LESSON 49

• TOPOGRAPHY - the configuration or shape and roughness of the ground
• TOPOGRAPHIC MAP - shows the representation of the character and relief of the earth’s surface which includes the location of natural and artificial features
• METHODS TO DEPICT A RELIEF:

  SPOT HEIGHTS

  HACHURES

  FORM LINES

  CONTOUR LINES

  LAYER TINTING

  SHADING

  RELIEF MODEL

  RIDGE AND STREAM LINING

  SUBAQUEOUS CONTOUR
• BATHYMETRIC MAP is one which is primarily used to show bottom contours of lakes, seas, oceans and other bodies of water.
• SPOT HEIGHTS -the elevations of important features and critical points such as roads, junctions, peaks, summits, sags and highway crossings that are indicated in the map - it provides definite and precise information regarding elevation
• HACHURES series of short lines drawn in the direction of the slope;
• FORM LINES -drawn when not enough vertical control is available or when the surface is too irregular or intricate to contour; such lines resemble contours, but are not drawn with the same degree of accuracy

  -made to show the shapes of the terrain rather than relief
• CONTOUR LINES most widely used method of quantitatively representing hills, mountains, depressions, and ground surface undulations on a two-dimensional sheet of paper
• LAYER TINTING -a scale of graded color tints or a system of different colors is used to show different zones of elevation
• SHADING old method used to show relative elevations on maps;; it is dependent upon shadows cast by the elevated portions of the land
• RELIEF MODELS provide the most striking and realistic expression of topography; the model is a representation of the terrain done in three dimensions to a suitable horizontal and vertical scales; they are made from wax, clay plastic, cardboard or other materials and shaped to agree with the actual terrain
• RIDGE AND STREAM LINING mainly used to emphasize the location of low and high ground; useful on aerial photographs; when applied to a topographic map
• SUBAQUEOUS CONTOUR -the portrayal of relief of the ground underwater is done by using depth curve

  -they are numbered as the water depths grow deeper, and they are based on the low water datum rather than the mean sea level datum of contours