Rocky shore environments in the Upper Silurian of Gotland, Sweden

The Ludlovian Hemse Group (Hemse Beds) of Gotland, Sweden, shows excellent examples of stromatoporoid biostromal reefs which are punctuated by evidence of episodic erosion. These result in irregular unconformities exhibiting sea stacks, shallow cliffs and planar erosion surfaces; these are interpreted as representing the development of carbonate rocky shorelines. Eroded reef surfaces are overlain by a variety of calcarenites and calcirudites, with the coarse grained and conglomeratic portions associated with the stacks and cliffs. Eroded surfaces are smooth and vary from planar to scalloped. Rare, eroded auloporid and bryozoan colonies encrust erosion surfaces and imply a fully marine environment, although under physically stressful conditions. The stromatoporoid biostromes were associated with rocky shores at various stages during the evolution of a biostromal reef complex. Rocky shores are poorly reported from Silurian rocks, but such environments have been recognised at several horizons in the Silurian of Gotland, demonstrating their importance in the sequence development.