THE GEOLOGICAL AGE OF CENTRAL AND WEST CORNWALL. 16.3 

 LIST OF ROCK SPECIMENS SENT IN ILLUSTRATION OF THIS PAPER. 



A. Fine-grained Mica trap from Newquay, containing hyaline quartz and 



nickel if erous pyrites. Very fresh. 



B. Fine-grained Mica-trap from the Ganuel. Very fresh. 



C. Fine-grained Mica-trap from near the mouth of the Gannel. Much 



decomposed. 



D. Much-decomposed Mica-trap from Boscolla farm. 



E. Moderately fresh Mica-trap from Treliss'ck Point. 



F. Much-decomposed mass containing fragments of quartz, coarse-grained ; 



from Trelissick Point. 



G. Fine-grained Specimen — much decomposed — from Lamb Creek. 



H. Fine grainel and decomposed — c intaining very little mica— from Flushing. 

 I. Fine-grained, much-decomposed, having a large felspar crystal (orthoclase) 



porphyritically developed — from Greenbank. 

 J. Moderately-fine-grained, fresh, from Mawnan Cliffs. 

 K. Fine-grained, moderately fresh, from near the Nare Point. 



Since the publication of the praper on this subject in the 

 Journal of the Royal Institution of Cornwall,* and the 

 discussions which took place in the Society's rooms, at Truro, 

 during the winter of 1882, we have not been able to make many 

 new observations in the field ; but the following notes, in addition 

 to and explanatory of the form«er paper, have been worked 

 out from our notebooks and from specimens collected during 

 the years 1878-81. A few errors which had crept into the 

 former paper, for some of which the author was responsible, 

 and for others the printer or engraver, will be corrected en 

 passant. 



Ladoch Beds. (Devonian ? Old Eed Sandstone ?) 



As before, the supposed geological age of these rocks is 

 marked with a query, but we see no reason to doubt the general 

 correctness of the opinions then advanced. 



We have, indeed, some independent evidence in support of 

 the conclusions formerly arrived at. According to Mr. J. A. 

 Phillips, who has devoted a great deal of attention to the 

 examination of these strata, many of them contain fragments of 

 igneous rocks identicalin composition with the "greenstones" 



* Part 1, Vol. VII, 1881. 



