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Page 6 of 8
Appendix A: Slopes and Terrain FeaturesI. SlopesThere are 4 types of slopes. Each type is shown by its contour lines. If the contour lines are close together, then the slope is steep. If the contour lines are far apart, then the slope is gentle.
A. Gentle slopeContour lines on the map will be far apart and relatively equally divided.  B. Steep slopesContour lines on the map will be close together and relatively equally divided.  C. Concave slopesContour lines on the map at top of the slope will be close together and far apart at the bottom of the slope. Person standing at the top of the slope will be able to see the people at the bottom very easily. When climbing this slope, it will be easier at the bottom and will get harder as you approach the top  D. Convex slopesContour lines on the map at the top of the slopes are far apart and closer together at the bottom of the slope. Person standing at the top of the slope will not be able to see the people at the bottom very easily. If you climb this slope, it will start out hard and will be easier as you get near the top. 
II. Basic Terrain FeaturesThe basic terrain features are derived from a complex landmass known as a mountain or ridgeline (see figure below) The term ridgeline and ridge is not interchangeable. A ridgeline is a line of high ground, usually with change in elevation along its top and low ground on all sides. There are a total of 10 natural and man-made terrain features that are classified from the ridgeline.
 A. Hill: A hill is is an area of high grounds. From a hilltop, the ground slopes down in all directions (3600.) Lines of contours on a map is shown by concentric circles with the highest (hilltop) at the center. 
B. Saddle: A saddle is a dip or low point between two areas of higher ground. A saddle is not necessarily the lower ground between two hilltops; it may be simply a dip or break along a level ridge crest.`if you are in a saddle, there is a high ground in two opposite directions and lower ground in the other two directions. A saddle is normally represented as an hourglass (see figure below)
 C. Valley: A valley is a stretched-out groove in the land, usually formed by streams or rivers. A valley begins with high ground on three sides, and usually has a course of running water through it. If standing in a valley, there is high ground in two opposite directions and a gradual inclination in the other two directions. Depending on its size and where a person is standing, it may not be obvious that there is high ground in the third direction, but water flows from higher to lower ground. Contour lines forming a valley are either U-shaped or V-shaped. To determine the direction water is flowing, look at the contours lines. The closed end of the contour lines (U or V) always points upstream or toward high ground (see figure below).
 D. Ridge: A ridge is a sloping line of high ground. If you are standing on the centerline of a ridge, you will normally have low ground in three directions and high ground in one direction with varying degrees of slope.Contour lines forming a ridge tend to be U-shaped or V-shaped. The closed end of the contour lines point away from high ground (see figure below).
 E. Depression: A depression is a low point in the ground or a sinkhole. It could be described as an area of low ground surrounded by higher ground in all directions, or simply a hole in the ground. Depressions are represented by closed contour lines that have tick marks pointing toward low ground (see figure below).
F. Draw: A draw is a less developed stream course than a valley. In a draw, there is essentially no level ground and, therefore, little or no maneuver room within its confines. If you are standing in a draw, the ground slopes upward in three directions and downward in the other direction. A draw is considered as the initial formation of a valley. Contour lines depicting a draw are U-shaped or V-shaped, pointing toward high ground (see figure below).
 G. Spur: A spur is a short, continuous sloping line of higher ground, normally jutting out from the side of a ridge. A spur is often formed by two roughly parallel streams cutting draws down the side of a ridge. The ground will slope down in three directions and up in one. Contour lines on a map depict a spur with U or V pointing away from high ground (see figure below).
H. Cliff: A cliff is a vertical or near vertical feature; it is an abrupt change of the land. When a slope is so steep that the contour lines converge into one "carrying" contour of contours, this last contour line has tick marks pointing toward low ground (see figure below). Cliffs are also shown by contour lines very close together and in some instances, touching each other (see figure below).
 
I. Cut: A cut is a man-made feature resulting from cutting through raised ground, usually a level bed for road or railroad track. Cuts are shown on a map when they are at least 10 feet high, and they are drawn with a contour line along the cut line. This contour line extends the length of the cut and has tick marks that extend from the cut line to the roadbed (see figure below)
J. Fill: A fill is a man-made feature resulting from filling a low area, usually to form a level bed for a road or railroad track. Fills are shown on a map when they are at least 10 feet high, and they are drawn with contour line along the fill line. This contour line extends the length of the filled area and has tick marks that point toward lower ground (see figure above).
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| Last Updated ( Monday, 13 June 2011 ) |
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