296 Peat Bogs. (July, 
mean high-water mark: these bogs are found to contain the 
roots and trunks of oak, yew, deal, hazel, sallow, and a 
timber like ash, also hazel nuts. In the south and west of 
Ireland lowland bogs are numerous, and it is a common oc- 
currence to find—off a coast where bogs now form the sea 
margin—peat from 8 to 12 feet deep, even at low water of 
spring tides, giving a depth below mean high-water mark of 
from 23 to 25 feet. In these bogs the roots and trunks of 
oak, yew, deal, willow, and hazel are found, similar to the 
tree remains that occur in the inland bogs. Off the south- 
east coast of England there are also submarine bogs; those 
in Romney Marsh and Pevensey Level being at nearly simi- 
lar depths below the mean high-water mark. It has been 
suggested that the peat accumulations found in lagoons, 
estuaries, and even on the open coast, may have grown at 
their present levels, the sea being kept out from them by a 
barrier of sand, gravel, or the like, which was subsequently 
swept away or moved inland. If, however, we consider a 
moment, the erroneousness of such an idea is apparent. 
Take, for instance, such places as Romney Marsh in Eng- 
land, or Wexford Estuary in Ireland, where we find the 
roots of oak 1 situ more than 15 feet below the mean low- 
water mark. These trees, at the time they were growing, 
would have been liable at any time to have been inundated, 
while even at low water of spring tides they would have had 
no drainage. Such trees as the willow and alder might pos- 
sibly grow under these conditions; but such trees as the 
oak, yew, fir, ash, and hazel require a drainage from the 
ground on which they grow; these, then, never could grow 
and arrive at maturity on ground below low-water mark. 
Such bogs, therefore, as those in which the remains of the 
last-mentioned trees are found, must have been while the — 
trees were growing above high-water mark. Moreover, the 
process of subsidence would seem to have been gradual, to 
allow the peat-forming plants time to grow and decay in oft- 
repeated succession. 
The plant-remains in the submarine peat are, as a general 
rule, similar to those found in the subaérial lowland or ‘‘ red 
bogs,” and we may reasonably conclude that the peat accu- 
mulated under very similar conditions,—that is, as a “red 
bog,” and not in a lagoon or marsh. It also must have 
taken a very long time to accumulate, as peat when drained 
will contract more than half its height, while if weighted 
and compressed—as the peat under estuary mud—it would 
be reduced a third or fourth more, so that the 5 feet of peat 
under the muds of Wexford Estuary would represent a 
growing bog of from 15 to 20 feet in depth. 
