Investigating the Geologic History of Southeast Minnesota by Constructing a Geologic Column
Summary
This activity is an inquiry-based, earth science field investigation of the geology of southeast Minnesota. Students will make observations of rock outcrops and landforms in the region using maps, pictures, and field sampling, then use these observations to construct a geologic column of southeast Minnesota. Students will use this column to interpret the geologic history of the region.
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Learning Goals
This activity is designed for students to:
- Refine observation skills and make detailed notes in a science notebook
- Practice geologic field techniques while collecting data during a field investigation and organize the data for interpretation.
- Interpret the geologic history of an area using the evidence present in rocks and landscape features.
Key Concepts
1. Forces and processes that are observed today also operated in the past.
2. Rocks that are lower in a geologic column are older than the rocks higher in the column.
3. The earth has changed over time due to changes in climate, earth processes, and the presence of living organisms.
Vocabulary
Index fossil
Sedimentary rock
Friable
Cross bedding
Shale
Dolomite
- Refine observation skills and make detailed notes in a science notebook
- Practice geologic field techniques while collecting data during a field investigation and organize the data for interpretation.
- Interpret the geologic history of an area using the evidence present in rocks and landscape features.
Key Concepts
1. Forces and processes that are observed today also operated in the past.
2. Rocks that are lower in a geologic column are older than the rocks higher in the column.
3. The earth has changed over time due to changes in climate, earth processes, and the presence of living organisms.
Vocabulary
Index fossil
Sedimentary rock
Friable
Cross bedding
Shale
Dolomite
Context for Use
This activity was designed for a high school Earth Science class taken by junior and senior students in a public high school. Class size in this course ranges from 15-30 students. It is designed as a field investigation with a few days of preparatory work in the classroom. In all, this activity is designed to be about 4-5 days in length.
Prior to doing this activity, students should have some practice making observations and recording them in science notebooks. They should also have some experience with topographic and geologic maps in the class as students may use them to help make sense of or confirm the observations they have made in the field. This activity is done within the first month of the earth science course that I teach, but it could be done at other times as well. I believe that the general ideas could be adapted to different settings, but there should be sufficient rock exposures or formations available to students for observation and sampling.
Prior to doing this activity, students should have some practice making observations and recording them in science notebooks. They should also have some experience with topographic and geologic maps in the class as students may use them to help make sense of or confirm the observations they have made in the field. This activity is done within the first month of the earth science course that I teach, but it could be done at other times as well. I believe that the general ideas could be adapted to different settings, but there should be sufficient rock exposures or formations available to students for observation and sampling.
Description and Teaching Materials
Pictures of southeast Minnesota landscape and geologic features are either distributed to groups of students or projected on a screen for the entire group. Students make observations for all or selected pictures, which are then shared and discussed together as a group or small groups can present their observations of a selected picture. If a SMART Board is available, students can highlight or make notes next to specific features and observations on the projected picture. This process should take 1-2 class days.
When the observations have been completed, students are either assigned to groups of 2-3 or choose their own and are asked to generate questions based upon the observations. My goal is for students to question how the landscape of the Cannon Falls area formed or inquire about the geologic history of this area. The field investigation day will help to answer some of the questions generated and provide more information about southeast Minnesota's geologic history.
Prior to going on the field investigation, students are instructed on how to use rock hammers, acid bottles, and hand lenses to make observations of rocks. These items are provided, but students may bring their own equipment as well, such as a camera. I also provide the template for a geologic column with our field site locations correlated to the various layers of the column to assist students in recording information and picturing the geologic structure of the landscape.
On the field investigation day, we travel to sites that I have selected to represent the landscape of the area. These sites are pre-screened and permission has been granted for any private land that we visit. Students make observations and take samples of the rocks. I also lead a short discussion at each site reflecting on what we observe and what it might mean. The entire field investigation could last a couple hours to an entire day.
On the day following the field investigation, the class will discuss their impressions, observations, and questions from their experiences the previous day. Then, students will work on processing their data and observations. They may use books, maps, and discussions with peers or me to help them generate their geologic column and write a short story interpreting what the column tells them about the geologic history of southeast Minnesota. To wrap up this activity, I discuss the geologic history of Cannon Falls and the surrounding region.
Teaching Notes and Tips
When planning your field investigation, remember to arrange for transportation early and plan a rain date ahead of time. If you would like to go to a site on private land (such as a gravel pit) or an education site (such as a nature center or cave), contact the company/individual well in advance to see if it is possible to bring students to the site and, if so, what the conditions of your visit will be. When choosing study sites, identify potential hazards that may exist and plan accordingly for them. If you will be stopping along roadsides, try to plan the route so that the bus can pull off the road easily and students do not have to cross the road to get to the study site.
To manage field equipment, assign a set of equipment to each group that they must return at the end of the field investigation. Place acid bottles in Ziploc bags or a similar container to prevent acid leakage. A whiteboard is also a handy tool for explaining particular features while out in the field. Remind students to write down the date and location in their field journal and indicate scale and orientation in their drawings.
Though I have conducted field investigations with students in the past, this activity is different in that I process observations and insights while at each site rather than waiting until we get back to the classroom. I used to wait to teach the content until after we return from the field, but now I teach the content "in context" while at each site. I also encourage students to not only make observations and record data in their notebooks, but also to reflect in their notes on what they see and what it may indicate.
To manage field equipment, assign a set of equipment to each group that they must return at the end of the field investigation. Place acid bottles in Ziploc bags or a similar container to prevent acid leakage. A whiteboard is also a handy tool for explaining particular features while out in the field. Remind students to write down the date and location in their field journal and indicate scale and orientation in their drawings.
Though I have conducted field investigations with students in the past, this activity is different in that I process observations and insights while at each site rather than waiting until we get back to the classroom. I used to wait to teach the content until after we return from the field, but now I teach the content "in context" while at each site. I also encourage students to not only make observations and record data in their notebooks, but also to reflect in their notes on what they see and what it may indicate.
Assessment
Students will be assessed in a variety of ways during this activity. They include:
- Informal assessment of students' observations and work ethic while out in the field through questioning and observation of student work
- Construction of a geologic column for southeast Minnesota and writing a short story interpretation of that column.
- Essay question on unit test asking them to describe the geologic history of the Cannon Falls area
- Informal assessment of students' observations and work ethic while out in the field through questioning and observation of student work
- Construction of a geologic column for southeast Minnesota and writing a short story interpretation of that column.
- Essay question on unit test asking them to describe the geologic history of the Cannon Falls area
Standards
9-12.III.A.7-use evidence to explain how Earth has changed over time