This letter gives a brief preliminary description of computer programmes for use by structural geologists. Since the GODPP was described at the Tectonic Studies Group meeting at Dundee in December 1976 a number of workers have expressed interest and this letter is intended to make the existence and scope of the package more widely known. Copies of the programmes involved may be obtained from the authors at University of Bristol.
The Geological Orientation Data processing package (GODPP) is a package of computer programmes principally aimed at helping the field geologist to process large quantities of structural and sedimentological orientation data. The programmes have been so written as to be independent of the model of computer used (see Appendix).
The package offers the plotting of orientation data on stereograms, maps, and rose diagrams and also offers reorientation routines.
This section of the package has facilities for producing Pi diagrams and contoured Beta diagrams with options for a vector mean or a best fit great circle, with the appropriate statistics (Mardia 1972). A large number of programmes to plot stereograms have been published (Robinson et al. 1963, Spencer & Clabaugh 1967, Warner 1969 and Bonyun & Stevens 1970). The majority produce line printer output, although a graph plotter has been utilised for the plotting of Pi diagrams (LaFountain 1970), but not apparently for contoured diagrams. GODPP has the advantage of producing Pi diagrams and contoured stereograms on a graph plotter. It also produces line printer output of contoured diagrams which allows