TRANSACTIONS OF SECTION C. 77 1 



North of a line drawn from Port Mooar through Snaefell to Peel, the general 

 dip of the slate is to the north-north-west at an angle varying from thirty degrees 

 to nearly vertical. 



The lowest beds exposed in this area crop at Port Mooar along the axes of a 

 series of anticlinal folds, which occupy the whole of the bay and extend south to 

 Gob-ny-Garvain. These beds consist of massive iron-stained quartzites and schists 

 overlaid by well-bedded slates. Northwards, by St. Maughold's Head and thence 

 to Ramsey, the slates dip steadily to the north-north-west, the angle of dip varying 

 between fifty and sixty degrees. Several dykes cut through the slate, whilst 

 quartz veins run in all directions. The dykes run very nearly in the line of strike, 

 and at first sight appear bedded and not intrusive. 



That the quartz veins originated subsequent to the dykes is seen by their pene- 

 trating the latter. 



Interbedded with the slates are thick sheets of volcanic ash much resembling 

 quartzites. 



The slates of St. Maughold's Head have yielded Valceochorda and certain oval 

 structures which are evidently organic. 



In the neighbourhood of Ballure Glen and Ballastowel Hill, the slates are 

 badly bedded, and full of irregular pebble-like inclusions, which give to the rock 

 a brecciated appearance. These have yielded the cast of a trilobite much resembling 

 Asaphus or yEglina, and also certain other structures which may possibly prove 

 organic. North and nortli-west from Ballastowell, the Skiddaw slates consist of 

 irregularly bedded iron-stained slates with interbedded volcanic ash, the latter often 

 of considerable thickness. 



Near Sully Glen Station occurs the singular and isolated hill of Cronk Lumark, 

 made up of a ' shivery ' slate. In a quarry on the north side of the hill specimens 

 were discovered of Dictyonema sociale and of a new species not yet described. 



A series of dip observations taken along Sully Glen, Tholt-e-Will, and over 

 the summit of Snaefell, shows that the dip changes round towards the west, 

 causing axes of the anticlinal folds to emerge on the west coast, a little 

 to the south of Peel, where the cliffs exhibit a series of contortions and folds not 

 unlike those of Gob-ny-Garvaia and Port Mooar. 



The conclusions deduced from these observations are as follows : — 



(1) That the Skiddaw slates of the north of the Isle of Man dip north-north- 

 west from an axis of folding which runs from Gob-ny-Garvain and Port Mooar on 

 the east to a little south of Peel on the west. 



(2) That there exists a series of contemporaneous beds of volcanic ash. 



(3) That the Skiddaw slates are fossiliferous, and by their fossils show a relation 

 with the Lingula Flags of the Cambrian. 



9. On the Volcanic Phenomena of Jaimn. 

 By Professor J. Milne, F.li.S. 



I 



10. On the Badiolarian Cherts of Cornwall. By Howard Fox, F.G.S. 



The Mullion Island radiolarian cherts were first recognised by Mr. J. J. II. 

 Teall, F.R.S., in rocks sent to him by the author last autumn, and a joint paper was 

 read at the Geological Society's meeting, February 8 last, describing the manner 

 in which they occur. Dr. Hinde accompanied the paper with a description of the 

 species recognised and with micro-photogi-aphs of the individual organisms. 



Last Easter Mr. Teall, Professor Lapworth, and the author traced these cherts 

 for about 650 yards in the cliffs and on the foreshore from the south end of Nelly's 

 Cove, near Porthallow, Meneage, to near Ligarath Point, south of the Nore Point. 

 Subsequently the author has examined the coast and some inland districts between 

 Ilelford River and Fowey, and has found other exposures in the following 

 places : — 



Pendoner Beach, Veryan (for about 1,000 yards). — Beds many feet thick at the 

 ■ •west end of this beach, on which the raised beach rests. Angular fragments of 



3 D 2 



