778 BEPOKT — 1893. 



9. On some Shelly Clay and Gravel in North-east Aberdeenshire. 

 By DuGALD Bell, F.G.S. 



This paper referred chiefly to a remarkable deposit of red clay, containing frag- 

 ments of marine shells, ■which Mr. Jamieson, of Ellon, had described some years 

 ago as occurring on the eastern border of Aberdeenshire, from sea-level up to about 

 300 feet.^ This clay seems to be derived, not from the rocks of the district, 

 but from rocks farther south, viz., in the Old Red Sandstone of Kincardine and 

 Forfarshire. In short, land-ice from the southward appears to have come along 

 the coast, bringing vs^ith it this red clay and other debris from the Old Red forma- 

 tion ; and this conclusion is confirmed by the strife on the projecting points along 

 the coast. 



The cause of this remarkable movement of the ice was, of course, the ice- 

 blocked condition of the North Sea, as suggested by the late Dr. Croll in connec- 

 tion -with Messrs. Peach and Home's admirable paper on the boulder clay of 

 Caithness. 



But the difficulty with regard to this ' fine red mud ' is that it seems to imply 

 ' deep or at least quiet veater ' for its deposition. There is no evidence at tlie 

 bottom of it of littoral moUusca, or of beach- sand and gravel between it and the 

 underlying grey boulder clay of the district, so that 'it looks as if still water of 

 some depth had at once taken the place of the glacier.' 



This Mr. Jamieson accounts ibr by supposing that ' the ice did not break up till 

 a considerable amount of submergence had occurred,' that deep-sea water at once 

 took the place of the glacier, and received from it the red mud with fragments of 

 shells taken up by it from some part of the sea-bed over which it had passed ; and 

 that these settled down immediately on the surface of the grey boulder clay ; and 

 this process he imagines to have begun at the extremity of the northward- 

 moving glacier, in the neighbourhood of Peterhead, and to have crept southward 

 along the coast as the ice gi'adually broke up. 



To this there appear several weighty objections; but the one to be specially 

 urged at present is this : — It was the ice-blocked condition of the North Sea that 

 compelled the ice from the Old Red district to move northward along the coast 

 from Stonehaven to Peterhead. As soon as this gave way the ice would un- 

 doubtedly pass on eastward out to sea. Where would it most likely give way 

 first^ — if not to the south ? So that before — probably long before — it was open sea 

 at Peterhead, it would be more free and open at Stonehaven. What, then, could 

 make the ice go northward, hugging the coast to Peterhead? The dominating 

 factor in the case was the ice-blocked condition of the North Sea. While this 

 continued, there could not be the deep still water there to receive the clay ; when 

 this ceased, there could not be the northward-movLng glacier to bring the clay. 



There seems to be but one way out of this dilemma. If deep and compara- 

 tively still water be required for the deposition of the clay, is it necessary to have 

 recourse to a ' great submergence ' in order to obtain it ? Must it be sea-water f 

 May it not have been accumulations of fresh-water caused by the ice passing across 

 the transverse valleys and hollows, and so forming lakes along its margin wherein 

 such sediments would accumulate ? Mr. Jamieson has in the kindest and most 

 candid way expressed his acceptance of this modification of his theory. 



This is exactly parallel to what has lately been made out by Mr. Lamplugh in 

 the neighbourhood of Flamborough Head ; - and it is confirmed by the sagacious 

 inference of the late Dr. Fleming, who, some fifty years ago, without knowing how 

 such lakes could be formed, surmised that the clay had been deposited 'in some 

 immense lake into which the sea only made a temporary irruption.' The author 

 concluded by suggesting that this explanation might yet be found applicable to 

 other localities, which had recently been the subject of investigation. 



" Quar. Jour. Geol. Soc, vol. xxxviii. p. 160. 

 * Ibid., vol. xlvii. p. 428. 



