75 
The Shingle Beach as a Plant Habitat. 
4. The Apposition type. Sometimes the current becoming 
modified proves inadequate to transport the drift to the end of a 
bank or beach, or the apex has become deflected in the landward 
direction so that the littoral current cannot reach it. From these, 
or analogous causes, the material will be deposited on the flank, 
where it will accumulate till lifted outside tidal limits as the result 
of an exceptionally high tide caused by a gale. In this way a suc¬ 
cession of closely approximated, more or less, parallel banks may 
be thrown up, one behind another, with the result that very extensive 
areas of shingle are produced (Text-fig. 1). 
Fig. 1. Apposition type of shingle bank. A, B, C, is a point of land; the 
arrow marks the direction of coastal drift ; the successive shingle banks lie to 
the right of the figure : modified from F. Drew. 
The outstanding example of this type is Dungeness, but a 
localised growth by apposition is by no means uncommon on the 
banks of the spit type, as is well illustrated at Blakeney. 
Several types additional to the above have been distinguished by 
American geologists who have made a detailed study of the shores 
of their pleistocene lakes, but it is not necessary for the present 
purpose further to elaborate the types. 
In the present paper we shall deal more particularly with the 
shingle spit and its modifications. This and the fringing type are of 
most frequent occurrence in England, and a sketch of the salient 
features of the spit will serve as a convenient introduction to the 
ecology of shingle. 
General Features of the Shingle Spit. 
In this type the point on the mainland at which the spit leaves 
the shore is a salient angle—a point at which the coast-line trends 
landwards owing to the presence of an estuary or other analogous 
feature. The axis of the bank continues the direction of that 
portion of the shore-line along which the supplies of shingle drift. 
