﻿592 MR. E. B. BAILEY ON RECUMBENT EOLDS IN THE [Nov. I9IO, 



(b) General Statement of the Problem. 



Before entering into a detailed account of the stratigraphy and 

 structure of the district, the main features will be set forth in 

 outline. 



The following stratigraphical sequence has been, established, but 

 whether it should be read upwards or downwards is a matter for 

 future enquiries to decide : — 



9. Eilde Flags (commonly classed with the Moine Gneisses of tbe Central 



Highlands). 

 8. Glen Ooe Quartzite (fine-grained). 

 7. Leven Schists (grey phyllites and ' Banded Series '). 

 6. Ballachulish Limestone (dark grey, with a thick cream-coloured margin 



against the Leven Schists). 

 5. Ballachulish Slates (black). 



4'. Striped Transition Series (separately mapped in certain localities only). 

 4. Apoin Qimrtzite (pebbly). 

 3. Appin Limestone (cream-coloured). 



2. Appin Phyllites (with a large proportion of flaggy quartzite). 

 1. Cuil Bay Slates (black). 



No exact measurements can be given in regard to the groups 

 enumerated above; but even the thinnest of them, the Appin Lime- 

 stone, is probably not less than 100 feet thick, while the Leven 

 Schists, Glen Coe Quartzite, and Eilde Flags must each of them 

 reach about 1000 feet : the other members of the sequence should 

 doubtless be reckoned in hundreds of feet. These rough estimates 

 refer to original thickness of deposition. Now, over wide areas, 

 various groups are reduced to mere films, or may be entirely 

 missing from the sequence as a result of the intensity of the folding- 

 movement to which they have been subjected ; elsewhere, again, 

 their dimensions have been mightily increased by reduplication — 

 another aspect of the same folding process. 



The details of stratigraphy, the consideration of which is deferred 

 for the present, vouch for continuity of sedimentation during the 

 formation of the great pile of deposit included in groups 1-8, for 

 all these groups are linked by passage-beds. The Eilde Flags (9) 

 also appear to be connected by a passage-zone with the Glen Coe 

 Quartzite (8) ; but, in this case, it would perhaps be premature to 

 come to a definite conclusion in regard to the nature of the junction 

 until a larger area has been surveyed. 



jSio feature of the stratigraphy affords a hint as to the original 

 order of superposition of the groups tabulated above, nor does the 

 degree of metamorphism assist in solving this difficult question. 

 As a matter of fact, there is increasing regional metamorphism in a 

 south-easterly direction, which affects all groups alike, so that the 

 Eilde Flags, in the Loch Eilde Mor district, are much more highly 

 altered than the same flags in the Fort William district. While 

 referring to metamorphism, it is important to bear in mind that an 

 aureole of marked contact-alteration surrounds each granite boss. 

 In these aureoles many of the subdivisions assume very special 

 characteristics, so much so that their definite correlation with the 

 equivalent groups beyond the range of the granites' influence might 



