114 S. V. WOOD, JTTN., AND F. AY. HARMER ON THE 



Boulder-clay, or Upper Glacial, which covers so much of England 

 and Scotland, and of which only the oldest or first-accumulated por- 

 tion is present in East Anglia, seems to us to have arisen from the 

 state of things we now propose to describe. 



As the submergence proceeded, and the sea, after occupying, as 

 fiords, the interglacial valleys of East Anglia, gradually rose over 

 the tablelands, so did the land-ice on the mountain districts of the 

 north of England accumulate and descend over the lower ground 

 until it formed a continuous sheet, which ultimately enveloped 

 probably every thing as far as it extended. The thickness of that 

 portion which descended over Yorkshire may eventually have 

 amounted on the lowest ground to 1200 or 1500 feet, though very 

 likely it was much less ; but though enveloping high and low ground 

 alike, its principal motion, and with it that of its moraine profonde, 

 was, as it seems to us, through the greater valleys only, to their 

 seaward termination. 



Thus a part moved through the great valley of the Tees, another 

 part through the great valley of Pickering, while a third moved 

 through the smaller valley of the Humber. None of these three, 

 however, concern us in relation to the East- Anglian deposits further 

 than that we recognize in that portion of the moraine which passed 

 through the valley of the Humber and forms the lower part of the 

 Glacial clay of Southern Holderness, or that in which chalk debris 

 is abundant, a deposit coeval with the Upper Glacial of East Anglia. 

 The moraines of the first two branches, which were contemporaneous 

 with this, were, it seems to us, extruded beyond the present coast- 

 line, and some way out in the present North Sea. 



The largest branch of the Yorkshire portion of the sheet is that 

 with which we have to concern ourselves, as it is that to which the 

 Upper Glacial clay of East Anglia owes its origin. This branch 

 moved southwards over Lincolnshire, as is proved, not only by the 

 profusion in that clay of Jurassic debris derived from the troughs 

 which lie between the chalk escarpment and the respective Oolitic 

 and Liassic escarpments of that county, but also by the occurrence 

 in it of lumps of the red chalk * which underlies the white chalk of 

 that county and of Yorkshire, but which ceases near Hunstanton, 

 in the extreme north-west of Norfolk. This red chalk debris has 

 travelled in one direction as far as the brow of the Thames valley, 

 where it occurs in association with the hard stony chalk of York- 

 shire and Lincolnshire, which constitutes the principal proportion 

 of the debris in the Upper Glacial clay of that district as well as of 

 East xlnglia in general ; and in similar association it has found its 

 way as far as the Cotteswolds, where it occurs in gravels which pro- 

 bably represent both the Middle and the Upper Glacial of East 

 Anglia, that clay dying out about thirty miles north-east of the 

 Cotteswolds. These gravels have been traced by Mr. Lucy t to alti- 



* Some of these lumps may be fragments of the pink bands which occur at 

 certain horizons of the Chalk in Lincolnshire and Yorkshire, but are confined 

 to those counties. 



t "The gravels of the Severn, Avon, and Evenlode, and their extension over 

 the Cotteswold Hills," Cotteswold Club, April 1869. 



