Answer the following map interpretation questions using as many different lines of evidence as you can gather from the map and from your text and lecture notes. Keep in mind that you are making educated guesses with some of these questions, so a good answer is one that is backed up with as much evidence as possible. If your answer is different from mine, I will accept it if it is well argued. Start by looking at the whole map, and use the information in the map margins. Use the USGS map symbols to help you interpret features. U.S. Geological Survey Map Symbols.

Fluvial Landforms

Menan Buttes, Idaho 7.5' USGS quadrangle (1:24,000 scale). Menan Buttes are two cinder cones, on the edge of a lava field to the northwest.

1. What is the channel pattern of the Henry's Fork River? Justify your answer.

2. What is the slope of this channel, from Little Island to its confluence with the Snake River? (I am looking for a quantitative answer.)

3. What type of sediment load do you think this river carries? What is your evidence?

4. What evidence do you see of meander migration? Of channel avulsion?

On the blackboard I have pasted up a set of maps from different parts of Nebraska.

Brewster SE, Nebraska 7.5' USGS Quad, and Boelus, Nebraska 7.5' USGS Quad.

Starting with the Middle Loup River shown flowing through stabilized Pleistocene dune fields on the
Brewster SE, Nebraska quad:

1. What is the channel gradient of this section of the Middle Loup River?

2. How does the channel of this river compare with that of the Henry's Fork River in Idaho?

On the Boelus, Nebraska 7.5' Quad:

1. Where is this section of the Middle Loup River in relation to the section examined above (give cardinal directions)? How do you know?

2. What differences do you see in the Middle Loup River on the Boelus map compared with the Brewster SE map?

3. What type of sediment load are these rivers carrying, and what is its probable source?

4. Look at the drainage patterns in the northwestern part of the Boelus map. What type of drainage pattern do you see here? What does this tell you about the underlying geology? Justify your answers.

The following maps show different reaches of the Platte River as it flows through Nebraska: Bayard SW, Nebraska 7.5' Quad; Kearney, Nebraska 7.5' Quad; Duncan, Nebraska 7.5' Quad; and Columbus, Nebraska 7.5' Quad.

Compare the Platte River channel pattern from the upstream end to the downstream end on these maps. Describe the channel characteristics on each of these maps, including channel width, pattern, gradient, etc. I am looking for quantitative measurements, not estimates. What other differences do you see?:

1. Bayard SW

2. Kearney

3. Duncan

4. Columbus

5. What factors are probably responsible for these variations?

6. What characteristics are most consistent throughout these reaches of the Platte River?

7. Which of the two cities, Columbus and Kearney, appears most likely to experience flooding? What evidence do you see for this answer?

All lab materials for this course are intellectual property of Dorothy E. Freidel, unless otherwise credited. Copyright D.E. Freidel, 2003. No portion of this material may be copied without written permission of the author.

Page last updated 10/5/04