24 ME. T. F. JAMIES0N OK THE [Feb. 1 906, 



V T I. The Chalk-Flints of Aberdeenshiee. 



In regard to the beds of Chalk-flints which occur in Aberdeenshire, 

 when I first saw them, more than forty years ago, I fancied that 

 the}' might have been derived from a bed of Chalk that had formerly 

 existed in the district. They are highly waterworn, and always 

 accompanied by a quantity of quartz-pebbles which are likewise 

 intensely waterworn. These I supposed might have been derived 

 from the quartz-rocks that occur in the district. The flints and 

 quartz-pebbles, however, extend for many miles along the top of a 

 ridge of granite ; and there I remarked that the granitic debris had 

 none of this water-rolled character. The staurolite- and mica-schists 

 (which form another part of the range of heights on w 7 hich the 

 flints lie) also show a similar absence of water-rolling. This 

 feature, in short, is confined to the flints and the quartz-pebbles 

 associated with them. It would, therefore, seem that both have 

 been transported from a distance in company, and that the water- 

 worn features had been impressed upon them before they were 

 brought to the district where they now lie. 



They do not occur on any part of the large spreading hill of 

 Mormon d in the northern extremity of Aberdeenshire, so far as 

 my observation goes ; but are mostly confined to a narrow belt of 

 country running in a general east-and-west direction to the coast 

 at Buchan Ness, a little to the south of the town of Peterhead. 

 More than one phase of the Glacial Period has occurred since the 

 flints were brought to Aberdeenshire, for this took place before 

 the epoch of the Red Clay. They have accordingly been swept 

 away, and re-arranged in many places by later developments of the 

 ice and other denuding agents. 



VII. Explanation of the Absence of Shell-Beds 

 in the Bed Clay. 



The general absence of marine fossils in the lied Clay of 

 Aberdeenshire may, perhaps, be accounted for in the following way. 

 During the preceding stage of the Glacial Period, when the subjacent 

 Boulder-Clay was laid down, the Scandinavian ice (as James Croll 

 first pointed out) appears to have occupied the shallow bed of the 

 North Sea and coalesced with the Scottish ice, so that the sea-water 

 was excluded from all the East Coast of Scotland, and nothing but 

 ice prevailed. Now, when the thaw began to set in, the thinner ice 

 which lay over the eastern and northern parts of Aberdeenshire 

 would no doubt melt first, and the water which took its place 

 would be fresh or brackish, so long as free communication with the 

 ocean was shut off by the Scandinavian Glacier. No migration 

 of marine life into it would therefore be possible, until the latter 

 glacier began to recede. It might have been a considerable time 

 before that took place; consequently, the Bed Clay would be deposited 

 in a sheet of water hemmed in by the ice, and it would only be at a 

 later stage that any marine forms of life would be able to gain 

 admittance. This later stage is probably represented by the clay- 



