Abstracts of Papers read on Geology. 463 



(11) On Systems of Folding in the PALiEozoic and ISTewee Eocks. 

 By G. Baerow, F.G.S. 



IN a paper published by the Geologists' Association the author has 

 given a brief outline of the nature of the crystalline area of the 

 Highlands and shown that it consists of three great lenticular masses 

 of thermally altered rocks. It is further shown that the outer and 

 unerystalline margins of these masses all trend roughly north-east 

 and south-west. The best known is that forming the south-eastern 

 margin of the crystalline area, which the author has followed, where 

 present at the surface, almost the whole distance from Stonehaven, 

 on the east coast of Scotland, to Omagh in the north of Ireland. 

 Eecent work suggests that this margin is also present on the west 

 coast of Ireland. 



This outer margin of crystallization is not confined to Scotland ; it 

 is also present in Anglesea, where the margin of the crystalline massif 

 is seen along a portion of the Menai Straits. It also occurs in the 

 Isle of Man, where the old rocks are identical with those of the lower 

 aureoles of thermometamorphism in the Southern Highlands. In both 

 cases the trend of this outer margin is the same — north-east and 

 south-west. Wherever this margin can be examined it has been 

 found to be a great line of resistance, and the folding in the adjacent 

 palaeozoic, and, at times, even newer rocks, is found to be parallel to 

 it ; it is in fact the cause of the strike of the folding ; under earth- 

 stresses the softer rocks have buckled up against a great resisting 

 crystalline mass. 



Thus, strictly speaking, there is no such thing as a Caledonian 

 Movement ; there are a series of resisting masses with parallel 

 margins ; the folding in North Wales is determined by the Anglesea 

 Archaean Bocks ; Caledonia has nothing whatever to do with it. 



If, now, we turn to the area in the south of Britain, we find 

 another system of folding ; this, too, the author believes to be due 

 to a similar cause. The outer margin of the old crystalline rocks in 

 Cornwall seems to be roughly east and west ; it certainly is not 

 north-east and south-west. It now remains to do in the north-west 

 of France what the author has done in North Britain — i.e. to trace 

 out the outer margins of crystallization and prove that the so-called 

 Hercynian system means simply that the boundaries of the resisting 

 crystalline masses, against which the newer rocks buckle up, now 

 trend east and west. If these facts are once grasped we have an 

 explanation of the local departure of the strike of the folding in the 

 north of England ; the lines of resistance locally depart from their 

 usual trend and the subsequent folding does the same. 



(12) On the Spieoebis Limestones oe Noeth Waewickshiee. By 

 G. Baeeow, F.G.S. 



THE typical Spirorbis limestone is a rather compact rock, usually 

 grey and generally containing the small fossil Spirorbis 

 carionarius. The number of these varies greatly ; at times several 

 specimens may be seen in one fragment ; often it is difficult to find 

 any, and, so far as experience has gone at present, they are never 



