David F. Clark

After a short illness D. F. Clark suddenly died at a very early age leaving his family, friends and colleagues disheartened.

His thesis was essentially ready for presentation at the time of his death and we felt that it was our duty to look at it to see whether or not it could be presented for post-mortem graduation.

It was with a sense of emptiness that we read the manuscript a few days after his departure. The thesis was good and sound. Since it was dealing with one aspect of the material of Stehman's Ph.D. thesis, we decided not to present it until Stehman's study was completed. The idea was that of adding vital comments or information based on the new results (as David would have done himself had he been alive).

It is surprising and, in a sense, flattering for the deceased that very little change is required today for this thesis to be presented for examination; so little in fact that Stehman and I decided that a page of comment would be sufficient.

This thesis, therefore, is exactly the manuscript that David would have presented with the addition of this comment.

Each of the cores with which this study deals is stratigraphically unique. Each locality shows a continuum of pelagic sediment with changing sedimentation rates, erosional surfaces and current deposited sequences that do not correlate from locality to locality (Stehman, 1975). This fact alone can be used to explain the puzzling differences in cores encountered in Charlie's study. The model presented in the Clark's discussion cannot usefully be applied, as Stehman has shown that little relationship occurs between physical sediment parameters and climate in the study. However, the important information which justifies presentation of this study is the nannoplankton data which shows variation and climatic history consistent with the climatic information determined by Stehman on the same set of cores. The arrival at conclusions, using an independent technique, similar to those already arrived at through sedimentological analysis attests to the thoroughness and care of the author and the ?reliability of his floral data.

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