In 1930, Colman (1933) made a study of the zonation of common intertidal animals and plants on Blackstone or Church Reef, Wembury. Four lines were marked out across the reef, and three of these, which radiated from his so-called ‘Central Rock’, were resurveyed during the summer and autumn of 1973. Besides the authors, help was given in the 1973 survey by Mr P. G. Corbin, Dr P. E. Gibbs, Dr P. K. Probert, Dr A. J. Southward, Mr R. L. Barrett and Mr T. J. Perry. Mr G. A. W. Battin was responsible for surveying and levelling, and Mr D. Nicholson for the photography.