REPORT OF MEETINGS FOR 1901 51 



Lastly : when the volcano is active for the last time it 

 often happens that the result of the final explosive outburst 

 is the ejection of great quantities of fragmentary materials, 

 which may end by falling back into the vent and then 

 choking up the pipe. Or, more commonly in such a case, 

 fluid rock, such as would be called lava if it flowed down 

 the sides of the cone, may fail to reach the surface, and 

 remain in the vent and consolidate there. In either of these 

 two cases the pipe thus filled-up is spoken of as a neck. 

 As already mentioned North Berwick Law, Traprain Law, 

 The Bass (and others) are examples of such volcanic Necks. 



The diagram Fig. 1., on Plate X. may serve to make 

 these points clearer. The part marked N. represents the 

 position of the part of the volcano out of which the Bass 

 Rock has since been shaped. 



The foregoing somewhat-lengthy digression was needed for 

 the purpose of preparing the way for an account of the 

 remainder of the history of the district under notice. This 

 history will, therefore, now be resumed : — 



The oldest rocks of Lower Carboniferous age seen near 

 Canty Bay are of sedimentary origin, and belong, as mentioned 

 before, to the Oil Shale Series. They are mainly sandstones, 

 which were evidently formed in the shallow waters of a deltaic 

 area. They show here and there sun-cracked surfaces, which 

 tell us plainly enough that they were formed quite close to 

 the surface. A remarkable feature connected with them is 

 the presence of great numbers of small faults or dislocations 

 of the strata, which, on closer examination, are seen to have 

 been formed contemporaneously, like the faults which traverse 

 the cleaved tuffs of Ordovician age at Tilberthwaite, near 

 Ambleside. Along with these faults, which can be well seen 

 close to the old inn on the shore at Canty Bay, there are 

 also many curious examples of contemporaneous contortions 

 of the strata. These contemporaneous contortions, it may be 

 remarked, form a very characteristic feature of the sandstones 

 of the Oil Shale Series in both Fife and the Lothians. I 

 have long regarded these as due to the effects of the earth- 

 quake shocks which heralded the incoming of the volcanic 

 conditions, and which affected so large an area of the midlands 

 of Scotland about this time. 



