CHAPTER XV 

 CONTOUR MAPS 



THE first contour or sea level of a country sweeps out round 

 its capes, and back inland at its gulfs and bays (compare Fig. 42 

 with Fig. 44). Capes exist where hills project out into the sea, 

 and gulfs where the sea penetrates into low ground or valleys. 

 The behaviour of the first contour gives a law which other 

 contours will of course obey, that the bulging out of contours 

 towards the low ground will signify the existence of a hill, and 

 the retreat of a contour towards the high ground will indicate the 

 place of a valley (Fig. 47). 



Except in very rugged and very flat country the swings of the 

 contours which indicate a valley will present a marked contrast to 

 the hill swings. Along the lowest line of the valley there runs the 

 course of the stream, its waterway. A contour will necessarily run 

 up one side of a valley until it meets the waterway ; then it will 

 double back, just like the coast-line at the end of a gulf, and 

 run along the opposite side of the valley. Valley swings will 

 therefore be angular and V-shaped, and the course of the stream 

 will join the points of the successive Vs. The slopes and shoulders 

 of hills are usually rounded without marked, angular ridges ; 

 consequently the hill swings will sweep round them in unbroken 

 curves of a general U-shape (Figs. 47 and 48). Inspection of a 

 contour map will thus at once show the situation of hills and 

 valleys by the shape of the contours, even if the drainage of 

 the country should not be otherwise indicated. Further, the 

 contours which form closed curves can only enclose hills and not 

 hollows unless the latter contain lakes without outlets (Fig. 44). 



Wherever the contours are close together slopes will be steep, 

 and in precipitous mountains they are so crowded that they 

 cannot be separately shown. When this is the case the slopes 

 are generally too steep to walk up ; indeed, they are usually 



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