April 15, 1880] 



NA TURE 



579 



this was ti submerge the area of Red Crag converted into land 

 during Sta-e I., so that the Contorted Drift lies upon it fifty feet 

 thick, and to cause the retreat of the ice which had given rise to 

 the Till to the si pes of the Chalk Wold ; whence masses of 

 reconstructed chalk were brought by bergs that broke off from 

 it and veie imbedded by their grounding in this drift, con- 

 torting it (and in those parts only) by the process. He then 

 traced, in the form of gravels at great elevations, the evidences 

 :ils and westwards, showing it 

 to have i icreased greatly in both directions, but mostly in 

 in cts these gravels with the Contorted 

 Drift by the additional evidence of one of these marl masses, in 

 which he f mid a pit excavated near the foot of Panbury Hill, 

 in the London-clay country of South Essex, and which hill is 

 1 to top by this gravel. The gravel which thus 

 covers 1 anbury Hill, ol which the summit has an elevation of 



1 ises in North Kent to upwards of 500 feet ; to between 



400 and 500 feet on the Neocomian within the Weald ; to 600 



rth Hants (where it overlooks the Weald), and also in 



joining parts of Bucks; to 420 feet in 



South Hants ; to 540 fett in Oxfordshire ; to 400 feet in Corn- 



upwards of 700 (and perhaps i.oco and more) in the 



Ids ; to 1,200 feet in Lancashire, and t > 1,340 feet in 

 North Wales. Eastwards, through Kent towards France, their 

 . 1 in the North of France appears to be about 

 130 feet ; from whence the evidences of the submergence are 

 furnished 11 irthwards by the Campinian sands and the diluvium 

 of North Germany and Holland. In Stage III. the author traced 

 the rise from this depre.-si.n, the increase of the ice fiom the 

 greater snow interception, caused by it on the Penine chain, and 

 the consequent advance of the glacier- or land-ice. This advance 

 give rise to the chalky Clay, which was the morainic mud-bank 

 which preceded this glacier, and was pushed by it as it advanced 

 and the land rose, partly into the shallow sea (where it covered 

 and protected for a time the gravel which was synchronously 

 forming there), and partly on to the land ; and by the aid of 

 lowed the islands that were overwhelmed by it. He 

 then showed, by a line on a map, the limit up to which this ice, 

 as it thickened, cut through and destroyed this first deposited 

 moraine and the gravel w Inch it had covered, as well as such 

 heds of Stage II. as were formed there, all this material being 

 pushed on to add to later deposited moraine. Outside this line 

 the gravel for the most part remains undestroyed, its contents, 

 particularly in the uppermost layers, showing that it was fed by 

 the approaching moraine. By the level at which the junction of 

 this gravel with the moraine clay occurs he traces the position of 

 the sea-line at this time (towards the end of the formation), and 

 finds it to rise along the south-eastern edge of the clay, from 

 40 feet in North-East Suffolk to 160 feet in South Essex, and 

 from that along the south-western edge to upwards of 350 feet 

 in North Warwickshire and the parts of Northamptonshire 

 adjoining, all this agreeing with the original increment of sub- 

 mergence in Stage II. He then showed, from evidence afforded 

 by the Vare and Gipping valleys, that this ice, ceasing to advance 

 in East Anglia, shrank into the valleys of that district, exposing 



ine it bad previously hid down to the growth of vege- 

 tation, and issued only through these valleys to the sea. The 

 Hoxne paleolithic brickeartb he regards as the deposit of a 

 lagoon produced from the interception of the drainage of this 

 surface by the glacier-tongue thus passing through the Waveney 

 valley. The Brandon palaeolithic brickeartb he regards as con- 

 nected with the same state of things. Tn Stage IV. he described 

 u and cannon-shot gravels of Norfolk as resulting from 

 the wasliingout of the morainic clay by the melting of this ice, 

 which, though shrunken into the valleys of the East of Norfolk, 

 still lay hi -h and in mass in West Norfolk ; and showed that, 

 by having regard to the different inclination of the land thus 

 traced, the p silion of this gravel is reconcilable in no other way. 

 The cannon-shot part of it he attributed to the torrents pouring 

 from this high-lying ice over the west side of the Wensum 

 valley ; and the plateau gravels to the deposition of other parts 

 ie spoil carried into East Norfolk at the commence- 

 ment of the process and while the ice had not thawed out of the 

 valley^, this gravel afterwards, as the valley-ice thawed, being 

 deposited in them. He also traced the excavation of the trough 

 occupied by the Bain and Steeping rivers in Lincolnshire to 

 the same cause. The finer or sandy part of this material has an 

 extensive spread in South-West Norfolk, forming thick beds ; 

 and in a thinner form spreads over North-West Suffolk, where 

 it wraps the denuded edges of the Hoxne and Brandon palaeo- 



lithic brickearths. In Stage V. he traced the line of gravels 

 that overlie the Chalky Clay where this clay entered the sea. 

