VEGETATION OF BLAKENEY POINT. 
503 
to the two ends. But, whereas the first or proximal minimum 
is not associated with the presence of bushes lower down on 
the flanks, these are abundant in the region of the second 
minimum, i.e., the youngest part. Prof. Oliver (loc. cit. p. 92) 
has pointed out that the bank moves inwards as a whole, slowly 
travelling towards the land, and this, taken in conjunction with 
the above distribution, clearly indicates that the parallel rows 
upon the crest are in the nature of relicts which represent 
former edges of the advancing shingle, which by its continued 
passage landward has given them their present position. 
(Fig. 6.) On the older parts of the bank the relicts have died 
out or are diminished in number, whilst in the younger positions 
the bulk of the bushes have not yet reached the crest, the 
shingle here having not yet overwhelmed them. The presence 
of more than a single line of bushes on older parts of the crest 
may have come about in more than one way. The more 
obvious explanation is that the advance of the shingle has not 
been constant, but intermittent in action: since the force which 
drives the shingle forward is applied from the seaward face, 
whilst the Suaedas occupy the landward, it is quite possible that 
owing to the width of the bank a considerable period of such 
driving activity (probably almost entirely due to storms) has to 
elapse before the angle of the shingle sufficiently approaches the 
critical, on the landward face, to advance appreciably. 
Such periods of preparation may be represented by a number 
of years, and would be followed by a period of readjustment, 
probably much less extended, involving, however, considerable 
advance. The distribution of seedlings of Suceda fruticosa is 
of importance here; they are mostly to be found on the landward 
edge, often upon the fan-like expansions which constitute the 
advancing face of the bank. All stages of development can be 
found, and a persistence of these would result in the formation 
of a somewhat irregular line of bushes parallel with the axis of 
the bank (Fig. 12). 
Another origin suggests itself from the study of the laterals, 
which, though much less probable, may in part explain the 
irregularities both in number and arrangement of the parallel 
