GEOLOGY 



The Dartmouth slates, intercalated at intervals with beds of hard 

 grit and quartzite (which on the Revelstoke coast display numerous 

 contortions), extend to a little beyond Hoist Point. Near Piskeys Cove 

 Pteraspis was found in them. Diabases and volcanic rocks occur in 

 them at the mouth of the Erme and in other places. 



Near Hoist Point the Dartmouth slates give, place to dark grey, 

 locally red stained, slates and shales with siliceous bands, crinoidal lime- 

 stone films and a horizon of crushed brachiopods. These have been 

 called the Ringmore beds ; they are in plicated association with dark 

 grey slates, locally red-stained, in which Pteraspis was found at Ayrmer 

 Cove by Brook-Fox. At the bend in the Avon, near its mouth, the 

 calcareous fossiliferous bands come in again, with (?) Monticuliporoid 

 remains, near to an inlier of Dartmouth slates. From Avonmouth to 

 Hope the section consists of dark grey slates with siliceous bands in 

 places and occasional traces of fossils. Bands of igneous rock of the 

 Torcross type occur in places. Interlaminated beds and slaty fine grits 

 with calcareous and hard carbonate bands come on at Beacon Point and 

 Woolman's Point. The Beacon Point rocks traced across the promontory 

 exhibit developments of grit, most conspicuous north of Malborough 

 and near Beeson ; their horizon is everywhere separated from the altered 

 rocks by dark grey slates without igneous bands. Throughout this 

 section there is a constant repetition of horizons by plication, and there 

 are numerous faults. 



The eastern coast proceeding from the altered rocks northward 

 begins with dark slates, as at Hope, overlying interlaminated beds which 

 contain crinoidal limestone films, at Tinsey Head, and hard grit beds, 

 at Beesands. The Tinsey Head and Beesands beds correspond to the 

 Beacon Point and Woolman's Point beds. The only doubt as to the 

 succession in these two sections is whether these rocks are a normal 

 outcrop or an anticlinal repetition of the Ringmore beds. In either 

 case, as every member of the series has its representative in the Looe 

 area, the rocks must be regarded as parts of the Meadfoot series. On 

 the east coast the Ringmore beds are not well shown. From Strete 

 Gate to Scabbacombe Head the Dartmouth slates form the cliffs with 

 igneous rocks here and there and grit beds. 



Proceeding southward from their faulted junction with the Middle 

 Devonian, south of Berry Head, the Lower Devonian section commences 

 with Staddon grits, grits and sandstones associated with slates and shales, 

 succeeded by dark slates with masses of dense fine grit, probably the top 

 of the Meadfoot series. In Southdown cliffs these give place to slates, 

 locally reddish, with very occasional crinoidal films and a seam of igneous 

 rock. On the south of Man Sands dark slates and interlaminated beds 

 with pale greenish igneous rocks of the Torcross type are in plicated 

 association with dark grey and red shales and slates with seams of crin- 

 oidal limestone with (?) Monticuliporoid corals corresponding to the Ring- 

 more beds. At Long Sands a mass of dense thick-bedded fine grit comes 

 in. Whether this is a repetition by fault or fold of the grits in the 



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