410 ME. J. PARKINSON ON THE GEOLOGY OF [Aug. I903, 



beds of the Volcanic Series abutting abruptly on their contorted face. 

 Locally, they are a fault-breccia without semblance of stratification. 



A field-quarry some two-thirds of a mile to the east- south-east 

 on the line of strike shows intense cortortion and brecciation in 

 the same hard slates, although not quite equalling the Trambley- 

 Cove exposure. 



Pursuing the same direction, finely-banded slates and slate- 

 breccia are found between Tredole and Tregania, occupying the 

 same position in regard to the under- and overlying beds. A small 

 quarry between Tregrylls and Gunvillick displays an identical rock 

 in an identical state. 



Quitting the true line of strike, we find the same slates at 

 Gullastem, greatly contorted and crushed. Between that inlet and 

 Barras Gug they are in places reduced to a state of breccia. 



Between Lill Cove and Yean Hole, about 300 yards north of 

 Trebarwith Strand, may be found important structures indicative of 

 the same tremendous pressure. At the former place the Tredorn 

 Beds, forming the top of the cliff, are reduced to a structureless state, 

 without sign either of bedding- or joint-planes ; below lies a zone, 

 some 20 inches thick, composed of the intensely contorted Blue- 

 Black Slates, interlaminated with some paler softer beds, similar to 

 those above, the whole affording a transition from one group to the 

 other. Below the contorted zone lies an undisturbed belt of 

 the same Blue-Black Slates. Application of great pressure has 

 clearly taken place, resulting in a slide at the junction of the hard 

 and soft rocks, where its effects are most obviously displayed in the 

 contorted zone. 



Somewhat similar structures have been produced at Vean Hole, 

 the direct continuation of the same slide. Two bands of the black 

 slate, some 10 inches thick, form, as seen in the cliff-section, 

 a series of three or four ellipses joined the one to the other 

 like the links of a chain. The rock forming the centres of the 

 ellipses is almost white, hard, somewhat brittle, and apparently a 

 reconstructed band of the overlying phyllites impregnated with 

 quartz. Numerous quartz-eyes appear in it. Above, the whole 

 grades into the Tredorn Beds ; below, into the Volcanic Series. 

 Intense crushing is shown also at Lye Head, Tintagel Head, and 

 to the east of Smith's Cliff". 



The low dip of the beds at Lill Cove seems opposed, at first sight, 

 either to great pressure or much differential movement. The rocks 

 of AVillapark (the western side of Bossiney Haven) present a some- 

 what similar appearance. Two dip-faults, combined to form a V, 

 bring in the Tredorn Beds and the Upper Blue-Black Slates. 

 Examination of the shore, however, shows that the movement has 

 been not merely vertical, but more or less parallel with the 

 bedding, where its greatest effects are exhibited near the junction 

 of the Blue Slates and the Tredorn phyllites. 



These facts, taken in conjunction with the great crushing from 

 Trambley Cove eastward (described above) make it probable that 

 intense compression affected the entire region : but, the present dip 

 being once acquired, motion took place most readily along the 

 directions of bedding. 



