The Geological Society of London has permitted me to quote widely from their excellent collection of papers in 'Magnetism and the causes of continental break-up' (eds. Storey, B., Alabaster, T. and Pankhurst, R.), Geol. Soc. of London, Special Publication 68.

The AGSO Journal of Australian Geology and Geophysics has also permitted me to draw upon the various excellent papers by R.S.Dietz, E.M.Shoemaker and C.S.Shoemaker, R.A.F.Grieve and M.Pilkington, and other leaders in their various fields. The general editor was A.Y.Glickson who, in addition, presented interesting papers. Unfortunately several of the 'elder statesmen' at this conference failed to last out the century.

Many of the diagrams in the text relate to arguments presented by various workers. Wherever possible, I have obtained permission from the author(s). However, many of the cited authors have died, sometimes decades ago. Hugh Heard, a close friend, was one such who fell by the wayside.

The Geological Survey of Canada have mapped wonderful structures in the northern regions of that country. Many of the structures are best seen in mosaics compiled from earlier photographs. The Geological Survey of Canada generously permit such photographs to be published, with acknowledgement.

An unusual situation exists regarding a coloured photograph of a 50 km diameter impact structure in the Sahara. This photograph is shown on page 25 of An Encyclopedia of Geology (1977), edited by A.Hallam. Without doubt, the photograph of this wonderful structure, which must be attributed to NASA, was taken sometime prior to 1977.

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