Spur and groove morphology from a Late Devonian reef

Spur and groove structures form on the windward side of modern coral reefs in response to wave action. Hitherto, no examples have been confirmed in th e Palaeozoic record. We confirm here ancient spur and groove morphology fro m the Teichert Hills, an exhumed platform atoll from the Upper Devonian (Fr asnian) reef complex of the Canning Basin, Western Australia. Oriented grow th of the reef-building metazoans (laminar tabulate corals and stromatoporo id sponges) proves an organic and constructional origin for the spurs. Groo ves acted as sediment traps that filled with coarse bioclastic sand and win nowed brachiopods derived from the back reef and reef flat. Geometry and st yle of ancient spurs and grooves may provide indications of ancient synopti c hydrodynamic regimes: on the basis of the relationship between modern cor al reef spur orientation and incoming wave direction, these ancient spurs a re inferred to have formed normal to refracted waves. The presence of these structures offers unequivocal evidence for the active growth of mid-Palaeo zoic reefs in wave-dominated hydrodynamic regimes, and demonstrates that re ef-building biota can show a common morphological response to wave energy i ndependent of taxonomic position. (C) 2000 Elsevier Science B.V. All rights reserved.