ON THE HESSLE BOULDER-CLAY OF LINCOLNSHIRE. 397 
32. On the Sournerty Exrnnsion of the Hesste BovurpEr-ciay tt 
Lincornsuirr. By A. J. Juxes-Brownez, Esq., B.A., F.G.S. 
(Read March 26, 1879.) 
(Communicated by permission of the Director-General of the 
Geological Survey.) 
ConTENTS. 
Introduction. 
Extension of the Hessle Clay in Hast Lincolnshire. 
Description of the Hessle Beds along the north border of the Fenland. 
The origin and mode of formation of the Hessle Clay. 
The Age and Equivalents of the Hessle Clay. 
Introduction. 
Tur group of beds to which in 1867 Messrs. Wood and Rome 
gave the name of Hessle Sand and Clay * have recently been in- 
vested with much greater interest and importance than was originally 
attached to them by these geologists when they first separated 
them from the other glacial deposits and described their mode of 
occurrence in the typical district of Holderness. 
In a communication to the ‘ Geological Magazine’ for 1872+, 
Mr. Searles Wood, jun., states that he and Mr. Rome, subsequently to 
the publication of their joint paper, ‘‘ traced an Upper Boulder-clay 
and underlying sand through the Vale of York into that of the Tees, 
which seemed to be a continuation of the Hessle Clay and Sand.” 
They noticed that the thickness of the clay was greater in the north 
than along the Holderness coast, and stated that they had reason 
for thinking the same beds extended into Cumberland and even into 
Scotland. 
The same authors had, in 1870, suggested the possibility that this 
sand and clay might correspond with the middle and upper members 
of the glacial series in the north-west of England ; and in his latest 
paper (1878) ¢ we find Mr. 8. Wood expressing his belief that the 
Hessle beds, “‘in the form of a (so called) Middle Sand and Upper 
Boulder-clay with occasional boulders, extend over the lower ground 
intervening between the Pennine chain and the coast in Cumber- 
land, Lancashire, and Cheshire, and reach along the north-west 
coast as far south at least as the north of Carnarvonshire.” He 
remarks upon the similarity of the fauna contained in these Middle 
Sands to that found in the gravel and sand underlying the Hessle 
Clay ; and he speaks of the southerly extension of this deposit in 
the following terms:—‘“ The southern limit of the Hessle Clay 
appears to be at Firsby, on the northern edge of the Lincolnshire Fen ; 
and, so far as I know it, the southern limit of the upper clay of the 
north-west of England appears to he at the same latitude in the 
Menai Straits; but on the eastern side the gravels of the formation 
* Quart. Journ. Geol. Soe, vol. xxiv. p. 146. 
t Geol. Mag, dee, i. vol. ix. p. 175. { Ibid. dee, ii, vol, y. p. 18, 
