135 
This is a remarkable circumstance, and before coming to 
a definite conclusion it would be necessary to examine upon the 
ground itself all the existing sections in the Old Red Sandstone 
and other rocks from Blakeney to Lydney. 
The whole of the iron-ore measures proper and the Mill- 
stone Grit series are absent in the Howbeach Valley, and there 
the Pennant rocks belonging to the lower coal measures rest 
immediately upon and are in contact with the Carboniferous 
Limestone. It is, however, curious to note that the direction 
of the strike of the Pennant rocks is about North 30° East, 
and South 30° West, and consequently are conformable to the 
direction of the general measures when not affected by dis- 
placement. There seems to be, therefore, strong evidence that 
the Pennant rocks, Trenchard and Coleford Hill delf seams, 
were deposited long ages after the Millstone Grit and iron-ore 
measures were removed by denudation. 
The horizontal width of the Carboniferous Limestone is 
less from the Howbeach Valley to Wigpool Northwards, than 
it is in any other part of the district; for instance, if we drew 
a line to the West of the Lydbrook Valley, or in a Southern 
direction from Welsh Bicknor, to the coal measures, the lime- 
stone would be found to be spread out from the river Wye for 
a distance of 24 miles, but if taken across the measures, at 
right angles to the dip, the width from Stowes Field to the out- 
croppings of the coal measures would be 1} miles. The nearest 
approach of the river Wye to the coal field, taken in a line 
from Court Field to High Beach, is about 580 yards. Drawing 
a line through Blackthorns to Goodrich Cross, in Herefordshire, 
_ the distance from the coal measures to the river Wye is about 
_ 440 yards, and from the same point in the coal measures to the 
commencement of the Carboniferous Limestone, the distance is 
_ about 225 yards. 
} Taken along the same line the width of the limestone is 
_ about 1,100 yards. 
If we produce a line from Blackthorns to Doward Camp, 
_ the distance from the commencement of the Carboniferous 
_ Limestone is about 320 yards; from this point to the river 
