Observing Abandoned and Undersized Valleys to Investigate the Drainage History of the Cincinnati Area

Sarah Johnson, Northern Kentucky University
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Summary

Using a digital elevation model, prehistoric drainage and modern drainage in google earth, students will locate abandoned valleys, interpret prehistoric drainage orientations, measure and compare valley and channel widths of "new" sections of the Ohio River with tributary valleys which have been used by both prehistoric and modern rivers.

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Context

Audience

I use this activity for a geomorphology course for undergraduate geology majors. The prerequisite for geomorphology is one previous geology course.

Skills and concepts that students must have mastered

  • Students should be familiar with using google earth - how to turn layers on and off and measure distances.
  • Student should be familiar with dendritic drainage patterns.

How the activity is situated in the course

I use this activity after we study streams and as an introduction to how glaciers have affected this region.

I have used a version of this in my geomorphology course, and a version in my introductory geology course.

Goals

Content/concepts goals for this activity

  • The width of river valleys is related to their age
  • A section of largest river in the area (the Ohio River) occupies a very young valley
  • Rivers that once flowed to the North prior to glaciation now flow to the South
  • River valleys are reused by different drainage systems
  • Drainage in the region has been disrupted multiple times by glacial activity

Higher order thinking skills goals for this activity

  • Use geomorphic data to interpret past processes

Other skills goals for this activity

  • use layers and measuring tools in google earth
  • use a digital elevation model

Description and Teaching Materials

Students download google earth files including a digital elevation model, prehistoric drainage and modern drainage files. Students use the DEM and the modern drainage to locate abandoned valleys and compare their valley elevations with modern valley elevations. Students then compare the width of of the Ohio river channel and valley, and the width of two tributary channels and valleys, and form a hypotheses as to why the tributary valleys are wider than the Ohio River valley. Students then view a layer showing the Teays river system and determine which way this ancient pre-glacial Teays river flowed in this region, and think about what happened to the water in this system when the first glaciers advanced into the area.

Teaching Notes and Tips

  • Students complete this activity in groups during class. After they complete and we review the activity I present a slide show illustrating the history and the glacial deposits in this area.
  • I have used a version of this for my introductory geology course - they need more leading questions to help them figure out why tributary valleys might be wider than the main river valley.

References and Resources