170 
ELEMENTS OE GEOLOGY. 
In the year 1821, M. Venetz first announced his opinion 
that the Alpine glaciers must formerly have extended far 
beyond their present limits, and the proofs appealed to by 
him in confirmation of this doctrine were acknowledged by 
all subsequent observers, and greatly strengthened by new 
observations and arguments. M. Charpentier supposed that 
when the glaciers extended continuously from the Alps to 
the Jura, the former mountains were 2000 or 3000 feet high¬ 
er than at present. Other writers, on the contrary, conjec¬ 
tured that the whole country had been submerged, and the 
moraines and erratic blocks transported on floating icebergs ; 
but a careful study of the distribution of the travelled mass¬ 
es, and the total absence of marine shells from the old gla¬ 
cial drift of Switzerland, have entirely disproved this last 
hypothesis. In addition to the many evidences of the ac¬ 
tion of ice in the northern parts of Europe which we have 
already mentioned, there occur here and there in some of 
these countries, what are wanting in Switzerland, deposits 
of marine fossil shells, which exhibit so arctic a character 
that they must have led the geologist to infer the former 
prevalence of a much colder climate, even had he not en¬ 
countered so many accompanying signs of ice-action. The 
same marine shells demonstrate the submergence of large 
areas in Scandinavia and the British Isles, during the gla¬ 
cial cold. 
A characteristic feature of the deposits under considera¬ 
tion in all these countries is the occurrence of large erratic 
blocks, and sometimes of moraine matter, in situations re¬ 
mote from lofty mountains, and separated from the nearest 
points where the parent rocks appear at the surface by 
great intervening valleys, or arms of the sea. We also oft¬ 
en observe striae and furrows, as in N^orway, Sweden, and 
Scotland, which deviate from the direction which they ought 
to follow if they had been connected with the present line 
of drainage, anfl^ they, therefore, imply the prevalence of a 
very distinct condition of things at the time when the cold 
was most intense. The actual state of North Greenland 
seems to afford the best explanation of such abnormal gla¬ 
cial markings. 
Greenland Continental Ice. — Greenland is a vast unex¬ 
plored continent, buried under one continuous and colossal 
mass of ice that is always moving seaward, a very small 
part of it in an easterly direction, and all the rest westward, 
or towards Baffin’s Bay. All the minor ridges and valleys 
are levelled and concealed under a general covering of snow, 
but here and there some steep mountains protrude abruptly 
