Oil BritisJi Di'ifls and the Interglacial Problem. 315 



Head, which from their character and position cannot be of 

 marine origin. Even at the exceptional places referred to, 

 where the fossils are more plentiful, there is a mixture of forms, 

 including- an abundance of the freshwater shell Corhicida flu- 

 viinalis, which seems to denote their derivation from pre-existing^ 

 local deposits ; and in the new section at Burstwick, described 

 by Mr. T. Sheppard,* these shelly gravels revealed the same 

 close association with the boulder-clay that is so frequently 

 displayed in the glacial gravels of the coast sections. 



The Kiniimgton Section. — There is, however, one case 

 known to me in the east of England, and only one, in which an 

 undoubtedly contemporaneous fauna occurs in beds intercalated 

 with the boulder-clay series.! At Kirmington, in North Lincoln- 

 shire, a brickyard is worked in a deposit of estuarine clay lying 

 in the middle of a broad shallow valley which cuts across the 

 Chalk Wolds about eight miles south of the Humber. Recent 

 investigation b}- a Research Committee of the Association, in 

 which I took an active share, has shown, somewhat unex- 

 pectedly, that the surface of the chalk at this place descends to 

 present sea-level, and that the estuarine warp is underlain by 

 over 60 feet of drift, consisting of sand and chalky gravel, with 

 two thick bands of tough clay containing far-travelled stones. | 

 The boring in which these beds were proved was insufficient to 

 show precisely whether the stony clays possessed the dis- 

 tinguishing features of true till, but there can be no doubt as to 

 their glacial character, since we know of no deposits of this 

 kind in the east of England except those of glacial age. At the 

 base of the estuarine warp, at 65 feet above Ordnance datum, 

 we found a thin seam of silt and peat containing a few freshwater 

 shells and plant remains, which, like the very scanty fauna of 

 the overlying warp, give no precise indication of climatal 

 conditions, though suggesting that the climate was cooler than 

 at present. The estuarine bed is overlain by a coarse gravel of 

 rolled flints, and in one part of the section this gravel is covered 

 by 3 or 4 feet of red clay with far-travelled stones, resembling 



* ' On another Section in the so-called Interglacial Gravels of Holder- 

 ness.' Proc. Yorks. Geol. and Polytech. Soc, vol. xiii. (1895), pp. 1-14. 



t The freshwater deposit which I found some years ago at Bridlington, 

 and at first thought to be probably intercalated with the boulder-clay, 

 proved on fuller exposure to lie above the boulder-clay, with which it had 

 become entangled by later disturbance. See Geo/. Mag., dec. ii., vol. vi. 

 (1879), p. 393; and '/'rtir. Yorks. Geol. and Polytech. Soc, vol. vii. (1881), 

 p. 389. 



J Pe/>. Britisli Assoc, for 1904, pp. 272-4. 



1906 September i. 



