Sedimentary Environments

John Dawson
,
Kirkwood Community College
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Summary

This lab emphasizes a few basic principles used to decipher past sedimentary depositional environments including sediment grain size, sorting, and arrangement along with sedimentary structures. The major strength of this lab is that students should be able to apply the principles relatively easily.

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Context

Audience

This is a lab activity for an introductory historical geology class (see course profile). This is designed for a two hour lab period with some time planned for brief lecture and clean-up. This also could work well as an in-class activity for a small class if you have a two hour lecture block.

Skills and concepts that students must have mastered

Students should already have learned about sedimentary rocks and also have had an overview of the major groups of fossils (coral, bivalve, brachiopod, etc.). They should already know the basic environments that are implied by grain size (high energy, low energy, shallow water, deep water).

How the activity is situated in the course

This is part of a sequence of activities and I try to place it in context to the lecture. It usually occurs about four weeks into the semester.

Goals

Content/concepts goals for this activity

Students should be able to:
1. Define depositional environments.
2. Identify size, shape, and arrangement of sediment grains.
3. Identify common sedimentary structures including mud cracks, ripple marks, cross bedding, and fining upwards sequences.
4. Identify the possible sedimentary environment based on characteristics of the sediments.

Higher order thinking skills goals for this activity

This activity does require the students to synthesize several concepts relating to sedimentary environments and to apply them to a unique situation.

Other skills goals for this activity

Description of the activity/assignment

This activity is designed for students to learn about sedimentary environments. Students will learn about grain size, shape, and arrangement and how it relates to deciphering sedimentary environments. Students are given a sediment sample to analyze. They first examine the sample under the microscope and then will use sieves to separate the sediments into size classes. They will also take time to compare their sample versus another group's sample in the classroom. They will also have an opportunity to look at rock specimens representing sedimentary structures including mud cracks, cross bedding, and ripple marks. In the end, students should gain some skills at using basic observations and data collection to interpret the original depositional environment.

Determining whether students have met the goals

More information about assessment tools and techniques.

Teaching materials and tips

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