474 MR. 1). BELL ON THE 8HELLY CLAYS [Aug. 1895, 



granite ; but ' looks more like what we should expect to find in a 

 district of Old Eed Sandstone, being of a decided brick-red colour, 

 exactly resembling the clay we find in the Eed Sandstone district 

 of Kincardine and Forfar.' 1 It also contains large round pebbles 

 of grey quartz with a smooth reddish exterior, such as are met 

 with in the Old Eed conglomerate of Kincardineshire. Moreover, 

 it contains many stones of a volcanic nature, unlike the rocks 

 of Aberdeenshire or the North of Scotland, but resembling the 

 masses of trap which occur in the Old Eed district of Forfar and 

 Kincardine. 



Other evidence exists, in the transport of local rocks, to show 

 that there has been a movement of the ice from the south ; and the 

 striae on some points along the coast, showing first an older set from 

 the W.S.W., or interior of the country, and then a newer set nearly 

 from the S., or parallel to the line of coast, together with the ' hard 

 and tough ' appearance of the clay itself in some parts, convinced 

 Mr. Jamieson that the agent was land-ice, which came from the 

 southward ' along the coast, grazing the surface of the rocks at the 

 projecting headlands, and bringing with it the red clay and debris 

 of the Sandstone formation.' 2 



The reason of this northward movement of the ice along the 

 coast was, as Mr. Jamieson also points out, the ice-blocked con- 

 dition of the North Sea, as demonstrated by Dr. Croll some five-and- 

 twenty years ago, 3 ' so that the Scottish ice would be unable to move 

 out to the eastward, and be compelled to turn along the coast in 

 the direction it seems to have actually taken.' 



The conclusions of the Geological Survey on these points agree 

 generally with those of Mr. Jamieson, though in one or two rather 

 important respects they differ. They agree in regard to the general 

 succession being (1) the grejr or lower Boulder Clay, (2) the inter- 

 mediate sands and gravels, and (3) the upper or Eed Boulder Clay. 

 They agree also in supposing a first or local glaciation for the grey 

 or lower Boulder Clay, and a later movement of the ice-sheet from 

 the south when the upper Eed Clay was deposited. With regard to 

 the latter the Surveyors say that it ' can be traced along the coast 

 as far south as Stonehaven, and there is little doubt that the 

 materials of which it is composed were brought from that quarter.' 

 Again, they refer to ' the ice-sheet that passed to the north and 

 left behind it the upper Boulder Clay.' 4 But they differ in that 

 the Surveyors pronounce the intermediate sands and gravels to be 

 interglacial, and to have been accompanied by a submergence of 

 360 or probably of 500 feet. The grounds on which this pro- 

 nouncement rests are not very apparent. We are told that while 

 these sands and gravels ' strongly resemble moraine-stuff,' they 

 have been ' washed and rolled,' and contain ' marine shell-frag- 



1 Quart. Journ. Geol. Soc. vol. xxxviii. (1882) pp. 160, 162. 



8 Ibid. pp. 165-66. 



3 Geol. Mag. 1870 ; also ' Climate and Time,' 1875. 



* Mem. Geol. Surv. Scotl. 1886, Expl. Sheet 87, pp. 23, 24. 



