BOULDER-CLAY IN LINCOLNSHIRE. 401 
This sudden change in the direction of the bank-like edge of the 
Hessle Clay is the more remarkable because, throughout the whole 
of its northern extension it clings closely to the edge of the Wolds, 
and runs into the depressions and valleys which furrow their 
eastern slopes. These, as pointed out by Messrs. Wood and Harmer, 
must have been in existence before the Hessle beds were deposited ; 
and I can quite confirm their account of the positions which these 
beds occupy in the Steeping valley, and agree with the main 
inferences deduced from the sections accompanying their paper. 
Seeing, therefore, that the Hessle Clay entered the Fen basin in 
the same manner as it did the Steeping valley, I expected to 
follow its continuation at the same level along the north border of 
the Fenland ; consequently the abrupt termination of its westward 
extension at a point about midway along this border, and its bank- 
like prolongation in a southerly direction, was the more surprising, 
especially as there did not appear to be any reason why it should 
not have extended much further westward. 
To this peculiarity and the possible reasons for it further reference 
will be made in the sequel; but I wish to draw attention to it at 
once as an important and interesting fact. 
§ 2. Description of the Hessle Beds along the North Border 
of the Fenland. 
I now proceed to give some description of the deposit as exhibited 
along the line of country above indicated, commencing near Burgh 
and noting the more important sections which were found in tracing 
the formation westward. 
First, with regard to the Boulder-clay about Burgh, although it 
varies very much in colour and character, and in the proportion of 
chalky material which it contains, I have not found it practicable 
to make any division of it into a newer and older clay. 
Burgh itself stands on an eminence composed of sand and gravel, 
through which wells have been sunk and water reached at a depth 
of about 20 feet. Whether this sand overlies the Boulder-clay or is 
a protruding knob of the Hessle Sand, I could not quite satisfy 
myself, but am inclined to take the latter view, as the clay seemed 
to close in upon it all round, and was visible at several points on 
the lower slopes without any strong springs being given off along 
the line of junction; in colour this Boulder-cluy is greyish, but 
more or less mottled with purplish-brown ; and it contains numerous 
chalk pebbles. 
From descriptions of the clay near Burgh, communicated to them 
by Prof. Judd, Messrs. Wood and Rome concluded that it belonged 
to the chalky basement clay of their coast section *; but I am in- 
clined to think that it is only a local form of the Hessle Clay. The 
latter presents itself with normal characters at a large gravel-pit 
less than a mile west of the town. There is a continuity of Boulder- 
clay land between this point and the places where a more chalky 
* Quart. Journ. Geol, Soc. yol. xxiv. p. 184. 
272 
