and Greensand Fossils in Aberdeenshire. 435 



concluding that because he finds a rock resting upon gneiss 

 it is therefore low in the geological scale, instances as an ex- 

 ample of the error such a conclusion would lead to, the flints 

 and chalk fossils of Banff and Aberdeen lying immediately 

 over it in these counties, and adds, "it is probable that the 

 denuded members of the cretaceous group once rested upon 

 it there." Prof. Jameson, in the Edinburgh Philosophical 

 Magazine, states the same opinion, adding, that it will pro- 

 bably be found in some of the hollows of this part of Scotland. 



This is one theory, — that the lower beds have been wanting 

 here, and the chalk of this bed has been removed by denuda- 

 tion, leaving the flints resting on the granite. Opposed to 

 this theory is the fact, that the flints are invariably very much 

 water-worn. True, even according to it they would have pre- 

 sented such an appearance, but not necessarily to such an ex- 

 tent ; and it seems that a denuding agency sufficiently power- 

 ful to produce the rolled effect noted would have removed 

 them as well as the other beds, especially as they occur, not 

 in hollows, but almost always on the sides and near the sum- 

 mits of hills. Mr. Nicol states his opinion thus: — " Probably 

 these recent secondary formations once existed here, or may 

 still be covered by the sea, and connected with the similar 

 beds in the Moray Frith. This opinion is confirmed by the 

 occurrence of lias, containing coal, at Hogenaes in the south 

 of Sweden, where it rests on gneiss and is covered by chalk." 

 This leads on to another theory which has been suggested to 

 account for these flints ; viz. that however such secondary beds 

 may have once existed here, these individual water-worn flints 

 owe their origin to a transporting agency which has brought 

 them from the chalk formations of the northern continent. 



The volcanic and tidal agencies (the latter modified by local 

 currents) seem to assume a direction between south-west and 

 north-east. All the mountain ranges and great formations of 

 our island assume in general that direction. The great moun- 

 tain range of Norway assumes the same. I am too unac- 

 quainted with Norwegian geology to be able skilfully to con- 

 nect it with Scottish. At Christiania there is a group belong- 

 ing partly to the lower and partly to the upper Silurian rocks. 

 True chalk with flints has been clearly determined in some 

 parts of Denmark. This Danish group may have been con- 

 tinued into Norway at one period, and afterwards removed by 

 denudation, the same agency transporting the flint nodules to 

 our shores. 



It may bear against such a supposition of transportation, 

 that the direction of the currents seem usually to have been from 

 south-west to north-east, and that for this theory they require 



2F2 



