Topographic+Maps

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What's the difference between a topographic map and a regular map? In a nutshell, topographic maps allow you to see a three-dimensional landscape on a two-dimensional surface. These maps show the land's contours, elevations, mountains, valleys, bodies of water, vegetation and more. This contour and elevation inf­ormation distinguishes them from other maps.

Co­ntour li­nes are the greatest distinguishing feature of a topographic map. Contour lines show elevation and the shape of the terrain. They're useful because they illustrate the shape of the land surface -- its topography-- on the map.
 * Contour lines** are lines drawn on a map connecting points of equal elevation, meaning if you physically followed a contour line, elevation would remain constant.

1) Where a contour line crosses a stream or valley, the contour bends to form a "V" that points upstream or valley. In the upstream direction the successive contours represent higher elevations. 2) Contours near the upper parts of hills form closures. The top of a hill is higher than the highest closed contour. 3) Hollows (depressions) without outlets are shown by closed, hatched contours. Hatched contours are contours with short lines on the inside pointing downslope. The bottom of the hollow is lower than the lowest closed contour. 4) Contours are widely spaced on gentle slopes. 5) Contours are closely spaced on steep slopes. 6) Evenly spaced contours indicate a uniform slope. 7) Contours do not cross or intersect each other, except in the rare case of an overhanging cliff. 8) All contours eventually close, either on a map or beyond its margins. 9) A single higher elevation contour never occurs between two lower ones, and vice versa. A change in slope direction is always determined by the repetition of the same elevation either as two different contours of the same value or as the same contour crossed twice.
 * Rules of Contour Lines** — Some basic rules or facts about contour lines are listed below.