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The line of correlation (LOC) in the graphic correlation of the 27 sections in a Frasnian composite standard conforms empirically to the pattern of biostratigraphic events, the bases and tops of ranges of conodont species. The guiding principle is to position the LOC so as to avoid range overlaps of well understood species that have not been observed to overlap in an actuaJ section. Several of the graphs used in the Frasnian composite standard display linear arrays through which the LOC effectively splits the bases and tops of species ranges. The patterns of arrays in other graphs, however, indicate a doglegged solution to the LOC, implying major changes in the accumulation rate within the section plotled against the composite axis. We do nol assume that a uniform rate of accumulation at the standard reference section (from which the scale of the composite axis derives) is necessary for the empirical effectiveness of graphic correlation.

The problem of correlation between the mostly mutually exclusive Palmatolepis and Polygnathus Frasnian conodont biofacies has been insoluble by traditional zonal biostratigraphy. The graphic correlations proposed here advance an initial hypothesis toward resolving the correlation of these biofacies. Subdivision of the Frasnian into 34.5 composite standard units represents a far finer resolution than any available through zonal biostratigraphy.

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