Sample images from USGS Topographic Maps: http://erg.usgs.gov/isb/pubs/booklets/usgsmaps/usgsmaps.html

How To Obtain Topographic Maps:
http://topomaps.usgs.gov/ordering_maps.html

Topographic Map Symbols:
http://mac.usgs.gov/isb/pubs/booklets/symbols/moreinformation.html

and

http://erg.usgs.gov/isb/pubs/booklets/symbols/

1.  Coordinate Systems

Divide students into groups. Ask each group of students to determine, to the nearest second, the latitude and longitude of the school building or campus using a USGS 1:24,000-scale topographic map covering the school and surrounding area.  Discuss the need for accuracy.  Use a 1:100,000 and a 1:250,000-scale map of the same area and discuss the difficulty of determining position depending on the map scale.  

Latitude and longitude are in base 60. Each degree contains 60 minutes. Each minute contains 60 seconds. Use the base 60 hours-minutes-seconds concepts with time to help them understand this. Transfer discussion to base 60 with latitude-longitude degrees-minutes-seconds, and the fact that in latitude-longitude, degrees refers to distance, not heat energy, and minutes and seconds refer to distance as well, not time.

Discuss the process of interpolation.  Draw a 2.5-minute grid on interior of USGS 1:24,000-scale topographic map using 2.5-minute tic marks on margin of map as a guide.  Write answers from all teams on the board.  

Materials Required:  Topographic map, sample benchmark (optional).

Discuss benchmarks. Why are they are important in mapping? Benchmarks and surveying are critical in making maps as accurate as possible in latitude (x), longitude (y), and elevation (z).  Discuss why people demand accuracy in mapping, including a discussion on the uses of maps, and which data users require the most accuracy.  Point out that the requirements of someone laying pipelines as opposed to someone locating climatic zones. If possible, obtain a benchmark from surveying company or catalog and show the class what these markers look like.

Show topo map symbols sheet and ask students to find as many benchmarks on the map as they can. What features are the benchmarks on? Discuss why certain features such as mountain peaks and railroad track sidings are better for locations to mount benchmarks than others. Discuss the permanency versus transitory nature of these features versus mounting the benchmark in sand or in a tree. Look at the  http://www.ngs.noaa.gov site at the National Geodetic Survey for discussion on surveying.  Discuss triangulation and leveling techniques. If possible, go on field trip and try to find one or more of the benchmarks the students have found on the topographic map. Be aware of safety considerations when finding benchmarks. Many are on busy intersections or along railroad tracks.

4.  Geographic Coordinate System - Convergence
  

Illustrate how lines of longitude converge from the equator to the poles. Illustrate the concept first on a globe. Next, show topographic maps of northern areas of the country (North Dakota, for example) versus maps in the southern part of the country (Texas or Hawaii, for example). Why are the maps in North Dakota narrower in the east-west direction than those in Texas and Hawaii? Measure the differences.  What is the distance between the 7.5-minute lines of longitude? Calculate how far it is between each minute of longitude, and then calculate how far it is between each degree of longitude. Measure on several different maps the distance between the lines of latitude. Ask the students why the latitude lines do not converge, and illustrate it on the globe.

5.  Comparing Coordinate Systems
  

Discuss how locations are measured on a piece of graph paper in geometry with the Cartesian coordinate system. Discuss why places on the Earth need to be located and measured according to a coordinate system as well. Three commonly used coordinate systems are latitude / longitude (the geographic coordinate system), the Universal Transverse Mercator (UTM) system, and the State Plane Coordinate System. For additional information on UTM, use the USGS Fact Sheet on the UTM coordinate system. All three of these coordinate systems are shown on USGS topographic maps. Ask the students to determine where the origin point is for each of the coordinate systems in use. Pair the USGS map with a state highway map or other state-based maps, county maps, or parcel maps that are in state plane coordinates.  Ask why map projections are used. Ask about the relationship between map projections and coordinate systems.  Discuss why are different coordinate systems are used for different purposes. Discuss which data users would prefer one system over another, including mention of local government needs versus global needs.  When does coordinate system have an advantage over another?

