1869. ] SEARLES WOOD—BOULDER-CLAY. 91 
less clay of the north of Flamborough with a similar clay, also 
wholly destitute of chalk, of which outliers cap the purple clay with 
some chalk in Holderness, where, as at Dimlington and near Map- 
pleton, the cliff-section shows the Glacial series to have undergone 
less denudation than elsewhere along that coast. We further 
pointed out that the long-known fossiliferous bed of Bridlington 
belonged to the Yorkshire Glacial formation; and we placed its 
horizon immediately superior to the chalky clay (a)—that is 
to say, in the lower part of the purple clay, wherein there is 
chalk, and at the horizon indicated in the accompanying vertical 
section (PI. VII. fig. 1). 
Now, while in Yorkshire we find the Glacial clay exhibiting the 
distinct feature of a gradual decrease and final disappearance of 
the chalk débris, succeeded by a deposit of considerable thickness, 
in which there is not a trace of chalk, the whole of the beds of the 
east and east centre of England indicate not only that débris 
from the chalk prevails throughout the series, but that it is to 
the full as copious in the uppermost layer that denudation has 
spared of the highest member of the series there as it is in the 
lowest. 
It is therefore only with the highest member of that series, the 
‘common wide-spread Boulder-clay of Kast Anglia, that I propose to 
discuss the relationship borne by the Yorkshire Boulder-clay. As 
regards the very considerable and, I think, important series of de- 
posits which are older than this wide-spread Boulder-clay, but are 
absent in Yorkshire and the north, I shall only have occasion to 
refer to them to the extent of pointing out the great distinction ex- 
isting between their fauna and that of the bed at Bridlington, and 
of indicating their place in the vertical section accompanying this 
paper, as the structure and distribution of these older series will, 
I hope, form the subject of a future communication by myself and 
Mr. F. W. Harmer, F.G.S., who has cooperated with me in working 
them out. 
The particulars of the considerable fauna obtained from Bridling- 
ton, and of the fauna collected from the Middle and Lower Glacial 
deposits of Hast Anglia, have received much attention from my 
father, and they will be tabulated by him with the fauna from 
the several horizons of the Crag and from the Postglacial beds of 
the eastern side of England, in his supplement to the Monograph 
of the Crag Mollusca. In the meantime, however, for the purposes 
of this paper, and to show, on the one hand, how entirely distinct 
these deposits are in their paleontological aspects from that of Brid- 
lington, and, on the other, how closely they are connected in those 
aspects with the Crag, the following list, embodying our results up 
to the present time, as far as they concern the beds under considera- 
tion here, has been revised by him* :— 
* The fauna of the Lower Glacial has been obtained with the assistance of 
Mr. Harmer, and that of the Middle Glacial with the same assistance and with 
that of Mr. I. T. Dowson, of Geldeston ; while Mr. Leckenby has rendered my 
father most valuable assistance in verifying the Bridlington shells. 
