Lesson Objectives 12/2/13 TLW, with 100% participation, Define a topographic map and state its uses. Describe how contour lines show the elevations, shape, and slope of the land. Identify the meanings of some symbols and colors used on topographic maps.

Map Notes As we go through the power point, please do the following: Take notes in your science notebook. Images: Composition Book: http://upload.wikimedia.org/wikipedia/commons/e/e5/Composition_book.jpg Topographic Map Example: Courtesy of the US Geological Survey Notepad and pencil: http://upload.wikimedia.org/wikipedia/commons/f/fe/Crystal_clear_right_to_left.png

Topography The study of the shapes and features of the Earth’s surface.

Topographic Map Shows the 3D shape and elevations of an area of land in 2D. Also known as Contour Maps

What do the colors on the topographic map represent? Blue lines/shapes - represent water features, such as streams and lakes. Brown – contour lines Black – Roads, buildings, railroads, other man made objects. Green – Woodland areas Red - Highways

Elevation Height above sea level

Sanger is 669 feet above sea level. The city of New Orleans is 6 Sanger is 669 feet above sea level. The city of New Orleans is 6.5 feet below sea level. What does sea level mean?

Map Scale Maps always have a scale printed somewhere on the map. For USGS maps it is at the bottom. On USGS the map portion below, the scale is 1:24,000. That means that 1” on the map is 24,000” on the ground or 1’ on the map is 24,000’ on the ground. PSC 121 Prince George's Community College

Map Scale There are also scales that can be used to determine distance for many different units using a ruler and the map scale. 1 mile 1 mile 1/2 mile 2000 feet 1 kilometer 200 feet PSC 121 Prince George's Community College

Contour Lines Elevation is indicated by contour lines. A contour line is a line of equal elevations (eventually a closed loop). All points on a contour line have the same elevation. 800 feet http://raider.muc.edu/~mcnaugma/Topographic%20Maps/contour.htm 700 feet PSC 121 Prince George's Community College

Contour Lines The elevation difference from one line to another is called the contour interval. On the map portion below the contour interval is 20 ft. 20 ft elevation decrease 20 ft elevation increase http://raider.muc.edu/~mcnaugma/Topographic%20Maps/contour.htm 20 ft elevation increase PSC 121 Prince George's Community College

Contour Lines The contour interval is usually printed on a topographic map. However, you can always calculate the interval from the lines with values. PSC 121 Prince George's Community College

Relief The difference between the highest elevation point and the lowest elevation point on a map 200 300 400 Units = feet What is the relief of this map? What is the contour interval of this map?

Topographic Map Rules Contour lines are closely spaced on steep slopes. Contour lines are widely spaced on gentle slopes.

Topographic Map Rules Contour lines near the top of a hill form closed, circular shapes. The top of the hill is higher than the highest closed contour line.

Contours and Profiles You can generate a profile of a landform from the contour lines on a topographic map. Click on image to see contours develop http://reynolds.asu.edu/topo_gallery/images/hillmap.gif Simple contour map PSC 121 Prince George's Community College

Topographic Map Rules Depressions without outlets are shown by closed hatched contours. The contour lines have short lines on the inside that are pointing down slope. The bottom of the depression is lower than the lowest closed contour line.

Topographic Maps Index Contour – Usually every 5th line is printed darker and has an elevation printed on it.

Rules for Contours Contour lines never cross

Rules for Contours 2. Contours form closed loops (even if not shown of the map.

Rules for Contours 3. Contours bend upstream (uphill) when crossing a stream.

Rules for Contours The maximum possible elevation for a hill is “1” less than what the next contour “should” be. The highest possible elevation of the hill is just below the value of  the next line that is not shown 90 80 70 60 50

Notice the two high points on the island Notice the two high points on the island. What is the elevation of the two high points?

Topographic Map Rules Where a contour line crosses a stream or valley, the contour line bends to form a “V” that points upstream. In the upstream direction, the successive contours represent higher elevations.

Tracking Flowing Water How does water always flow? DOWNHILL How can we tell what direction (N,S,NW,ESE) is downhill? PSC 121 Prince George's Community College

Tracking Flowing Water You can look for elevation changes since water will flow from higher to lower elevations. Here the stream flows toward the northwest. 2000 ft 2100 ft PSC 121 Prince George's Community College

Tracking Flowing Water You can look at the contour lines as they cross the stream. They will always point upstream. Downstream Upstream PSC 121 Prince George's Community College

Tracking Flowing Water You can also look at where two streams merge. The merge will form a V that points downstream. Direction of flow PSC 121 Prince George's Community College

Satellite Map A map made of pictures of the Earth taken from a satellite orbiting the Earth. Andes Mountains Satellite Image: http://upload.wikimedia.org/wikipedia/commons/thumb/f/fd/Andes_70.98343W_35.78028S.jpg/800px-Andes_70.98343W_35.78028S.jpg Satellite orbiting planet: http://upload.wikimedia.org/wikipedia/commons/5/59/Spac0558_-_Flickr_-_NOAA_Photo_Library.jpg