Carboniferous evolution of The Burren and Cliffs of Moher

The Mississippian limestones of the Burren are exposed in an exceptional glacio-karst landscape in extensive exposures. These bioclastic limestones range in age from the Holkerian to Brigantian regional substages of the Viséan, based on foraminferan assemblages.The platform carbonate succession contains cyclic sedimentation patterns with bryozoan, crinoidal, coral, brachiopod and algal communities responding to glacio-eustatic cyclicity. The formations exposed are the Tubber, Burren and Slievenaglasha formations. The Burren Formation contains well-developed palaeokarst horizons.
The Cliffs of Moher expose Pennsylvanian deltaic siliciclastic sedimentation. These units form part of a fine-grained continuous basin-fill sequence recording offshore prodeltaic through prograding delta slope to delta top environments. Thicker, coarser sandstone beds are readily visible as they project slightly and form overhanging ledges. Channels are clearly seen in some sections.The exceptionally large outcrops of the Cliffs of Moher host a growth-fault complex which affects strata up to 60 m in thickness and extends laterally for 3 km. The succession contains laterally extensive condensed horizons in shales with bands of ammonoids that range from the H1b to H1c ammonoid biozones (Chokierian to Kinderscoution regional substages). Thin sandstones known locally as ‘Moher Flagstones’ contain an abundance of the trace fossil Psammichnites, that are used for facing, paving and roofing.