What is primarily indicated by gradient lines on a topographic map?

Gradient lines on a topographic map, often referred to as contour lines, are essential for understanding the terrain's elevation changes. When these lines are closely spaced, they indicate a steep slope, while wider spacing suggests a gentler slope. Each contour line represents a specific elevation above sea level, allowing individuals to visualize the rise and fall of the land. This is crucial for various applications, including navigation, land-use planning, and outdoor activities like hiking or camping, as it provides a clear depiction of the landscape's vertical characteristics. Understanding this aspect of topographic maps is fundamental for anyone needing to analyze geographic information effectively.