304 The Rev. W. Buckland on the Plastic Clay Formation. 



hazel and other trees, was discovered to lie under the bed of indu- 

 rated mud, that forms the surface of that peninsula. 



These data throw much light on the natural operations that were 

 going on, between the period of the last retreat of the diluvian 

 waters, and that at which sea walls began to be erected against the 

 rising waters of the Thames. The substratum of clay and gravel 

 mentioned by Capt. Perry, formed the first surface of the valley 

 uncovered by mud or water, and lying at a small elevation above 

 the then existing high water level of the river. The sediments of 

 the river gradually raised its bed, and caused its waters to spread 

 laterally over the adjacent low lands ; first converting to marsh 

 by inundations at high tides, and at length completely burying, by 

 its daily sediment of mud, those tracts which in the early periods 

 of the rise of the bed of Thames, had been quite dry and covered 

 with extensive forests. The horns of stags that inhabited them lie on 

 the surface of the moor log, which appears to be the wreck of these 

 ancient forests, first converted to swamps as the water began to 

 reach their level, at length wholly destroyed by the constant inun- 

 dation of the ground on which they grew, and still affording evi- 

 dence of their position and extent, in the roots and trunks that lie 

 buried on the surface and in the mass of the moor log, and over 

 which a bed of mud has subsequently been deposited by those gra- 

 dually rising waters which caused the destruction of the forest. 