6.  Precision of Coordinates
  

Discuss the precision of latitude and longitude readings off of a USGS topographic map. As an analogy, start by asking why hours have to be divided up into minutes and seconds for increased precision.  You might start the discussion with: "I were to meet you after school, I might say 4:00pm, and if you and I showed up at 3:58 and 4:02, respectively, it would not be that important.  We understand that we don't mean "exactly" at 4:00, but rather, around but reasonably close to 4:00. However, if you were launching a spacecraft, it is critical that you state that the launch will be at 4:00.0355, for example.   Therefore, some events are fine to be set up as approximate time, but others need greater precision. Similarly, with locations on the Earth, sometimes an approximate location will do, such as "in front of the library." However, if you were installing high-speed Internet lines in front of the library, you would need to know precisely where to dig and install the lines. You would need more than degrees of latitude and longitude. Up to 60 miles may separate a degree of latitude or longitude. For increased precision, you would need readings down to the tenths of a second of latitude and longitude of its location. This is why people have divided degrees of latitude and longitude into minutes, and minutes into seconds.

7.  Absolute versus Relative Location
 

Discuss the difference between absolute location and relative location.  What is the difference between 42 degrees 7 minutes and 31 seconds north latitude, 101 degrees 15 minutes and 44 seconds west longitude with the phrase "northeast of Pleasant Grove"?  When is absolute location important, and when is relative location important?  Can you think of instances where they are both important? Which one does GPS measure? Which one(s) can you determine with a USGS topographic map?

8.  Map Projections
  

Ask students to examine the map projection of a chosen USGS topographic map versus other maps.  Show that each map is drawn according to a specific map projection. Discuss the advantage and disadvantage of different map projections.  Why do Greenland and Canada look so large on a Mercator projection?  You can use low-tech tools for illustration such as peeling an orange and trying to flatten out the peel on a flat surface. You can take advantage of high-tech tools such as a Geographic Information System (GIS) as follows. Draw a circle on the map of the Earth, and then change the projection, observing how it becomes distorted with different projections. Determine how and why the distance from Honolulu to Los Angeles varies, and how the angle with the equator varies.  Illustrate with a globe and topographic maps.  Discuss why the process of drawing the earth on a two dimensional piece of paper causes distortion in distance, direction, area, and angles.

Use the USGS poster map projections, as well as cartography texts to illustrate how distance, direction, angle, or area have to be distorted.  When is it best to distort distance/direction/angle, or angle?  If you had to choose 3 of the 4 attributes to keep accurate, what would they be?

Illustrate how choosing the map projection depends on the application. Illustrate how the projection of the map is more evident on a small-scale than on a large- scale map.

If possible, read sections of book "How to Lie with Maps" (by Mark Monmonier) to further illustrate these concepts.

9.  The History of Cartography
 

Examine how maps were made in the past and the present.  Obtain some negatives and scribing materials from a film or drafting company.  Obtain a scribing instrument; a sharp nail or compasses end will suffice. Pencil in some contour lines on the film and have students try to follow them with the scribing instrument.  Alternatively, use pencils and tracing paper laid on top of USGS topographic maps. Discuss the fact that most topographic maps were prepared using manual scribing instruments and tracing. Discuss why film was used rather than paper: Film does not shrink or swell as much as paper with changes in temperature and humidity, thus preserving the National Map Accuracy Standards.  

Use the USGS Teachers Packet "Exploring Maps."  This packet contains two posters illustrating historical maps back to the Babylonians, through the Middle Ages, to present-day maps.

Use samples from "Mercator's World" or other historical map journal.

Illustrate with samples from the Library of Congress map WWW page.

10.  Modern Cartography
 

Discuss geographic information systems (GIS) , and the capability of drawing all points, lines, and areas on the computer.  Ask the students what the advantage is of making maps on the computer versus by hand.  Advantages include the ability to easily change the symbology, projection, scale, and then to have the map layers available for analysis in a GIS.

