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

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

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

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

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

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

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

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

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

Slope Steep Slope Gentle Slope

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

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

X Y

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

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

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

Greenland Mercator map size Map Distortions Greenland Mercator map size True size of Greenland

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

Example: