Presentation on theme: "Topographic maps show…. - USGS: Uses for topographic maps… -"— Presentation transcript:
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 calculatedUsing the formula …..BM:
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 mapsThe goal was to provide complete topographic map coverage of the U.S.more than 54,000 maps have been madeentire area of the 48 contiguous States and Hawaii.
6 Making a topographic map Combination of….Field work –plane table surveying: measurementsSetting benchmarksChecking 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, swampsswamps, cliffs, quarriesmountains, valleys, parksand man-made features of the land:Buildings, housesRailroads, bridgesroads
8 Topographic map Symbols / Key Appendix Text book page 697
12 Topographic maps are used for… engineering,energy exploration,natural resource conservation,environmental management,public works design,commercial and residential planning, andhiking, camping, and fishingBecause 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: reliefShow the elevation of landmeasure the height of mountains,depths of depressions and the ocean floorsteepness of slopes.
15 Contour Lines Are a type of “isolines” prefix iso- means same Always brown for land or blue for waterThey 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.20202020
18 Match the contour map with the profile of the land BEDCFA
19 If the contour lines are …. very far apart – not closely spaced.The land is very flat here.Very close contour linesShow very steep slope
20 Contour IntervalThis 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? XEach line represents 20feet of elevation
23 Depression ContoursA 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 ft200 ft100
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 contourSee slope by the spacing of contour linesUnderstand map symbols and colorsUse a map scale to measure distanceFind the source of river flow by the direction that contour lines bend.
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 pointsdistance between two pointsSlope = RiseRun
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/kmFor 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 =16001400200 ft19. Run: Distance: ______ miles0.420. Slope:200 ft / 0.4 miles =500 ft/miRise: Pt. C: ft – Pt. D: ft = Run: slope =100 ft0.5 miles16501550200 ft/mileRelief: (highest elevation - lowest elevation)1700 ft ft =400 ft.
38 What would the profile of this land feature look like from A to B?
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 mapseach map covers a four-sided area of7.5 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)______________milesDo the same for longitude.How many minutes of distance does it show?
48 Alaskan ScaleBecause 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 covers15 minutes of latitude and longitudeThere are 2,700 maps in the Alaska 15-minute quadrangle series.