Visit web sites running Internet map server software, where students can construct a map with a web browser. See http://rockyweb.cr.usgs.gov/public/outreach/ for a list of some of these sites. These include the National Atlas and The National Map.

11.  Aerial Photo Interpretation
 

Obtain a USGS aerial photograph of an area from the USGS (use PhotoFinder at  http://edc.usgs.gov/Webglis/glisbin/finder_main.pl?dataset_name=NAPP) and also a USGS topographic map covering the same area.  Ask students how they can identify a stadium, lake, golf course, school, office building, hospital, church, stream, mountain, and other features on an aerial photograph.  The world is more complex than is at first realized.  Schools may have an athletic track if it is a high school, but what about scholls in a dense urban area?  Do they always have a track? Some schools may have a characteristic "pull out" drive for drop-offs, but does your school have one?

Ask students to identify the time of year that the photograph was taken. What are the clues?  Do the leaves on the trees provide any hints? Ask students to identify the time of day the photograph was taken?  What are the clues? What does the presence or absence of vehicles in the school parking lot tell you about the day of the week and the time of day? What is the best time to take a photograph if you were going to make a map from the photograph?  Near solar noon is best to minimize shadow.  Near the summer solstice is best also to minimize shadow, except in heavily timbered areas, when "leaf-off" times are best in March and November.

12.  Analysis of Stereo Aerial Photographs
 

Discuss the need to see the world in three dimensions for creating contour lines.  Show "magic eye" images. Can the students see them in three dimensions?  Obtain a stereo viewer and obtain stereo aerial pairs.  Hubbard Scientific is one publisher of these in print form. There are also many stereo pairs on the web. If students have difficulty, tape the photographs on the table in the correct overlap position.  Use the aerial photo finder at the USGS at http://edc.usgs.gov/Webglis/glisbin/finder_main.pl?dataset_name=NAPP to illustrate the concept of consecutive photographs along a single flight line to obtain stereo.

13.  Creating Maps from Aerial Photographs
 

Print a USGS aerial photograph of your school or other location. Lay a sheet of tracing paper over the photograph and tape it down. On the tracing paper, decide which features you will categorize and then map. These can include streets, sidewalk, the school building, trees, streams, the playground, the track, the flagpole, and other features. Decide the color and symbology that you will use to draw each feature type. How should each feature be mapped such that the map doesn't become too complicated or cluttered?  Use the USGS topographic map symbols sheet as a guideline.   Make maps that include all elements of "TODALSIGS"--Title, Author, Date, Author, Legend, Scale, Index, Grid, Source.  How can students decide which features should be mapped?  Discuss the reason why the real world needs to be simplified to make a map.  For every theme that is drawn on a map, there are themes that are omitted (for example, soils). How can you determine the scale of your map? Go outside and pace off a feature, such as one side of the school building, and compare it to the distance on your map. Use the two numbers to determine the scale factor.

14.  Analyzing Physical Features on Topographic Maps
  

Examine at the list of physical features on http://rockyweb.cr.usgs.gov/public/outreach/featureindex.html, such as eskers, drumlins, glaciers, playas, bajadas, canyons, mesas, coastal features, sand dunes, marshes, floodplains, volcanoes, alluvial fans, lava beds, karst, and so on.  How are these features identifiable on topographic maps? What are the sizes of each of these features?  What is the most suitable scale with which to examine the entire physical feature? What is the national or regional pattern of these physical features? How do physical features affect population settlement amount and patterns?

15.  Analyzing Change on Topographic Maps
  

Obtain historical prints of topographic map from USGS, and compare to latest printed edition.  What are the reasons for land use change?  Which areas change quite a bit, and which areas change little. Why do some areas change much and others change little? What are the local, regional, and national forces that act on a locality to make it change? From what cardinal direction do the changes come from? It could be from a force that is outside the map extent. What is the magnitude of the forces that cause land use change, locally, regionally, and nationally?  Examine USGS 1:24,000, 1:100,000, and 1:250,000-scale maps to answer these questions.  For example, is there an urban area to the west of the area under study that is causing the changes?  

