184 
THE AGE OF THE WYE. 
softenings is a Terj much slower process than it is in ‘ the case of 
an exposed Yertical wall or cliff, because there is no washing 
away of the loosened particles, and these must form a con- 
siderable protection against atmospheric influences, increasing 
rapidly with the depth. Taking, in fact, the rate of first wear 
from the old Market-house, and assuming that the “ surface 
softening ” has now penetrated to 20 feet, I find from calculation 
that the penetration varies as the square root of the cube of the 
time. 
There is, however, one bed of the old red which is a perfect 
weather stone. This is a very strong bed 18 or 20 feet thick, 
which is to be found towards the upper parts of the higher hills 
around the northern and western borders of the Forest of Dean 
— it lies about 320 feet below the bottom of the mountain 
limestone—it is mostly in the form of a conglomerate, but there 
are places where it is a fine-grained sandstone, and in all cases 
a perfect weather stone. This great bed is seen cropping out on 
the north-western faces of most of the hills surrounding the 
Forest of Dean, such as Penyard, Howl, Bishop’s Wood, Great 
and Little Doward, and at Staunton, where it forms the ridge or 
summit of the Buckstone Hill (one of the highest in the Forest 
of Dean), the old Buckstone, or rocking-stone, itself being a piece 
of it, about 80 tons in weight, which had fallen away from the 
cliff and bedded itself some 20 or 30 feet below, frowning over 
the hill side. 
The rocking-stone is, no doubt, where' it was placed by 
nature; but it has evidently been artificially undercut to a 
knife edge, and with wonderful skill, if we fully consider the 
.difficulty and the delicacy of the operation, with the mechanical 
appliances then known. Think of the enormous weight of the 
stone, its great size and its awkward bulk. It is about 18 feet 
long, 14 feet wide, and 5 to 6 feet thick, besides the pyramid 
