Drainage basin patterns and stream courses
This activity has benefited from input from faculty educators beyond the author through a review and suggestion process.
This review took place as a part of a faculty professional development workshop where groups of faculty reviewed each others' activities and offered feedback and ideas for improvements. To learn more about the process On the Cutting Edge uses for activity review, see http://serc.carleton.edu/NAGTWorkshops/review.html.
This page first made public: May 2, 2008
Skills and concepts that students must have mastered
How the activity is situated in the course
Content/concepts goals for this activity
Higher order thinking skills goals for this activity
Other skills goals for this activity
Description of the activity/assignment
The first day of class begins with a discussion of the components of a drainage basin and typical drainage basin patterns, including dendritic, parallel, trellis, rectangular, radial, annular, and multibasinal. After viewing the typical textbook diagrams of these drainage basin patterns, each student is given his/her own topographic map and a geologic map from the same region. The students are given the following instructions:
1.Write a one paragraph description of your study area, and include the following information:
- Quad. name
- Drainage basin pattern(s)—in bold
- Geological influence
The maps are usually distributed in the last 10 minutes of a 50-minute class period, so that the students have some time to get familiar with the maps and ask any questions that arise immediately. Recommended 7.5 minute quad.s for the exercise include:
dendritic: Effingham, IL; Alma, WI-MN
parallel: Ithaca West, NY; Antelope Peak, AZ
trellis: Waldron, AR
rectangular: Hillsboro, KY; Cumberland MD-PA-WV
radial: Mt. Rainer, WA
annular: Maverick Spring, WY
multibasinal: Whitwell, TN; Oolitic, IN
The Website http://rockyweb.cr.usgs.gov/outreach/featureindex.html is also a useful reference for other topographic maps.
On the second day of class, we discuss the initiation of channels and basin morphometry. After lecturing on topics like tractive force, micropiracy, cross-grading, and bifurcation, we discuss typical stream courses (i.e., insequent, consequent, subsequent, obsequent, and resequent). In the last 5 minutes of class, the paragraphs from the previous day are redistributed in such a way that every student has a paragraph written by one of their peers and a new set of maps. The students are given the following instructions:
1.Rewrite/edit what you have been given, if necessary, to emphasize the bolded drainage pattern.
2.Decide whether the stream patterns are representative of consequent, insequent, or subsequent stream courses.
3.Explain your reasoning using the geologic map.
- Discuss the influence of the resistance of geologic materials on the stream course.
- Discuss the influence of slope on the development of the stream course.
Once final paragraphs are submitted, they are redistributed to the entire class so that all students have a complete set of paragraphs describing a variety of drainage basin patterns and stream courses from a variety of geologic settings. Maps remain in the classroom for the duration of the term so that students can reference them if they choose to.
Designed for a geomorphology course
Has minimal/no quantitative component
Determining whether students have met the goals
Download teaching materials and tips
- Activity Description/Assignment (Acrobat (PDF) 35kB May2 08)