2 8o SCIENCE PROGRESS. 



Devon from the east, they once covered the district. The de- 

 position of Eocene beds at Bovey Tracey on Pre- Cretaceous 

 rocks however shows that the district was affected by the Mid- 

 Cretaceous uplift (or at any rate by one in Post-Cretaceous 

 and Pre-Eocene times) if the Cretaceous rocks once extended 

 over Devon, but the nature of the Bovey beds indicates the 

 probability of the former extension of similar beds over 

 Devon and Cornwall, and suggests the final great uplift of 

 the Devon-Cornwall mass in Miocene times. 



Coming now to the Welsh area, we find Triassic rocks 

 dipping away from it on the north, east and south, and 

 Rhaetic rocks on the south, in a manner which suggests the 

 elevation of Wales in Mesozoic or Tertiary times. We have 

 no direct evidence of the extension of Cretaceous rocks over 

 the area, but even if an uplift occurred in Mid-Cretaceous 

 times which prevented the accumulation of the Cretaceous 

 rocks over the area, the Welsh rocks were probably worn 

 down to a peneplain before the great Miocene earth-move- 

 ments. 



Examination of the geology of England in fact indicates 

 that had the Miocene tilt been in an opposite direction, giving 

 the newer strata a westerly dip instead of an easterly one, 

 the Highlands of Britain would be on the east side, the 

 Mesozoic rocks would be denuded there, and the London 

 ridge and similar ridges now buried beneath newer deposits 

 would form a hilly country occupied by the more ancient 

 formations, whilst the west of England and possibly Scot- 

 land and Ireland would consist of low ground formed of a 

 peneplain of old rocks, or more probably of Triassic beds and 

 even later deposits, possibly as modern as the Cretaceous 

 and Eocene beds. It must be remembered that even if the 

 west existed as land in Eocene times, the characters of the 

 lignites and basalts of the Western Isles of Scotland and 

 Ireland suggests their former extension as plateaux over 

 much wider areas (4), and they may well have extended 

 over much of the country now occupied by older rocks. 



To return for a moment to Wales : The newer rocks 

 which surround the older Palaeozoic rocks of the Principality 

 are continued across the Irish Sea and St. George's Channel, 



