I] INTRODUCTORY 11 



development of clean columnar stems. The Brigg 

 'dug-out,' now in the Hull Museum, Avas discovered in 

 an old alluvial valley of the Ancholme river, formerly 

 connected with the Humber, and it may be that 

 it was used by Neolithic man as a ferry for river- 

 service (7). 



From the period claimed by archaeologists we 

 pass by gradual stages into the domain of the 

 geologist. As Huxley wrote, 'when even the dim 

 light of Archaeology fades, there yet remains Palae- 

 ontology, which... has brought to daylight once more 

 the exuvia of ancient populations, whose world was 

 not our world, who have been buried in river beds 

 immemorially dry, or carried by the rush of waters 

 into caves, inaccessible to inundation since the dawn 

 of tradition (8).' The length of time represented by 

 a succession of long-lived individuals of the same 

 species becomes enormously extended when we pass 

 to the history of families, and disinter from the 

 sediments of other ages the remains of extinct types. 

 As we descend the geological series familiar types 

 gradually disappear, and through a succession of 

 changing floras we penetrate to the fragmentary 

 records contained in the older rocks until the absence 

 of documents sets a limit to our quest. 



The Scots pine shares with the oak, the beech, 

 the aspen, the yew, and several other trees the right 

 to be included in the native flora of Britain. In the 



