434 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [April 22, 



both sides of the Yealmpton limestone ; and it contains much dark- 

 bine slate, and occasionally, as at Gooswell, some calcareous bands. 

 These blue slates occupy the middle of the trough, and are quarried 

 near Brixton and north of Ludbrook, &g. At Harberton the trough 

 deepens, being thrown down on the north as already described, and 

 higher beds occupy the interval between this place and the Dart. 

 These latter consist of thick slates in which much volcanic matter 

 is disseminated, interstratified with bands of grit ; and for the most 

 part they yield a red soil. Volcanic rocks are frequent ; and on the 

 east of the Dart there are some calcareous bands associated with 

 them, as also much red and purple grit. Good sections of these 

 rocks are to be seen in the vicinity of Totnes and in the descent to 

 Bow Bridge ; and the manner in which they have been brought into 

 relation with the limestones of Dartington, Boston, and Berry Pome- 

 roy has been already explained. The continuation of these rocks 

 across the Dart is somewhat interrupted by the upthrown limestone 

 of Stoke Gabriel, and by the southern portion of the Berry Pomeroy 

 limestone, which is similarly throT\Ti up at Longcombe Cross. 



The variegated argillaceous slates (partly claret-coloured) which 

 form the lower portion of this upper group rest upon the limestones 

 of Berry Pomeroy, Arton, Loventor, and Marldon ; and immediately 

 above the limestones they are occasionally fossiliferous, as in Berry 

 Park ; but they have yielded little that can be determined, and the 

 species do not appear to differ from those contained in the slates below 

 the limestones. These beds dip to the east and south-east, and pass 

 under the purple and greyish grits of Blagdon Cross, Beacon Hill, 

 Ockham, and Cockington; while the beds throvm off the Stoke 

 Gabriel and Taiberton limestones dip to the north under the grits of 

 "Windmill Hill and Collaton, thus forming a shallow basin which is 

 occupied by the Triassic rocks of Painton. Much of the red colour 

 appears to be due to the action of the atmosphere upon the bases 

 contained in the rock, and beds which are light-coloured often yield 

 a red soil ; but the blue slate appears especially liable to become 

 claret - colour e d . 



The rocks thrown off on the south of the anticlinal axis extending 

 from Mudstone Bay to Yealmpton are precisely similar to the lower 

 beds contained in the above-mentioned sjmclinal trough, and consist 

 of grey and dark-blue argillaceous slates, the latter often changed to 

 a purplish or red colour. These rocks are well seen in the railway- 

 sections east of Greenway House, where they contain some beds of 

 ash. Prom Greenway they are continued by Ditsham and Combe, 

 where they have been quarried for slates, and by JSTew House, on the 

 Avon, to Modbury, and thence south of the Yealmpton limestone to 

 Staddiscombe, near Phmstock, and to the coast at Withy Hedge in 

 Plymouth Sound. Above these are beds of slate, much of which is 

 reddish, containing bands of grey, yellowish, or purple grit. These 

 grits, apparently, do not form continuous beds ; at least they cannot 

 be followed many miles on their line of strike. The follomng section 

 is seen on the Torquay and Dartmouth railway between the tunnel 

 at Greenway Farm, south of Galmpton, and the station at Kings wear. 



