44 



Relation op the Keuper and Eaa;Tic Series to the 

 Devonian Rocks of West Somerset. 



In North Devon neither the New Red, Rhsetic or Lias series 

 occur, it is even questionable if they were ever deposited in that 

 area^ nowhere west of Porlock are they known. It is evident 

 everywhere that the older or Palseoozic Rocks, both Devonian 

 and Carboniferous were placed in their present general position, 

 prior to their denudation by the New Red Sea, or deposition 

 of the Trias series, this is gi-andly shown in the deep 

 valleys of Bridgewater, Stogumber, Milverton, and Luckham, 

 which are but deep and filled in depressions in the Lower and 

 Middle Devonian series. Section III shows the position of the 

 Exmoor and Quantock Hills, with the Stogumber and Bridge- 

 water valleys; the latter may contain a greater series of 

 Secondary Strata than the Stogumber valley, and may be 

 deeper, and well expresses the probable island like condition of 

 the Exmoor and Quantock Hills at the time of the deposition of 

 the New Red and Lias series. We have no proof that the Lias 

 ever covered these elevated ranges; although the upper Lias of 

 Dundry Hill, near Bristol, and Glastonbmy Tor is 600 feet above 

 the level of the Severn, and patches of Lias he high upon the 

 flanks of the Mendip Hills, The amount of denudation these 

 ranges must have undergone is testified by the great spread of 

 the Breccia and Conglomerate that occupy the vaUeys mentioned 

 east of Wiviliscombe, from Thorn St. Margaret, to Milverton 

 and Fitzhead. An immense area is occupied by the so called 

 Dolomitic Conglomerate and Breccia, and those who have not 

 visited the valley, and especially Tipnoller Quarry, north-east 

 of Wiviliscombe can form no conception of the magnitude 

 of the destruction, by denudation, of the Devonian Rocks com- 

 prising the Exmoor Forest Range, and the Quantock Hills, 

 especially so, when acquainted with the mode of occurrence and 

 spread of the waste over the valleys ; these beds are frequently 

 worked for lime, when they contain pebbles from the bands 

 of Devonian Limestone, which strike along the east flanks of 

 the Exmoor and Quantock HiUs, this is especially the case 



