Exam 3 Flashcards
Where is groundwater present?
Where minerals in the crust have pores or fractures
What is an aquifer?
An underground layer of water-bearing, permeable rock
What is an aquitard?
An impermeable or low permeability sediment or rock that hinders water flow
Where is most freshwater found?
In the ground as groundwater
What is a water table?
A boundary zone which separates unsaturated zones from saturated zones
How does the water table rise and fall with the seasons?
Water table is higher during wet seasons, and lower during dryer seasons
What is porosity?
The total volume of open space within sediment or rock
What is the difference between primary and secondary porosity?
Primary forms within the sediment, while secondary develops later
What is permeability?
The flow of water due to the connectedness of pore space
What is an unconfined aquifer?
An aquifer which intersects/ comes in contact with the surface
What is a confined aquifer?
An aquifer which exists beneath an aquitard
What is a disadvantage of an unconfined aquifer?
They can be easily contaminated
What is Darcy’s law?
An equation that describes the flow of a fluid through any porous space
What is a recharge area?
An area which water permeates the rock into an underground reservoir or an aquifer
What is the difference between a connected and disconnected losing stream?
The placement of the water table
What is hard water?
Water with high levels of calcium or magnesium
How can deserts be classified?
Based on how much rainfall it receives per year (Less than 25 cm)
Are deserts always hot?
No
What is the orographic effect?
As the air cools, water precipitates and falls
Is climate change normal? What isn’t normal about our sudden increase in climate?
Climate change is normal, but the rate of modern-day climate change isn’t
How is the heat of the planet controlled?
By the oceans
What is a major factor that determines where the location of deserts?
Atmospheric moisture circulation
At what latitudes are deserts found at?
30 degrees North, 30 degrees south
What are some other factors which contribute to the formation of desserts?
Cold ocean currents adjacent to a tropical desert, poor management of farmland, deforestation
What is an important geological agent when it comes to the formation of deserts?
Wind
What is suspension?
Silt carried in suspension produces well-sorted deposits with distance
What is loess?
Silt left by continental glaciers
What are desert pavements?
Deposit of sediment after fine grains blow away
What is a yardang?
Rock outcrop sculpted by sand abrasion
What are some factors which determine how sand dunes are created?
Abundant of loose sediment, energy to move sediment, obstacle to trap sediment and a dry climate
How are arid landforms created
They can be shaped by water, thus flash floods are common
What are playa lakes?
Products of rainfall and evaporation (usual ephemeral pools of water in a desert)
What is desertification?
When land loses its vegetation and turns into a desert
What is a glacier?
A thick mass of recrystallized ice, which lasts all year long
How are glaciers formed?
Snowfall accumulates and survives the following summer, snow burial causes compaction
What are the three conditions to form a glacier?
Cold climate, snow must be abundant (more snow than snow melt), snow must not be removed by other agents
What are the two types of glaciers?
Alpine (mountain) and continental (ice sheets)
What is the flow of alpine glaciers?
Flow from high to low elevation in mountainous settings
How do continental glaciers flow?
Ice flows out from the thickest part of the ice sheet
Where are two major ice sheets on Earth?
Greenland and Antarctica
How does glacial ice move?
Basal sliding, and plastic deformation
What is basal sliding?
Meltwater forms at the base of glacier, water decreases friction as ice slides downwards
What is plastic deformation?
Under high pressure, rather than breaking, ice bends much like plastic
At what depth does plastic deformation occur?
60 m
What factors impact how fast a glacier moves?
Steeper hills, wet bottoms, and greater velocity are seen at the centre
What is the zone of accumulation?
The area of net snow addition
What is the zone of ablation?
The area of net loss
Where does the zone of accumulation and ablation meet?
The equilibrium line
What happens when accumulation = ablation?
If ablation and the glacial toe stays in the same place
What happens if accumulation > ablation?
The glacial toe advances
What happens if accumulation < ablation?
Glacial toe will retreat upslope
What is the difference between tidewater glaciers and ice shelves?
Tidewater glaciers are valley glaciers entering the sea while ice shelves are continental glaciers
What is sea ice?
Nonglacial ice formed by frozen sea water
What is a cirque?
Bowl-shaped basins on a mountain
What happens when ice in a cirque melts?
Creation of a tarn (lake)
What is an arete?
A mountain formed by the edges of two cirques
What is a horn?
Formed by three or more cirques which surround a peak
What is a fjord?
U-shaped glacial troughs flooded by the sea
What is a hanging valley?
Valley which has been deeply scoured by glacial ice, leaving the tributary valley “hanging” above the main valley
What is a roche moutonee?
An asymmetric hill
What is (glacial) plucking?
Wind removing sediment from other end of a mountain
What do glaciers act like?
Large-scale conveyor belts which pick up, transport and deposit sediment
What is the debris at the toe of a glacier called?
An end moraine
What is a moraine?
Unsorted debris deposited by a glacier
What is a lateral moraine?
A moraine which forms along the side of a valley glacier
What is a medial moraine?
A moraine formed from the merging of two lateral moraines
What are the different types of glacial sedimentary deposits
Glacial till, erratics, glacial marine sediments, glacial outwash, loess, glacial lake-bed sediment
What is glacial till?
Sediments dropped by glacial ice - consists of all grain sizes
What is an erratic?
A boulder transported long distances by glacial ice
What is a glacial marine?
Sediment from an oceanic glacier
What is glacial outwash?
