Earth Science Regents Practice Exam 2025 – Complete Study Resource

To determine the highest possible elevation on a contour map, the most reliable method is to use the highest marked contour line. This is because contour lines represent elevations above sea level, and the highest line provides a definitive indication of the maximum height in that area.

When interpreting contour maps, it's essential to understand that elevation values increase as you move from lower to higher contour lines. If the contours are evenly spaced, the area between the highest contour line and the next contour line may contain the highest peak, which is why identifying and using the highest marked contour line is critical.

To clarify, while it might seem that subtracting from the next contour could yield a result related to elevation, it does not help in establishing the peak elevation. Similarly, multiplying by two or adding one to the contour lines does not provide any real method for determining actual elevations, as these calculations do not correlate with the principles of contour mapping. Therefore, using the highest marked contour directly informs the elevation in question accurately.