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A draw, sometimes known as a re-entrant in
A draw, sometimes known as a re-entrant in orienteering
Orienteering is a group of sports that involve using a map and compass to navigation, navigate from point to point in diverse and usually unfamiliar terrain whilst moving at speed. Participants are given a topographical map, usually a specia ...
, is a terrain
Terrain (), alternatively relief or topographical relief, is the dimension and shape of a given surface of land. In physical geography, terrain is the lay of the land. This is usually expressed in terms of the elevation, slope, and orientati ...
feature formed by two parallel ridge
A ridge is a long, narrow, elevated geomorphologic landform, structural feature, or a combination of both separated from the surrounding terrain by steep sides. The sides of a ridge slope away from a narrow top, the crest or ridgecrest, wi ...
s or spur
A spur is a metal tool designed to be worn in pairs on the heels of riding boots for the purpose of directing a horse or other animal to move forward or laterally while riding. It is usually used to refine the riding aids (commands) and to ba ...
s with low ground in between them. The long area of downward sloping low ground itself is the draw, and it is defined by the spurs surrounding it.
Characteristics
Draws are usually etched in a hillside by water flow, are usually dry, but many contain an ephemeral stream or loose rocks from eroded rockfall. In a draw the ground always slopes downward in only one direction, and upward in the other three. The slope on a draw is generally quite sharp, with a clearly establishedfall line
A fall line (or fall zone) is the area where an upland region and a coastal plain meet and is noticeable especially the place rivers cross it, with resulting rapids or waterfalls. The uplands are relatively hard crystalline basement rock, and the ...
and characterized by a generally steep vertical drop over a short horizontal distance. There is essentially no level ground and little or no maneuver room within the draw. On a topographical map, the contour lines depicting a draw are U-shaped or V-shaped, pointing toward high ground.
A draw can be conceptually thought of as the inverse of a spur, much how a valley can be considered the inverse of a ridgeline. In land navigation training, students are typically taught to visualize these features by making a closed fist with their hand; the knuckles form "hills" individually (and a ridgeline collectively), and from there the fingers represent spurs while the gaps in between fingers represent draws.
Comparison with valleys
Draws are less developed stream courses than valleys, and are similar to valleys on a smaller scale; however, while valleys are by nature parallel to a ridgeline, a draw is perpendicular to the ridge, and rises with the surrounding ground, disappearing up-slope. In some cases, a draw could be considered as the initial formation of a valley.Etymology
The term "draw" has almost completely supplanted usage of "re-entrant" in common parlance; apart from a few geologists, only orienteers regularly use latter term.See also
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{{reflist Canyons and gorges Slope landforms