Mountain peak, closed curve, low outside and high inside, ▲ symbol; The periphery is low and the middle is high, and the slope line is drawn outside the contour line, and the slope drops outward; The basin is depressed, the closed curve is high outside and low inside, the periphery is high and the middle is low, and the slope line is drawn inside the contour line, and the slope drops inward; Ridge line, contour line convex to the lower ridge line? From the top of the mountain to the towering part of the foothills, the ridge line is also called the watershed line; Valley, contour convex to high valley connection? The low-lying part between ridges, the valley line is also called the catchment line. Saddle, a pair of ridge contours? There is a saddle shape between two adjacent peaks, the saddle is the highest point of the valley line and the cliff is the lowest point of the ridge line. Many contour lines intersect and overlap in one place, which is close to the vertical hillside and is called a cliff. The protruding part of the upper part of a cliff is called a cliff or precipice.