 This entry to the sea over the Severn drainage system took place 

 by way of the watershed between the Wetland and Avon, and 

 by the valley of the latter. Its entry into the sea over the 

 Thames system was by way of the watershed between this 

 system and that of the great Ouse in South Bucks, as we:i as by 

 the valley of the Colne, Lea, and Koding, and over the lower 

 part of the watershed in Sonth-East Essex, Its entry into the 

 North Sea v. s by the valleys of the Blackwater, Gipping, and 

 other Essex and Suffolk valleys, the entry by the Yare and 

 Waveney beii g far out beyond the present coast-line. lie also 

 traced, by similar evidence, the extent to which the sea entered 

 the Trent system after the ice vacated it. This line of gravel 

 (after allowing for the case that the level of the junction of the 

 gravel beneath the clay represents that of the sea-bottom, while 

 that over the clay more nearly represents that of the sea-top), he 

 showed to correspond with that of the junction of the gravel 

 beneath the clay so far as this is not destroyed in the parts 

 where the ice did not shrink into the valleys ; and it a] 

 with this line, supplemented by the amount of rise in the interval 

 where the ice did so shrink. Along the south-western edge of 

 the clay this line of gravel, subsequent to the clay, falls from 

 near 400 feet in Bucks to 150 feet in South Essex ; from whence 

 northwards along the south-eastern edge, it falls uniformly to 

 Ordnance datum in central East Suffolk, and probably con- 

 tinued to fall to ico feet or so below this at the extreme point 

 where the ice from the Yare valley entered the North Sea far 

 beyond the present coast. Along the north-we-tern edge of the 

 formation this line falls northwards in a corresponding way to 

 that on the s uth-ea tern edge, save that, starting there from near 

 350 feet, it does not fall below, if even quite down to Ordnance 

 datum near the Wash. He then traced the extent to which the sea 

 on the west, deepening in that direction in accordance with the 

 original depression of Stage II., entered the valleys of the area 

 covered by the ice of the Chalky Clay as this vacated it : the 

 carrying out through the Welland and Avon valleys of the red and 

 white chalk spoil of the Bain-Steeping trough, and its deposition 

 in the Cotteswold gravel up to a high level, coming from the 

 Avon system over the Gloucestershire water-parting into the 

 valley of the Evenlode, a part of the Thames system. All river- 

 gravels north of the point where the line of gravel ever the clay 

 sinks below Ordnance datum, he regards as concealed helow the 

 alluvium, and at depths proportional to the fall of that line. 

 Examining in detail the grounds for the contrary opinion hereto- 

 fore held by himself and by geologists in general, that the great 

 submergence succeeded the principal glaciation of England, he 

 rejected that opinion ; and no longer regarding the basement 

 clay of Holderness (with its ancient molluscan facies) as identical 

 with the Chalky Clay, but as moraine synchronous with the Till 

 of Cromer, he considered the gravels with shells at extreme 

 elevations in Lancashire to have preceded all glacial clays but 

 these, and to have escaped destruction by the advance of the ice 

 during the rise only at the south end of the western slope of the 

 Penine chain, those on the eastern having been wholly swept 

 away ; but that gravels were deposited on the east side of the 

 Penine after the dissolution of the Chalky-clay ice up to the 

 reduced height of the sea-level at that time, and so far as the ice 

 of the purple clay allowed the sea to come. He then relin- 

 quished the opinion formerly held by him that the passage of the 

 Shap blocks was due to floating ice, and referred this to the 

 land-ice crossing the Penine chain consequent upon greater 9 ow 

 interception from the progress of the rise ; and to the same 

 cause he referred the drift which rises high on the eastern slo e 

 of the Penine ridge north of the Aire. To this crossing of the 

 ice having diverted first a part and then the whole of the ice- 

 supply of the Chalk-clay glacier he attributed first the shrinking 

 of that glacier into the valleys in East Anglia, and afterwards its 

 dissolution by the agencies always rife in the Greenland ice (but 

 which are there balanced by continual reinforcement), when by 

 this diversion its reinforcement by ice from the Penine chain 

 ceased. The purple clay of Holderness, being thus in its lowest 

 part in Holderness coeval with the valley-formed portion of the 

 Chalky Clay of Norfolk and Suffolk (or " third Boulder-clay " of 

 Harmer), was the moraine of this invading ice, which, after 

 crossing at Stainmoor, divided against the eastern moorlands of 

 Yorkshire ; and one branch going north of these 1 

 through the valley of the Tees, sent off an arm down their 

 eastern flank, the moraine from which is the narrow belt of 

 purple clay which skirts the Yorkshire coast north of Holderness, 