Sediment transported by meltwater - mud is removed while grains are rounded
What is a majority of outwash composed of?
Sand and gravel
What are glacial lake-bed sediments?
Rock flour settles out of suspension in deep lakes
How are kettle lakes formed?
Stranded ice blocks
What are drumlins?
Along, align hills of molded till
What is an esker?
A long sinuous ridge of sand and gravel
What are some consequences of continental glaciation?
Ice loading and sheet rebound, rise in sea levels, the draining of lake Agassiz
How stable is the Earth’s surface?
It is mostly unstable
What is mass wasting?
Downslope motion of rock, soil, sediment, snow and ice
How fast can mass wasting occur?
Fast or slow
What is mass movement?
Costly natural hazards
Why is mass movement important to the ck cycle?
It is the initial step in sediment transport and an agent of landscape change
What are the four factors which classify mass movement?
Type of material, velocity of movement, nature of the mass, and movement environment
Rank mass movement from slowest to fastest
Creep, slumping, lahars and mudflows, debris flow, and rock slides
What is a creep?
A slow downhill movement caused by soil expansion and contraction
What is solifluction?
Low downhill movement of tundra
What is slumping?
Sliding regolith of coherent rocks
What three distinct features does a slump have?
Head scarp, toe, discrete faulted slices
What do mudflows, debris flows, and lahars have in common?
They have H2O rich movement
Where are mudflows most common?
In tropical settings with rainfall
What is the difference between debris/mudflows and lahars?
A lahar can only be classified as such if mud or debris originated from a volcano
What are the three types of submarine masses?
Submarine slumps (semicoherent blocks), submarine debris flows (broken materials move as slurry), turbidity currents (Sediment moves as clouds)
What are the two dynamic forces in slope stability?
Downslope (gravity) and resisting forces (material strength)
Where are larger forces present?
In steeper slopes
What is the “Angle of repose”?
Loose granular minerals assume a sloped angle
What is loading?
Adding weight to the top of a slope
What is angle?
Steepening a slope beyond the angle of repose
What changes can affect the strength of a slope?
Weathering (weakens regolith), vegetation (stabilizes slope), water (reduces slope strength)
What are several factors which are significant to mass movements?
Relief and climate (more rainfall creates more water-based problems)
How can we prevent mass movement?
Geologic mapping, revegetation, terracing etc.
What is orogenesis?
Mountain building
What are some processes involved in mountain building?
Uplift, deformation, jointing etc
What do young mountains look like? What to older mountains look like?
Young mountains are high and steep while older mountains are eroded remnants lowered by erosion
What is the difference between undeformed and deformed rocks?
Undeformed beds are horizontal with no folds or faults, deformed beds are tilted with metamorphic alteration and have folds and faults
What is strain?
Change in shape caused by deformation
What are the three types of strain?
Stretching, shortening, and shearing
What are the two major types of deformation?
Brittle and ductile
What factors does deformation depend on?
Temperature, pressure, deformation rates, and composition
What is brittle deformation and where does it occur?
Rocks break by fracturing and it only occurs in the shallow crust
What is ductile deformation and where does it occur?
Rocks deform by flowing and folding, occurs at 10 - 15 km in depth
What is compressive stress?
Takes place when object is squished, shortens and thickens material
What is horizontal tension?
Occurs when object is pulled apart, lengthening and thinning material
What occurs during shear stress?
Surfaces slide past each other, neither thickens or things material
What is a strike and a dip?
A strike is a horizontal intersection with a tilted surface, while a dip is the angle of a surface down from the horizontal
What is the purpose of joints and veins?
Water often flows through joins and dissolved minerals precipitate through veins
What are the three types of faults?
Dip slip, strike-slip, oblique slip
What is the difference between a reverse fault and a normal fault? (Dip slip faults)
Reverse fault: hanging wall moves up fault slope
Normal fault: hanging wall moves down fault slope
What is a thrust fault?
A reverse fault with a gentle dip
How are strike-slip faults classifed?
By sense of motion (Right lateral and Left lateral
What is the amount offset by faults called?
Displacement
What special terminology is used to describe folds?
Hinge: The curvature
Limbs: Curved side
Axial plane: Connects hinges of the layers
What is an anticline?
Fold which looks like an arch
What is a syncline?
Fold which opens up like a trough
What is a plunging fold?
Has a tilted hinge
Where are the oldest rocks located in domes and basins?
Domes: Oldest rock in the centre
Basin: Younger rocks centre
What is a flexural slip?
Layers slide past each other
When does passive flow form?
In hot, soft and ductile rock at high temperatures
What does both horizontal and shear compression do to rocks?
Horizontal compression causes rocks to buckle while shear causes rocks to fold
What is a craton and what are the two types?
A crust which hasn’t been deformed in 1 GA – shields and platforms
What is the difference between shields and platforms?
A shield is made up of Precambrian metamorphic rocks and igneous rocks – platforms are shields which are covered by a layer of Phanerozoic strata
What is a barchan (Crescentic) dune?
Strong wind in one direction, small sand and limited vegetation
What is a transverse dune?
Weak wind in done direction, large sand, perpendicular to wind, limited vegetation
What is a parabolic dune?
Arms stabilized by upwind vegetation, semi-circular blowouts that elongate
What is a longitudinal dune?
Winds flowing in opposing directions, two slip faces which align with the wind
What is the fastest growing dune and why?
Star dunes because of multidirectional wind
