VEGETATION OF BLAKENEY POINT. 19 



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 



