NCEES Principles and Practice of Surveying Practice Exam

What type of map includes lines of equal magnetic declination?

1. Isometric map

2. Topographic map

3. Isogonic map

4. Geologic map

The correct answer is: Isogonic map

The isogonic map is specifically designed to depict lines of equal magnetic declination, known as isogons. Magnetic declination refers to the angle between magnetic north and true north, and isogonic maps illustrate variations in this angle over geographic areas. These maps are particularly useful for navigators and those involved in the field of geodesy, as they allow them to correct for the difference between magnetic and true bearings. In contrast, other map types serve different purposes: isometric maps represent three-dimensional phenomena on a two-dimensional plane, often using contour lines; topographic maps display the physical features of a terrain, including elevation changes and landforms; and geologic maps illustrate the distribution and nature of rock formations. Each of these maps does not focus on the variation of magnetic declination across a region. Thus, the isogonic map stands out as the correct choice for this question, specifically addressing the topic of magnetic declination.