302 NEOZOIC TIME. [CHAP. XIII. 



continued, and that the sea encroached farther and farther 

 on the forest-clad land, the submerged levels being covered 

 with a greater or less thickness of marine clays and sands, 

 while the valleys were converted into estuaries and filled 

 with thick accumulations of alluvial mud. These are the 

 conditions which now exist on our southern and south- 

 eastern shores ; everything points to a recent submergence, 

 with pauses during which peat beds were formed, and 

 there is no evidence of any more recent upheaval. 1 Similar 

 phenomena occur as far north as Lancashire and the south 

 of Yorkshire, but are not found much farther north. I 

 am informed by Mr. Hugh Miller that on the east coast 

 north of Durham there is no proof that the valleys have 

 ever been cut to a lower level, since the Glacial period, 

 than their present depth ; and when we reach the Forths 

 of the Forth and Clyde the phenomena connected with 

 valley erosion are altogether different. There are buried 

 forests, and they are covered by marine alluvial clays, but 

 the forests seldom run below low-water mark, and the 

 marine clays are now raised high above it, forming wide 

 plains or " carse-lands " from 30 to 45 feet above mean 

 sea-level. 



In Scotland, therefore, it is clear that the last movement 

 was one of upheaval, and it would appear that this up- 

 heaval was contemporaneous with or later than what we may 

 call the Neolithic subsidence of England, for the Carse- 

 clays contain relics of Neolithic man. If the last movement 

 which our islands have experienced had been similar 

 throughout their extent, England would have had her 

 carse-lands, and the lower tiers of raised beaches which 



1 The raised beaches of Brighton, Selsea, Portland, and the Cornish 

 coasts are generally regarded as much older than the submerged forests. 

 They probably date from the previous elevation (Palaeolithic time), and 

 must not be confounded with the 25 and 50-feet terraces of the Scottish 

 coast. 



