Seas 
Geological Society of Londons 235 
derness (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 i, kaise of the ice during the rise only at the 
south end of the western slope of the Pennine chain, those on the 
eastern having been wholly swept away; but that gravels were 
deposited on the east side of the Pennine 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 relinquished 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 Pennine chain consequent upon greater 
snow interception from the progress of the rise; and to the same 
cause he referred the drift which rises high on the eastern slope of 
the Pennine 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 
Chalky-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 Pennine 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 moorlands 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, 
and spreads out wider in Holderness. This arm in consequence of 
the Chalky-clay ice not having (from the westerly increment of 
depression) descended the eastern slope of the Wolds, found sea 
there covering the basement clay of Holderness, in which sea it 
stopped between the Humber and the Wash, by means of which the 
lower part of the purple clay up to the level of about 150 feet, 
contains intercalated in it beds of sand and gravel, and contains 
shells and shell-fragments, as does the Lancashire clay similarly 
extruded beneath the sea. The other branch came south along the 
western flank of the east moorlands and through the Vale of York, 
where it ended, and became stationary in the sea as this entered the 
Trent system on the final dissolution of the chalky-clay glacier. 
The author discovers no trace of anything like the intercalation 
of warm periods up to the stage with which he concludes this part 
of his memoir ; and leaves the description of the later beds, as well 
as an examination how far arboreal vegetation and the coexistence 
of Pachyderms and Proboscideans can be reconciled with the con- 
tiguity of extensive land-ice, for the concluding part of it. 
