Landforms Produced by Streams and Groundwater
Introduction
Streams act on landscapes with tremendous mechanical force (especially during floods) making them the principal erosional agent in nature, while groundwater primarily acts as a chemical agent, and can remove large volumes of soluble carbonate rocks in areas of high rainfall. In both cases the shape of the landscape provides an important clue to the activities of these geological processes.
In this exercise you will practice identification and interpretation of some of the common landforms produced by the action of streams and groundwater.
Objectives
Upon completion of this exercise, you should be able to:
Identify common landforms on topographic produced the action of streams and groundwater
Determine whether landforms are the result of deposition or erosion
Predict the future evolution of the landscape
Materials
Maps provided by your instructor
Background Information
Calculating gradient:
1.Determine the vertical difference (relief) in feet between 2 points rise.
2.Measure the horizontal distance in miles between the 2 points using graphical scale run.
3.Divide the rise by the run to determine the gradient in feet per mile.
Pre-lab Assignment
Using your textbook, lecture notes or the internet familiarize yourself with each of the following stream and groundwater-related landforms then, on separate sheet of paper, briefly define each in your own words.
1.alluvial fan
2.braided stream
3.channel bar
4.cutbank
5.delta
6.distributary
7.floodplain
8.meandering stream
9.natural levee
10.oxbow lake
11.point bars
12.stream terraces
13.tributary
14.V-shaped valleys
?
In addition, define the following are key vocabulary in your own words so you may succeed in this laboratory exercise.
1.alluvium
2.aquifer
3.groundwater
4.hot spring
5.karst topography
6.permeability
7.porosity
In Class Laboratory Exercises
A. Hydrologic Cycle Using your Hydrologic Cycle Figure from your textbook answer the following questions.
1. On a worldwide basis, more water is evaporated into the atmosphere from the oceans or from land? _____________
2. Approximately what percent of the total water evaporated into the atmosphere comes from the oceans?
Percent from oceans = ocean evaporation x 100 = ______________________________________________
Total evaporation
*** Notice in the figure that more water evaporates from the oceans than is returned directly to them by precipitation.
3. Since sea level is not dropping, what are the others sources of water for the oceans in addition to precipitation?
__________________________________________________________________________________________________
B. Streams
Ennis, Montana 15 minute quadrangle map. Write your answer to each question on line to the right.
1.What is the scale of this map? ___________________
2.What is the magnetic declination in this area? ___________________
3.Crooked Creek and Short Creek are both ___ of Jordan Creek. ___________________
4.Where does the Jordan Creek discharge its water? ___________________
5.Is Jordan Creek a perennial or intermittent stream? ___________________
6.What is the elevation of the local base level in this area? ___________________
7.What direction does the Madison River Flow south of Ennis Lake? ___________________
8.What is the gradient (slope) of the Madison River south of Ennis Lake? Show your work for credit.
___________________
9.What type of stream channel is Madison River south of the lake? ___________________
10.What depositional landform has developed along the southern shore of Ennis Lake? ___________________
11.What type of stream channel is Madison River north of the lake? ___________________
12.The Cedar Creek Alluvial Fan is a classic example of an alluvial fan. Note the branching pattern of stream channels on the surface of the fan. What is the name for channels of this type?___________________
13.Why did an alluvial fan develop at this location? _________________________________________ ________________________________________________________________________________________________________________________________________________
14.Below, draw a cross-section image of an alluvial fan from the toe (bottom) to the head (where the fan touches the mountain front).
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