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geomorphology > glaciers, igneous, folds and faults > Flashcards

glaciers, igneous, folds and faults Flashcards

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1
Q

What is epigenetic versus syngenetic permafrost?

A

Epigenetic forms from climate cooling(accumulation). Syngenetic is from a change in vegetation or increase of deposition of top soil. Peat provides insulation for more permafrost.

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2
Q

What is equilibrium line?

A

mass of ice in accumulation zone = mass of ice - forward movement out of zone + new accumulation.

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3
Q

What are taliks?

A

localized unfrozen layers, in continuous permafrost areas.

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4
Q

Where are taliks located?

A

Are on top, beneith, or in permafrost layers.

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5
Q

How do deformatable sediments affect ice movement?

A

sediments in the ice can take up strain. These sediments are water saturated and unconsolidated.

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6
Q

What controls height of moraine?

A

Size of glaciers

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7
Q

Is ice a plastic or brittle material?

A

both

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8
Q

What is dead ice?

A

When a glacier or ice sheet ceases to move and melts.

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9
Q

What is the difference between pluvial lakes and proglacial lakes?

A

Pluvial lowers the temp, reduces evap, and causes lake levels to increase. Proglacial is when glacial meltwater is damned by some sort of barrier. Commonly terminal or lateral moraines.

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10
Q

What is a dropstone?

A

Xenoliths inside strata of ice

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11
Q

What is a tillite

A

lothefoed till

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12
Q

What are drumlins?

A

Ellipitcally elongated hills, with axis paralell to glacial movement,and perpendicular to ice margin. Blunted upglacier and tapered down glacier.

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13
Q

What are theories on the oragin of drumlins?

A
  • subglacial streaming of obsticles that create resistance to glacial flow.
  • incremental accretion of till
  • lee side deposition (flutes)
  • subglacial fluvial erosion and deposition
  • differential erosion and deposistion within- subglacial deformable bed.
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14
Q

How do glaciers erode?

A

Abrasion

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15
Q

What factors control the degree and rate of abrasion?

A

How much debris, Addition of fresh debris, Type of debris, meltwater to remove floor and keep sharp edge, velocity of glacier over bed, thichness of ice, amount of basal water.

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16
Q

What are the types of crevesses?

A

Radial, longitudnal, transverse, and cheveron.

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17
Q

What erosional features are left by glaciers?

A

striations, grooves, polish, chattermarks, cresent fractures, fracture cracks, faceted grooves, cirques, aretes, horns, troughs, fijords, fingerlakes, rock drumlins.

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18
Q

What is the longitudinal profile like in many glacial valley?

A

very irregular with frequent changes in slope.

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19
Q

WHat features are associated with the topography?

A

Paternoster lakes/ cyclopean stairs

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20
Q

What are varves?

A

fine grained silt/clay couplets.

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21
Q

How do varves form?

A

Form in deep part of lakes, silt layers are graded but silt/clay couplet is not. Couplets represent one year of deposition.

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22
Q

How do flutes form

A

Long narrow parallel ridges. Long axis parallel to ice movement, often associated to drumlins. Thought to form when boulders become lodged in ice. As the ice flows around them it produces cavities. Then water saturated sediment is squeezed up into the cavity.

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23
Q

What are the depositional environments in a glacial setting?

A

Glacial-deposited directly from active or stagnant glacial ice. Till depo. Subglacial and soperglacial.
Resedimantation(mass wasting)- flow till
Glacial fluvial- deposited by meltwater streams
Glacial lacuatriane- Deposited in glacial lakes
Glacoal marine- deposited in marine estuaries and in ocean.

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24
Q

What are disintigration ridges and trenches?

A

Disintergration ridges-Hills with depression in the middle, can be circular or liner.
Distenergration trench- sediment fill ice valley, ice melts more sediment overlays ice, rest of ice melts forming a trench of arch where ice was last.

