1. TOPOGRAPHY

2. What is a Topographic Map? Earth's surface shape shown by contour lines Contour lines - lines connecting points of equal elevation measure mountain height, ocean depths, slope steepness Allows planning for – parks hiking/riding building/construction drainage

3. Reading Topographic Maps Contours – lines of different widths Contours never cross Used to determine elevations – index contours are wider Elevations printed along index contours Narrower contours found between index contours – help show more details of land surface

4. Contours close together = steep slopes Widely spaced contours = fairly level/flat ground slope relatively level contour interval = elevation difference between adjacent contour lines Reading Topographic Maps (continued)

6. Index Contour (Elevation = 100’) Index Contour (Elevation = 200’) Every 5 lines: (200-100)/5 = 20’ Therefore, contour interval = 20’

7. What Does It All Mean? The more contour lines packed closely together represent steep, cliff-like areas

8. What Does It All Mean? The more two contour lines are spread apart, the flatter the area

9. What Does It All Mean? Contour lines that form a mountain-like shape show where water has cut a path (valley)

10. Predictions How might this area’s landform change over time?

11. Change in topography of Mount St. Helens after it erupted in 1980

12. Causes of Change Weathering – Break down of rock into smaller pieces – sediment (sand and soil) Erosion – movement of sand, soil and rock Deposition – settling and layering of sand, soil and rock.

13. Causes of weathering, erosion and deposition of Earth Wind Water – rivers, waterfalls, streams, oceans, rain, ice Plate tectonics – Mountains, trenches, ridges, rift valleys, fault lines Earthquakes Volcanoes Plants and animals including humans

14. Remember… Topographic maps can help you find elevations, Trails, and Places to climb Topographic maps show you the “lay of the land” (landforms) by connecting points of equal elevation Index contour lines are darker and have an elevation associated with it The ‘Contour Interval’ is the elevation distance between two adjacent lines Scales are usually shown in inches or feet