Discuss physical changes versus human-caused change. Examples of maps with physical changes include Earthquake Lake Montana, South Pass Louisiana, and Mt St Helens, Washington. Examples of maps with human-caused change include any map containing a reservoir or urban area.  Have students speculate and draw what the area will look like in 10, 20, and 30 years from now.  Look at the Map Mysteries lessons on http://rockyweb.cr.usgs.gov/public/outreach/mapmys.html for more ideas.

16.  Analysis of Impact of Public Land Survey System (PLSS)
On the American Landscape
  

Discuss the 1785 Ordnance Act that Jefferson signed into law.  Obtain the "baselines and meridians" Public Land Survey map from USGS that shows the spread of the township and range system for dividing up land for settlement, beginning in Ohio and spreading west. Roads in these states were often laid out running due north, south, east, and west. States that were settled before this Act was signed display a "metes and bounds" road network, where the roads run in a variety of directions, but rarely due north, south, east, or west.

Discuss why Texas has no PLSS (it was a separate country for a period of time).  What is the impact of this system on the rural landscape?  Compare the human-built landscape in Virginia - - roads and boundaries - - versus the "rectangular" landscape in Kansas.  What is the impact of this system on the urban landscape?  Show maps of cities in PLSS states versus cities in non-PLSS states.  Note, for example, the regular grid in the Phoenix street pattern vs the irregular pattern of streets in Atlanta.  Emphasize how an act from 1785 continues to affect the routes we took to get to school today!  Did you travel on a section-line road to reach your school today? Compare the metes-and-bounds and PLSS systems versus the long lot system of the lower Mississippi River floodplain. Why and how did the long lot system develop?

17.  Creating Profiles
 

Draw several lines, called transects, across a USGS topographic map. Create cross-sections (profiles) along these transects, using the contour lines to determine the elevation at each position along the transect.  Where is the topography steepest?  Flattest?  Why?

What forces are most active on the landscape in this area? Landslides?  Floods?  Erosion?  Tectonism?  Coastal storms? What forces were most active in the past?  Glaciation?  Were the past forces the same as today's forces?

Compute the slope both in percent and in degrees.  Have students plan a railroad and a road from point A to point B through a mountainous region.  Give students a constraint of 8% for the maximum road grade and 2% for the maximum railroad grade.  Compare students' routes. Show map with railroad on it in another area, and have students compare the number of twists and turns, and calculate the total distance, between roads and railroads. Why do roads and railroads have different criteria for construction?

Discuss map scale.  A large scale map (for example, 1:24,000) is a larger number (fraction) than a small scale map (such as that at 1:100,000).  Compare to more commonly used fractions. Is 1/10 of a pizza larger or smaller than 1/100 of a pizza? 1/10 is larger, and correponds to a larger-scale map.

Discuss a trip from your city to another city in the world that is several thousand kilometers away. Start by using a globe. When would you need a map at a large scale versus a small scale? You may need a small scale map to travel from your city to the other city, but then when you reach the other city, you need a large scale map to reach the block of your final destination within that city.

A fine illustration of scale is in answering a question: Is California splitting off into the Pacific Ocean? Examine the Point Reyes California USGS topographic map at 1:50,000.  At this scale, yes, it is "splitting", in the sense that the land over the San Andreas Fault has sunk to the point where the Pacific Ocean has flooded the area.  At a smaller scale, we can say that "no, the land is not splitting off into the Pacific Ocean."

20.  Analyzing Cultural Features on Topographic Maps
  

What are the major commercial activities of the area shown on the selected topographic map?  How are these activities reflected in the cultural, or human-built, features on the map?

Do people want to move to this area?  Why? Is this a fast or slow-growing, or declining, area, and why?  What forces act to limit or promote growth? Are the forces local, regional, national, or international in scale?

Why are certain land uses concentrated in certain areas?  For example, what kind of buildings are near railroad tracks? Near stadiums? Near universities?  Near interstate highways?  Why?

