What About
Topography?
Background Information
The topography of the lower Columbia Basin includes canyons,
hills, and valleys. Topography is a three-dimensional
representation of the Earth’s surface on a two- dimensional
surface (paper) as seen from overhead looking directly down.
Topographic maps have contour lines that show topographic
features such as canyons, mountains, plains, and plateaus.
Topographic maps of the Tri-Cities area show such features as
Red Mountain, Zintel Canyon, Iowa Flats, and the Rattlesnake Hills.
Elevations and the shape of the terrain are shown by the contour lines. Roads,
towns, mines, benchmarks, water, types of vegetation, along with many other
features also are included on topographic maps using map symbols and colors.
Topographic maps are often nicknamed "topo maps" for short. The U.S.
Geological Survey has been making topographic maps since 1882 and has
completed maps for the entire country. These maps are in feet and
miles, but new maps are being produced using metric measurements.
The topography of the lower Columbia
Basin includes canyons, hills, and valleys.
How are the scales on a topographic map interpreted?
Scales are represented as ratios such as 1:24 000 to 1:500 000, where the larger the denominator the smaller the scale. For
example, on a 1:24 000-scale map, each inch represents 24,000 inches or 2000 feet. On a 1:316 800-scale map, each inch
represents 316,800 inches or 5 miles. A 1:24 000-scale map provides more detail with its larger scale. Topographic maps
generally cover an area bounded by 7.5 minutes of latitude and 7.5 minutes of longitude (about 160 square kilometers),
and are known as 7.5-minute quadrangle maps.
What do contour lines on topography maps represent?
If you look at a topographic map, the solid, curving lines are contour lines that indicate the elevation and shape of
terrain. The elevation change between any two adjacent countour lines (the contour interval) is the same everywhere on
a given map. If the contour interval is 10 feet, the elevation changes 10 feet within these adjacent lines. Contour lines
close together indicate steep mountainsides or cliffs. Gentle sloping hills or flat plains have contours farther apart from
each other. Experienced map readers can look at the contours and visualize the three-dimensional shape of the land.
“Cutting” a line through the contours enables the map reader to draw a profile of that section of the mountain or plateau.
Hachure marks along a contour show depressions, for example, of a crater or the mouth of a volcano.
Who uses topography maps?
Hikers, campers, snow skiers, city and county planners, the Fish and Wildlife Service, Forest Service, miners, loggers,
highway planners and construction workers, travelers, surveyors, geologists, engineers, and scientists are just a few of the
people who use topographic maps. Knowing the shape of the terrain enables a hiker to plan a hike. Highway planners
determine the best routes for highways knowing the cut and fill areas. Surveyors locate benchmarks, and geologists locate
their actual positions relative to the map and can determine if changes to the land have occurred.
http://science-ed.pnnl.gov | www.midcolumbiastem.org
Suggested Activities
1. See how many objects and places you can find on a topographic map.
Obtain topographic maps of your local area (see sources below): Richland, Kennewick, Benton City, Columbia Point,
Badger Mountain, and Pasco 7.5-minute series quadrangle maps are a good start for the Columbia Basin. Have students
take turns looking at the map and have them list all they can find on the map. This exercise will introduce the students
to the maps in general. Pass out the USGS Topographic Map Symbols leaflet and have students search again with
more knowledge of what the symbols represent. Students will enjoy locating where their home is on the 1:24 000-scale
map. Challenge them to transfer this knowledge to the 1:100 000-scale Richland Quadrangle map. Post the map in the
classroom, and use flag pins labeled with their names.
2. Build a local mountain.
Here’s how: Enlarge Red, Candy, and Badger mountains from the 1:100 000-scale Richland Quadrangle map. Outline
the 100-foot contour intervals, and use this for the student’s pattern. Draw a radius line through the contours to be used
as a guide to match up the layers of elevations correctly once they are all cut out. Students will cut along the lowest
contour, say 200 feet. Place the pattern on cardboard, trace and label the cardboard with the elevation and the position
marker. Now cut the pattern along the next contour line at 300 feet. Trace and label as before. Continue for all contour
lines. Cut out the cardboard elevations, and assemble, matching the position markers. Place clay balls or additional
small pieces of cardboard to separate the layers about 1 centimeter apart. When completed, the students discover how
the two-dimensional map actually represents a three-dimensional terrain. Extensions: Have students paper mache their
models. Produce a profile through a section of their mountain. Students could also create their own topography maps
using the Topographic Map Symbols, guide. These maps can be shared with other students to see if they can draw and
visualize the student’s terrain. Create a topographic map of the school grounds.
Questions a scientist might ask. How has the terrain changed from past maps? Where am I standing relative to this
map? What caused these topographic features? What are the contour intervals?
What scale map meets my needs? What historical or archaeological features are
Notes
noted on this map?
“Science is constructed of facts as a house is
of stones. But a collection of facts is no more
a science than a heap of stones is a house.”
—Henri Poincare
Other Resources
1. Full Option Science System (FOSS), Lawrence Hall of Science, University of
California, Berkeley, California. Landforms; Build A Mountain & Bird’s Eye View
(Grades 5-6).
2. How to Teach with Topographic Maps, 1998. Dana Van Burgh, Elizabeth Lyons
and Marcy Boyington, National Science Teachers Association, Arlington, Virginia.
3. The Practical Geologist, 1992. Dougal Dixon, Simon and Schuster, London.
4. U.S. Geological Survey, Map Scales, Factsheet, October 1993.
(USGS map supplier: Spokane Earth Science Information Center (ESIC);
509-368-3130 or call 1-888-ASK-USGS.)
Web Sites
1. US Geological Survey, Earth Science Information Center -http://ask.usgs.gov/
2. U.S. State Topographic Maps -https://www.arcgis.com/home/item.html?
id=931d892ac7a843d7ba29d085e0433465
May 2016 | Second Edition
Keep in mind this fact sheet is intended
to be used only as background information to support your effort to encourage
inquiry-based science, which parallels the
way scientists uncover knowledge and solve
problems.
Acknowledgements
The Shrub-Steppe Ecology Series was a
product of a public/private collaboration
led by PNNL called the Partnership for Arid
Lands Stewardship (PALS), funded by a U.S.
Dept. of Education Eisenhower Grant. Writer
Rebecca Moak; Series Editor Georganne
O’Connor; Project Manager Karen Wieda.