topographic maps reading contour maps. topographic maps show the shape of the land by the shape of...
Post on 13-Dec-2015
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Topographic Maps Reading Contour Maps Slide 2 Slide 3 Slide 4 Slide 5 Topographic maps show the shape of the land By the shape of the contour lines on the map Slide 6 How do you read this map? Slide 7 Rules for Reading a Topo Map: circles=hills or mountains close lines=steep slope (cliff=escarpment) far apart lines=flat or gentle slope stream flow=contour lines bend upstream (rule of vs) The higher the elevation, the smaller the circle in a series of closed contour lines Lets practice reading one Slide 8 The highest and lowest point The highest point or elevation on a contour map is equal to the highest possible elevation -1 (without going to the next contour line) The lowest point or maximum depth is found in a depression. This is indicated by hachured contour lines. This is equal to the depth of the depression -1. The minimum depth will always be the value of the depression -1. Slide 9 Profiles and gradient A profile is a cross sectional view of the land or a side view. We can easily create a profile. The gradient of the land refers to the steepness of the land. The formula is on page 1 of the ESRT. Slide 10 Other important features: Magnetic Declination: is given at the bottom of the map usually. Magnetic declination, sometimes called magnetic variation, is the angle between magnetic north and true north. Magnetic declination changes over time and with location. http://www.ngdc.noaa.gov/geomag- web/#declination Slide 11 Magnetic Declination Slide 12 Map Scale 1 inch=2,000ft Slide 13 Finding Gradient Use formula: Gradient = change in Field Value/Distance Unit: for exampe field value unit/meter or field value/mile Lets try a problem Slide 14 Slide 15 Slide 16 Creating a Profile Sum Up 1. Mark Contour Lines 2. Line up Paper and Mark contours lines, label with elevation 3. Line up scrap paper with grid. Move paper up and down to plot points. 4. Connect points with a smooth line/curve as directed