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Office Hours. Mon: 11:30 AM to 12:30 PM & 1:45 PM to 3:00 PM Wed: 11:30 A M to 12:30 PM Thr : 9:15 AM to 12:30 PM Fri: 10:00 AM to 12:00 P M. Lesson 9. Topographic Profiles Hess, McKnight’s Physical Geography , 10 ed. A3-A4. What is a “topographic profile?”.
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Office Hours Mon: 11:30 AM to 12:30 PM & 1:45 PM to 3:00 PM Wed: 11:30 AM to 12:30 PM Thr: 9:15 AM to 12:30 PM Fri: 10:00 AM to 12:00 PM
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 • 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 • If a computer program is not available, lay a piece of paper down along line AB • Start from point A: wherever a contour line intersects the edge of the paper, place a short tick mark AND write down the elevation • 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. • Next, transfer your paper with the tick marks, elevation, and features to a chart (will be provided) • Align your writing along the bottom of the chart • Start at point A: transfer your measurements along the X and Y-axis’ moving toward point B. • Connect the dots • Finish by adding the locations of mountain peaks, streams, roads ,etc.
SnowvilleTopo Example: • Using the Snowville topographic map from last week, construct a profile along line AB. • 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
SnowvilleTopo • Let’s see how our hand-drawn profile compares to a computer-generated image. • http://www.geocontext.org/publ/2010/04/profiler/en/
Vertical Exaggeration • In our previous example, the y-axis intervals were the same as the elevation contours on the topographic map • In our case, the vertical scale we used matched the horizontal scale • 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, cont. • To determine the amount of V. E., simply divide the horizontal distance one inch represents by the vertical distance one inch represents
Vertical Exaggeration, con.t • For the Snowville topographic profile: • The vertical distance on the graph was • 1” = ~100’ • The horizontal distance on the graph (not shown) was • 1” = ~100’ • Divide the horizontal (scale) distance by the vertical distance: • = 1.0 • Thus the V. E. is 1.0 X (or the same as the horizontal distance)