414 THE CULM OF SOUTH DEVON : EXETER DISTEICT. [Aug. I9II, 



stones containing Posidonomya becheri and other fossils constituting 

 the fauna of the Pendleside Series. But in North Cornwall and 

 the area west and east of Dartmoor, an apparently different order of 

 deposition was found among the beds. Along the coast near 

 Boscastle the Upper Devonian slates underlay carbonaceous shales, 

 and these were succeeded by grits with occasional flows of lava, 

 while the radiolarian cherts were not met with for a distance of 

 some 3 miles farther north, and tben 90 feet of them formed the 

 headland known as Firebeacon Point. Eastwards, this order was 

 continued as far as Dartmoor, and near Launceston limestones 

 were seen dipping beneath radiolarian cherts. These limestones 

 contain Posidonomya becheri • but no fossils had been found in 

 the cherts. It was, however, difficult to believe that the massive 

 cherts which formed a nearly continuous outcrop for 20 miles were 

 not on the same horizon as the beds at Codden Hill. If this were 

 so, the position of the Codden-Hill Beds with regard to the lime- 

 stone beds in North Cornwall differed from their position in North 

 Devon. 



But it must be remembered that overthrusting had reversed the 

 normal succession over wide areas in North Cornwall. At Tintagel 

 this had affected the Upper Devonian sequence, while at Holne on 

 the Dart, south-east of Dartmoor, the Upper Devonian was thrust 

 upon the Culm beds. It did not, therefore, seem improbable that 

 overthrusting might have brought about the apparent difference 

 in the succession in North Cornwall. 



The Author, in reply to Dr. Sibly, said that the bulk of the 

 plants sent to Mr. Arber came from the north of the area, but 

 broken plant-remains occurred throughout the series. 



