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= 
51 
the flora met with on the Continent, but the writer had frequent 
opportunities of discussing with him the general features of the 
district, and he has since been indebted to him for an extensive 
series of notes on the Coalfields of Belgium and the North of’ 
France, dealing especially with the physical geology of those 
countries in a manner so comprehensive as to furnish material for 
a much more exhaustive paper on the subject than is possible on’ 
the present occasion.* Time will only admit of calling attention’ 
to a few of the more important features in typical localities, but 
the writer would desire to express his great obligation to Dr. 
Hovelacque for the valuable information received on the subject. 
OVERLYING ROCKS. 
In comparing the geological features of the two coalfields, it 
will be convenient to group these notes under various heads, 
beginning with the overlying rocks, which naturally come first in 
order. 
It is hardly necessary to explain that throughout the greater 
part of the Somerset Coalfield, the carboniferous strata do not 
come to the surface, being overlaid for the most part by secondary 
rocks of varying thickness. Between the Mendip Hills and the 
centre of the Radstock basin these overlying strata consist of the 
Lias, Rhetic and New Red Sandstone, the latter occupying the 
bottom and lower slopes of the valleys, while, on the higher 
ground, the New Red is overlaid by the Rhetic and Lias, which 
occupy the summit of most of the table lands in and around 
Radstock. 
0 
* In a subsequent letter from Dr. Hovelacque, he wished to explain 
that the notes referred to were not entirely his own, but were rather a 
recapitulation of the principal works on the subject, including the 
following papers by Professor Gosselet, to. which he was largely 
indebted, viz., “ Etude des terraivs primaires du Nord de la France et 
du Boulonnais ;” ‘“ Esquisse géologique du Nord, 1880 ;” and 
“L’Ardenne, 1889.” 
