286 Mr. S. V. Wood on the Events which produced and terminated 



presence of limestone formations was the exception. The beds 

 of the Wealden, however, are of a highly argillaceous character 

 throughout, the extensive sand-beds among them being rarely- 

 free from a considerable intermixture of aluminous particles, as 

 the wet and intractable soil of nearly the whole Wealden area 

 attests. It is therefore not unreasonable to infer that districts 

 abounding in metamorphic rocks formed the larger portion of 

 the area from which the waters that furnished the Wealden 

 sediment were collected. There are no "such areas from which 

 we could derive these waters at all comparable in magnitude with 

 those surrounding the western part of the English Channel, or 

 the shores of the St. George's Channel, both of which channels 

 are formed by depressions dating back into the palaeozoic period, 

 and consequently existing as valleys of drainage during the 

 Wealden epoch. 



To estimate the lay or inclination of the land surrounding the 

 Wealden basin during the progress of that formation, it is neces- 

 sary to eliminate from the features which that land now presents 

 the effects that have been produced by the great tertiary anti- 

 clinals of the South-east of England. Anterior to the formation 

 of these anticlinals the South-east of England remained, until the 

 close of the Wealden formation, a basin more or less landlocked; 

 and after the eastern barrier had become submerged, and during 

 the upper cretaceous age, it formed the site of a deep bay or 

 gulf, after which, with an interval of dry land between the 

 secondary and tertiary periods, it remained an open gulf, 

 although diminished in extent, until the age of the crag. The 

 anticlinals, in converting this sea-bed into elevated land, reversed 

 the inclination that the area of the British Channel possessed 

 during the entire mesozoic period. The extent of this reversal 

 is to be measured by the amount of elevation which the sea-bed 

 has undergone where these anticlinals occur. The amount of 

 this is probably not less than 4500 feet*, and has affected 

 the whole of England east of a line joining Dorsetshire and the 

 Norfolk coast. Although this fact is so well understood, I enlarge 

 upon it here to show how great must have been the effect of these 

 anticlinals in modifying the inclination which, previously to the 

 upheaval taking place, the land of the South-west of England 

 possessed. The whole of the British Channel east of Dorsetshire 



* In the Isle of Wight we have at the least the following above the sea- 

 level : — 



Tertiaries to the top of the Hempstead series (Forbes) 2030 feet. 



Upper cretaceous and gault (Fitton) 1500 „ 



Lower cretaceous (Fitton) 800 „ 



Wealden incompletely exposed, say (Forbes) . . . 200 „ 



Total ...... 4530 „ 



