Investigating geologic features and processes: A field investigation for earth science students at Leif Erickson Park, Duluth, Minnesota.

Laurie S. Severson, Woodland Middle School, Duluth, Minnesota, adapted from "A Teacher's Guide for Geologic Field Investigations in Northeastern Minnesota", by John Green and Paul Weiblen, editor: William C. Phinney.
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Summary

In this field-based study, students will investigate geologic features and processes along the north shore of Lake Superior at Leif Erickson Park in Duluth, Minnesota. Students will make and record systematic quantitative and qualitative observations along a 500 foot section of shoreline. In small groups, they will use their observations to develop questions to investigate and use collected data and thoughtful reasoning to make logical predictions about the processes that formed these features and outcrops and the sequence of events leading to their formation. Students will present their findings to the class who will collectively use evidence supported debate to come up with a group conclusion. At the conclusion of the activity, students will express new questions they might have and discuss items that they could further investigate.

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Learning Goals

This activity is designed for students to experience a true hands-on field investigation in an actual geologic setting while observing rocks and features they have studied in class as well as fine tuning their observational skills. Students will actively collect and analyze their own data at this site thereby practicing what actual geologists do. They will communicate their findings to the class using their data as evidence to support their predictions about the processes that caused the rocks and features.

Concepts covered will include
1. rocks exposed at the earth's surface give geologists clues to help them interpret the geologic history of an area
2. bedrock in northeastern Minnesota contains features that are clues to the state's glacial history
3. different rock types react differently to the same erosional processes-i.e. wave action breaks down sedimentary rocks faster than igneous rocks
4. cross cutting relationships (i.e .veins and dikes) help geologists determine the sequence of events in earth's geologic past
5. a whole rock outcrop looks a lot different and contains a lot more information than a single hand specimen.

Vocabulary:
-Outcrop
-Bedrock
-Igneous
-Metamorphic
-Sedimentary rocks
-Striations
-Glacial till
-Fault
-Dike cross-cutting relationships
-Interflow sandstones
-Cross-beds,
-Differential erosion

Context for Use

I plan to use this field investigation with 8th grade classes of no more that 24 students at a time. I estimate the activity to take about a half day or so. This site illustrates so many geologic concepts and features that it could certainly be expanded in time allotted and the grade level that it is used for. I will use this lesson in the spring after we have covered the 3 rock groups, how they form and how to identify them. Our two most recent units covered will include weathering and erosion and glaciers. Students will have visited outcrops behind our school where they will have practiced making and recording accurate qualitative and quantitative observations in a systematic manner. They will be familiar with group work and will have practiced sketching their observations. They will know their pace in order to record their observations on a very basic base map. This unit will precede our unit on geologic time and earth history, hopefully generating interest in these topics prior to their introduction. I hope to have a few GPS units available for locating their individual sites on the base map.

Description and Teaching Materials

I will introduce the activity with: We are going to do an actual field investigation where you will see many of the rocks and geologic features that we have studied in class. You will use your observational skills to make interpretations about the formation of the rocks and features and propose a story about the sequence of events leading to their formations.

Students will have field notebooks and will know how to use individual pace measurements and how to use the GPS units to determine their exact location on the base map. The 500 feet of shoreline to study will be flagged. I will give students 15-20 minutes to walk the beach along the outcrops. While doing so, they will be asked to record 10 or more observations about what they observe as well as any questions that come up. I will emphasize noting any major changes they see. We will then gather as a large group to write down on a large board the list of questions and observations that came up. I will then divide them into small groups and assign a segment of shore that includes one of the following: l. glacial till, polish and striations, 2. beach area with sand and pebbles etc., 3.dike (cross-cutting relationship), 4. sandstone with cross-beds, 5. fault, 6. area of fractured, altered rock, 7. calcite veins cutting across layers.

They will be asked to make an additional 10 or more accurate observations of their area and then to make 10 more stressing the need for both qualitative and quantitative measurements and sketches. Guided questions for each group are: 1. What kind of rock type(s) and features do you have? 2. What is your evidence? 3. How do you think this area formed? What process(es) were part of the formation? 4. What is your proof? 6. What kind of earth processes are still at work? As a group, they will be asked to come up with one question that could be furthered investigated in their section and to give a brief idea about how they would go about the investigation.

Students will present their findings to the large group including their evidence based data and how they collected it. A brief description will be put on a large base map for later classroom use.

Students will have tape measures, GPS units, metric rulers, hand lenses, and basic rock identification keys available to them. They will record their observations/data in their field notebooks.

After students have heard all the presentations, I will ask each of them to come up with a prediction as to what went on in the past in this 500 feet of shoreline? What was the likely sequence of geologic events that formed this section of shore? What might this area have looked like a million years ago? What kind of environment was present? What will it look like one million years in the future? Include your evidence for your predictions based on the data you collected today. This would probably take place in the classroom the following day. We would then debate predictions as a large group. Students will be asked about any new questions that they may have.

This field area was chosen from "A Teacher's Guide For Geologic Field Investigations In Northeastern Minnesota" by John Green and Paul Weiblen, editor: William Phinney, sponsored by The Minnesota Department Of Education with cooperation of The Minnesota Geological Survey.

Teaching Notes and Tips

I'm predicting that this could take a lot more time than a half day. Since this site requires busing, I want my students to see as much real geology as possible. This small area contains a huge package of north shore rocks and features and is easily accessible for many of my students. The wrap up and/or group presentations could take place back in the classroom, although it would be nice to have the outcrops readily available. Permission slips are of course a must as is a discussion of procedures and safety along the shore. Kids will have lots of questions, so I will have arranged for several local geologists to be along to assist.

Assessment

I will circulate and ask questions during the fieldwork. Students will record their individual and group observations and questions in their field notebooks. I will collect these from each student at the end of the project. They will be graded for completeness and quality as well as their grasp of the concepts presented. Group presentations will also be assessed according to completeness, following directions and how well their predictions were supported by their data.

Standards

The target Minnesota Academic Science Standards are 8.I.B.1 and 8.I.B. 2-systematic observations, careful collection of data, logical reasoning to develop hypotheses and generalizations made to more complex systems from a simple system.

References and Resources