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