Lab 06.Topographic Maps

Lab 06.Topographic Maps - Name:_ Section: _ Lab 6...

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Name:___________________ Section: _______________ Lab 6 TOPOGRAPHIC MAPS In this lab, we will introduce you to topographic maps used in the earth sciences. These maps serve a variety of purposes. Some map where different rock types are, while others might show earthquake occurrences. We can map many different geological phenomena on the topographic maps. In today’s lab, we are going to see how to use maps that present the shape of a three-dimensional land surface onto a two-dimensional page. A topographic map is a two-dimensional representation of a three-dimensional land surface. It shows the three-dimensional land surface by elevation, or relief. Most United States topographic maps are published by the U.S. Geological Survey. Topographic maps have several essential features, including: The name of map (quadrangle name) The location designated by lines of latitude and longitude Contour lines and contour intervals. A scale bar that relates distance on the map to actual miles or kilometers. A declination symbol a small drawing of the state at the bottom of the map. A Quadrangle is a map unit and it is a section of the earth’s surface that is bounded by lines of latitude and longitude. Lines of latitude measure distance in degrees from 0 o at the equator to 90 o N at the North pole or 90 o S at the South pole, while lines of longitude measure distance in degrees east and west of the Prime Meridian , a line that runs from the North Pole to the South Pole through Greenwich England. Measurements for the geographic coordinate system (e.g. latitude and longitude) are expressed in degrees, minutes, and seconds. 1 o (1 degree) = 60’ (or 60 minutes) 1’ (1 minute) = 60” (or 60 seconds) When reading the location of a position using the geographic coordinate system, latitude is expressed first then longitude (e.g. 33 o 30' north latitude; 117 o 15 ' west longitude). Contour lines : Contour lines are the most common method used to depict relief (the representation of the shapes of natural terrain features) and elevation (the vertical distance of a position above or below a datum plane). A contour line is an imaginary line on the ground above or below a datum plane, which most commonly is sea level. Index contour : the heavier (darker) line on a contour map, labeled with its elevation. Every fifth contour line is a index contour in the topo map; it is used as a starting point for figuring out other elevations. intermediate contour lines
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Lab 06.Topographic Maps - Name:_ Section: _ Lab 6...

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