bree_hernandez_lab_14
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Dec 6, 2023
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Glaciers (Lab 14)
For this lab you will need the following:
●
Google Earth
●
Glaciers KMZ file (posted in the lab 14 assignment link in Canvas)
●
Calculator
Alpine Glaciation — Active Ice
Southeast Coastal Alaska
Click the link for the “Glaciers” KMZ file to begin this activity.
Double click the “?” icon for the Southeast Coastal Alaska placemark to fly to it. This view presents an
overview of the extent of modern glaciation occurring in that area.
1.
Double click the icon for placemark A in the Places panel to fly in for a closer look.
a.
What evidence can you cite that supports the idea that glacial ice flows as if it is a very thick, viscous
plastic?
The glacial landscape is in a V-shaped valley and the fluvial landscape appears to show atributary valley.
The valleys are different shapes because a V-shaped valley is filled with ice, which erodes, and deepens
the valley, which causes glaciation. Thick accumulations of glacial ice add weight to the crust, and as the
mantle beneath and yet it convects and flows like a very viscous liquid.. The fluvial valley's shape is the
result of erosion after valley glaciation.
b.
What term describes the dark material at placemark A? Fly up to the glacier to find the source of that
material, and describe the source of it.
The term used to describe the dark material at placemark A is Alpine Glaciers. Alpine glaciers begin high
up in the mountains in bowl-shaped hollows called cirques. As the glacier grows, the ice slowly flows out
of the cirque and into a valley. Alpine glaciers (a.k.a. valley glaciers) originate in mountains, mostly in
temperate and polar regions but even in tropical regions if the mountains are high enough.
2.
Double click the icon for placemark B in the Places panel.
a.
Describe the change in width of the tributary glaciers to the right and left of placemark B that occurs
as they join the main glacier in the foreground of this view.
The tributary glacier to the left of the mark was much wider than the one on the right . They were both
wide until they joined the main glacier.
b.
What are some possible causes for the observed change in the width of these glaciers?
On the left side compared to the right, the center layer has melted more. The temperature of the Earth
has undergone a number of significant changes, according to geological records. These have been
brought on by a variety of natural phenomena, such as variations in the sun's activity, volcanic emissions,
changes in the Earth's orbit, and carbon dioxide concentrations
3.
Double click the icon for placemark C in the Places panel.
a.
What term properly describes the deep fractures in the glacial ice here?
These are called crevasses.
b.
What does the presence of these fractures suggest about the physical properties of the ice here?
The glacial ice was moving perpendicular to the crevasses since they occur in the transverse direction of
the movement of the glaciers. Also, the moving glacial ice has started breaking from the main ice block.
c.
Explain how a glacier can exhibit properties that suggest both plastic flow and brittle fracture in the
same place. Consider the thickness of glacial ice, and the factors that make ice capable of plastic flow.
An avalanche or an icefall added its mass to the rest of the glacier.
Alpine Glaciation — After the Ice
Galena Mountain and Turquoise Lake, near Leadville, Colorado
Open the “West of Leadville, Colorado” folder and click the icon for the Location 1 placemark to fly to it.
The landscape here has recently been modified by alpine glaciation, and in fact a few small glaciers exist
at the highest elevations today.
1.
Fly to and study each placemark, A through F, in order. Name the glacial landform at each placemark,
and briefly describe how it was formed.
A:
Horn Fork Cirque Glacial Landform: Cirque Formation: A cirque is a bowl-shaped depression that
forms at the head of a glacier. It is formed by glacial erosion, where the ice scours and plucks the rock
and soil from the mountainside, creating a hollow basin.
B:
Missouri Lakes Glacial Landform: Glacial Tarn Formation: A glacial tarn is a small, shallow lake that
forms in a cirque as the glacier retreats. When the glacier melts, the ice leaves behind a depression in
the rock that fills with water.
C:
Fancy Lake Glacial Landform: Arete Formation: An arete is a narrow, sharp ridge that separates two
cirques. It forms when two glaciers erode parallel valleys that intersect at a high point, leaving a sharp
ridge of rock.
D:
Mount Massive Glacial Landform: Horn Peak Formation: Horn Peak is a pyramidal peak that forms at
the head of a cirque. It is created by the intersection of three or more arêtes, which are formed by glacial
erosion.
E:
South Willow Creek Glacial Landform: U-shaped Valley Formation: A U-shaped valley is a glacially
eroded valley that has steep, straight sides and a flat bottom. It is formed by the abrasive action of glacial
ice as it moves downhill, carving out the valley and smoothing the sides.
F:
Independence Pass Glacial Landform: Hanging Valley Formation: A hanging valley is a tributary valley
that is perched above the main valley floor. It forms when a smaller glacier flows into a larger glacier, and
when the larger glacier retreats, the smaller glacier is left high above the main valley floor.
2.
Double click the icon for placemark G in the Places panel, and turn on the “Turquoise Lake Map” layer
and the “Profile from G to H” path by checking the boxes next to them in the Places panel. Refer back to
the display as you construct a topographic profile across the Turquoise Lake valley from placemark G to
placemark H.
a.
What letter of the alphabet does the shape of your profile most nearly resemble?
The changes in glaciers in terms of their shapes of the valley moves from the "V" to the "U" shapes.
b.
Fly back around the area you explored at placemarks A–F and comment on the cross-sectional shape
of the glacial valleys in the area.
The formation of a glacial valley takes place in an event where glacier travels down and across a slope.
They carve the valley by the scouring action leading to the formation of various shapes based on the
intensity and the possible impacts and factors that might be evident during the process.
3.
Reduce the opacity of the Turquoise Lake Map layer to about 20%, and turn off the Profile from G to H
path. Then double click on any of the placemark I icons in the Places panel. Placemarks I are hovering
over cirques carved by ice that flowed off toward the top of your screen (ESE from cirques toward
Turquoise Lake).
a.
Double click the icon for placemark J to fly to it, and describe the appearance of the landform at
placemark J. What is that landform called, and what is the origin and composition of the material it’s
composed of?
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Finger lakes are lakes that are located in long glacially formed depressions. The crust is depressed in
areas of continental glaciation due to crustal loading from the weight of heavy glacial ice. Except for
those that cover entire continents like Antarctica and Greenland, basins grow at the margins of
continental glaciers, and these basins fill with glacial meltwater, forming proglacial lakes.
b.
Double click the icon for placemark K to fly to it, and describe the appearance of the land at
placemark K. What is that landform called, and what is the origin and composition of the material it’s
composed of?
When I have travelled through placemark K then I find out that landform is Tarn which are basically
glacial lakes which are formed when there is formation of cirque due to glacial erosion. Later on these
cirques are filled with water to form pond or pool which are basically smaller water bodies of lake
shaped that are called Tarn / corrie loch.