1874. | Peat Bogs. 305 
dated ; subsequently the fir trees grew upon them, and came 
to maturity. After the growth of the forests the trees would 
attract the rain, and the climate would again become moist, 
when peat-producing plants would flourish, till eventually 
the pines were also destroyed and replaced by bogs. Against 
such a theory it must be allowed that, after the forests were 
destroyed, the climate ought to have again become dry, yet 
there does not appear to have been any material change 
during the last two hundred years, since the destruction of 
the great upland forests in Ireland recorded in the annals. 
In conclusion, we may attempt to make a rough estimate 
of the years that have passed since the beginning of the 
growth of the oak forest. Some of the largest oaks in the 
bogs have been calculated, by their rings, to be more than 
two hundred years old, while fir trees, by similar indications, 
are found to be over one hundred years old. Many bogs are 
a more or less felt-like mass, but in others each year’s growth 
is represented by a layer or lamina, and these lamine in the 
brown turf are usually from fifteen to twenty in number per 
inch, or about two hundred in a foot, while in the black turf 
the average is about four hundred in a foot. From these 
data the age of the oaks under the previously mentioned 
Castleconnell bog may be as follows :— 
Mak forest age . . yl 4 about, 300 yearse 
Five feet black turf, at 400 years ATOOt Lalit. 2OOOU ,s 
‘Time allowed for the change of climate, say 100 ,, 
Meal torest age .. .° . Shela about BOO a5 
‘Twelve feet mown turf, Ai 200 years afoot . 2400 ,, 
5000 
Such an éstimate is evidently very low, as it ignores the 
white turf or clearing,—also the different artificial stoppages 
of the growth of the peat, one considerable stoppage, at least, 
being during the time the road to Goig was being made and 
used: we, however, learn that in this part of Ireland at 
least five thousand years must have elapsed since the oak 
first began to grow. 
