Final answer:
The most common contour interval for 7.5-minute maps is 80 feet, used for detailed terrain representation. When making topographic maps, contour lines are drawn based on field data collection with contour intervals, such as 100 meters, indicating changes in elevation.
Step-by-step explanation:
The most common contour interval for 7.5-minute maps, which are topographic maps used by the United States Geological Survey (USGS), is 80 feet. The 7.5-minute map series provide detailed information about the terrain and topography of an area, allowing geologists, hikers, planners, and other users to understand the landscape. When creating or reading these maps, contour lines represent elevations above sea level and are spaced at regular intervals to indicate changes in elevation. An 80-foot contour interval means that each contour line on a map is 80 vertical feet away from the next.
As for the task of creating a coastal topographic map, one would need to hike the area with a GPS receiver to record elevations at various points. This data would then be used to draw continuous contour lines with the specified contour interval, which in this case would be 100 meters. On Map 1, with a contour interval of 40 meters, each contour line needs to be labeled with its corresponding elevation. In exercises involving map scales, such as using a scale of 1 inch-5.5 miles or 0.5 inches=100 miles, proportions are used to convert measurements on the map to real-world distances.