Contour maps - Analysis and Interpretation

This lab has three parts. The second part will get us started with ArcView, the other two work with paper maps.

Group members:

A. Manual Slope Measurement

Port Orchard Quadrangle 1:62,500 1937

• Set the dividers to 1000 feet (on the graphic scale), count the contours in this distance at a few locations around "Fort Ward" and other parts of Bainbridge Island.
• Estimate the slope by dividing rise (number of contour lines times contour interval) over run (the spacing of the dividers.
• Set the dividers to 500 feet. See what values you obtain (particularly in the vicinity of "Toe Jam Hill" on the south of Bainbridge Island...)

What happens with shorter distances?

B. Digital Slope calculations

• In the 258 folder on the L: drive, Open (double-click) the project lab4dem.apr
• (There is much to learn about how to save files and all that for later, but for now it helps to set the working directory to C:\temp or to c:\258Temp...)
• Use the Identify tool to obtain spot elevations in the grid "ebrmgrd". (some of this is shown by demonstration...)
• Create a new theme Surface menu at the top: Derive Slope, examine the slope results (Derive Aspect as well...)

How close are the results you obtained in Part A to the results in this database?

What might account for the differences?

C. Landform Interpretation

Take a look at the contour map examples. Each one shows the connection between landforms and the surface processes that created them.

What clues can you extract for each kind of terrain?