NR 009 Final Exam New 2023 with complete solution
What is a natural community?
- recurring groups of plants and animals found in particular physical environments
o Ex. Rocky vs wet areas
o Look at the major physical characteristics: is it a forest? Meadow? Marsh?
According to Tom Wessels, wh...
nr 009 final exam new 2023 with complete solution what is a natural community recurring groups of plants and animals found in particular physical environments o ex rocky vs wet areas o look at th
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NR 009 Final Exam New 2023 with complete solution
What is a natural community?
- recurring groups of plants and animals found in particular physical environments
o Ex. Rocky vs wet areas
o Look at the major physical characteristics: is it a forest? Meadow? Marsh?
According to Tom Wessels, what three overarching categories affect the composition of
plant communities?
- Topography, substrate, disturbance history
o Topography: shape of the land; elevation, steepness of a slope, aspect
o Substrate: physical and chemical characteristics of the rock or dirt; bedrock geology,
soil composition, nutrients
o Disturbance history: past events that influence the way a place looks today; invasive
species, blights/diseases, current/prior land use (farming, fire, logging, beaver activity)
What is an orogeny?
- Forming of a mountain range through crushing of the earth's crust
Grenville Orogeny
o a collision where the outer/higher layers of the crust fold & fracture which resulted in
the proto-NA plate fusing with the plate to the east to create the Grenville super
continent.
o Metamorphic rocks formed (created from the heat and pressure of collision)
o Mountain range gone, eroded to a flat sea level plane, but rocks still remain in the
Adirondacks.
Iapetus Ocean
o Plates diverge, ocean fills in between the 2 plates
o Sediments (which eroded off the edge of the continent, washed into the shallow
ocean) lithifies into limestone and shale; microscopic organisms in the ocean die, pile
up in layers which adds calcium to rocks
o Rocks can be found in islands/lowlands of the Champlain valley
Taconic Orogeny
o Formed from subduction of proto-NA, and created a chain of island arc, which
eventually collided w PNA
o Metamorphic rock created, and the green mtns were formed
o Magma that came to the surface from volcanoes in the island arc forms igneous rock
Acadian Orogeny
o Iapetus ocean closed; Avalon collided with PNA
o Granite created, magma cooled and lithified
o Granite formed into domes; erosion exposes the granite at the surface.
In which region of Vermont can metamorphic (or igneous or sedimentary) rock be
found? What event(s) created these?
- Sedimentary: Champlain valley
o Ex. Monkton quartzite (sandstone), shale (mudstone), dolostone
- Metamorphic: green mtns (middle of VT, most of the state)
o Ex. Slate, marble, schist
- Igneous: NE Kingdom
o Ex. Granite
, Explain how the slate used for many slate roofs originally formed and how/why it
metamorphosed. What about marble? Granite?
- Shale becomes slate, sedimentary to metamorphic; shale is a mudstone, so it formed
in the deep ocean, metamorphized with temperature and pressure.
- Taconic orogeny: most heat and pressure formed mountains (of slate), etc.
- Marble: metamorphic, formed from shells of microorganisms, comes from dolostone
(calcium rich)
- Granite: igneous, formed form magma cooling
What is glacial till?
- an unsorted mixture of all different sediment sizes including gravel, boulders, sand,
silt, and clay
- Carried beneath the glaciers and is dropped off as glacier recedes.
How were Lake Vermont and the Champlain Sea created? At what elevation was the
surface of each?
- Lake VT: 620ft above sea level, sourced from glacial melt
o Ended because the glacial ice dam broke, letting the water into the N Atlantic like a
bathtub
- Champlain Sea: 320ft above sea level, sourced from N. Atlantic Ocean
o Ended because of isostatic rebound: cut off from ocean; glacial ice dam blocked the
lake from draining north, but it broke and connected to the Atlantic.
What surficial material would you find beneath the top layers of soil at the following
elevations (assuming you are in the Champlain Valley): 620 feet above sea level, 320
feet, 100 feet, 795 feet, 400 feet. Explain the events that left behind these materials.
- 620ft: Lake VT (deltaic or beach sand)
- 320ft: Champlain sea (deltaic sand)
- 100ft: Champlain sea (sand)
- 795ft: glacial till
- 400ft: Lake VT (silt/clay)
What is horizontal sorting? What does this have to do with sediment deposited during
Lake Vermont and the Champlain Sea?
- Horizontal sorting: sediments carried based on size & density
o Large, round, densest sediments deposited first (shallower water, near shore)
o Small, flat, less dense sediments
o With evaporation, suspended sediments fall (deeper water)
What is isostatic depression and rebound? How does this connect to the Champlain
Sea?
- Isostatic depression: sinking of the crust caused by heavy weight (glaciers)
- Isostatic rebound: when land masses rise after huge weight is lifted (ice sheets
retreating)
Define regolith, soil, bedrock, and parent material.
- Regolith: "rock blanket", eroded sediment, etc. on top of the bedrock, unconsolidated
pieces
- Soil: the part of the regolith that is changed by chemical weathering & biological
activity (transformation)
- Parent material: the material that weathers to produce soil
Describe the major characteristics of each soil horizon (color, organic matter, etc.)
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