398 A. J. JUKES-BROWNE ON THE HESSLE 
carry the submergence a little further south, viz. over the Cam- 
bridgeshire Fen.” 
These last words have reference to another correlation which Mr. 
Wood has attempted to establish between the Hessle Sands and 
certain valley-deposits in the south of England; he has repeatedly 
urged that the Cyrena-brickearths of the Thames valley and the 
older postglacial gravels in Norfolk and Cambridgeshire were of 
the same age as the Hessle beds. 
Dr. J. Geikie * accepts Mr. 8. Wood’s correlations, but looks upon 
the Hessle Clay asa truly glacial deposit ; in the occurrence, therefore, 
of Cyrena fluminalis below this clay he sees a proof that the shell 
‘“‘ which has been usually looked upon as evidence of the postglacial 
age of the deposits in which it occurs did really live in interglacial 
times.” He also regards the older river-gravels in 8.E. England as 
belonging to the same period and therefore of interglacial age. 
Mr. Skertchly likewise adopts these views, and proceeds to argue 
for the great age of some of the Suffolk and Cambridgeshire gravels 
on the ground that there is evidence of their being anterior in date 
to the formation of the Hessle Boulder-clay. 
Since, therefore, the Hessle Clay appears destined to become a 
stratum of reference, by their relation to which the interglacial or 
postglacial age of various other deposits, both in the north and south 
of England, is to be measured, it is of great importance that the 
limits of its extension should be accurately defined, in order that its 
relations to gravels of newer and older date may, if possible, be 
ascertained. 
Now its southern boundary has never been satisfactorily deter- 
mined. Messrs. Wood and Rome, in their original paper, pointed 
out that it extended down to the edge of the marsh land surrounding 
the Wash, and that it might be found to underlie part of this 
ground +, but they did not attempt to trace it beyond Firsby and 
Steeping. 
During the last two years I have been engaged in surveying the 
southern end of the Lincolnshire Wolds and the country bordering 
the northern edge of the Fenland. I first made myself acquainted 
with the character and behaviour of the Hessle Clay between Great 
Steeping and Burgh, and subsequently followed it westward along 
the fen edge, the result of my examination being to convince me 
that not only is the above surmise correct regarding its continuation 
underneath the fen beds, but also that its surface extension stretches 
much further westward and southward than had previously been 
supposed. 
I am now permitted to lay before the Society the observations 
which have led me to this conclusion regarding the southerly 
prolongation of the Hessle Boulder-clay in Lincolnshire, and to 
supplement them with some remarks upon the gravels in this and 
more southern counties which are supposed to belong to the same 
period of time. 
* Great Ice Age, 2nd. edit. p. 379. 
t+ Quart. Journ, Geol. Soc. vol. xxiy. p. 173. 
