Dr. P. E. Kent congratulated Dr. Flinn on a very useful topographical compilation on a critical part of the U.K. Continental Shelf. He offered some comments on the deeper structures in relation to the topographical features which Dr. Flinn had described.
In the north North Sea it is now known that the international boundary (the mid-line) lies a short distance east of a large fault-trough edge, the bounding fault being of tensional (normal) type with a throw of some thousands of feet. It would be a matter of interest to find whether Dr. Flinn's easterly n-s swell coincided with the upthrown flank of this structure, or whether it lay further east.
West of the Shetlands the structure is known from extensive seismic surveys to consist of a series of east-tilted blocks, bounded by large west-facing fault-scarps. On the top of these blocks sediments are fairly thin but thicken northwards; they are tentatively ascribed to the Tertiary. The sediments between the faults are ascribed (provisionally) to the Mesozoic and it appears that the structures may have developed progressively through part of Mesozoic time. Interpretation of the geological history of this area will remain obscure until boreholes have dated the rocks over a range of structural positions in this area.