Exam 1 - Key - University of Colorado Boulder

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Part IV: Multiple Choice - 2 points each
1. The Mid-Atlantic Ridge is an example of
A) Convergence
B) Divergence
C) Subduction
D) Folding
2. Tectonic plate motion is driven by
A) Conduction
B) Convection
C) Compression
D) Magma plumes
3. The lowest layer of the atmosphere, the troposphere, extends to about 10 km (except
at the poles). Half of the atmosphere's mass is above you if you are at about
A) 4.0 km
B) 5.5 km
C) 7.0 km
D) 8.5 km
4. Temperature is a measurement of
A) Heat capacity
B) Average heat capacity
C) Kinetic energy
D) Average kinetic energy
5. Chinook winds are always
A) Warm
B) Cold
C) Long-lasting
D) Fast
6. True alpine vegetation covers about how much of Earth's land?
A) 1%
B) 3%
C) 10 %
D) 14 %
7. Alpine plants exhibit seasonal phenology, which means that they exhibit temporal
control of
A) Seed maturation
B) Sprouting
C) Flowering
D) All of the above
8. Most avalanche-related deaths are caused by
A) Sluff avalanches
B) Slush avalanches
C) Slab avalanches
D) Earthflows
Part V: Short Answer – 5 points each
1. Give at least two reasons why the "local" perspective might be important for defining
a mountain?
There is no universal definition for a mountain, so the local impression may be the single
defining factor.
Peattie wrote that a mountain should “…enter into the imagination of the local people."
What defines a mountain (in terms of height) might be relative to the local, surrounding
landscape/topography.
Mountains may be defined according to local traditions or to religious or cultural
practices.
2. Marine fossils have been found on top of Mt. Everest. How might this be possible?
As the Indo-Australian slammed into the Eurasian plate (two continental plates), great
amounts of compression and folding occurred. The continental plates were originally
located below sea-level, however the boundary between the two plates was compressed
and thrust upward, eventually becoming part of the mountaintop.
3. Describe major differences between continental and oceanic plates.
Continental plates are older, thicker, and less dense than oceanic plates. Continental
plates are also made predominantly of silica and aluminum while oceanic plates are made
predominantly of silica and magnesium.
4. Describe three different processes by which mountains can form and give examples of
each.
Possible processes include…
Convergence - continent/continent – compression, folding
Convergence - continent/oceanic (subduction okay too)
Volcanic Activity
Hotspots
5. How do oceanic and continental hotspots form? Give an example of each.
Hotspots form when stationary magma plumes are hot enough to break through the crust.
6. Why does temperature generally decrease with elevation?
Temperature decreases with elevation because pressure decreases. Air masses rising into
areas of lower pressure expand, and in expanding they do work. By doing work, the air
loses kinetic energy and cools down.
7. Why is there more precipitation at higher elevations?
Because temperatures are cooler at higher elevations, an air mass will reach saturation
more quickly (cold air holds less moisture than warm air). When the temperature cools to
the dew point, water vapor in the air mass condenses and may eventually precipitate.
8. Imagine elevated ozone (smog) levels have been recorded in Colorado's high country
and the Denver region is believed to be the source. Explain how this might be possible
and say whether the ozone problem is diurnal, nocturnal, or continuous.
A valley breeze forms when sun rises and begins to heat the Front Range’s mountain
slopes. This differential heating causes the warmed air to rise upwards, creating an
upslope circulation. This circulation carries pollution from the valley/plains up into
mountains. The problem is diurnal.
9. Describe at least 5 challenges plants face in the alpine zone.
Low temperatures
Extreme temperature fluctuations
Limited water availability
High winds
Less CO2 than at lower elevations
High UV radiation
Low nutrient concentrations in the soils  stunted growth
Very short growing season
10. Name and describe three specific ways alpine plants adapt to low water conditions
Stomatal control – plants open their stomates at night only, preventing evapotranspiration
during the day
Succulence – plants have developed thick waxy leaves that store water
CAM – plants produce acids to carry out photosynthesis without the need to open
stomates for gas exchange during the day, when evapotranspiration is high
Dessication tolerance
Extensive below-ground biomass and root systems
11. In what ways does snow affect vegetation patterns in the alpine zone?
Snow insulates against low or fluctuating temperatures.
Snow protects against high winds and high radiation.
Snow retains moisture for the soil and plants.
12. Describe osmotic adjustment
To avoid the freezing of exposed tissue, plants increase the solute concentration in their
cells. This allows them to lower the freezing point of the cells.
13. Give three reasons why frost action is likely to occur in mountain areas.
Mountain environments experience extreme temperature fluctuations (rain can fall,
trickle into cracks, and then freeze). There is a lot of exposed rock. The rock, because it
has likely been folded, twisted, or upturned in some way, is composed of fractures, which
facilitate frost wedging. (Lots of precipitation also accepted as an answer.)
14. Explain how vegetation (or revegetation) inhibits avalanching.
Vegetation anchors snow and prevents sliding. If sliding does occur, vegetation can
barricade the moving snow mass and prevent extensive drifting.
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