420 PEOCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 22, 



are no doubt the same beds repeated bj the subordinate anticlinal 

 and synclinal folds ; and faults may have destroyed the continuity of 

 a bed, and thrown it out of the line of strike, as is the case in the 

 vicinity of Padstow. The limestones and fossiliferous bands range 

 on either side of the axis of the trough, which trends from Constantine 

 Bay, by Padstow and St. Michaels, to Lower Amble, round to the 

 south-east of St. Kew ; and some of these higher beds consist of 

 purplish argillaceous slate very similar to some of that associated 

 with the volcanic rocks of Saltash and St. Germans, to be noticed 

 hereafter. 



The fossils of the Padstow district occur chiefly at Permizen Bay, 

 Dinas Cove, and Penquean, and consist of Petraia Celtica, Phacops 

 latifrons, P. laciniatus, Athyns concentHca, Atrypa desquamata, and 

 OriJioceras Ludense, Phill. (which are also South-Petherwin forms), 

 Sjnnfera speciosa, Pentamerus hrevirostns, StreptorJiynchus umbra- 

 cidum, String oeeplialus giganteus, Cyathocrinus megastylus (which 

 are Middle Devonian), and Spirifera hysterica, which is a Looe and 

 also a Lynton species, but is said to occur likewise in the limestone 

 of Woolborough near jSTewton Bushell. Prom Bedruthen Steps, Mr. 

 Pengelly has ; obtained specimens of Pteraspis Cornid)icus, M'Coy; 

 and this is the lowest horizon on which it has hitherto been observed. 

 "We have therefore six species occurring in the Padstow area in 

 common with South Petherwin, and six in common with the Looe- 

 river district, with two that belong to intermediate stations, viz. 

 Spirifera speciosa, which occurs also at Tintagell, and Phacops lati~ 

 frons at liskeard. See Table III., p. 450. 



These rocks rise, on the south of the trough, to the anticlinal axis 

 of St. Breock's Down ; and in all probability the slates which contain 

 the calcareous and fossiliferous rocks of St. Columb Perth and jS'ew 

 Quay, are the same beds repeated on the south side of the axis*. 

 This axis extends from the coast north of Trenance Point, near 

 Morgan Perth, to the Camel above Polbroke, and brings up lower 

 rocks, which consist chiefly of thick pale-coloured slates with bands 

 of hard gTey grits, the whole much traversed with veins of quartz, 

 fragments from which, mingled with those from the grits, are strewed 

 abundantly over the surface of the down. Eastward of the Camel, 

 the country to the south of the axis, about Bodmin and Lanivit, is 

 thrown up by the granite of St. Austell, and the dip becomes 

 northerly, at for the most part low angles. This upcast is aided by 

 a line of fault which extends from the east of Bodmin, by the Black 

 Pool Barrow, to the west of Lostwithiel. The crest of the St. Breock's- 

 Down axis, which is formed by the arenaceous beds, thus becomes 

 relatively depressed ; and the country round about Bodmin, west of 

 the fault, and between it and the Camel, consists chiefly of the thick 

 slaty rocks which form the flanks of the axis, and some unimportant 

 bands of grit, undulating off to the northward. At the quarries at 

 Castle Canyke, and about Bodmin Down, the angle of dip is about 

 20° ; south of Bodmin Down bands of grit rise to the south and crop 

 out, 



* See, further, De la Beclie, Keport, p. 88. 