Construct plaster models of areas on topographic maps.  Flood one inch, draw a contour line in marker, flood one more inch, draw another line, etc. Remove water, look at lines from above, to illustrate the concept of contour lines.

Alternatively, use clear salad trays from food stores. Trace one contour line on each tray. When completed, you will have a see-through 3D model of your landscape. For more information, see the Topo Salad Tray activity on the USGS Education Page.

23.  Analysis of Urbanization Over Time
 

Using USGS topographic maps of metropolitan areas, examine the urban area. Examine older versus newer urbanization.  How do you know which is older? What are the differences in the street pattern, and why?  Discuss how and why the chosen urban area first began, and how and why it spread.   In which direction(s) is it growing, and why?  Was there a river or other physical feature that helped the urban area get its start?

Why is older urbanization usually along straight streets and with smaller homes, versus newer urbanization?  Discuss popular culture and consumer preferences.

How much urbanization is occurring in your selected city? Is it more or less than other cities of comparable size? Why? What local, regional, national, and international forces are acting on the city to make it change?

24.  Create Slope Maps
  

Create slope maps from USGS topographic maps by examining contour lines.  Divide the map area into categories and use a symbol identifying the slope in that area.  Use a smaller area of the topographic map if the relief is too complex.  Use categories 0-5%, 6-10%, and so on, or other interval depending on the map selected and create polygons where the slope falls within these categories.  What is the relationship of land use to slope?  What slopes are most human settlements located on?

Obtain a USGS Slope map of San Francisco and compare this map to a topographic map.  Does slope influence land use in San Francisco?  What slopes are the tall downtown buildings located on, and why? What slopes are residential areas on versus commercial and industrial areas?

Alternatively, use a Geographic Information System (GIS) and USGS digital elevation model (DEM) data to create slopes in a digital mapping environment. Make a 3D model of your selected area and discuss the relationship of slope to land use and hydrography.

25.  Create Aspect Maps
  

Aspect refers to the direction (north, east, south, west) that the slope faces.  Create aspect maps by examining contour lines on USGS topographic maps. Discuss who would be interested in the direction that slopes face.

Compare the vegetation on north-facing versus south-facing slopes.  What influence does aspect have on soil moisture, plants, and animal habitat? What aspects are ski areas usually built on?  Why are ski areas usually located on north- facing slopes?  Discuss microclimates of slopes. Where would they be located in the southern hemisphere? Discuss earth-sun relationships.

26.  Analysis of Humans and Hydrography
  

Discuss floodplains, rivers, and settlement.  How do rivers both encourage (with trade and traffic) and discourage (with flooding) settlement? Why does one bank of a large river aid the growth of a large city, while the other bank is sparsely populated?  This may occur if one bank was higher and flood-free, and the other was historically flood-prone.

One example is Omaha Nebraska, on the high west bank of the Missouri River, versus Council Bluffs, Iowa, on the flood-prone east bank. Omaha grew faster than Council Bluffs and remains the primary city in the region to this day. What is the elevation of both of your selected banks?  Discuss the importance of a city site to be on a flood-free site, higher than the floodplain.

27.  Site versus Situation
  

Site refers to the physical attributes of a location, such as soil, drainage, climate, and so on.  Situation refers to the advantages and disadvantages of one location over another location, considering trade routes, transportation, and other regional and national and international connections.

Discuss site versus situation with USGS topographic maps at different scales.

Examine the New Orleans West, Louisiana 1:24,000-scale map.  Estimate the amount of land below sea level.  Which areas were flooded by Hurricane Katrina in 2005? Discuss the sustainability of draining of the land for a city site on a river delta.  Discuss site versus situation here and elsewhere.  New Orleans is a poor site (prone to flooding) but has a good situation (near the mouth of a large river).  Discuss the impact of global sea level rise on New Orleans.  Discuss another location that is a good site but a poor situation (for example, a well-drained location in the middle of plain, far from an overland route or river).