32 VEGETABLE SUBSTANCES. 



and the cultivated plain, the bottom of the moss was 

 lower than the general level of a sort of ridge that 

 formed the boundary between them. But in this 

 ridge there was one depression, not unaptly called 

 the " Gap;" and through that the flood of moss 

 and water descended. This gap was from 100 to 

 150 feet in width; and there can be no question 

 that the resistance which the fluid met with in it 

 tended to the safety of the people : for had the whole 

 come upon them in a continued sheet, the danger 

 and difficulty of escape would have been much 

 greater. 



Pine is not the only timber found in those bogs, 

 though it be the kind most frequently met with in 

 a mountainous country, more especially of those 

 places where forests of pines are still growing, or 

 which are favourable to their growth. Pines do not 

 thrive in low situations, or by the banks of slow- 

 running rivers. The timber which grows best in 

 those situations (in cold countries) is alder, and it 

 is consequently the timber most generally found in 

 river-side peat; though, in consequence of the 

 warmth, peat is hot very apt to form in such situa- 

 tions. The greater accumulations of it are on higher 

 grounds, and often on the summits of the mountains. 



In some places, which are of intermediate height, 

 there often appears a singular stratification in the 

 bogs, which indicates a succession of changes of 

 climate, all for the worse; and as the junctions of 

 these strata are sometimes pretty well defined, it is 

 difficult to account for them by any regular succes- 

 sion of seasons. We are thence led to conclude, 

 that, after the one species was formed, a pause of 

 some years at least must have taken place before the 

 soil and climate were in a fit state for the production 

 of the others. There may be exceptions; but in so 

 far as our observation has gone, the oak forms in 



