38 MR. T. F. JAMIESON ON THE [Feb. I906, 



coast seems to have been formed under conditions very similar to 

 those under which the Eed Clay of Aberdeenshire was laid down. 

 It also ranges up to a similar or even greater height, being found 

 occasionally at fully 300 feet above the present sea-level. Like the 

 Eed Clay, it often passes into, or is interlaminated with, beds of 

 fine sand. 



Seeing that this dark -blue clay mingles with the red in the 

 district where they meet, near Peterhead, there is every reason to 

 believe that both belong to the same stage of the Glacial Period. 

 Both have evidently been deposited under water, at least the finer- 

 grained stoneless varieties. Both have undergone much denudation, 

 and are frequently covered by coarser material containing ice- 

 scratched stones. The dark-blue clay is the repository of the 

 Jurassic debris, which seems to have been derived from the waste of 

 strata in the Moray- Firth basin ; while the Eed Clay of Aberdeen- 

 shire is the repository of material from the Old Eed Sandstone of 

 Kincardine and Forfar, with its associated volcanic beds. It is in the 

 Eed Clay that we also find the curious debris of Crag-shells and yellow 

 Secondary limestone, the source of which is difficult to conjecture. 



The water under which these clay-beds were deposited must 

 have extended all round the coast from Aberdeen by Peterhead, 

 Fraserburgh, and Banff, to the Moray Firth, seeing that they can 

 be traced along the whole of that distance to near Inverness. If 

 their deposition followed close upon the decay of the preceding 

 cover of land-ice, we may suppose that they would form first 

 where the ice was thinnest, and where consequently it would 

 melt away soonest. This would probably be at the angle of the 

 coast near Fraserburgh, while latest of all would be the clay-beds 

 near Inverness (such as that at Clava), and those to the south of 

 Aberdeen where the Eed Clay came from. 



The remains of the shell-beds at Clava and Ardersier show that, 

 at the time of their deposition, the sea-water must have occupied 

 the head of the Moray Firth; and when such was the case, deposits 

 of marine silt must have been formed all along its shores. What 

 has become of them all? No other instances are known along the 

 head of the Firth, except the two that I have mentioned ; and it 

 was by a mere lucky accident that the Clava one was discovered, 

 Mr. Fraser having heard from some farmers that shells had been 

 noticed in a clay-pit there, which led him to make a search. The 

 recurrence of intense Glacial conditions, which is proved by the 

 heavy bed of Boulder-Clay covering the shelly silt at Clava, affords 

 an explanation of the destruction that has overtaken these marine 

 beds. Although no other instances of their occurrence are known 

 between Inverness and the mouth of the Spey, yet farther eastward, 

 between Cullen and Fraserburgh, remains of Arctic, shells are not 

 so extremely rare. Now, this harmonizes with the belief that it was 

 the recurrence of Glacial conditions which caused the destruction, 

 for the ice would be heaviest and most destructive at the head of 

 the Firth whence the flow proceeded. 



The preservation of the mass of stratified sand and silt at Gamrie, 



