what contour line show?
http://www.google.com/search?q=contour+line&rls=com.microsoft:en-us:IE-SearchBox&ie=UTF-8&oe=UTF-8&sourceid=ie7&rlz=1I7GGIE_en
and
http://images.google.com/images?q=contour%20line&rls=com.microsoft:en-us:IE-SearchBox&oe=UTF-8&sourceid=ie7&rlz=1I7GGIE_en&um=1&ie=UTF-8&sa=N&hl=en&tab=wi
Contour lines on a map or a topographic map represent imaginary lines that connect points at the same elevation or altitude above a reference point, usually sea level. They indicate the shape of the land and its relief by showing areas of higher and lower elevation.
Contour lines on a map typically form closed loops and can be close together or far apart. When contour lines are close together, it indicates a steep slope or a rapid change in elevation. Conversely, when contour lines are spaced farther apart, it suggests a gentle slope or flat terrain.
By following the pattern and shape of contour lines on a map, you can determine the lay of the land. For example, if the contour lines form concentric circles, it signifies a hill or a mountain. If the contour lines are very close together and form a series of U-shaped or V-shaped lines, it suggests a valley or a depression in the landscape.
Contour lines provide valuable information for hikers, planners, geologists, and other professionals who need to understand the terrain and its features. They help in identifying the elevation and steepness of slopes, locating peaks and valleys, planning hiking or biking routes, predicting potential drainage patterns, and much more.