568 Geological Society, 



eiFect produced by the intrusion of homblendic trap throughout this 

 part of Devonshire. 



In the parish of Kington, veins of trap, on approaching the granite, 

 are said to become more compact, and in the proximity of it, to be 

 distinctly crystalline. Associated with the culm strata are bedded 

 traps, apparently of contemporaneous origin ; but the close of the cul- 

 miferous period is stated to have been marked by irruptions of the 

 porphyry found at Pocombe-hill, and other places near Exeter. At 

 Western,, in the parish of Ide, it rests upon the culmiferous shale ; 

 but Mr. Austen says, it might be considered to rest on the new red 

 sandstone, as that formation flanks the base of the hill. In the quarry, 

 however, where the porphyry is worked, it has been cut through, 

 and found to rest upon shale*. This rock has contributed largely 

 to the formation of the conglomerates of the new red sandstone. 

 Trap dykes are very common among the older slates, and have pro- 

 duced decided effects on them, and the general features of the 

 country. Their age the author does not attempt to define ; but from 

 their being more abundant in the older than in the newer rocks, he 

 conceives that they may have been, in part, irrupted before the latter 

 were deposited. In the coast section, beds of hornblendic trap are 

 included in the transition shale, to which they adhere by the lower 

 surface, but not by the upper. Similar, imbedded, trappean rocks 

 occur at Black Head, west of Babbacomb ; the sixth mile-stone 

 between Teignmouth and Torquay; near the village of North 

 Whilborough, and at East Ogwell. 



The author then describes the phsenomena, which appear to have 

 accompanied the disturbance of the strata at different periods, be- 

 ginning with those considered to be most recent. 



The undulations and deep combs in the new red sandstone, he 

 aays, are not due solely to denudations, but to elevations and depres- 

 sions of the beds while the formation was beneath the sea. On the 

 surface there are no indications of disturbance, the angular irre- 

 gularities having been rounded before the district became dry land. 

 The Watcomb Fault, however, he conceives, was produced by a 

 subsequent operation, as it preserves its angular outline ; and other 

 instances are mentioned of unobliterated faults. 



Mr. Austen next describes, with reference to this part of the sub- 

 ject, the raised, marine beds in the estuary of the Exe, the raised 

 beaches at Hope's Nose, the Thatcher, and to the west of Berry Head ; 

 he mentions also those which occur at intervals along the southern 

 coast of Devon. 



• [I observed, in 1825, in one of the Radden quarries at Thorverton 

 near Exeter, that the porphyritic amygdaloid was overlaid by the red marl, 

 the sandstone of that formation appearing to graduate into the subjacent 

 amygdaloid, which was also intersected by irregular nearly horizontal veins 

 of the former rock. The phaenomena here are altogether such as might 

 naturally be supposed to result from the intrusion of the igneous rock into 

 the new-red-sandstone formation, at least j)rior to the consolidation of the 

 latter, if not during its deposition. See the papers referred to in p. 566 

 note».-E.W.B.] 



