280 
THE DOVER COALFIELD. 
Oct., 1890. 
THE DOVER COALFIELD AND ITS CONNECTIONS. 
BY THE REV. J. M. MELLO, M.A.. F*.G.S., ETC. 
(Concluded from page 174.) 
The central and uppermost part of the Mons basin being 
clearly defined, we might picture to ourselves the underlying 
strata as lying in regularly deposited beds, the outcrops of 
which would form zones parallel to the original shore lines to 
the north and south, but subsequent lateral pressure has much 
disturbed this arrangement, even if it ever existed. The beds 
have been upheaved, so that the beds on the north dip towards 
the south, whilst those on the south dip north, and the whole 
area is consequently basin-shaped, but the disturbance pro¬ 
duced by lateral thrust is very great, and the beds have been 
distorted. The southern portion of the area is sharply up- 
tilted, and the greatness of the disturbance is shown by the 
numerous folds; beds which were once nearly horizontal 
having been compelled to adapt themselves to a restricted 
space. On the border of this southern area the pressure has 
actually produced inversion of the beds. Thus, at Mons, 
where about eighty beds are workable, it is said that “ a single 
seam may be passed through six times in one single pit 
1,050ft. deep, and the strata which, if horizontal, would be 
nine miles broad, are squeezed into an area only seven miles 
across.” In another boring the same seam has been pierced 
ten times in succession. The inversion of the beds in one 
case has been so complete that, after passing through Tertiary 
and Cretaceous strata, 78m. of Silurian and then 84m. of 
Devonian and Carboniferous rocks have been found. 
At Charleroi the compression of the coal measures is 
remarkable, a breadth of 8J miles of flat strata having been 
narrowed to less than half that distance, and no fewer than 
twenty-two principal folds have been produced here. The 
upper seams are absent, and the number of coal seams 
becomes less towards Namur, where the lowest only are 
present. 
As we have seen, the coal measures which, from Liege to 
Moijs, are for the most part exposed, dip beneath the creta¬ 
ceous rocks as they approach France, and overlie a concealed 
area of Carboniferous Limestone, which, it is said, appears to 
rise beneath them as a sort of protuberance, yet one hardly 
to be attributed to upheaval, as the underlying beds do not 
break through the coal measures. Had upheaval here taken 
place, there would have been fractures and disturbances owing 
to this cause, of which there are now no visible traces. The 
