184 
ELEMENTS OF GEOLOGY. 
Connection of the Predominance of Lakes with Glacial Ac¬ 
tion. —It was first pointed out by Professor Ramsay in 1862, 
that lakes are exceedingly numerous in those countries where 
erratics, striated blocks, and other signs of ice-action abound; 
and that they are comparatively rare in tropical and sub¬ 
tropical regions. Generally in countries w’here the winter 
cold is intense, such as Canada, Scandinavia, and Finland, 
even the plains and lowlands are thickly strewn with innu¬ 
merable ponds and small lakes, together with some others 
of a larger size; while in more temperate regions, such as 
Great Britain, Central and Southern Europe, the United 
States, and New Zealand, lake districts occur in all such 
mountainous tracts as can be proved to have been glaciated 
in times comparatively modern or since the geographical 
configuration of the surface bore a considerable resemblance 
to that now prevailing. In the same countries, beyond the 
glaciated regions, lakes abruptly cease, and in warmer and 
tropical countries are either entirely absent, or consist, as 
in equatorial Africa, of large sheets of water unaccom¬ 
panied so far as we yet know by numerous smaller ponds 
and tarns. 
The southern limits of the lake districts of the Northern 
Hemisphere are found at about 40° N. latitude on the Amer¬ 
ican continent, and about 50° in Europe, or where the Alps 
intervene four degrees farther south. A large proportion of 
the smaller lakes are dammed up by barriers of unstratified 
drift, having the exact character of the moraines of glaciers, 
and are termed by geologists morainic,” but some of them 
are true rock-basins, and W’ould hold water even if all the 
loose drift now resting on their margins were removed. 
In a paper read before the Geological Society of London in 
1862, Professor Ramsay maintained that the first formation 
of most existing lakes took place during the glacial epoch, 
and was due, not to elevation or subsidence, but to actual 
erosion of their basins by glaciers. M. Mortillet in the same 
year advanced the theory that after the Alpine lake-basins 
had been filled up with loose fluviatile deposits, they were 
re-excavated by the great glaciers which passed down the 
valleys at the time of the greatest cold, a doctrine which 
would attribute to moving ice almost as great a capacity of 
erosion as that which assumed that the original basins were 
scooped out of solid rock by glaciers. It is impossible to 
deny that the mere geographical distribution of lakes points 
to the intimate connection of their origin with the abun¬ 
dance of ice during a former excess of cold, but how far the 
erosive action of moving ice has been the sole or even the 
