214 The Scottish Naturalist. 



give place to sand. No continuous section of the deposits is 

 visible ; but the finer-grained portions appear to be more or less 

 well-bedded. The coarser gravel and shingle, however, show no 

 distinct bedded arrangement. Although I searched every ex- 

 posure for organic remains I could not find any. The deposits 

 appear to be quite unfossiliferous. Are we justified, therefore, in 

 supposing that this terrace is an old sea-beach? Surely if marine 

 organisms lived off the Forfarshire coast at the time these deposits 

 were being accumulated, some trace of them should now be met 

 with. The post-glacial raised.beaches all contain such relics in 

 greater or less abundance, and why, therefore, should this older or 

 late glacial terrace be apparently as destitute of them as any 

 fluviatile accumulation? Here, then, is a problem for local geolo- 

 gists to solve. It has greatly puzzled me, and I have no explana- 

 tion to offer, that carries complete conviction to myself. Possibly 

 the absence of marine relics is more apparent than real; and 

 some lucky observer may yet succeed in detecting fossils. One 

 explanation of the phenomena however, has occurred to me, and 

 I throw it out now, for the consideration of my geological friends 

 of the Dundee Naturalists' Society. It is obvious that the terrace 

 marks an old water-level and that it belongs to the close of the Ice- 

 age. If it be of marine origin, then it is likewise obvious that 

 before it could have been formed the great Scoto-Scandinavian ice- 

 sheet that occupied the basin of the North Sea must already have dis- 

 appeared. But, as I have said, the terrace contains no evidence of 

 such marine conditions. Now is it not possible that the deposits in 

 question may have been laid down before the ice-sheet had 

 entirely melted away? If we suppose the surface of the ice-sheet 

 to have been gradually lowered by ablation it is obvious that the 

 land would be the first to reappear, for the ice which covered it 

 would not be so thick as that which occupied the basin of the 

 North Sea. There probably was a time, then, towards the close 

 of the last Ice-age when the lowgrounds of Scotland were denuded 

 of their glacial covering, while the ice-sheet, greatly reduced in 

 thickness, continued to occupy the depression of the North Sea. 

 At that time permanent snowfields would still cover our mountains 

 and hills ; and great glaciers would still flow down our valleys to 

 join the attenuated Scoto-Scandinavian ice-sheet. The enormous 

 accumulations of shingle and gravel, belonging to the period of 

 retreat of the icefields, show that notwithstanding the severity of 



