The Origin of our British Flora 
have been living in the sixth glacial stage, and to have 
known nothing whatever about it! 
But unfortunately for this explanation, the land is sup- 
posed to have been 25 to 30 feet lower during the sixth 
glacial stage, and if this is the case the Roman wall 
should show that it was not intended to reach as far as 
the modern sea-beach, but only to about 25 or 30 feet 
above that level. Here, then, is a little antiquarian point 
which turns out to be of great scientific importance ! 
Otherwise it is very difficult to understand why the 
traditional Scotch forest has utterly vanished and left no 
trace whatever in the uppermost or recent peat. But 
there has not been yet, by any means, sufficiently exten- 
sive researches to be sure if this is the case or not. 
On the Continent there are some authors who have 
traced the effect on the plant world of quite similar 
fluctuations of climate in the later stages of the Ice 
Age. What corresponds to Geikie’s sixth Ice Age is, for 
instance, earnestly required by Schulz. 
The North German heath, a “ mantle of coarse sack- 
cloth with a border of silk,” which occupies an enormous 
area of North Germany, is supposed by Graebner to have 
been once a Scotch pine forest. He, however, does not 
think apparently that it was destroyed by man, but by 
some Climatic change or the impoverishment of the soil.” 
But in Switzerland and central Germany it is supposed 
that the destruction of the forests by mankind took place 
between 400 A.D. and 1200 A.D., which is just the period 
during which our Scotch traditional forests were de- 
stroyed. The reader will see how much has yet to be 
discovered before it is possible to bring tradition and 
antiquarian discoveries into line with modern geological 
and botanical research, 
But leaving these interesting little details, it is clear 
that, as regards our general British flora, it may be con- 
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