncated by an unconformity, shaped as a lenticular body, or deposited locally.
98
Correlation of units by Lithology
Only distinctive units may be used to correlate with a high degree of confidence. Many sedimentary units are composed of different lithologies deposited simultaneously
99
Correlation of units by Sequence of strata
Rock units may repeat in an orderly fashion allowing a correlation of the entire sequence to be made.
100
Correlation of units by Rock Properties
Strata may be correlated by means of their electrical or radioactive properties as measured on a well log.
101
Correlation of units by Key Beds
Layers that have been deposited simultaneously over large areas, volcanic ash, beds rich in fish scales, oysters or corals.
102
Correlation of units by Index Fossils
The ideal index fossils should be easily identified and distinguishable from other fossils, have lived during a short geologic time span, have lived in different environments, be distributed in a wide geographic area and be abundant. Examples of index fossils are graptolites and ammonites.
103
Correlation of units by Fossil Assemblages
Groups of several fossils species are more useful for correlations because there is a grater opportunity for the assemblage to be present than a single species.
104
Unconformities
Represent a time break in a sequence of beds
105
Angular Unconformity
Strata below the unconformity are cut off and are overlain at an angle by the beds above the unconformity. Separate units that have discordant strieks and/or dips.
106
Nonconformity
Sedimentary deposits rest upon older igneous or metamorphic rocks.
107
Disconformity
Beds above and below an unconformity are parallel, but the unconformity is not parallel to the bedding.
108
Paraconformity
Unconformity is parallel to the strata above and below it.
109
Anticline / antiforms
Upwarp. Shows oldest units at the center and younger units at edges when exposed at the surface / in map view.
110
Syncline / Synforms
Downwarp. Shows youngest units at the center and older units at the edges when exposed at the surface / in map view.
111
Sills
Concordant features emplaced along zones of weakness such as faults or sedimentary bedding planes parallel to other lithologic units.
112
Dikes
Discordant features that are parallel-sided, generally of constant thickness and relatively restricted in areal extent cutting across many lithologic units.
113
Cataclastic metamorphism
identified by faults that have a zone of breccia, cataclasite, or mylonite associated with them.
114
Regional Metamorphism
laterally extensive, covering the entire map. and includes rocks such as slate, phyllite, schist, gneiss, migmatite and eclogite.
115
Contact Metamorphism
Concentric bands around the boundaries of intrusive igneous rocks. The bands or rings are superimposed on other stratigraphic and structural boundaries. Hornfels is the characteristic rock.
116
Age of Man
Quaternary Period | Holocene & Pleistocene Epochs | Present - 1.8 m.y.a
117
Age of Mammals
Tertiary Period | Pliocene to Paleocene Epochs | 1.8 - 65 m.y.a
118
Age of Reptiles
Mesozoic Era | Cretaceous - Triassic Periods | 65 - 248 m.y.a
119
Age of Amphibians
Permian & Carboniferous Period | 290 - 354 m.y.a
120
Age of Fish
Devonian & Silurian Period | 354 - 443 m.y.a
121
Age of Invertebrates
Ordovician & Cambrian Period | 443 - 543 m.y.a
122
Life on Earth Sequence
1. Age of Invertebrates
2. Age of Fish
3. Age of Amphibians
4. Age of Reptiles
5. Age of Mammals
6. Age of Man
123
Tephrochronology
uses discrete layers of tephra-volcanic ash from a single eruption to create a chronological framework. Such an established event provides a "tephra horizon".
124
Paleomagnetism
the study of the record of the Earth's magnetic field in rocks, sediment or archaeological materials. Uses certain minerals in rocks that lock-in a record of the direction and intensity of the magnetic field when they form. Provides information on the past behavior of Earth's magnetic field and the past location of tectonic plates.
125
Palynology
"Study of dust" Uses particulate samples, organic or inorganic, to give clues to the life and environment that produced them.
126
Paleontology
Study of fossils to determine organisms evolution and interactions with each other and their environments.
127
Amino Acid Dating
Relates changes in amino acid molecules to the time elapsed since they were formed.
128
Obsidian Hydration Dating
A geochemical method of determining age in either absolute or relative terms of an artifact made of obsidian. Obsidian absorbs water when exposed to are at a well defined rate, this absorption can be measured with depth profiling.
129
Dendrochronology
Scientific method of dating tree rings to the exact year they were formed, this also can provide information on climate and atmospheric conditions.
130
Pedogenic Soil Dating
Examines the evolution of a soil in different environments to provide a Quaternary date for weathering.
131
Electron Spin Resonance Dating (ESR Dating)
Used to date newly formed materials which radiocarbon dating cannot or materials that have been previously heated like igneous rock. Measures the amount of unpaired electrons in crystalline structures that were previously exposed to natural radiation.
132
Thermoluminescence Dating
Measures the accumulated radiation does, of the time elapsed since material containing crystalline minerals were either heated or exposed to sunlight.
133
Fission Track Dating
Based on the damage trails, or tracks, left by fission fragments in certain uranium-bearing minerals and glasses.
134
Radiometric Dating
Technique used to date materials such as rocks or carbon in which trace radioactive impurities were selectively incorporated when they were formed. The method compares the abundance of a naturally occurring radioactive isotope within the materials to the abundance of its decay products which forma t a known constant rate of decay.
