Lab 5 Weathering and sedimentary rocks Online Supplement
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University Of Georgia *
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1121L
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Geology
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Feb 20, 2024
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Lab 5: Spring 2024
Lab 5: Weathering and Sedimentary Rocks
Student Name: Emily Matthews
(For TA Use) Raw score_____/39
Points______/100
To complete this lab, find supplied materials in eLC in the folder Assignment Lab 5: Weathering and Sedimentary rocks Word .doc file and a powerpoint.
Use a word processor to modify this file and type in your responses. Whatever word processor you use,
save your work as a PDF or Word Doc and upload it to eLC.
Write down questions that develop and ask your TA during meeting time of the lab or via email. Familiarize yourself with the slides in eLC
and watch any videos linked
. Linked videos are in your slideshows AND on this worksheet. Answer the questions below to receive credit. Items are not necessarily in order, so you will have to do some searching and remember where you have found things and go back to them.
Before a sedimentary rock can form, pieces of other rocks must be weathered out of position and then transported downhill and then downstream through some erosion process or processes. Interestingly, sedimentary rocks are possibly the most important rock type of the three major types of rocks we will cover (others are igneous and metamorphic rocks) because sedimentary rocks contain earths record of life, as fossils, and many of the main energy sources humans use for our society are derived from sedimentary rocks. Further, water resources people depend on are often contained within
sedimentary rocks. Let’s find out more.
1)
From the slide show presentation in eLC that your TA will help you cover, what are the two types of weathering that lead to rocks crumbling? (2 points)
Physical and Chemical weathering
2)
Sometimes people think of weathering and erosion happening hand-in-hand, and these processes often do occur simultaneously. However, these ideas are two different things. Weathering is purely the break-down of rock material, and erosion is: (2 points)
How sediments are transported by things like water, gravity, wind, ice, etc.
3)
Eventually all transported sediment stops, at least temporarily. These depositional areas are unique to the environment that brought in the sediment and caused it to stop moving. The compaction and sedimentation of sand grains yields a particular rock called: (1 point)
Sandstone
4)
The four different agents that move rock and transport it are: (4 points)
Aeolian, Fluvial, Glacial, and Colluvial
5)
In detrital sedimentary rocks, what three minerals tend to survive longest because they are resistant to erosion processes? (3 points)
Clay, feldspar, and quartz
Lab 5: Spring 2024
6)
From the video with minerals at the Mica Mine from week 3 lab, the sedimentary rocks in the area are shown at the beginning of the video and discussed at the end. During the discussion of the mineral quartz, weathering processes are described. https://www.youtube.com/watch?
v=wa4_bC4tgc8
After a mineral like quartz breaks off of other rocks, what will happen to that mineral material during its journey downstream? Eventually this leads us to many of the sand grains found all over the world. (2 points).
It forms large components inside sedimentary rock and becomes round and smaller 7)
Layers of rock found throughout much of the Earth’s surface are sedimentary rocks. In Bangs Canyon of Colorado, what are the two rock layers’ names discussed there? (2 points)
Chinle and Wingate
8)
In what physical orientation are the two rock layers of Bangs Canyon? (1 point)
Horizontal
9)
The rock layers are said to be Jurassic and Triassic in age in the video, which means they might have dinosaur fossils in them. Watch this video to learn about fossils in sedimentary rocks and how you might identify them: Sedimentary rocks and dinosaurs - YouTube
. Rocks like these in the video are very close to the Mica Mine at a place called the Mygatt-Moore Quarry.
A. What two dinosaur names are given in the video? (2 points) Sauropod and Camarasaurus
B. What sedimentary rock type is best at preserving dinosaur bones out of the 3 discussed? (1 point)
Shale
C. Why might conglomerate cause damage to bones? (2 points)
A powerful flood stream can break and separate the fossil.
The Morrison Formation rocks at Mygatt-Moore, and the Chinle and Wingate rocks of Bangs Canyon, are all terrestrial sedimentary rock layers. This means the sediments accumulated on land either in rivers and streams or, in the case of the Wingate, as large sand seas like the Sahara. 10) Rocks that are more likely to deposit offshore include chemical sedimentary rocks, where precipitated minerals like calcite form the rock called limestone (1 point)
11) Deposition by evaporation of large quantities of water may leave behind sea salt, which is the minerals: Gypsum and Halite (2 points)
Lab 5: Spring 2024
12) One of the consequences of burying organic material, like peat or forests or jungles, is that the sediment may accumulate so much that water is squeezed out, the rocks become heated and density of the organic material increases. This process is the basic description of how what energy resource forms? Coal (2 points) 13) The matrix of a sedimentary rock contains small rock material between larger grains. Sometimes, that matrix isn’t there and there is simply empty space between grains. In some rocks underground, the empty spaces of rocks may contain water, or oil, or natural gas. As society continues to use these resources extracted from rock, the importance of understanding how many rocks layers have these resources and how much is there is critical to continuing to live the way we do. The holes in rocks are called: pores (1 point)
14) What is the general trend of grain size if one is to move downstream in a river? It may be necessary to move tens to hundreds of miles to see these differences. (3 points) Grains become less course and more rounded as they move downstream. Weaker minerals are weathered out along the way.
15) Synthesis: Toward the end of the slide show there is a picture of the Grand Canyon. These sedimentary rocks have accumulated in rocks that are thousands of feet thick. Many of the rock layers contain sediments that were originally transported from rocks of the Appalachian Mountains, even though the Grand Canyon region is in Arizona. Use the information you have collected in your mind in working through the slides, videos and questions to explain the whole process of how Appalachian rocks got to Arizona as newer sedimentary rocks. Use the following key words by placing each one in a complete sentence in a logical order: smaller and more rounded, transport, weather or weathering, flowed from _______to ________, diagenesis, time,
deposition. (7 points)
The rocks of the Appalachian mountains broke off and got transported via aeolian, fluvial, glacial, or colluvial agents. During transportation the rocks combine with other sediments along the way to become a new sedimentary rock, diagenesis, which becomes smaller and more rounded as it travels. Eventually, the new sediments make it from the Appalachian mountains to
the Grand Canyon.
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