They cannot deadend. Contours are perpendicular to the direction of maximum slope. Water flow is perpendicular to contours. The slope between contour lines is assumed to be uniform. The distance between contours indicates the steepness of the slope.
Smooth lines imply gradual slopes and changes.
Concentric closed contours that increase in elevation represent hills. A contour forming a closed loop around lower ground is called a depression contour. Spot elevations at tops of hills or bottom of depressions make maps easier to read. Contour elevations are shown on the uphill side of lines or in breaks to avoid confusion. Cuts and fills for levees or canals produce straight or geometrically curved contour lines with uniform, or uniformly graduated spacing.