Activity 4.1 - Review of Sedimentary Processes
Joy Branlund (Southwestern Illinois College)
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This activity was selected for the On the Cutting Edge Reviewed Teaching Collection
This activity has received positive reviews in a peer review process involving five review categories. The five categories included in the process are
- Scientific Accuracy
- Alignment of Learning Goals, Activities, and Assessments
- Pedagogic Effectiveness
- Robustness (usability and dependability of all components)
- Completeness of the ActivitySheet web page
For more information about the peer review process itself, please see https://serc.carleton.edu/teachearth/activity_review.html.
- Reviewed: December 20, 2012 -- Reviewed by the InTeGrate Materials Review Process
- First Publication: October 16, 2014
- Reviewed: July 17, 2017 -- Reviewed by the On the Cutting Edge Activity Review Process
Summary
Even though students will read about sedimentary processes and the mineral resources thus formed, they will need some practice in order to truly grasp the concepts.
Topics
Sedimentary Geology,
Mineral Resources Grade Level
College Introductory, College Lower (13-14)
These materials have been
reviewed for their alignment with the Next Generation Science Standards as detailed below.
Overview
This in-class discussion activity addresses the MS level "rock cycle" DCI (ESS2) and focuses on mechanical and chemical weathering.
Disciplinary Core Ideas
Natural Resources: Humans depend on Earth’s land, ocean, atmosphere, and biosphere for many different resources. Minerals, fresh water, and biosphere resources are limited, and many are not renewable or replaceable over human lifetimes. These resources are distributed unevenly around the planet as a result of past geologic processes. MS-ESS3.A1:
Earth’s Materials and Systems: All Earth processes are the result of energy flowing and matter cycling within and among the planet’s systems. This energy is derived from the sun and Earth’s hot interior. The energy that flows and matter that cycles produce chemical and physical changes in Earth’s materials and living organisms. MS-ESS2.A1:
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activities from Teach the Earth on a specific topic.
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Upon completion of this segment, students should be able to:
- Describe the processes that act to make sedimentary rocks, specifically mechanical weathering, chemical weathering, and erosion.
Context for Use
This activity should be done after students have read about sedimentary processes but before the other sedimentary activities (
Mining Sand and
Mining Salt). This activity is meant to stress sedimentary processes, so it should be used in classes with a rock cycle learning objective. This activity can be completed in classes of any size, and (with some modification) in online settings.
Description and Teaching Materials
Students often have a hard time grasping the concept of weathering, even with the simple examples that they see every day (such as dissolution and oxidation, a.k.a. rust). This activity will allow students to think about weathering and erosion, and also consider how humans (due to mining activities) increase weathering and erosion rates.
Part 1
The colored shapes represent minerals, and white space is pore space (space in rock that is filled with air or water). The original sediment (or rock, on left) at the surface is exposed to rain (the arrows from above) and hence, chemical weathering. The gray minerals are not soluble, so remain unchanged. The purple minerals are made of red and blue elements. The purple minerals react with the water, which preferentially removes one element (the red) from the mineral and carries that element deeper into the ground, where it crystallizes as a new mineral. Weathering therefore separated the blue from the red elements, and concentrated those elements. A mining company interested in the blue element will mine rocks/sediments right at the surface, whereas a mining company interested in the red element will extract deeper rocks/sediments.
![[creative commons]](/images/creativecommons_16.png)
Provenance: Image created by Joy Branlund, Southwestern Illinois College.
Reuse: This item is offered under a Creative Commons Attribution-NonCommercial-ShareAlike license http://creativecommons.org/licenses/by-nc-sa/3.0/ You may reuse this item for non-commercial purposes as long as you provide attribution and offer any derivative works under a similar license.
Chemical weathering affects minerals differently. This activity addresses this by showing a drawing of a hypothetical rock on Earth's surface and the underlying sediment. That hypothetical rock contains two minerals, one stable (it resists weathering) and one that dissolves. The soluble (unstable) mineral in the example doesn't completely dissolve but rather one element is extracted. This is similar to the alteration of ilmenite in the Mining Sand activity; iron is removed from the mineral by chemical weathering, leaving a more titanium-rich mineral behind.
It helps to review this drawing (found in the Unit 4 background reading and on this page) in class. Then, ask students to imagine a Peanut M&M.
- What will happen if you put some water on the Peanut M&M? Answer: The color will wash off.
- What will happen to the remaining M&M? Answer: The sugar coating will eventually dissolve but not the peanut.
The Peanut M&M is similar to the rock in the example. The color part of the sugar coating is like the red element in the purple mineral. The peanut is like the grey mineral.
Additionally, you can point out that mechanically weathering often accelerates chemical weathering. For example, if you chew the M&M, then the candy-coating will dissolve faster.
Part 2
When humans extract mineral resources, they increase weathering and erosion rates. Given that students learned about mining in the previous unit (Unit 3), they can be asked to link mining and weathering/erosion. This can be done verbally with the entire class. Instructors should stress that this is a review/application of concepts from the reading assignment.
- What do we call it when mining companies blast apart the rock to get to a mineral resource? Answer: Mechanical weathering.
- What will happen to the rate of chemical weathering in a place that has been mined, with waste rock either in piles or filling the mine site? Answer: Chemical weathering will occur at a faster rate.
- What is a consequence of this higher chemical weathering rate?
- Large trucks are filled with gravel at a quarry and then carry this gravel to build a road on the other side of town. This is an example of ____________ Answer: Erosion.
Note: The questions in Part 2 can be presented as multiple choice questions and used with clickers.
Teaching Notes and Tips
- Instructor may need to spend additional time with this review and activity if students have not completed the Unit 4 background reading.
Assessment
There is no formal assessment of this activity; assessment is embedded into the discussion questions above.
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