Hikers, climbers and hunters often use topographical maps when charting an expedition in mountainous areas.
All maps have a horizontal scale, the distance represented on the map by a specific measurement. For example, 1 inch may equal 100 miles. Topographic maps feature a vertical scale in addition to the horizontal scale. Together, the horizontal and vertical scales allow you to determine three-dimensional features on a map. The vertical scale on a topographic map is also called the contour interval.
Instructions
1. Identify the different types of contour lines on the topographical map. The map contains a legend that helps you identify them. Thick contour lines are the index contours, featuring specific elevations printed on them. Thinner lines between index contours are known as intermediate contours. Four intermediate contours can be found between each index contour, according to the Geospatial Training and Analysis Cooperative.
2. Locate the map legend that lists the contour change. It looks like a typical horizontal scale legend, but it is labeled as the contour interval. If the contour change is 40 feet, which is common on a 7.5-minute quad map, the elevation change between each intermediate contour is 40 feet. The elevation change between each index contour is 200 feet.
3. Use the vertical scale to determine the elevation of specific points. Locate the nearest labeled line and count the number of lines above or below it to the point you are interested in determining. Multiply the number of lines by the contour interval. Add or subtract the result from the marked contour line.
Remember that contour lines are continuous loops. They encompass smaller and smaller areas as they get closer to peaks.
Tags: between each, contour interval, contour lines, horizontal scale, between each index
