Stratigraphy of Ponca State Park

Marc Bathke

Allen Consolidated Schools

This activity will be used in a middle school earth science course as a culminating project for stratigraphy

Students must have an understanding of the laws of superposition and origin of horizontality. Also students must understand how to make good observations and be capable of interpreting their observations.

This activity is used as a culminating project for the stratigraphy unit.

Use the principle of original horizontality and the principle of superposition to identify the oldest to youngest layers in the river cut. Observe and identify the types of sedimentary rock layers present and use the observations to interpret the environment that formed the rock layers. Use fossils to compare ages of different rock layers and construct a geologic timescale for the stratigraphic column.

Collect observations for each rock layer, analyze the observations and formulate a hypothesis for the formation of each layer.

Work in small groups to develop a stratigraphic column for the river cut. Construct a model to demonstrate the processes that formed each layer and present the model to the class.

To prepare for this field study, students do background reading on the principle of original horizontality, and the law of superposition. Students should be able to apply the principles to find the relative age of rock layers in a sequence. The students will also need to know what environmental factors lead to the formation of shale, limestone, siltstone, and sand stone. Knowledge of disconformities and crossbedding would also be beneficial in the understanding of how the rock layers were layed down. The task for each group of students is to collect observations for each rock layer, and describe the environmental factors that lead to the formation of each layer. The students then will construct a stratigraphic column and present thier findings to the class. After presenting the class will go to the interpretive center and compare thier findings to that of the interpretive center.

Students have met the goals of this activity when they present thier observations and interpretations to the class. Each group will be graded on how well they observed each layer and interpreted the environment that supported each layer.

http://outdoornebraska.ne.gov/parks/guides/parksearch/showpark.asp?Area_No=143
http://www.usd.edu/missouri-river-institute/upload/GSA07.pdf
http://www.nature.nps.gov/geology/inventory/publications/s_summaries/MNRR_scoping_summary_2009-0105.pdf