256 Pfof' Sedgioick on the Origin [April, 



law) to an elevation which is many times greater than the rise 

 of the same tides on more open parts of the coast. Any set of 

 causes which greatly modify the form of a deeply indented 

 coast, must, therefore, inevitably produce considerable local 

 effects upon the level of high-water. 



Let these remarks be applied to the eastern shores of England. 

 We know that during the last 1000 years, the sea has made 

 enormous encroachments on many parts of Suffolk, Norfolk, 

 Lincolnshire, and Yorkshire ; not only modifying the whole con- 

 tour of the coast, but at the same time forming chains of shoala 

 and sandbanks by which the velocity and the direction of the 

 tidal currents must have been more or less affected. The waters 

 have, therefore, during successive ages, been propelled into the 

 recesses of the coast by different forces, and up different systems 

 of inclined planes ; and must in consequence have ascended to 

 different levels. Such effects as these will reach their maximum 

 on the shores of large bays and estuaries, like the Humber and 

 the Wash of Lincolnshire. 



The form of the Wash of Lincolnshire must have been greatly 

 changed since the epoch of the diluvial detritus, partly by the 

 degradation of the neighbouring cliffs ; but still more by the 

 encroachments of alluvial silt which has been pushed down into 

 it by the waters of the Witham, the Glen, the Welland, the 

 Nene, and the Ouse.* If an undulating line be drawn through 

 these several rivers a few miles above the estuaries in which 

 they terminate, it may be taken as an approximation to the form 

 of a part of the coast in very ancient times before the great accu- 

 mulation of alluvial matter. The country within this line then 

 presented a low undulating surface, gradually rising on every 

 side of the Wash towards the high lands ; and it was probably 

 almost covered with forest trees, with the exception of a few 

 very low regions through which the rivers descended to the sea, 

 and which were partially flooded at the time of high-water. But 

 in the present state of things, the flood-tides, after filling the 

 lower part of the Wash, are pushed on towards the ancient line 

 of coast through a number of estuaries, the sides of which con- 

 verge towards the interior, and on that account force the waters 

 up to a higher level than they could reach on a coast which was 

 less indented. And after the flood-tides have been thus pushed 

 up into the mouths of the rivers, they do not now, as in former 

 times, mix with the freshwater and cause a reflux, extending far 

 into the interior of the country ; but after rising, almost at once, 

 to a high level,t they are pent up between arcificial banks, and 

 soon stopped altogether by locl;s and other works connected 



» A long note containing some details connected with the drainage of the fens bor- 

 deling on the Wash, arrived too late for the press, but wUl be affixed to the coHthuia. 

 tioii of this paper. — Edit, 



f See note 2, p. 244. 



