Review of Recent Geological Literature. 195 
upward for the next six or seven feet, to a hight of about twelve feet 
above the base of the stratified clay, including, at the top of this por- 
tion, the layer of till before mentioned, half a foot thick, in which fossils 
are wanting. Thence upward, the first fossils noted are arctic and 
boreal; but at three feet above the thin till deposit the frequent occur- 
rence of Turritella terebra implies a more temperate sea, and this 
species, with others of Astarte and Cardium, denote a depth between 
20 and 75 feet. Similar mild temperature and moderate depth are 
shown for the next six feet vertically. Lastly the temperature of the 
sea became again arctic, and its depth appears to have increased again 
to at least about 130 feet, denoting a vertical submergence of fully 
300 feet. 
Throughout this deposit of stratified clay (excepting its inclosed 
thin layer of till) foraminifera occur plentifully, but with important 
variations in the vertical range of species. Their number in Robert- 
son's list is 83, and in Munthe's list 112, the number common to both 
lists being 59. These, and the ostracoda likewise, afford less informa- 
tion than the mollusca concerning the physical conditions of the sea 
in which the deposition took place; but they seem to present no evi- 
dence of a contradictory character, such as might bring any doubt 
against the conclusions before stated. 
An earlier report by the same committee of the British Associa- 
tion, published in 1893, giving details of their examination of the 
Clava section, is discussed by Dr. Munthe in the last nine pages of his 
paper. This report, and later articles on the same subject by Mr. 
Dugald Bell, a member of the committee, were noticed, with full notes 
of the section, by the present reviewer in the American Geologist for 
January, 1896 (vol. xvii, pp. 45-47), with approval of the minority re- 
port of that committee (by Dugald Bell and Prof. Percy F. Kendall). 
in which the Clava clay and its shells, occurring at the altitude of 487 
to 503 feet above the sea, are supposed to have been supplied from an 
ice-sheet that had eroded preglacial marine beds from the basin of 
Loch Ness (now about 50 feet above the sea and 774 feet deep), de- 
positing the Clava strata in a glacial lakelet held temporarily in a nook 
of the Nairn valley by a barrier of ice which later advanced again, 
forming the overlying till. From this opinion I yet see no suf- 
ficient reason to recede, although Prof. James Geikie. in "The Great 
Ice Age" (third ed., 1894, pp. 139-143, 155), and Dr. Munthe, in this 
paper, strenuously argue for the marine deposition of the fossiliferous 
Clava bed. Perhaps the most noteworthy objection to their view 
which can be drawn from the Clava fossils is the occurrence together 
there, in considerable numbers, of Litorina litorea, a species whose 
habitat is limited to shores and very shallow water, and other species, 
as Leda pernula and Natica gronlandica, which are unknown as shore 
species but live in depths of 20 to 50 fathoms or more. The assemblage 
of fossils at Clava. including 23 species of mollusca, seems to me most 
accordant with their reference to glacial transportation, while the ab- 
sence of marine beds at similar altitudes elsewhere throughout the 
British Isles further enforces the same explanation. 
