Glacial Gravels, etc., of Eastern England. 537 



which ought never to have been dropped, for, so far as can be 

 judged, they are the Yorkshire representatives of the Upper Crag 

 beds in Norfolk, in which, as is well known, Arctic shells occur. 

 It is noteworthy that the beds at Bridlington contain vertebrate 

 remains from the Crag, Eocene, and older beds (Woodward's 

 Geology, p. 499). 



It would also seem that the shell beds at Kelsey Hill, near Hull, 

 which are overlain by Boulder-clay at Speeton, where they occur 

 below the Lower Purple Clay, and at Aby, near Claythorpe, in 

 Lincolnshire, are also of late Crag age. I find that after I had 

 written this Mr. Carvell Williams had suggested the same conclusion ; 

 and if it be sustained it enables us to solve a considerable difficulty, 

 namely, how to account for the Norwich Crag having been 

 such a local deposit as it has been hitherto deemed to be. It 

 enables us to connect the East Anglian Crag, as Mr. Carvell 

 Williams has done, with the fragments of Crag beds which have 

 occurred on the coast of Scotland in Aberdeenshire and Nairnshire. 

 We must remember that as we get further north we must expect 

 the shells during the period of the Norwich Crag, as in our own 

 time, to show a more and more Arctic facies. I am not sure, in fact, 

 whether all the drift shells on the British coasts which have been 

 treated as glacial are not derivative, and ought not really to be 

 classed as equivalents of the later Crag shells of Norfolk. 



With the disappearance of these shells from the category of true 

 glacial debris, and with the proof that they are derivative, disappears 

 the postulate of an Interglacial climate in so far as it has been based 

 on the shelly sands of Eastern England. It also opens the way for 

 an explanation of these sands very different to that usually adopted. 



As I have said before, the opinion is now pretty general that all 

 the clayey matrix of the so-called glacial clays of Eastern England is 

 a derivative product, and that it is not, in fact, a clay ground down 

 from argillaceous rocks de novo by whatever distributed and arranged 

 the so-called glacial beds, but that it was ready-made clay when that 

 instrument began its work. It was taken up ready-made from the 

 various beds of clay exposed to its influence — in some places 

 from the Kimeridge and Oxford Clays, in others probably from 

 London Clay and the clays of the Plastic Series, and in others, 

 again, from the so-called Chillesford Clays of the Crag deposits. 



Everyone who has written in any detail on the subject, seems to 

 allow that the clay which forms the magma or body of the Boulder- 

 clays was derived from pre-existing beds of clay. This conclusion 

 is, in my view, equally true of the so-called sands and sandy gravels. 

 The sands associated with the Boulder-clays of Eastern England are, 

 so far as I know, all derivative also, and were ready-made as sands 

 when the instrument which laid down the so-called glacial beds 

 began to operate. For the most part they are rearranged Crag sands. 

 In part, also, they are probably rearranged sands of the Bagshot and 

 Beading Series; these recent beds having, doubtless, before the 

 denudation of the Fens occupied a much larger area in Eastern 

 England than they do now. 



