Prime purpose of this lecture is to present on Topography. Topography is the lay of the land. It shows relief using contour lines. Relief- highs and lows of Earth’s surface. Relief can be calculated; take the difference between the highest point and the lowest. Example: Mountain peak 20 m. lake 10m; 20m- 10m= 10m. The relief of this area is 10m. Connect points of equal elevation. Everything connected to that line has the same elevation. Elevation- the distance something is above sea level. Sea level= 0m or 0ft.