1. Activity 26 Boomtown’s Topography

2. Challenge: What can topographical maps tell you about the stability of a building site?
Key Vocabulary: Stability Stability of the land is a major factor in deciding whether an area is suitable for building. If an area has had unchanging topography for an extended time, it is considered more stable. This makes the area a more desirable building site than an area that has changed.
GO TO PAGE 11

3. Create this table in your journal
Boomtown Through Time
100 Years Ago
20 Years Ago
Today
Marsh
Hillside
Cliff

4. procedure Read the introduction on page 11.
Complete steps #1-5 on page 12.
IMPORTANT: Make sure you RECORD your observations from step #3 on your “Boomtown Through Time” table.
When you are finished, answer Analysis #1-4 in our notebooks!

5. Boomtown through time:

6. Analysis Questions (page 12)
Work in your groups to answer questions #1, #2 and #3. (Answers should be written in complete sentences in your journal.)
Work independently to answer question #4. WHY are there possible problems? Refer to the paragraph you wrote in your journal at the beginning of this activity.

7. Answers to analysis questions
1. The contour interval is 25 meters. (This is approximately 75 feet.)
2. A.The major changes through year period are:
movement of the cliff (receded west)
branching of the river
more land in the delta
significant road and house construction
increased curvature of the river

8. 2B. The changes from 20 years ago to today are:
significant change in the hill, which has become steeper on the southeastern side
Some movement of the cliff, which continued to recede to the west at a steady pace
More branching of the river and
Some addition of land in the delta

9. Answers continued A. The Seaside Cliff seems to be the most stable:
Cliff has moved less
It changed at a more steady rate
The Delta marsh is the least stable because it shows the most change in its contour lines
The evidence for this is the contour lines that show how the heights have or have not changed over time.

10. Answers continued
The maps DO indicate that there may be problems because of changes to the building sites and to the Rolling River. If the landforms continue to change there could be expensive repairs and potential safety concerns at the building sites in the future.