x SUPPLEMENT TO THE CRAG MOLLUSCA. 
be the same as the sand 5’ of the pit behind the church, containing the fossiliferous bed 2, 
the identity of the Chillesford with the Bramerton section fails ; and the idea forces itself 
that the Fluvio-marine Crag of the Bramerton section, and its overlying sands, which 
pass so uninteruptedly up into the Chillesford beds, are newer than even the Scrobicularia 
Crag itself. 
It, however, appears to us the more probable alternative, that the sands marked ? are 
not the Chillesford sands of the pit behind the church, but some later deposit ; probably 
the Middle Glacial sand (8), which, in a pit only a furlong north of the church, occurs 
under the Boulder clay (9). Figure XVII accordingly represents the section on this 
hypothesis, and on the assumption that if a clear section were carried down from the 
Chillesford clay of the pit behind the church into the Red Crag, it would disclose that unin- 
terrupted passage of the formations into each other which is represented on the left side of 
the figure ; the sands marked ? lymg somewhat in the way suggested by the broken line. 
It is important to observe that while this probable conformity exists at Chillesford, 
the Red Crag of Walton is clearly unconformable to the Chillesford beds which overlie it ; 
the sands of those beds (5’) lying on a very irregular surface of the Red Crag and filling 
up the depressions in it (see Section XXI); while both these sands and the laminated 
clay (5) above them overlap the Crag on the south side, and rest there on the London 
clay (see Section Q).' Nothing, therefore, can be clearer, we think, than that the Walton 
Crag, so distinguishable by its fauna from the newer Red Crag beds 4” and 4’”, had been 
denuded before the Chillesford beds overspread it, and is quite disconnected from them. 
If the hypothesis presented in Section XVII is true, we see that the northern part of 
the Red Crag area continued to receive accumulations up to and during the time when 
the Fluvio-marine Crag was deposited ; and that from a depression which then set in, 
the Fiuvio-marime Crag gave place, through the sands shown in the Bramerton section 
without symbol, to the marie deposit, 2, of that place; while the sandbank 
deposit, 4”, of the Chillesford section gave place through the beds 4” to the same 
overlying bed 2; the submergence carrying the sands 5’, in which this bed @ occurs, 
over the Walton Crag. 
‘he other instances which exist of the Chillesford beds over the Red Crag area, such 
as those on the eastern side of the Deben, opposite Woodbridge, do not afford any 
section which would show their conformability, or the reverse, to the underlying Red 
Crag; but the appearances, as far as they go, all point there to an unconformability. 
How far the sands which, in some of the excavations for phosphatic nodule working, 
seem to pass down into the Red Crag by thin seams of comminuted shell in their lower 
part may belong to the Crag, it is difficult tosay. They are not, we think, the Chillesford 
' Tn Section Q this overlap is represented as existing at the northern end also; but as the face of the 
cliff is there obscured, this is uncertain. 
The bed @ can be detected in Walton Cliff, but the shells are in too decayed a state for extraction ot 
even recognition. 
