55 PROCEEDINGS OF THE GEOLOaiCAL SOCIETY. 



modified by subsequent pressure, which, however, I strongly suspect 

 operated before the basement-Cambrian conglomerates were formed, 

 and this pressure acted, in some cases at least, on rocks already 

 foliated. Further, the occasional interbedding of quartzites with 

 these schists is a proof of sedimentation, and in these cases (to speak 

 of no others) the foliation agrees with the bedding. 



Other Districts in England and Wales. 



Over the remaining districts in England and Wales I must pass 

 briefly. As regards the St. Davids district, I have nothing to add to 

 the remarks which I made last year ; but, through the kindness of 

 Mr. Allport, I have had the opportunity within the last few weeks 

 of examining a fine series of slides and specimens representing parts 

 of the Malvern range. Of these I trust that before long he will 

 send us a notice; but I may say that the coarse-grained rocks 

 from the northern hills exhibit the effects of compression, to which, 

 as in the case of the granitoid gneisses of Wales, their present 

 gneissic structure may in some cases be due. At ihe southern end 

 of the range, however, rocks more distinctly foliated and non-igneous 

 in origin are found, together with true mica-schist. The granitoid 

 gneisses on the flaulxs of the Wrekin present considerable resem- 

 blances to rocks which I have obtained from masses elsewhere 

 of admittedly " Laurentian " or Hebridean age, though their struc- 

 ture has in places been much modified by subsequent crushing. 

 There can be no doubt, I think, that Dr. Callaway is fully justified 

 in including them in the same general group as the rocks of the 

 Malvern Hills. The rhyolitic rocks of the Wrekin district and of 

 other areas, in short the various masses of slates, agglomerates, and 

 old rhyolites, which, though older than the Cambrian group, cannot 

 be very widely separated from it, hardly fall within the scope of 

 my present subject. 



Scotland. 



In the summer of 1879 I examined the rocks around the upper 

 part of Loch Maree, and communicated to the Society the results of 

 my work. Since then I have had opportunities of examining con- 

 siderable collections from this and other districts of Scotland, and in 

 the autumn of last year spent some time in the former district and 

 at Gairloch. The rocks of this last region have an exceptional im- 

 portance because their Hebridean age is universally admitted, and 

 their distinctive characters and probably higher position in the series 

 have been pointed out by more than one observer. In my description 

 I shall suppress microscopic details, but I may remark, once for all, 

 that I have verified every point of importance by the examination 

 of slides cut from specimens collected by myself. Commencing with 

 the elevated moorland between Gairloch and PoUewe, we find 

 abundantly on the eastern side of the watershed moderately fine- 

 grained, very distinctly banded gneisses. Quartzo-felspathic and 

 more micaceous * layers alternate, varying in thickness from 2 or 3 



* The mineral is commonly a black mica, but hornblende also occurs. 



