We spend the first of three lab periods walking up a bedload-dominated stream bed that is a tributary stream to the Mohawk River. We notice the obvious flights of terraces along the stream. I ask the student to count them and walk up on them and think about how they came to be. We then think about how we might survey them, and document their presence. The students have a good idea what we're up to as we have stadia rods and abney levels. Then we go through the routine of measuring terrace heights using the modern stream as a datum. I then divide students into 3 teams and assign each team a different reach of the creek. In total we cover about 1 km., and teams are responsible for measuring the height of stream terraces above the modern stream and measuring with a tape measure their distance upstream from our starting point. On the second week we repeat this exercise on another stream, and then I compile all students data into an Excel spread sheet and ask them to do some simple calculations and plot longitudinal profiles of the modern streams, with terrace remnants plotted above the modern. They do this for both sides of each stream. They also plot a cross section of the stream valley at one point of their choosing to illustrate whether the terraces are paired or unpaired. On the final week, we tour the eastern Mohawk valley looking at much larger terraces that were produced by incision of the Mohawk, and we go to an outcrop of varves deposited in Glacial Lake Albany that crop out at the base of one of the terraces. The students thus get a sense of the large changes in base level that must have affected all the tributary streams in the region.
Has minimal/no quantitative component
Addresses student fear of quantitative aspect and/or inadequate quantitative skills
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- Subject:
- Biology
- Life Science
- Material Type:
- Activity/Lab
- Homework/Assignment
- Provider:
- Science Education Resource Center (SERC) at Carleton College
- Provider Set:
- Teach the Earth
- Date Added:
- 08/18/2019