THE GEOLOGICAL AGE OF CENTRAL AND WEST CORNWALL. 187 



present day, — but there does not seem to be any evidence in 

 support of this hypothesis. We have followed the Strata from 

 Gerrans Baj^, through Philleigh and on to St. Clements, without 

 finding any material variation in dip or strike ; there is 

 apparently a continuous downward succession for a distance of 

 at least 5 miles. At St. Clements, however, we come to beds 

 of an entirely different character, our "Ladock Beds" striking 

 E. and W. — and overlying the others. Of course we do not 

 pretend to trace exactly the topographical boundaries of the 

 respective series in any greater detail than was indicated in the 

 sketch-map which accompanied the former paper. This is work 

 which must be done by the officers of the geological survey, 

 with their staff of attendants and fossil-collectors, — but it is 

 very significent, that in places near the junctions of the two 

 rocks we frequently find the Ladock Beds on the higher ground 

 while the Lower Silurians are exposed in the valleys. 



Believing as we do that the Quartzytes are of Llandeilo age, 

 it does not seem to us unlikely that the geological horizon of the 

 Lingula Flags may yet be identified in or near the valley of 

 the Fal, and possibly still older rocks in the neighbourhood of 

 Wheal Jane, and thence right across the Eedruth mining district. 



The S.W. extension of the Lower Silurians to and beyond 

 Hayle was determined — so far as purely stratigraphical evidence 

 would suffice — after several visits to the locality, and so indicated 

 on the sketch-map already referred to. Mr. Peach's discovery 

 of fossils resembling Eofhyton^ — a form occurring in the Alum- 

 Schists of Sweden, supposed to be of the same horizon as the 

 Skiddaw slates — in the quarry opposite the mineral floors at 

 Hayle, will probably be regarded as evidence confirmatory of 

 the views formerly expressed. 



PoNSANOOTH Beds. (Cambrian?) 



We have not much to add to what was said of these beds in 

 the paper so often referred to. That they underlie the Lower 

 Silurians and that they differ greatly from them in strike, dip, 

 and mineral composition will be evident to all who study these 

 rocks in the field. The surface area occupied by them 

 must be very small compared with what exists at a 



* Trans. B.G.S.C. Vol. IX., pp. 57, 58. 



