GEOLOGICAL NOTES ON THE ISLE OF PORTLAND. 61 



existing agencies, < but to causes in operation at the end of 

 the Glacial Period, and before the land had assumed its pres- 

 ent position and shape ; when the south coast of England was 

 fringed by a beach, remnants of which are seen in many places 

 from the Bristol Channel to Brighton. At the present day, long: 

 lines of beach are carried away into deep waters, leaving the 

 rock bare of sand or shingle ; but the destruction of the coast- 

 line in those days was due to causes more violent and destruct- 

 ive, of which I shall speak further on. Between Abbotsbury 

 and Wyke Regis, the Bank is separated from the mainland by a 

 narrow sea, varying in breadth from half to a quarter of a mile. 

 Messrs. Bristow and Whittaker account for this, under the sup- 

 position that the land has been worn away by the action of 

 streams and rivulets, flowing from north to south, leaving this 

 narrow channel between the mainland and the Bank. Mr. 

 Osmond Fisher, on the other hand, views " the Fleet " as the 

 eastern half of a submerged valley, its former western eide 

 having been encroached upon and destroyed by the waves of 

 the West Bay, previous to the accumulation of the Bank. On 

 riewing the Bank from end to end one remarkable feature is, 

 its regularity and form ; it is a continuous grand curve from 

 Burton Cliff to Portland, and is independent of the minor con- 

 figurations of the intervening coastline. Whatever may be the 

 cause of the previous arrangement of the pebbles of the Bank 

 with regard to their size, both Sir John Coode and Professor 

 Prestwich think that the Bay had been scooped out to a great 

 depth, and the debris which could not escape from the Bay 

 because of the direction of the prevailing winds, had formed 

 the Bank. 



I will now direot your attention to the raised beach at Port- 

 land Bill, to which I have already referred, and which 

 has been treated exhaustively by Professor Prestwich in an 

 important and able paper entitled ' ' the Phenomena of the Quater- 

 nary period in the Isle of Portland and around Weymouth." I 

 had the good fortune to accompany the Professor during his 



