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



No chalk ever occurs with these flints, but there is occasionally 

 some whitish earthy matter of a non-calcareous nature, consisting of 

 silicate of alumina, derived no doubt from the weathering and waste 

 of the flint-pebbles. This has sometimes been mistaken for chalk. 



The north-eastern extremity of Aberdeenshire consists of low 

 undulating ground, in the midst of which rises a large lumpy hill 

 called Mormond, 769 feet high, composed of quartz-rock and 

 staurolite-schist. At the western base of this hill is a low tract 

 of coarse-grained grey granite. Blocks of this granite are scattered 

 over the hill and far up it, to a height much exceeding that of the 

 rock in place, while some of the smaller granitic debris is to be 

 found on to the very top. There I also found stones of hard white 

 quartz showing marks of strong glaciation, one of them being 

 ground down to a smooth edge and streaked with fine scratches, 

 showing that the abrasion had been most intense ; but I found no 

 flints on the hill. 



XII. Extent and Depth or the Ice. 1 



All this seems to indicate pretty clearly that the ice had gone 

 over the top of Mormond. From this hill westward to Inverness, 

 at the head of the Moray Firth, is a distance of 80 miles in a 

 straight line. If the glacier extended all the way, and was high 

 enough to pass over the top of Mormond, as it seems to have done,, 

 it would be at least 800 feet thick along the coast opposite that 

 point, and probably more. Then, if we allow an average slope of 

 only half a degree, or 46 feet per mile, along the surface of the ice 

 to Inverness, this would amount to 3680 feet on the 80 miles, 

 to which add 800 feet for the height at Mormond, making 4480 feet 

 for the altitude at the head of the Moray Firth. But the average 

 surface-slope of the Greenland ice, where Nansen crossed it, is a 

 good deal more than this, so that, in all probability, the height at 

 Inverness was greater than I have stated. 



XIII. Southern Border oe the last Ice-Sheet where 

 it crossed the Spey. 



There is some interesting evidence to show at what point the 

 southern edge of this great ice-stream crossed the Spey at the last 

 time of its extension thither. Along that river, above Fochabers, 

 the sandstone-rocks are of a deep red, and the Boulder-Clay derived 

 from them is of the same hue. This red clay has been carried 



1 The ice-sheet which filled the basin of the Moray Firth was at one time so 

 extensive that its right flank flowed round the northern parts of Banff and 

 Aberdeenshire, while its left turned round over Caithness, originating the shelly 

 Boulder-Clay of that quarter. 



[Since this paper was written I have seen an article by Dr. W. Mackie, 

 of Elgin, in Trans. Edin. Geol. Soc. vol. viii (1901) p. 91, on the distribution of 

 erratics over Eastern Moray. It contains man}' interesting observations on 

 the subject. At Ben Binnes and some other places on the east side of the 

 Spey to the south of Bothes, boulders are found which Dr. Mackie believes to 

 have come across the valley from the west during some part of the Grlacial 

 Period, probably by the agency of land-ice. — T. F. J., Nov. 25th, 1905.] 



