Tieshia Brown Lab 5 Assignment
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Georgia State University *
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1113
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Geography
Date
Feb 20, 2024
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7
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Lab 5: Weathering GEOG 1113L – Introduction to Landforms Lab
Name: Quantieshia Brown (Tieshia)
I.
What is Weathering?
1.
What does weathering create/provide and what would Earth’s surface be composed of if weathering did not happen?
After breaking down the rocks, weathering creates fragmented materials or sediments which become the raw material for other rocks and the formation of soils. If weathering did not happen, the Earth’s surface would be solid bedrock. 2.
What is the difference between weathering and erosion?
The difference between weathering and erosion is that weathering is the process of prepping the rock materials to be moved and erosion is when rock material actually gets moved. 3.
Describe the process of frost wedging (frost action).
The process of frost wedging also known as frost action is when the water has been absorbed into the pores of a rock, the rock expands when it freezes, building up stress and causing the rock to break. Frost wedging or frost action can break off anything from small grains to large boulders which is an important process in cold environments where freeze-thaw cycles are common. 4.
Similar to frost wedging, salt wedging
fractures rocks through crystal growth within the pores of the rock. These crystals originate from saltwater
inside the rock that later evaporates and leaves behind salt crystals
.
5.
The two previously mentioned types of weathering are both forms of what?
Mechanical Weathering
6.
Which type of weathering causes metal to rust?
The type of weathering that causes metal to rust is oxidation. 7.
Weathering that alters minerals in a rock via water, oxygen, carbon, and/or other organic acids is called what?
Chemical Weathering
8.
Which type of weathering causes karst topography?
The type of weathering that causes karst topography is chemical weathering
. 9.
Name three features you might find in a karst landscape.
Three features you may find in a karst landscape are sinkholes, sinking streams, and caves. 10.
What is one fact (from the video) about caves that you find interesting?
One fact I found interesting from the video is frost wedging and how this is the process that my water and pipes go through during the winter. I now understand why the pipes in my apartment complex burst. 11.
Tree roots, lichen, and humans all play a part in weathering as well. Which type of weathering is this called?
The type of weathering that tree roots, lichen, and humans play a part in is chemical weathering.
II.
Weathering Resistance
Use the two images below to answer questions about weathering resistance. Assume all rock layers in both images have been subjected to the same type/amount of weathering.
Image A:
1.
Which color/pattern represents a rock layer that is MOST resistant to weathering compared to the others?
The black pattern is the most resistant to weathering. 2.
Which color/pattern represents a rock layer that is LEAST resistant to weathering compared to the others?
The light gray pattern represents a rock layer that is least resistant to weathering. 3.
Which colors/patterns represent rock layers that share the same level of resistance to weathering compared to the others?
I think the dark gray pattern represents a layer of rock that shares the same level of resistance as the black pattern.
Image B:
4.
Within the red box, which layer appears to be most resistant to weathering (A, B, or C)?
Layer B
5.
Within the red box, which layer appears to be the least resistant to weathering?
Layer C
6.
What is one indication that a rock layer is more resistant to weathering?
One indication that a rock layer is more resistant to weathering is looking at how solid and dark the rock is. A great example of a rock that is more resistant to weathering is igneous rock.
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III.
Physical Vs. Chemical Weathering For each location below, be sure to explore the photo by dragging your mouse around the 360
o
view around you and using the scroll feature on your mouse to zoom in and out on specific parts of the image. Answer each question that accompanies the link.
1.
Visit Apikuni Falls in Glacier National Park. Some of these rocks have a white color, but they have an orange color when they are exposed to water from the waterfall. Which type of weathering is producing the orange-colored rocks? a.
Carbonation
b.
Oxidation
c.
Exfoliation
d.
Frost wedging
2.
Visit Stone Foundation in Wisconsin. There is evidence in this 360
O
photo for which type of weathering? a.
Salt crystal growth
b.
Oxidation
c.
Exfoliation
d.
Frost wedging
3.
Visit Starved Rock State Park in Illinois. What type of weathering do you see in this 360
O
photo? a.
Carbonation
b.
Oxidation
c.
Exfoliation
d.
Frost wedging
4.
Support your claim about the weathering in Starved Rock State Park with evidence you observe in the 360
O
photo. What type of weathering is this (chemical or physical)?
My reasoning for choosing carbonation as the type of weathering is because the picture shows that after it rained, the water was mixed with carbon dioxide which formed carbonic acid. Looking at the walls it appears that the carbon dioxide and moist air affected the cave walls which created the carbonic acid and acid that caused the rocks to react. This is the process of chemical weathering. 5.
