404 Proceedings of Royal Society of Edinburgh. [sess. 
geologically speaking, it is of recent origin, being built up of very 
light and friable soil — mostly the moraines of those enormous 
glaciers which covered Denmark and the surrounding seas during 
the Ice Age. It is probable that lime strata of different geological 
ages occur nearly everywhere beneath the soil, rising in certain 
places to the surface, and in other places not far below the surface. 
The soil itself is commonly very rich in lime, which is washed out 
by the rivers and carried into the lakes. The rainfall is not great, 
only about 614 mm. (24 inches) per annum; and this, in con- 
junction with the lowness of the country and the friable soil, 
accounts for the fact that the rivers are all small — rarely more 
than about 50 feet in breadth, with level courses (falls being 
quite unknown), and transporting only a small quantity of water. 
The outflow of water from the rivers is greatest in spring after 
sudden thaws, and least in summer (especially in dry seasons) and 
in autumn, increasing considerably in November and December, 
with their abundant rainfall. As an example we may take the 
river Skern in Jutland, which in summer discharges at its outlet 
only about 500 cubic feet per second, while in spring it may dis- 
charge about 7500 cubic feet per second. 
Denmark is now rather deficient in lakes, though at an earlier 
period they must have been more numerous. They are all very 
small, the largest covering an area of only about 40 square kilo- 
metres (about 14 J square miles), while the great majority are much 
smaller. Their depth is inconsiderable, as was to be expected in 
a low and flat country; exceptionally, depths of about 120 feet 
have been recorded, but the majority are only 40 to 60 feet in 
depth, while some of the largest lakes are in fact merely great 
pools, with a maximum depth of only 10 to 12 feet. Denmark is, 
on the whole, a flat country, with no deep depressions, and most of 
the lakes are roundish in outline, long and narrow lakes being rare ; 
formerly the lakes were much more irregular, but owing to the 
silting up of the bays and shallower parts the shore-lines show very 
few sinuosities, though some of the larger lakes are very irregular. 
The renewal of the water in the lakes goes on very slowly. As 
the amount of water carried into the lakes by rivers is always 
greatest in spring and slowly diminishes in summer, it will be 
understood that the level of the lakes is highest in spring and 
