736 REPORT—1899. 
The coal measures contain the usual carboniferous plants—Sigillaria, Lepido- 
dendron, and ferns, and the usual Stigmarian roots and rootlets, and, like those 
which we struck in the borehole at Dover, are probably horizontal. The coal is 
bright and blazing, and breaks up into little cubes, but slightly deformed by 
pressure into the lozenge-shape. In this respect it agrees with the coals of Dover, 
and like them shows no sign of crushing. The horizontality of the beds in both these 
cases may be accounted for by the boreholes happening to strike the bottom of a 
carboniferous synclinal fold. This conclusion, viewed in the light of the coalfields 
of France and Belgium on the one hand, and of Somerset on the other, is more 
probable than the view that they extend horizontally over a very large area. 
It is strengthened by the fact that the rocks, probably Devonian, struck at the 
bottom of the borehole at Brabourne, some few miles to the west, are inclined at 
a high angle. They here are a portion of an anticline which is probably related 
to the coal measures above them, as the Devonian axis of the Mendip Hills is 
related to the syncline of the Somerset coalfield. 
In my opinion the coal measures of Ropersole are a portion of the same series 
as those at Dover. Here, as at Dover, the question of seams of coal resolves 
itself probably into a question of sinking deeper. Here only two unimportant 
seams have been met with in a thickness of 197 feet. There twelve seams were 
penetrated in a thickness of 1,054 feet 6 inches, the thickest 4-feet seam being at 
the bottom. 
The Ropersole boring establishes the fact that the Dover coal measures extend 
northwards for a distance of eight miles and beyond in the direction of Canterbury. 
It remains now to see how far the range of the South-eastern coalfield has been 
proved by other borings. None of the three others which are now being carried 
on by the Kent Coal Exploration Company at Ottinge, Hothfield, and Old Soar 
to the north of Tonbridge has been carried deep enough to give any evidence. 
We are, however, indebted to Mr. Etheridge! for conclusive proof that its 
south-western boundary does not extend as far to the south-west as Brabourne. 
Here a fine-grained grey argillaceous sandstone, in my opinion Devonian, was 
struck in a boring at a depth of 1,921 feet 5 inches from the surface, the strata 
being inclined at a high angle, and being covered by a red dolomitic conglomerate 
of Triassic age, just as similar rocks occur in the central axis of the Mendip Hills. 
‘This boring has verified the exact position of the Pembroke-Mendip anticlinal fold, 
which I mapped in 1894.2. It ranges in a north-west and south-easterly direction 
close under the line of the Chalk downs from Folkestone to Wye, a few miles to 
the north of the theoretical line of my map, and forms the southern boundary of 
the South-eastern coalfield. In Somersetshire it emerges from beneath the 
Triassic and Jurassic strata in the Mendip Hills, and in Northern France along the 
low hills sweeping from Hardinghen past Ferques in the direction of Cape Gris 
Nez, where, as in the Mendip range, it is traversed by many faults. 
The coal measures set in in Kent at a sufficient distance to the north-east of 
Brabourne to allow of the presence of the Carboniferous Limestone and Millstone Grit. 
These probably dip at the same high angle as the Devonian below. Their south- 
western boundary can only be accurately defined by further borings such as that 
which we are now carrying on at Ottinge, about two and a half miles to the north- 
east of the scarp of the Downs, and six miles to the south-west of Ropersole. Their 
range to the north and the east still remains to be proved. They are, however, 
continued under the Channel, and have been proved by the boring at Calais in 
1850 as well as those carried out in 1898 at Strouannes near Wissant. In this 
district they are clearly shown by other borings to be faulted into the Devonian 
and other pre-coal-measure rocks. 
The thickness and value of this South-eastern coalfield can only be estimated 
by the exposed coalfields of Northern Frence and Belgium, and of Somerset. 
That of Liége is 7,600 feet thick and contains eighty-five seams, presenting an 
1 Brit. Assoc. Bristol Meetinz, 1898. 
2 The Probable Range of the Coal Measures in Southern England. Zrans. Federated 
Institution of Mining Engineers, vol, vi. Map. 
