1. A contour line must never divide or split.2. A contour line must never simply end. Somewhere (usually off the map) the two ends of a contour line must jointo enclsoe an irregularly circular region.3. A contour line must represent one and only one elevation.4. A contour line may never intersect other contour lines (overhanding cliffs are a rare excpetion, in which casethe hidden contours are dashed).5. Contour lines form a V pattern when crossing streams. The V always points upstream (uphill).6. closely spaced contour lines indicate a steep slope; widely spaced lines indicate a gentle slope.