382 REVIEWS—GEOLOGICAL EVIDENCES OF MAN’S ANTIQUITY. 
into the other: the glacial manifestations being gradually beaten back, 
as it were, to within their present arctic and alpine boundaries. 
Above the clay, gravel, and boulder deposits accumulated during 
this interval of cold, lie various other beds of clay, loam, sand, and 
gravel, accompanied locally by bog-iron-ores, calcareous tufa, peat, and 
sundry related matters of comparatively modern origin—many of 
these beds, indeed, being still under process of formation. Great 
changes of level have been continually going on during the accumu- 
‘lation of these different materials; and portions of the original sea- 
‘bed have been raised high above the water-line, at varicus localities. 
4Gravel deposits containing marine shells of existing species occur, for 
example, at considerable heights on the coasts of Norway and Sweden, 
in Eastern Canada, Maine, and numerous other places. On the south 
coast of the Island of Sardinia, an ancient sea-bed, containing shells 
of the modern oyster and mussel, with fragments of pottery and other 
wrought objects, occurs at a height of between two and three hun- 
dred feet above the present sea-level. These deposits in many places, 
‘moreover, exhibit in themselves a thickness of over a hundred or even 
two hundred feet. It is evident, therefore, that although recent in 
geological sense, many ages must have rolled away since the com- 
mencement of their accumulation. Sir Charles Lyell, in the work 
before us, basing his calculation on the known rate of uprise of the 
Scandinavian coast, computes a period of at least 12,000 years for the 
elevation alone of the Sardinian sea-beach ; and the unknown interval 
before the commencement of the upward movement, and that which 
has elapsed since its close, must be added to this, in attempting to fix 
the date of the imbedded pottery. Based on a similar calculation, 
the shell-beds of the Norwegian coast are assumed to have occupied 
in their upward passage from their original place of deposition, an 
interval of no less than 24,000 years. And yet these are amongst the 
latest geological records of the Earth’s history: even subsequent in 
some instances, as proved by the Sardinian pottery, to the actual ap- 
pearance of Man. : ’ 
The shells of marine and fresh-water mollusca, enclosed in these 
recent geological deposits, belong, as already stated, to existing species, 
although some are no longer met with in the localities at which the 
deposits in question occur. The mammalian remains preserved in 
these accumulations are likewise referrible in great part to existing 
forms; but some are altogether extinct. The more remarkable of the 
latter, in the eastern continent, comprise: the mammoth and some 
