22 MR. T. P. JAM1ES0N ON THE [Feb. I906, 



than the Chalky Boulder-Clay of that region. In the Ellon 

 district of Aberdeenshire the regular succession, beginning at the 

 surface, is — (1) Upper Boulder-Clay and gravel ; (2) the Bed-Clay 

 Series, consisting of clay, sand, and gravel ; and (3) grey Boulder- 

 Clay, which usually rests upon the old rocks of the district, and 

 seems to have been lodged by a sheet of ice coming from about 

 west-north-west. 



Recently, however, I have found remains of a still older Boulder- 

 Clay of a very distinct character. These instances occurred near 

 Ellon railway-station, between the line of railway and a low rocky 

 eminence called the Craigs of Auchterellon. This eminence 

 consists of a mass of gneiss jutting out across the valley on the 

 north side of the Ythan, and rising to a height of nearly 100 feet 

 above that stream. Some wells have been sunk at the east side of 

 these rocks, and it was in digging them that this older clay was 

 discovered. After getting through the Bed Clay and the underlying 

 grey Boulder-Clay, a mass of very dark indigo-coloured clay was 

 reached, of a finer quality, with fewer and smaller stones ; but 

 what was most remarkable, was the circumstance that it contained 

 small fragments of sea-shells, generally mere crumbs, but some few 

 of them in such condition as enabled me to recognize Cyprina 

 islandica, Astarte arctica, and a bit of a Balanus. Moreover, some of 

 them showed clear marks of glacial rubbing, like those met with in 

 the Caithness Drift. Now, the grey Boulder-Clay here has never 

 yielded any trace of shells or other organisms. It has always 

 proved barren, with no remains of animal or vegetable life. This 

 dark blackish clay is, therefore, evidently a distinct and older 

 deposit, and its occurrence in this particular spot has no doubt been 

 due to its lying on the east and lee side of the rocky eminence, 

 which sheltered it from the demolishing action of the ice-stream 

 that lodged the grey Boulder-Clay, whose flow was here from west 

 to east. 



Many other wells have been sunk at Ellon, but it is only in those 

 close to the east side of the Craigs that this older black clay has 

 been found ; and it is thickest in those wells which are nearest to 

 the east side of the rocks. 



It is also the case that the Bed Clay is thickest and best preserved 

 on the east side of similar eminences, and for the very same reason : 

 these having sheltered it, to some extent, from the denuding action 

 of the later ice-sheet, which lodged the Upper Boulder-Clay and 

 gravel. In the well nearest the Craigs the black clay was 20 feet 

 thick, and then the bottom was not reached. In another, a little 

 farther off, about the same thickness was got, but here the bottom 

 was apparently touched. It was covered by 20 feet of the grey 

 Boulder-Clay, above which came 6 feet of waxy Red Clay, and 

 6 inches of arable soil at the surface. In both wells the black 

 clay contained remains of shells, and was of similar character. 



The discovery of this old dark Boulder-Clay, so distinct in its 

 features, and lying below the grey (which is the bed usually found 

 next the rock in this quarter), brought to my recollection the fact 



