32 MR. T. F. JAMESON ON THE [Feb. 1 906, 



probably date from near the close of the Glacial Period. At all 

 events, they must be of later age (I should think) than the mollusca, 

 the remains of which are got in the silt at Clava, to be mentioned 

 in the sequel (pp. 33-34). 



XIV. Period oe Submergence — Shell-Beds. 



We find that during a certain stage of the Glacial Period there 

 was a marked retreat of the ice, and that water occupied the 

 coastal district eastward from Inverness. In my paper on the Ped 

 Clay of Aberdeenshire, I adduced evidence to show that, from 

 the mode of its deposition and the altitude to which it extends, 

 the submergence in the district where that clay occurs must have 

 exceeded 300 feet. As much of the country stretching round the 

 corner of Aberdeenshire to the Moray Firth lies below this level, 

 a submergence of that amount would extend into both districts. 



The question now arises, What was the nature of that sub- 

 mergence ? Was it caused by a depression of the coast below the 

 sea, or was the district covered merely by a sheet of fresh water 

 enclosed between the ice and the land ? In the Ped Clay itself, 

 although we occasionally find a few scanty remains of sea-shells, 

 these on the whole are rare, and generally more or less broken. 

 No bed of them has been found in place. At Annochie, however, 

 on the coast a little to the south of Rattray Head, where a tile- 

 work formerly existed, there is a bed of fine dark- blue silt, passing 

 underneath the beach and extending some distance inland, in which 

 I found Arctic shells having all the appearance of being em- 

 bedded in their native mud. Although the position is close to the 

 present level of the sea, the assemblage of species is decidedly a 

 deep-water one, and indicates a very considerable amount of 

 submergence. The prevailing forms were Nucula tenuis and Leda 

 pygmcea, both occurring in a perfect state, with the olive- coloured 

 epidermis quite unruffled. There were also specimens of the large 

 Arctic form of Saxicava arctica, a Cylichna which appears to be the 

 G. alba of Brown, likewise the little Bulla turrita of Holler (other- 

 wise known as Utriculus jpertenuis of Gould, var. turritus), and one 

 or two small shells belonging to the genus Axinus (otherwise termed 

 Lucina or Cryptodon). One of these seemed to be A. ferruginosus. 

 Another was thought by the late Dr. Torell to be the Axinus 

 Sarsii of Philippi. All these species are Arctic, and go down into 

 very deep water, as will be seen from the following table giving the 

 range of depth according to G. 0. Sars, in his ' Mollusca Eegionis 

 .Arcticse Norvegiae' Christiania, 1878: — 



Fathoms. 



Nvcula tenuis 20 to 300 



Leda pygmcea 20 ., 650 



Saxico.va arctica ,, 300 



Cylichna alba 10 „ 300 



Bulla turrita 10 ,, 60 



Axinus ferruginosus 40 „ 300 



Axinus Sarsii 60 ,, 300 



Also a large specimen of Cornuspira foliacea and other foraminifera. 



