A HISTORY OF DEVONSHIRE 



Worth propounded the theory that the Dartmoor granite is the stump 

 of an old volcano, the effusive materials from which were removed by 

 denudation and incorporated in these breccias. 



The presence of Upper Devonian fossils of north Devon types in 

 some of the stones in the Lower New Red breccias of Tiverton, Silver- 

 ton and Cadbury suggests a current from the north or north-west. 



It seems therefore that the outliers of Lower New Red gravel at 

 high levels are the relics of the valley bottoms of a contour which has 

 been since so entirely changed by denudation that not a vestige of the 

 higher land in their vicinity is left. The succeeding New Red sub- 

 divisions point to more tranquil deposition, except the well worn pebbles 

 of the Budleigh Salterton beds, which, from the replacement of pebbles 

 of extraneous derivation by those of local origin as they are traced north- 

 ward, seem to indicate the pushing forward of a shingle beach during 

 a period when the sea may have gained access to the lacustrine areas. 

 The succeeding Sandstones contain Labyrinthodont remains, and under- 

 lie the Keuper Marls without any appearance of discordance. 



There is no proof of the nature of the denudation of the palaeozoic 

 surface subsequent to the deposition of the Lower New Red beds until 

 the Cretaceous period, when, after the earlier Secondary rocks by an 

 uprise on the west, or a depression on the east, had been tilted, the Cre- 

 taceous sea cut a plane across them on which the earlier Cretaceous 

 sediments were transgressively overlapped and the descending series of 

 older formations overlain. In this and the subsequent deposition of the 

 Eocene clays and gravels the older rock area was no doubt invaded, and 

 the irregularities of its earlier contour planed and modified. 



On the Cretaceous tableland the clay or loam with flints or chert 

 fragments attains a thickness of 30 feet or more in places, filling pipes 

 in the Greensand, and in the Chalk where present. It is very rare to 

 find any extension of water-worn gravel on the Cretaceous summits, such 

 as is found near Staple Hill on the Black Downs and on Great Haldon. 

 This accumulation seems to be connected with the planing of the Creta- 

 ceous rocks about the period of their emergence in Tertiary times, and 

 suggests the shorn remnants of argillaceous Tertiaries deposited on the 

 relics of the Chalk, which had become mixed with flints and been 

 carried down by subsequent percolation into pipes and potholes dissolved 

 out of the subjacent rocks. The accumulation has been displaced with 

 the Greensand on which it rests by a considerable north and south fault, 

 repeating in Stockland Hill the escarpment above Honiton. 



Between Haldon and Kingsteignton near Oldchard, Hestow farm 

 and Ideford, saccharoid red-brown siliceous boulders are met with. 

 They are probably greywethers and — coupled with the sands and gravels 

 retained in potholes in the Devonian limestone and those fringing the 

 Bovey valley — they point to a considerable amount of Eocene denudation 

 and subsequent removal of resultant deposits. The lake basins of Bovey 

 and Petrockstow do not appear to be due to local subsidences on fault / 

 lines, although the high dips of the sands on the south of the Bovey / 



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