164 H. MØLHOLM HANSEN 
but without a simullaneous change of the environment in the same 
direction. As a matter of fact the result is that “the tin burns” 
after cold winters and in hot summers, which is due to the fact 
that in the winter the plants miss the protection afforded by the 
jadar soil, and in the summer its moisture. 
Even if a transformation of mo to tün is not as profitable as 
the transformation of myri to tün, it must, however, on the whole 
be an advantage to farming. It is, however, questionable whether 
this is the right way of cultivating the mo. The investigations 
described in the present treatise have shown that water is the means 
of protection for southern plants on moist soil, while snow protects 
southern plants on the drier soils. Hence if a cultivation of the 
mo equally effective to that of the myri is desired, it should tend 
to utilise our knowledge of the importance of the snow-covering 
rather than aiming at the continued transformation into tun. 
The importance of the snow-covering for the southern plants, 
and hence for the plants valuable to farmers, has long since been 
very thoroughly brought home to all parties concerned. 
When the first Icelanders came to the island, c. 874 A. D., the 
country was covered with woods “milli fjalls ok fjäru”. This how- 
ever, is probably an exaggerated statement, says Thoroddsen, 
“but it is quite certain that the lowlands and valleys must have 
been more abundantly clothed with copse wood then than now, 
even if it must be assumed that large stretches of sandar, myrar, 
and lava fields were also then devoid of woods.” Thoroddsen sup- 
poses, however, that when Iceland was first settled, the woods ex- 
tended to an altitude of 600 m above sea-level, and that, at the 
beginning of the 10th century, they covered an area of 4—5000sq. km. 
In 1911 the total wooded area had been reduced to 454 sq. km. 
According to Helgi Jönsson (1900 p. 76), this great reduction 
has been caused by “reckless exploitation”. But by destroying the 
trees, the constant snow-covering which was dependent on the pre- 
sence of wood was also destroyed and, simultaneously, the luxuriant 
forest undergrowth which was again dependent on the snow-covering, 
and which formed, entirely or partially, the food of the farm ani- 
mals. The great decline in old Icelandic culture, which numerically 
resulted in the population being reduced to half its former number, 
must no doubt be directly referred to the destruction of the woods. 
The correlation between these two factors has been outlined above. 
