By Julie Dial
Background
Topographic maps show much more than location, elevation and cultural features. To an earth scientist who knows how to read topographic maps, the maps reveal the features of the land surface. This information is valuable when one is faced with navigating the land surface to reach a specific area. Contour lines (represented by brown on topographic maps) connect points of equal elevation on the map. The spacing of contour lines shows the inclination of slopes, the depth of a depression, and the general relief (variation in elevation) of an area. Slope steepness and relief can be determined by the spacing between contour lines that are next to one another. In general, if the space is close together, slopes are steep and the relief is high. When the spacing of the contour lines is further apart, the slopes are gentle and the relief is low.
Purpose
Become familiar with the rules that govern contour lines. Apply these rules to topographic maps. Expand abilities in reading topographic maps.
Materials
- Alda topographic quadrangle
- knowlege of contour line rules
Procedure
Answer all questions below using the topographic map.
Map Questions:
- What is the contour interval of the map?
- What is the relief for the land between the south channel of the Platte and it's middle channel?
- What contour rule did you use to determine the answer above?
- In what direction are the intermittent streams flowing over the land in question number 2?
- How did you determine the direction of water flow?
- What geologic feature does Campbell Cemetery occupy along the south channel of the Platte River?
- If you were to hike from Campbell Cemetery slightly southwest to the first lake, would you be walking uphill or downhill?
- This lake sits in what type of feature?
- What is the name for the marks that encompass the lake?
- Describe the relief in which the lake sits and the other lakes to the southwest.
- Justify your answer for question number 10.
- What type of geologic feature do the lakes in number 10 sit on?
- If you were to climb the slopes to get to the lake in number 8, would you expect a gentle or steep climb?
- Justify your answer in number 13.
- If you were to hike from the school in Alda to the Wood River due south, would the landscape be gentle and low or steep and high?
- Would you be hiking up or down slope?
- What type of feature does the water in S4, T10N, R10W occupy?
- What contour rule did you use to determine your answer for number 17?
- How high does the feature in number 17 rise above the land surface?
- What geologic feature rests in the south channel of the Platte River?