258 PROCEEDINGS OF THE GEOLOGICAL society. [ Mar. 8, 
After reading Mr. Pame’s paper, I visited the various spots in my 
own neighbourhood where the middle cretaceous beds are exposed, 
and found the order and relative thickness in all the same. The 
phosphate nodules are abundant in the upper greensand, but they 
are generally small m the top beds; below come the fire-stone or 
malm-rock bands, twenty to twenty-five feet thick, and beneath these 
again other beds of bright green earth, of which one portion is argil- 
laceous: this lower green band is the gault. The concretions of 
phosphate of lime are not so uniformly spread through the thickness 
of this mass as in the upper greensand, but occur in two seams, one 
in the argillaceous portion, the other lower, and only a little within 
the limits of this division of the series. These two beds of phosphate 
nodules, as well as a seam of pyrites, which in open sections pro- 
duces a brown band in the gault deposit, are remarkably persistent. — 
Although this order of the beds is constant for twenty miles 
along the course of the North Downs, it by no means follows that 
the discovery of phosphate beds will invariably reward those who 
may explore for them along the foot of that escarpment. In this re- 
spect all published geological maps will mislead, as they give a most 
incorrect representation of the course of the subordinate members 
of the middle cretaceous group. Research is already very strongly 
recommended in various quarters, but this will often be attended with 
a fruitless expenditure, unless it is accompanied with a clear under- 
standing of the accidents which affect the relative positions of the 
various strata along this range. All published sections too are equally 
delusive. 
When seen from some distance within the Wealden area, the upper 
Iie of the North Down range seems to rise to a nearly uniform level ; 
but when the beds which compose these hills are more closely im- 
spected, it will be found that whilst the dip of the whole mass is to the 
north, the amount of dip varies continually from the horizontal nearly 
to the vertical—that beds of very different parts of the series are 
brought up to the crest of the escarpment—and that the range in 
reality presents a series of long undulations. With such a structure, 
the extent of the series exhibited in any one section will depend on the 
amount of inclination, bemg most where the dip is most rapid. But 
in addition to this, a fault, and one which in some places is of very 
considerable amount, runs along the base of the chalk escarpment ; 
the lower greensand beds which occupy the south side of the gault 
also undulate, but the two sets of undulations do not correspond ; 
that is to say, they have not their greatest curves opposite one another. 
The reverse indeed is very frequently the case, the greatest amount 
of disturbance on one side facing a small amount on the other, and 
thus it happens that in some places the beds of upper greensand. 
and gault are exposed, and in others carried down below the surface ; 
so that if laid down on a map they would be represented only at 
intervals along the base of the escarpment, as north of Gomshall, 
beneath Newlands Corner, near Guildford, at Puttenham and Seale: 
but it would require a map on a very much larger scale than that of 
the Ordnance to enable one to lay down these minute and complicated 
details. 
