Outcrop Investigation: What can our rocks tell us about the past?

This activity is designed for students to reconstruct a piece of Earth's history through observation of a local outcrop. Students will record detailed observations of the outcrop in a field notebook. Next, they will hypothesize what our environment was like in the past while providing evidence to reinforce their hypothesis. Additional skills that my students will use include working in cooperative groups, the application of the principle of superposition, basic inquiry skills of observation and questioning and presenting information.

Vocabulary:
-Transgression
-Regression
-Uniformitarianism
-The principle of superposition and original horizontality
-Sandstone
-Limestone
-Shale

This field investigation is intended for two, fifty minute classes of about 30 eighth grade earth science students and can be modified to work with any local outcrop. The sedimentary rock outcrop we will be investigating sits about 10 minutes away by bus, which gives us 50 minutes of field time over two class periods. A day in the classroom of discussion and reflection will follow each day in the field. My students will have mastered some inquiry process skills including recording, discussing and expanding on observations, but will have no prior knowledge of rocks or Earth's history before we conduct our field investigation of this particular outcrop. We will conduct this field investigation in October, following our study of local surface water and landforms. Each student will wear a hard hat at all times while at the outcrop for safety purposes.

At the beginning of our rock unit, my students and I will head to a local outcrop to determine what the rocks can tell us about the past environment of the Winona area. This investigation will take four days, two in the field and two days of discussion and reflection back in the classroom. The day before our field investigation, I will inform my students to bring their field notebooks and writing utensils to class along with long pants, hiking shoes and clothes that can get a little dirty. Students will be provided with hard hats on the bus and instructed to wear them at all times while in the field. Once at the outcrop, we will begin with observation. I will designate an area of outcrop for observation and assign students their cooperative learning groups of three. Students will have 30 minutes at the outcrop each investigation day. We will take five minutes for each group to share one observation in the field on the first day following ten minutes of initial observation and end each field day in similar fashion. The rest of our field time will be spent making detailed observations of the outcrop. We will share and focus our observations in the classroom on day two. Each group will share one observation or question at a time from day one. Due to the inconvenience of bussing and limited field time, vocabulary terms will be addressed and discussed in the classroom at this time. Students will then be asked to select an observation or question to pursue that might tell us something about the past environment of our local area. Day three will be spent at the outcrop where students will investigate their questions or expand on observations. The last five minutes of day three will again be spent sharing and discussing observations in the field. This will be continued in class on day four where the students will present their findings and questions to the class. Each group will then be asked to describe what the next step would be in each investigation. Some groups might want to modify their question while others might think of another hypothesis or investigation they want to conduct. Finally, students will write a reflection of what they learned about Winona's past environment at the end of the fourth day and present them to the class.

This is the first time my students will head to the field without any instruction of content. I will bring my TIMES XI white board to the outcrop each day and briefly address any new vocabulary and concepts as they emerge from observations and questions. Unfortunately, we only have fifty minutes of total field time so most of this content will be addressed and discussed in my classroom on non-field days. As students share observations and questions that deal with new concepts and vocabulary, I will call attention to them and provide my students with the term and explanation or definition. They will be responsible for all new vocabulary terms and concepts addressed in these discussions. Someday when I get my own schedule and bus, this can all be accomplished in the field.

Learning goals will be assessed when each field notebook is handed in, enabling me to check all individual observations, new vocabulary terms and reflections. Student participation will be monitored and assessed in each discussion throughout this activity while observations of journals and group discussions in the field also serve as informal assessments with instant feedback.

Minnesota Academic Standards Earth and Space Grade 8
I. History and Nature of Science
1. The student will know that scientific investigations involve the common elements of systematic observations, the careful collection of relevant evidence, logical reasoning and innovation in developing hypotheses and explanations.
III. Earth and Space Science
2. The student will describe how features on the Earth's surface are created and constantly changing through a combination of slow and rapid processes of weathering, erosion, sediment deposition, landslides, volcanic eruptions and earthquakes.
3. The student will describe the various processes and interactions of the rock cycle.
4. The student will interpret successive layers of sedimentary rocks and their fossils to document the age and history of the Earth.
5. The student will recognize that constructive and destructive Earth processes can affect the evidence of Earth's history.
6. The student will classify and identify rocks and minerals using characteristics including but not limited to density, hardness and streak.