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Topographic maps show…. - USGS: Uses for topographic maps… -

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1 Topographic maps show…. - USGS: Uses for topographic maps… -
DIRECTIONS: Read pp on topographic maps in your text book and complete the boxes below. Topographic maps show…. - USGS: Uses for topographic maps… - Contour lines are…. - Contour intervals: Slope can be calculated Using the formula ….. BM:

2 Topographic Maps TOPOGRAPHIC MAPS

3 Topographic map is a model, which attempts to show a 3-D world in a 2-D format.

4 A flat picture can look 3-D using shading or color

5 Topographic Map History
In the 1870’s, the U. S. Geological Survey (U.S.G.S.) began making topographic maps The goal was to provide complete topographic map coverage of the U.S. more than 54,000 maps have been made entire area of the 48 contiguous States and Hawaii.

6 Making a topographic map
Combination of…. Field work –plane table surveying: measurements Setting benchmarks Checking with overlapping aerial photographs to provide stereoscopic coverage of areas being mapped.

7 USGS Topographic Maps and man-made features of the land:
Topo. maps show natural features of the land: rivers, lakes, swamps swamps, cliffs, quarries mountains, valleys, parks and man-made features of the land: Buildings, houses Railroads, bridges roads

8 Topographic map Symbols / Key Appendix Text book page 697


10 Natural features

11 Bathymetric or Water features

12 Topographic maps are used for…
engineering, energy exploration, natural resource conservation, environmental management, public works design, commercial and residential planning, and hiking, camping, and fishing Because engineers, highway officials, land use planners, and other professionals use USGS topographic maps as tools, map accuracy is vital. Dependable maps are also important to campers, hikers, and outdoorsmen.

13 On a contour map, topography is shown as a series of curved brown lines called CONTOUR LINES
Is the land FLAT or HILLY?

14 Contour Lines Show the shape of the Earth's surface.
the terrain / topography. Show the high and low areas: relief Show the elevation of land measure the height of mountains, depths of depressions and the ocean floor steepness of slopes.

15 Contour Lines Are a type of “isolines” prefix iso- means same
Always brown for land or blue for water They are always closed loops that don’t cross. They connect points of the same height above sea level. example, a 20 foot contour line connects all places on the land that are exactly 20 feet above sea level. 20 20 20 20


17 Profile view Overhead or bird’s-eye view

18 Match the contour map with the profile of the land

19 If the contour lines are ….
very far apart – not closely spaced. The land is very flat here. Very close contour lines Show very steep slope

20 Contour Interval This is the vertical distance between adjacent contour lines. Most topographic maps have a contour interval of 20 feet or 40 feet (100 feet in very steep terrain, like mountains, 5 or 10 feet in flat terrain, like farmland)

21 What is the contour interval on this map?
X Each line represents 20feet of elevation

22 Index contours: dark, numbered contour lines

23 Depression Contours A contour that indicates a hole and is represented by a "hachured" brown line. A depression is a point inside a contour that is lower than the contour; What is the elevation of the depression below? 130 ?

24 What is the contour interval? What is the elevation of points A and B?
A= _____________ ft B= ____________ft. 100 ft 200 ft 100

25 Contour lines form a “V” and bend upstream when they cross a river or stream.
The contour lines bend uphill toward the source of the river.

26 So far…. You should know.. What a topographic maps is
How to draw and interpret contour lines, How to determine contour interval, index contour See slope by the spacing of contour lines Understand map symbols and colors Use a map scale to measure distance Find the source of river flow by the direction that contour lines bend.

27 4. A G E C D B F

28 3. of 20 ft.

29 2 55 E D

30 4. 150’ 150’ 138

31 5.

32 5.

33 SLOPE can be determined by the spacing of the contour lines
SLOPE can be determined by the spacing of the contour lines. But how STEEP is the slope of the terrain?

34 Finding the Slope or gradient of the terrain on a topographic map.
Slope = Elevation between two points distance between two points Slope = Rise Run

35 Rise (elevation) = 3900 meters Run (distance) = 5 km
What is the Slope = ?????

36 Rise in elevation = 3900 m Running distance 5 km Slope or gradient =
780 m/km For every kilometer you hike, you are climbing up 780 meters (about 2300 feet or 23 stories) in elevation! WOW, that’s a steep climb!

37 Interpreting (Slope) Graphs Text questions 18- 22 page 61
18. Rise: Pt. B at _____ ft – Pt. A at ______ ft = 1600 1400 200 ft 19. Run: Distance: ______ miles 0.4 20. Slope: 200 ft / 0.4 miles = 500 ft/mi Rise: Pt. C: ft – Pt. D: ft = Run: slope = 100 ft 0.5 miles 1650 1550 200 ft/mile Relief: (highest elevation - lowest elevation) 1700 ft ft = 400 ft.

38 What would the profile of this land feature look like from A to B?

39 Devil’s Tower, WY.

40 Making a profile of the terrain using a topo map.

41 Every contour line from point A to point A’ needs to be plotted as a data point on a that shows elevation

42 Every contour line from point A to point A’ needs to be plotted as a data point on a that shows elevation


44 Before the 1980 eruption After the eruption
The summit and side has been blown away.

45 A portion of the side of the mountain was “blown away” leaving the mountain less steep. Flatter terrain then before. *Construct the profile activity

46 Scale Most topo maps are produced at a scale of 1:24,000
Also known as 7.5-minute quadrangle maps each map covers a four-sided area of 7.5 minutes of latitude and 7.5 minutes of longitude. The United States has been systematically divided into quadrangles, all the adjacent maps can be combined to form a single large map!

47 Math Time! Find the Latitude (upper right corner) ____º _____’ ____”
Find the latitude (bottom right corner) _____° _______’ ______” Subtract _______’ ______” How many minutes of distance does this map show? *Bonus: How many miles is that? (Hint: 1° of latitude = 65 miles) ______________miles Do the same for longitude. How many minutes of distance does it show?

48 Alaskan Scale Because of its LARGE land area and sparse population, the primary scale for mapping Alaska is 1:63,360 (1 inch = 1 mile). Each Alaska quadrangle map covers 15 minutes of latitude and longitude There are 2,700 maps in the Alaska 15-minute quadrangle series.

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