144 



THE BOOK OF NATURE STUDY 



The coast-line of the country represents the intersection of the 

 relief of that country with the flat plane of the sea surface. As 

 represented in a map, the coast-line gives what is called the 

 " contour " of the country. If the sea level were to sink, the 

 contour would alter its shape, and the area inside it would 

 increase ; while, if the level rose, further alteration in shape and 



FIG. 42. Portion of Fig. 39 to show the effect of a submergence of 

 400 feet. Compare Fig. 44. 



diminution in area would ensue. Suppose the level of the sea 

 surface were to rise 100 feet, it would intersect the land 

 everywhere at this higher level, and a new shore-line would be 

 produced within the original one. The line of this imaginary 

 shore-line might be drawn on the map, and it would join all 

 those places which were 100 feet above the original sea level. This 

 might be called the contour of 100 feet. Suppose the sea level to 



