B-Lab Report 04 Ohio - All Versions
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School
University of South Florida *
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Course
2000
Subject
Geology
Date
Apr 3, 2024
Type
Pages
8
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Report 4-1 Activity 4.1, Topography of Ohio (9 Minutes) O
BJECTIVES
: (a) To learn about Ohio’s landscape by examining topographic maps; (b) To understand the relationship between Quaternary glaciation and landscape. 1.
First look at the Ohio State Topographic Map, which provides an overview of the landscape of the entire state. The land can be divided into two main regions. One of the principal regions is characterized by bumpy topography
–
hills, valleys, many streams. The other principal region is very flat. On the base map of Ohio below, shade in the bumpier region. (2 points, ☆
) 2.
The green areas signify woods. Why do you think there are more green areas in the southeast portion of the map? (1 point,
☆☆
) 3.
The boundary between the two regions is seen in more detail on the Columbus 1:250,000 scale quadrangle topographic map. What geologic process is responsible for forming the hilly terrain seen on the southeastern part of this map? Be as specific as you can. What is your evidence? (3 points, ☆☆
) 4.
Now compare the Ohio topographic map with the map
of
the Quaternary Geology of Ohio. What geologic difference seen on the Quaternary Geology map explains the different topographic regions? (3 points, ☆☆
)
EXTRA CREDIT: How does glaciation affect the landscape? Describe the physical processes that occur when an area is glaciated and the effect on the shape of the land. (5 points, ☆☆☆
) Activity 4.2, Terrigenous Clastic Rocks (13 Minutes) O
BJECTIVE
: To learn how to recognize the main terrigenous clastic rocks: conglomerate, sandstone, siltstone, shale, and mudstone.
Although limestones were the dominant rock formed in Ohio at the beginning of the Paleozoic era, terrigenous clastic rocks
were also formed. This activity contains five rocks labeled OA-1 through OA-6, representing the important terrigenous clastic sedimentary rocks conglomerate
, sandstone
, siltstone
, mudstone
, and shale
. 1.
For each rock, write a simple description in your own words that will aid you in identifying it in the future. Do not simply emphasize color! Make sure you use a sediment card. (2 points each, all ☆
) Laboratory Number Four: Ancient Rocks and Critters of Ohio
Name: Partners:
Report 4-2 Rock Description OA-1: Sandstone OA-2, OA-5: Shale OA-3: Siltstone OA-4: Conglomerate OA-6: Mudstone 2. Look carefully the conglomerate, OA-4. Use the chart on the inside cover of your laboratory manual to determine the roundness of the clasts. What do you think explains this shape? (3 points, ☆☆☆
) Activity 4.3, Sandstones (17 Minutes) O
BJECTIVE
: To learn how to determine sorting and roundness of clasts in sandstones, through examination of both hand samples and thin sections. Rocks OX-1 through OX-4 are late Paleozoic sandstones collected from northeastern Ohio. 1. Determine the predominant clast size in samples OX-1 and OX-2 by comparing them with your sediment card. (1 point each, ☆
) Clast Size OX-1 OX-2 2. Using a hand lens, determine the sorting and roundness of the sand grains
–if you can! If you can’t, explain why. Use the charts on the inside cover of your lab manual; do not just guess. (2 points each, ☆
) Sorting Roundness OX-1 OX-2 3. Examine the thin sections of OX-3 and OX-4 under the microscope and determine the sorting and roundness of the sand grains. Again, use the charts on the inside cover of your lab manual. (3 points each, ☆
) Sorting Roundness OX-3 OX-4 4. Examine thin section CC-S-1. This thin section was made by embedding loose sand grains in epoxy and shaving a piece of the solidified aggregate into a thin section. a. Notice that the sand grains are surrounded by epoxy. Is the epoxy opaque, isotropic, or anisotropic? HINT: the same epoxy holds the rock slice to the glass slide. (2 points, ☆
). b. Describe the rounding and sorting of the sand grains in CC-S-1. (3 points, ☆
) Sorting Roundness CC-S-1 Activity 4.4, Ordovician Rocks of Ohio (13 Minutes) O
BJECTIVE
: To learn how to recognize limestones and silty limestones, which were formed during the Ordovician Period in Ohio.
Report 4-3 Rock OO-1B was collected from an area fifty miles southeast of Cincinnati and is Ordovician in age. 1.
First examine the hand sample of OO-1B. Does the rock contain either calcite or aragonite? How can you tell? (2 points, ☆☆
) 2.
Now examine the thin section of OO-1B. What two minerals can you identify in the thin section? HINT: One of them is easy
–you’ve just identified it!
(4 points, ☆
) 1. 2. 4.
What percentage of this rock consists of terrigenous clasts? Do not just guess. Use the charts on the inside cover of your lab manual. You should be able to estimate percentages within one picture on the chart. (2 points, ☆
) EXTRA CREDIT: What name would you give this rock? (i.e., sandstone, conglomerate, etc.) Justify your answer! (4 points, ☆☆☆
) Rock OO-12B was collected from the same locality as OO-1B, approximately fifty miles southeast of Cincinnati, Ohio. 5.
First examine the hand-sample of OO-12B. What name would you give this rock? (1 point, ☆
) 6. Was this rock formed in a marine or terrestrial (land-based) geologic environment? Justify your answer! (2 points, ☆☆
) Marine or terrestrial? 7.
Without using acid, do you think this rock has been
extensively dolomitized? Why or why not? (2 points, ☆☆☆
) EXTRA CREDIT: Examine the thin section of OO-12B. Notice that many different fossils can be recognized in thin section. Some of them are corrugated and undulating like this: ⌣⌢⌣⌢⌣⌢
, while others are straight and dark like this: ====. The squiggly, undulating fossil shells are brachiopod shells and are composed of calcite, while the straight, darker shells are mollusk (clam) shells and are made of aragonite. Examine the fine structure of the crystals that make up both shells. In one of them, the crystals are parallel to the walls of the shell, and in the other they are perpendicular. Sketch both arrangements below and indicate which one is a brachiopod shell. (4 points, ☆☆
) Brachiopod shell: Clam shell: Activity 4.5, Silurian Rocks of Ohio (9 Minutes) O
BJECTIVE
: To learn how to recognize and interpret Silurian rocks from Ohio.
Rocks of Silurian age are relatively rare world-wide because they are infrequently preserved. In this activity, you will be examining a Silurian rock from near Dayton, Ohio, rock
OS-6.
1.
First examine the hand-sample of rock OS-6. What is the
major mineral in this rock? (3 points, ☆
)
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