238 TRANSACTIONS AND PROCEEDINGS OF 'JHK [Sf.ss. lxvi. 



Important, but slow, changes, however, were in progress 

 at each stage, by the operation of which Britain assumed 

 more and more of its present features ; but none of these 

 changes have left any direct record of what was taking 

 place in the vegetable world, nor of what species were 

 living on the adjoining area that formed dry land. 



Following the Eed Crag comes the marine deposit 

 known as the Norwich, or Mammaliferous, Crag. The 

 fossil contents of this tell us of increasing communication 

 with the colder seas of the north, and also of the diversion 

 elsewhere of the warmer currents that had previously 

 reached what is now East Anglia from the south. Further- 

 more, the remains of large vegetable-eating mammalia 

 occurring in the Norwich Crag speak eloquently of the 

 existence, not far off, of vast woodland areas and extensive 

 pasture lands. 



Above the Norwich Crag come in two thin beds con- 

 taining still larger percentages of boreal mollusca, whose 

 species tell us plainly enough of increasing cold. These 

 rocks are the Chillesford Crag below, and the Weybourne 

 Crag above. 



Then follows a thin geological formation, which, in the 

 present connection, is of the very highest importance. 

 This is the well-known " Forest Bed," which, by the way, 

 is not exactly what its name would seem to suggest.^ It 

 is not an old woodland area submerged, but in reality 

 it is part of the delta of a great river which flowed in the 

 direction of what is now Britain from some continental 

 area to the east. A considerable number of facts point 

 to the river in question having been the ancestor of the 

 present Ehine. The evidence shows plainly enough that 

 the so-called Forest Bed is little else than a deposit formed 

 a long time ago under exactly the same conditions as now 

 obtain in the Norfolk Broads. The difference between the 

 two lies in the fact that the river which gave rise to the 

 old " Broads " came from the east, and not from the west, 

 as is the case with the Broads with which we are familiar 

 at the present day. The essential differences between the 



•* By the way, the word "Forest" simply meant, as its etymology 

 suggests, a place outside of the limits of cultivation, without reference 

 to the presence of trees. 