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25
How do they relate to pingos?
Area that is earth covered in ice
26
How does the fact that ice is anisotropic help in glacier movement?
It deforms on the 'A' axis more than 'C' axis. Compressive straights of ice are high on 'C' and weak on 'A'
27
What is a firn?
Intermediate state between snow and ice
28
What is glacial surging?
forward surging , several meter per day/ for weeks or months. Often follows stagnation of the front. Cuases thinning in upper segments. Surface is blocky with extensional crevasses. Terminal moraine contested.
29
What controls the speed of glaciers?
May relate to weather, fault slopes in glacier, sudden release of obstruction. Seasonal affects free water.
30
What are moulins?
Roughly circular vertical like shaft within glacier through which water enters from surface.
31
What is an arete?
steep ridges seperating cirques and or valley glaciers.
32
What is a horn?
A erosional landform the is at the intersection of 3 or more cirques.
33
What is a cirque?
An erosional landform that is bowl shaled hollow neat the head of glacier in a mountaious region, has steep headwalls and on the downvalley side.
34
What is a glacial trough?
U-shaped valley due to abrasion, plucking , widening, of orginal v-shaped vellay.
35
What is a fijord?
A erosional landform made of steep cliffs.
36
Paternoster lakes are what?
strong of lakes formed in glacial trough.
37
What is a whaleback?
A ersonial landform that is streamline, steeper portions downslope.
38
What is an ice wedge polygon?
contraction cracks often hexagonal pattern when viewed from above. Form from peat, occur in permafrost peatlands. Evidense of extreme cold.
39
What is a pingo?
dome shaped hill with ice core, bds dip outward from center, open, vertical gradient of flow, pressure. center water freezes as it rises, expands upward and pushes up material above. They often have ruptured tops.Closed starts in a lake, then the lake drains, freezing, zone rises as ground water freezes, excess pore water pressure pushes up the ground above.
40
What is a diamicton?
mixed compoition and fracture, compact and dense. depositied by ice or water from melting of ice.
41
Lodgement till(basal till) is what?
formed substancially under ice. due to frictional driving over irregualrited in the substratum. - Release of debris by pressure controlled melting. Deposited material is alligned parallel to ice direction very compact low porosity.
42
Ablation till is what?(also called meltout till or flow till)
formed by melting ice, stagnant glacier saturated sediments can flow. More porosity often sort sizes cawhat n be highly deffered.
43
What is a lateral moraine?
formed on valley glaciers from accumulation of rock debris along side of glacier. Preserved in subsequent valleys as they are above stream erosion level. Formed below equilibrium lines.
44
What are medial moraines?
formed by intersection of 2 tributary velleys and the their lateral moraines. Usually not preserved. Then and in middle of valley.
45
What are end moraines?
occur in single and contenital glaciers. ICe contact deposits made of till. Movement of debris later ice to snow requires glacier at equilibrium, lowering of ablation cover, squeezing out saturated substrata. ice pushing.
46
What is a terminal moraine?
represent the furthest advance of ice front
47
What is a ground moraine?
till deposited below ice lodgement of ablation fill, leaves low relief over hummocky terraine.
48
What is a dead ice moraines?
Disentigrating of moraines from which ice melt over a broad front. Landform k irregular, numerous depressions and mounds. knob and kettle topography.
49
What is an interlobate moraines?
contential glaciers, form lobes, those are moranies inbetween lobes. Can be very large, deposited between ice flows.
50
What are washboard moraines?
Low relief ridges, often parallel, evenly spaced, from annual accumulations during retreat, advances in winter retreats in summer.
51
How is the bottom of the Quaternery or plestiocene eroded?
Defined as the Gauss/ Matrani paleman epocj 2.588my
52
What is continueous permafrost?
exist over landscape as an uninterupted layer.
53
What is discontinuous permafrost?
extensive marginal zones at the edge of continous.
54
What is sporadic permafrost?
small islands of permafrost are stteled in unfrozen areas.
55
What is alpine permafrost?
found at higher elevations in areas outside continous or discontinous zones.
56
What are subsen permafrost?
frozen ground that exisits in the sediments beneth seawater.
57
What governs how igneous landforms will look?
1. Nature of extruded materials. (basaltic lava will spread over a large area produce land with subdued slopes, silica will not. 2. Distribution of vents and fissures. 3. Volume of outpourings 4. duration of volcanism 5. Age of volcanic activity 6. intensity of erosonal activity
58
What si a dike?
a discordant, cut across bedding, can cross each other. and terminate abruptly
59
What is a sill?
A concordant form that often forms resistant ledges or caps.
60
What is a laccolith?
Concordant masses that dome country rock
61
What are iclandic fissures?
Basaltic fissure eruptions that are free flowing Ex. columbia river basalt.
62
What are hawian eruptions?
sheilds and some fissures. Fissures, caldreas, pits, and mobile lava with some gas. minor ash, and occaional rapid gas
63
Strombolian eruptions are?
small intensity eruptions of basaltic lavas. Charaterized by intermittent explosions or fountaining. fragment and bombs each eruption episode from gases.
64
What is a vulcaran eruption?
more intemse ertuption. Lava fragments may be too viscous and dont form andecitic dacrtic bombs.
65
What is a vesuvian eruption?
Violent sxpulsion of gas charged magma from stratocone vent. usually after long period of mild activity. Usually centered to a considerable depth. Lava ejaculated in explosive spray, repetadly, tephra
66
What is a cinder cone?
Small area , steep sides bowl shaped in center, may be alinged with fractures, lava frequently extruded from the bottom of cones, unconsolidated material, easily erode. May be parasitic.
67
What is a caldera?
Large depressions, massive eruptions of voluminous pyroclastic sheetflows.
68
What is a splatter cone(hornito)?
usually driven by magmatic explosions. may take the ofrm of ramparts or small steepsided structures. developes when lava is forced up throght an opening in the cooled surface of a flow and the accumuates around the opening.
69
How does silica content, viscosity, and gas content direct the type of volcano that forms?
Silica content more silica makes for higher viscosity. Gas in these high viscosity magma makes them more explosive.
70
What is a Maars?
Explosive eruption the lead to shallow below surface crater.
71
What is a tuff cone?
controlled by water in contact with magma. Hot dry tephfra builds scoria cones. Wetter will form tuff rings and very wet will form a tuff cone.
72
What is a fissure eruption?
Flood basalt plateaus and plaines cover areas exceeding 1000km2. Generally low relief. Sometimes step like from erosion and flows.
73
What is a dome?
Formed from viscous silictic lava. If lava dome grows entirly by internal inflation similar to a ballon is called an endogenous dome. If magma breaks the surface of dome flank and adds layers this is exogenous.
74
What is a shield volcano?
Low profile, very large, overlapping flows, some fissures in flanks, cinder cones on shield, large central crae, gentle slopes.
75
What are composite Volcanoes?
Strato volcatio steep sided radial drainage, central crater. Steeper slopes or flancks. Steep slope near the summit becuase of viscous lava. gentle slopes of base becuase base is composed of a accumulation of eroded material.
76
What are the two main lava types?
Felsic-fledspar, quarts, grantie, rhylitte, dacite, domes, high viscoisty explosive. Mefic-silicate magma rich in magnesium or iron. Low viscosity less explosive. Hawaii
77
What is an axial plane?
surface which divides a fold as symmetrically as possible.
78
What is a hinge line?
line along which the maximum curvature of a fold occurs.
79
What is a plunge?
Angle of hinge line to horizontal plane.
80
What is a trend?
Compass orientation of plunge.

geomorphology (2 decks)

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