Page 276 - Laboratory Manual in Physical Geology

ACTIVITY ACTIVITY

9.5 Relief and Gradient (Slope) 9.6 Topographic Profile
Analysis Construction

THINK | How are topographic maps used to THINK How is a topographic profile
About It calculate the relief and gradients About It | constructed from a topographic map,
(slopes) of landscapes? and what is its vertical exaggeration?

OBJECTIVE Calculate relief and gradients from OBJECTIVE Construct a topographic profi le from
a topographic map and apply the gradient data to a topographic map using the graph paper, and then
determine a driving route. calculate its vertical exaggeration.
PROCEDURES PROCEDURES
1. Before you begin , read Relief and Gradient 1. Before you begin , read Topographic Profi les and
(Slope) on p. 244. Also, this is what you will need : Vertical Exaggeration below. Also, this is what you
___ Activity 9.5 Worksheet (p. 257 ) and pencil will need :
___ calculator ___ Activity 9.6 Worksheet (p. 258 ) and pencil
2. Then follow your instructor’s directions for ___ ruler and calculator
completing the worksheet. 2. Then follow your instructor’s directions for
completing the worksheet.

Calculating Gradient (Slope)—The Math How to Obtain a US Topo Map or
You Need Orthoimage
You can learn more about calculating slope Watch a 6-minute USGS video ( http://gallery.usgs.gov/
(gradient) at this site featuring The Math You videos/663 ) and follow these steps:
Need, When You Need It math tutorials for
students in introductory geoscience courses: Step 1: Go to the USGS Store ( http://store.usgs.
http://serc.carleton.edu/mathyouneed/ gov ). Select “Map Locator and Downloader.”
slope/index.html
Step 2: At the Map Locator and Downloader site,
you will see a map of the United States.
Topographic Profiles and Vertical A. To the right of the map, select “MARK POINTS:

Exaggeration Click on a place to add a marker.”

A topographic map provides an overhead (aerial) view B. Also to the right of the map, select “SHOW US
of an area, depicting features and relief by means of its TOPO” (orange bar).

symbols and contour lines. Occasionally a cross section of C. All of the US Topo maps and images are displayed
®
the topography is useful. A topographic profile is a cross in GeoPDF format and can only be viewed
®
®
section that shows the elevations and slopes along a given with Adobe Reader or Adobe Acrobat . If your
®

line ( FIGURE 9.16 ). To construct a topographic profile, computer does not have Adobe Reader (or Adobe

®
follow the steps in FIGURE 9.16. Acrobat ), then download and install it by selecting
the “Get Adobe Reader” bar at the bottom of
Topographic Profiles—The Math You Need the page or go to Adobe ( http://get.adobe.com/
You can learn more about constructing reader/ ).
topographic profiles at this site featuring Step 3: Search for a place/quadrangle in US Topo.
The Math You Need, When You Need It math You can use the “Search” bar above the map to search
tutorials for students in introductory geo- for an address, place name, or a specific quadrangle
science courses: http://serc.carleton.edu/ (by name). You can also zoom in or out on the map

mathyouneed/slope/topoprofile.html and change it to a satellite or topographic view. As

you zoom in, the outlines of quadrangles will appear

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