Abstract - We thank James for his comments on the ideas we put forward to explain the intriguing and, in some respects, enigmatic features associated with the Lake Hope polygonal fault system. We recognise the uncertainties concerning the mechanism that has given rise to these and to similar faults elsewhere, which have stimulated an unusually wide variety of interpretations. However, so far as was possible we followed our normal practice of giving greater credence to the relative certainties of the geometrical and kinematical data and conclusions, than to an inherently uncertain dynamical interpretation. In responding to James's comments we wish to emphasise that models proposed for natural structures invariably represent simplifications that will not match individual examples in every detail. In this case of a new model for a widespread but only recently recognised type of fault system, the crucial question is whether or not this type of fault system is generated by a density inversion beneath the faulted sequence. Our model is similar to that of Henriet et al. (1991), who also attribute the formation of folds and faults to density inversion, but it differs significantly from the model of Cartwright & Lonergan (1996, 1997). Although we have confidence in the model proposed, we expect it to undergo progressive refinement as further data for this and similar related systems become available. This refinement will, eventually, allow a more precise description of both the structures and the mechanism than we have been able to provide. At this stage, however, we believe the model presented is the one that best accommodates the existing evidence and data constraints.
Journal of the Geological Society, London,
157, 1261-1264, 2000.