398 Mr. S. V. Wood on the Belgian Equivalents of 
rate geological map of Belgium, by the late M. Dumont, indicates 
in a still clearer manner the area occupied by the Campinian 
sands and rolled stones, and by the overlying Loess, as well as 
the relative positions of the two beds* ; and in the following 
woodcut map | have reproduced, as well as the smail scale will 
allow, the destribution of the two beds, as shown on the map of 
M. Dumont, adding to it the area of the eastern border of Eng- 
land, for the purpose of enabling a comparison to be made of 
the distribution and position there of the Boulder-clay (4) and 
underlying lower Drift (g), with the Loess and Campinian beds of 
the Continent. In Belgium the grouping of the two deposits 
shows that the valleys have been in some cases cut through the 
Loess down to the Campinian sands, where that deposit underlies 
the Loess, as, for instance, in the neighbourhood of Brussels and 
of Bilsen ; but in this respect the grouping of the beds is much less 
striking than in the case of the eastern counties of England. The 
coincidence between the valleys cut through the Loess and those 
of England, in point of time and mode of origin, is shown in a 
way that the limits of this paper do not permit me satisfactorily 
to enter upon. In the paper on the formation of the valleys, 
before referred to, I attempted to show that the valleys of the 
east of England, which cut through the upper and lower Drift 
of that region, resulted from the denudation having been regu- 
lated by the disturbance of the floor of the sea of the upper Drift, 
which took place in the form of a series of circular movements. 
The more important of these movements affecting that part of 
England originated in three centres, one of which was near 
Canterbury, another immediately south of the Isle of Wight, 
and another in the North Sea, off Flamborough Head +. 
So far as I have been hitherto able to trace them, the circular 
movements emerging from these three centres, with others of 
similar character and simultaneous origin emerging from centres 
on the Continent, appear wholly to have formed the valleys which 
* The three deposits are by him placed in the following descending order: 
Loess (limon Hesbayen) ; 
Sables Campiniens ; 
Cailloux roulés. 
+ Although these three series form the principal valleys of this part of 
England, a close investigation of the Ordnance Sheets appears to disclose 
otherinequalities of surface, that are parts of circlesoriginating at much more 
remote centres, and whose effect has, from distance, become proportionately 
feeble. I hope ata future day to show the whole grouping of these circular 
phenomena, and the effect of their reciprocal pressure in France and Bel- 
gium, as well as in England, and the manner in which, in the south of this 
country, subsequent but more localized and powerful movements have su- 
pervened on them. The short notice of them published in the ‘ Phil. Mag.’ 
is very incomplete, and in some respects imperfect. 
