Figure 25. U. S. Geological Survey 1:24,000 quadrangles used as base maps 



in this study 



17. On the sea shore and the rivers subject to the 

 tides, the high and low water lines are to be surveyed 

 accurately; and the kind of ground contained between 

 them, whether sand, rock, shingle or mud marked 

 accordingly. The low water line is taken by offsets 

 whilst running the high water, and when not too far 

 apart from each other, but when their distance is 

 great they must be surveyed separately: a couple of 

 hours before the end of the ebb, and the same time 



45 



