CHAP. XIV. IN BRITISH PHYSICAL GEOGRAPHY. 275 



this region is of such moderate elevation above the sea, that 

 it would be almost equally laid under water were there a 

 sinking of no more than 600 feet. 



To make this last proposition clear, I have constructed, 

 from numerous documents, many of them unpublished, the 

 map, fig. 40, given at p. 278, which shows how that small 

 amount of subsidence would reduce the whole of the British 

 Isles to an archipelago of very small islands, with the ex- 

 ception of parts of Scotland, and the north of England and 

 Wales, where four islands of considerable dimensions would 

 still remain. 



As to the district south of the Thames and the Bristol 

 Channel, it seems to have remained land during the whole 

 of the glacial period at a time when the northern area was 

 under water. 



The map, fig. 40, p. 278, just alluded to, represents simply 

 the effects of a downward movement of a hundred fathoms, 

 or 600 English feet, supposed to have been uniform over the 

 whole of the British Isles. It shows the very different state 

 of the i^hysical geography of the area in question, when con- 

 trasted with the results of an opposite movement, or one of 

 upheaval, to an equal amount, of which Sir Henry de la 

 Beche had already given us a picture (from which I have 

 borrowed the map, fig. 41, p. 279), in his excellent treatise 

 called " Theoretical Eesearches."* 



If we are surprised, when looking at the first map, fig. 40, 

 at the vast expanse of sea which so moderate a subsidence as 

 600 feet would cause, we shall probably be still more asto- 

 nished to perceive, in fig. 41, that a rise of the same number 

 of feet would unite all the British Isles, including the He- 

 brides, Orkneys, and Shetlands, with one another and the 

 continent, and lay dry the sea now separating Great Britain 

 from Sweden and Denmark. 



* Also repeated in De la Beche's Geological Observer. 



