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Lesson 9 Topographic Profiles Hess, McKnight’s Physical Geography, 10 ed. A3-A4

What is a “topographic profile?” Last week we discussed USGS topographic maps ◦ 3D landscape on a 2D map ◦ Use contour lines to connect equal elevation intervals ◦ This is known as a “plain view” map A topographic profile is literally a “side view” along a line drawn over the topographic map ◦ They show changes in elevation along a line

Constructing a Topographic Profile 1. On the topographic map, determine what profile you would like to measure ◦ For this exercise & the homework, this is given as the line segment AB 2. If a computer program is not available, lay a piece of paper down along line AB 3. Start from point A: wherever a contour line intersects the edge of the paper, place a short tick mark AND write down the elevation 4. Continue along the line to point B ◦ Along the way, mark wherever a mountain peak, valley, or stream is located ◦ Also mark any other important features (roads, buildings, etc)

Constructing a Topographic Profile, cont. 5. Next, transfer your paper with the tick marks, elevation, and features to a chart (will be provided) 6. Align your writing along the bottom of the chart 7. Start at point A: transfer your measurements along the X and Y-axis’ moving toward point B. 8. Connect the dots 9. Finish by adding the locations of mountain peaks, streams, roads,etc.

Example 1

Example 1, cont.

Snowville Topo Using the Snowville topographic map from last week, construct a profile along line AB. ◦ You may use your printout, or come up to the screen ◦ The elevation at point A is 2093 ◦ The elevation at point B is 2085 ◦ Remember to draw both contour lines as “tick marks” AND important features Once you are done, raise your hand and I will check your work

Snowville Topo Let’s see how our hand-drawn profile compares to a computer-generated image. profiler/en/ profiler/en/

Vertical Exaggeration In our previous example, the y-axis intervals were the same as the elevation contours on the Snowville topographic map In our case, the vertical scale we used matched the horizontal scale ◦ The vertical scale was equal to the graphic scale which was given in the lower-left corner This brings us to vertical exaggeration

Vertical Exaggeration, cont. Vertical exaggeration is created to emphasizes differences in elevation and to show relief ◦ e.g., when there is a large amount of V. E., small hills appear to be tall mountain peaks on the graph

Vertical Exaggeration, con.t

Vertical Exaggeration, cont. To determine the amount of V. E., simply divide the horizontal distance (i.e., the denominator of the fraction/ratio) by the vertical distance 1” represents on the graph

Vertical Exaggeration, con.t