Abstract

The proposal for a symposium on the Triassic rocks of Britain sprang from two sources. The first was the inauguration by the Council of the Geological Society of a series of Committees to review the stratigraphical nomenclature and correlation of the Phanerozoic rock succession. It was apparent in the case of the Trias that existing published data provided an inadequate basis for such a review, and that it was desirable to organize up-to-date regional appraisals of modern information.

The second incentive was provided by the very vigorous discussion which followed the reading of Dr Audley-Charles' paper on the Stratigraphical Correlation of the Triassic rocks in Britain, a discussion which showed that much unpublished information in fact existed and that particularly critical aspects of the correlation could be investigated on the basis of existing data. In addition results of a study of the correlation of the German succession with the North Sea Trias and that of eastern England have now become available.

The major problem which has remained unsolved in British Triassic stratigraphy has been the establishment of reliable time planes, in a series which is essentially continental and lacking macrofossils, and in which classification has hitherto been entirely on a lithostratigraphical basis. New data of correlative value are now being supplied by palynological investigation, by evidence at some horizons from microplankton, by study of cyclothemic units and by electric, radioactive and mechanical logging of boreholes. The original basis of correlation is therefore being replaced by new lines of investigation many