Differential weathering
means that some rocks break down more easily than others. For example, in this picture of a dolerite dike, you see a dark igneous rock forming a prominent low wall extending into the ocean. It sticks out above the beach sediment on either side of it (mostly sand) because the sand has formed from rocks that weathered away more easily. We consider the dolerite dike more resistant to weathering, because it resists weathering. Differential weathering in an outcropping of rock can produce dramatic landscapes. If a rock weathers easily, it will break down easily making gentle slopes. If a rock resists weathering, it will make steep cliffs. Visit Monument Valley in Arizona. Notice that the towers of rock are more resistant to weathering, while the gentle sided slopes at the bottom of the towers weather more easily.
Now visit LaSalle Canyon at Starved Rock State Park in Illinois. The evidence of differential erosion is less obvious. Describe where in the LaSalle Canyon you see resistant or easily weathered layers. What evidence can you observe of differential weathering? I think there are easily weathered layers to be seen, specifically towards the right of the picture where we see dark igneous rock. It appears that differential weathering can be seen at the bottom of the picture closer to the ground where there is a smooth surface.
6.
One type of physical weathering not covered yet is abrasion
. A scratch on your skin or eye is called an abrasion and an “abrasive” person is someone that grates on your nerves. So, this form of weathering is just like it sounds. When sand or silt is picked up by water or wind and bumps into other rocks, it can round off the edges, making things smooth. River rocks are rounded because they roll around in rivers, bumping into one another and chipping off their rough edges. Sand carried by river water acts like sandpaper, smoothing the surface of the rocks. For example, see this photograph of rounded pebbles
. Abrasion also happens as a result of wind carrying sand. Visit Devil’s Garden in Grand Staircase – Escalante National Monument in Utah. The towers of rock are called hoodoos. How are Devil’s garden hoodoos an example of differential weathering? Provide evidence from your observations of the 360
O
photo.
This is an example of differential weather because the rocks in this picture have produced a dramatic landscape. Further observing the image, I noticed the smooth and gentle slopes that are created under the dramatic landscape of the three rocks. Not only is the landscape show signs of a smooth and gentle slope, but looking at all the rocks, there is a gentle slope forming on all of them. 7.
What evidence is there in the 360
O
photo of Devil’s Garden that the hoodoos and other rock outcrops were weathered by abrasion?
Looking at the top of the other rocks towards the left of the hoodoos, I noticed how smooth the top of the rock surface is. I noticed how the edges are rounded which makes the rock create that smooth surface.
IV.
Karst Topography
Choose one of the five locations provided and visit the Google Earth link: 1. Central Kentucky Karst, USA
, 2. Sof Omar Cave, Ethiopia
, 3. Postojna Cave, Slovenia
, 4. Tenglong Cave, China
, 5. Waitomo Cave, New Zealand
.
Once you have chosen your location, utilize the following links to learn more about karst topography and answer the questions below. https://home.wgnhs.wisc.edu/wisconsin-geology/karst-sinkholes/
https://www.nps.gov/subjects/caves/karst-landscapes.htm
https://education.nationalgeographic.org/resource/karst/
https://people.uwec.edu/jolhm/Cave2006/Karst.html
https://www.gsi.ie/en-ie/programmes-and-projects/groundwater/activities/understanding-irish-
karst/karst-landforms/Pages/default.aspx
1.
What is one indication that the location you chose has karst topography? Take a screenshot of this feature (must be visible in the picture) and attach it below along with the name of the feature.
I have chosen Waitomo Cave, New Zealand. I think this location has karst topography because the view appears to have cave-like features with the mountains I see that can be caves. 2.
The most common bedrock that makes up karst topography is what?
Limestone is the most common bedrock that makes up karst topography.
3.
What are two negative impacts of karst topography?
Karst topography can be a dangerous location to live in because as the bedrock of the area erodes, it can create things like a sinkhole that is hazardous to the community around it. This type of phenomenon causes very bad accidents if people are driving or can cause destruction to homes. Another negative impact of karst topography is that it
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can disrupt drainage networks where streams and rivers cannot flow above ground continuously. This can cause severe drainage trouble. 4.
What are three facts about karst topography from the provided links that you found interesting?
•
Sinkholes form from the bottom up as the sediment immediately above the bedrock is the first to be washed into the voids. (
Fact 1 Link)
•
Karst is ideal for storing water as an aquifer and provides vast amounts of clean drinking water to people, plants, and animals. (
Fact 2 Link)
•
Dry valleys and Springs are common types of karst landforms. (
Fact 3 Link)