Northampton Community College-GEOL 201-In this lab you will identify how stream characteristics are related

| March 14, 2016

Question

Laboratory Questions

Purpose:

In this lab you will identify how stream characteristics are related to erosion and deposition. You will also familiarize yourself with drainage patterns and topography modification by streams.

Reading Assignment:

Read sections 10.1 through 10.8 inclusive

Review the Lab Assistant – Streams found above in this chapter folder.

Materials Needed:Ruler, Thin String, Calculator

Exercises: (Show math for partial credit)

1. Describe the differences between the two streams shown in Figure 10.1 in terms of valley width to channel width ratio, sinuosity (review Figure 10.3), and erosion (vertical vs horizontal). (3pts, Reference Section 10.2)

2. Based on what you learned in from last weeks textbook chapter, describe the possible types of mass wasting occurring on the valley walls of the Yellowstone River in Wyoming (Figure 10.1a) (2pts)

3. Using the partial topographic map in Figure 10.4, compare the course of the Big Horn River between points B and A with that of its tributary between points C and D. Fill in the table below: (7pts, Reference Section 10.2-10.3)

Big Horn River (B-A)

Unnamed tributary (C-D)

Channel length, (Actual length of the stream following all the curves)(miles)

Straight line length (Straight length between start and end points)(miles)

Sinuosity (Channel Length / Straight Line Length) (no units)

Highest Elevation (feet)

Elevation of Point B =

Elevation of Point C= 4,130′

Lowest Elevation (feet)

Elevation of Point A =

Elevation of Point D=

Vertical drop (feet)

Elevation B – Elevation A =

Elevation C – Elevation D =

Gradient (Vertical Drop / Channel Length)(feet/mile)

4. If we assume the relationships between the data in Question 3 represent typical streams, what can you say about the apparent relationship between stream gradient and sinuosity? (i.e. If we measure a certain sinuosity, what can we infer about the gradient?) (1pt, Reference Section 10.2)

5. Read Exercise 10.4 and answer the following five questions. Note: Figure 10.9 covers three pages. You are comparing the St Francis and parallel streams [(10.9a) tributary of the Mississippi River], the Meadow River (10.9b), and the Arkansas River (10.9c). Notice that one side of the valley is out of view for the St. Francis river. You should also check your analysis by looking at some elevations where they cross the stream. This will give you the vertical drop of the stream, within the map area. Be aware that the scale of the maps is not the same for the three maps so you may want to estimate the valley widths before answer the questions. (Reference Section 10.3-10.4, Textbook)

A) Which stream has the smallest stream valley? Describe the spacing of the contour lines near the stream? (1.5pts)

B) Which stream valley has a very large flood plain and the most meandering scars and oxbow lakes? What is the name of one of the lakes? (1.5pts)

C) Which stream valley has large meanders, a valley width to steam width ratio of about 4-6′ (valley is about 4x-6x larger than stream width), and many sand bars (small “islands”)? (1pt)

D) The valley width to steam width ratio gives is an indicator of lateral erosion (past an present). List the maps in order of smallest ratio (valley width and steam width similar) to largest ratio (valley width much larger than stream width). (1pt)

E) Based on you above answers, which steam has the most vertical erosion? Which has the least vertical erosion (most horizontal erosion)? (1pt)

6. What type of drainage pattern is demonstrated by the map in Figure 10.16? (1pt, Reference Section 10.5)

7. Read through Exercise 10.8 and review Figure 10.17. What is the evidence that the Susquehanna River is a superposed stream? What type of geologic structures underlie and cause the valleys and ridges? The “V” shaped ridges are a clue (Geologic structures are in Chapter 9 of the textbook). (2pts, Reference Section 10.7 and Lab Assistant – Faults and Folds)

8. Look at both the aerial image and the topographic map in Figure 10.21. Which area is more prone to flooding, Jefferson city or Cedar City? Why? (2pts, Reference Section 10.8)

9. Read through Exercise 10.11 and look at the map and images. Now look at Slide 15 of the Lab Assistant – Streams. The map on this slide shows the Rio Grande River in 1936 and the Present.
A) What is going to eventually happen to the meander loop at letter “J”? What is it called now, and what will it be called in the future? (2pts)

B) If river is the boundary between the United States and Mexico, what letter indicates a location where land area may soon transfer from Mexico to the United States? (1pt)

C) Look back at the map and aerial image in the lab manual where the infrastructure of Brownsville and Matamoros are directly across from each other on a meander of the river (center of images). What could be done to prevent the this meander from moving? (1pt)

I am falling behind on these labs for my class, this semester is almost over and trying to keep up need help. This lab is from the

Laboratory Manual for Introductory Geology, 3rd Ed., by Allan

Ludman and Stephen Marshak. W.W. Norton & Company. New

York, N.Y. 10110 (ISBN 978-0-393-93791-6 )

Chapter Ten (Landscapes Formed by Streams)

If I can get any help to these questions it would be much appreciated!

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