232 Oliver and Tansley. 
in the field-book. By the adoption of this practice the mapped 
squares will be uniformly orientated and liability to confusion 
avoided, and at the same time the position of any square on the 
area in process of survey will be evident. When a square has been 
mapped it is well to attach a conspicuous band to its denominating 
post. 
A surveyed square is reproduced in the accompanying figure 
78. The ruled lines in the field book are omitted. 
Fig. 78. Map of a square with 100-foot side on a scale of • The small 
portion ruled off at the top left-hand corner is represented on a large scale 
by the gridiron method in fig. 80. The boundaries of the plant-associations 
are represented by dotted, the physical features by continuous lines. The 
scale round the edge of the map is marked in lengths of 10 feet. 
This square is a piece of the salt-marsh of the Bouche 
d’ Erquy, already referred to, and although without special value 
detached from the map of which it is a fragment, it may serve to 
illustrate the method. 
The physical features surveyed are marked in continuous lines, 
the boundaries of the plant-associations in dotted lines. The 
former include abrupt depressions or “pans” in the upper right 
