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Topographic Maps *these notes go on pages 19 AND 21 of your Plate Tectonics INB!!*

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Presentation on theme: "Topographic Maps *these notes go on pages 19 AND 21 of your Plate Tectonics INB!!*"— Presentation transcript:

1 Topographic Maps *these notes go on pages 19 AND 21 of your Plate Tectonics INB!!*

2  topography means “shape of the land”  topographic maps graph a 3D landscape on a 2D surface showing elevation Mount Rainier, Washington

3 Contour Lines:  contour lines connect areas of equal elevation above or below sea level  index contours are darker with elevation marked  intermediate are lighter with no elevation


5 Contour Interval:  the elevation change that each line represents  FORMULA: distance between index contours ÷ # of contour lines

6 Water Direction:  “Rule of V’s”: contour lines make V’s indicating direction of flow of rivers & streams  V’s point uphill  help map reader interpret elevations of intermediate contours around stream


8 Hills:  contour lines are increasing in elevation within other contour lines  closer lines are together, the steeper the slope

9 Depressions  dips or major holes in land (from sinkholes, volcanoes, etc)  perpendicular contour lines, called hachures, point into depression Lip of depression is highest point

10 Benchmarks & Colors:  benchmarks: area of measured elevation in between contour lines (marked by an X or BM)  colors:  brown- contour lines  blue- water  green- forest, woods  black, pink & red- manmade structures

11 Gradient/Slope  how steep a hill is (look how close lines are!)  formula: = ∆ in elevation ÷ straight line distance  Units: m/km OR ft/mile

12 Slope Steep Slope Gentle Slope

13 Line A Distance =.5 miles Elevation Change = Slope =

14 Topo Map Profile:  cross sectional view along a line drawn through a topo map  HOW: 1.make a line through your map & label (X-Y, X-X’, etc.) 2.use edge of paper and make “ticks” every time a contour line intersects 3.record elevation next to each tick

15 X Y

16 4.transfer ticks onto a graph, or graph paper 5.connect the dots to get a side view along your line!


18 Map Projections  mathematical means of transferring info from 3D to 2D; different “views”  most have flaws because of curved surface  projections & flaws: (1) mercator- distorts areas near poles; view entire world (2) gnomonic- distorts areas away from center point; view poles (3) polyconic- distorts poles & Equator; view mid- latitudes (4) globe- no flaws; view entire world to scale

19 Mercator Projection Gnomonic Projection Polyconic Projection Three most common types of map projections are:

20 Map Distortions Greenland Mercator map size True size of Greenland

21 Map Scales:  mathematical relationship between objects on a map and their true life size  ratio or fraction  larger the number on the right, greater the amount of area map covers  same unit on each side  bar scale gives quick visualization of distances on a map


23 Example:

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