existing Physical Cames during stated Periods of Time, 267 



Figs. 6, 7. Sections showing the Increase of Landguard Point 

 between 1804 and 1844. 



Beach end in 



u, a. Low-water level of ordinary springs. 



The cliff on the western side of the harbour is about 1 mile 

 long and 40 feet high, and the encroachment of the sea appears 

 to have been at the rate of I foot per annum between the years 

 1709 and 1756, so that the annual supply of detritus was equal 

 to 40 cubic feet for each foot of frontage. Between 1756 and 

 1804 the advance increased to nearly 2 feet per annum; so that 

 the annual removal of cliff amounted to nearly 80 cubic feet for 

 each foot of frontage. 



Between 1804 and 1844 the encroachment of the sea averaged 

 10 feet per annum, and the annual removal of detritus must have 

 amounted to 400 cubic feet for each foot of frontage. It was 

 during this latter period that extensive dredging for cement stone 

 took place at the base of the cliff. 



On the eastern side of the harbour events of an opposite cha- 

 racter have occurred, for Landguard Point has gained 50 feet 

 per annum in length during the last 30 years. The addition 

 thus made to the land, and to the " littoral zone,^^ presents an 

 interesting example of the rapid accumulation of a local deposit 

 under favourable circumstances. From the appearance of the 

 beach, it would appear that the shingle and sand of which it is 

 formed have been brought from the north, in which direction 

 there are recorded instances of great destruction of land by 

 storms during the last 300 years. The aspect, however, of much 

 of the coast-line appears as if it had remained unaltered for a 

 very long period, except in the manner Mr. R. A. C. Austen* 

 alludes to when he remarks, "that although the sea for months 

 together, and in places even for whole years, may not acquire 



* Austen, Quart. Journ. Geol. Soc. vol. vi. p. 71-73; and De la Beche, 

 Geol. Observer, 1861, p. 65. 



T2 



