XXIV SUPPLEMENT TO THE CRAG MOLLUSCA. 
Tur Great Cuaixy Cuay, on Upper Gracia (No. 9). 
This wide-spread unstratified deposit extends over the eastern and the east central 
counties, and is there wholly unfossiliferous. In the parts traversed by the sections it is 
mostly of no great thickness, owing apparently to denudation ; but further from the 
coast, and away from the main valleys, its thickness is more considerable, amounting in 
the west of Suffolk to as much as 120 feet,! and in Cambridgeshire to still more. Where 
it does not descend, as it often does, in a plunge, but rests evenly on the Middle Glacial 
sand, as around Woodbridge and in Sections T and U, this clay not unfrequently passes 
down into that sand by a passage bed consisting of a few feet of the clay which becomes 
more sandy downwards, until it shades off into the subjacent sand. In other places it lies 
evenly upon the sand in a conformable manner without any such passage bed; and there 
can be little question that the succession was effected by tranquil deposition, uninterrupted 
by any change of conditions other than those which produced a new kind of sediment. This 
clay all may admit to be the result of the degradation of the Cretaceous, Oolitic, and Liassic 
districts by land ice—the moraine profonde of the great enveloping ice sheet of the Upper 
Glacial period; but no one can look at the even way in which it overlies the sand in. 
Kessingland and Hopton Cliffs (Sections T’ and U) without being convinced that it could 
not have been so placed by the action of land ice, since this could not have failed to crumple 
up and distort those sands, just as the intruding bergs bringing the marl masses churned up 
the contorted drift. Section P shows what an ice plough of the period of the clay No. 9 
would accomplish. ‘The Crag and the overlying sand, 8, of this section appear on one side 
of the cutting at the East Suffolk Railway Junction; but in the short space of the width 
of the cutting they are cut off so entirely, that the opposite side presents nothing but a 
churn up of sand and London clay; while a piece of the Red Crag thus ploughed out 
has been left two miles off, at a high level, in a mass of gravel about the junction of the 
Middle Glacial sand with the chalky clay, and is exposed in a pit south of the “ Sparrows 
nest.” If this be the result of the grounding of an ice island, as we cannot doubt it was, 
how much of the sand of Hopton and Kessingland Cliffs would have been left under the 
pressure of the land-ice sheet itself? Nevertheless this clay, not only in these cliffs, but 
all over East Anglia, is quite as unstratified as is that of Scotland and the north of 
England, and it is everywhere, except on the Yorkshire coast, quite as destitute of organic 
remains. 
The species given in the Crag Mollusca and its Supplement from the Upper Glacial 
formation are from the Bridlington bed, the age of which appears to us to be posterior to 
that of the great chalky clay of Hast Anglia (No. 9) ; the bed occurring in a continuation of 
1 This was the total thickness in the cutting and contractor’s well beneath it at Horseheath on the 
borders of Cambridgeshire and Suffolk. The cutting and well at Old North Road Station of the Cambridge 
and Oxford Railway showed this clay there to be about 160 feet in thickness. 
