Gallery of Carboniferous at Doolin and Fisher Street, Co Clare
Photographs taken in June 2008 on the SEPM Field trip to Co Clare, Ireland, by Christopher Kendall of Carboniferous outcrops at Addragoole west of Doolin and close to Fisher Street. These included the Dinantian Burren Limestone Formation and the overlying Namurian Clare Shale and Gull Island Formation.
The images of the Dinantian Burren Limestone Formation include karst pavements and the associated topography. Exposures can be seen to be composed of shallow water carbonate. Note the clints (limestone blocks) and grikes (joints and fractures formed by Variscan folding (Coller, 1984)) extensively enlarged by Pleistocene dissolution (Williams, 1966). Even though the shore is almost devoid of vegetation, some still is colonizing the elevated areas above sea level with prominent grikes.
The images of the overlying Namurian Clare Shale and Gull Island Formation were taken in the steep cliffs to the south east of Fisher Street. Here the work of Gill (1979), Collinson et al. (1991), Martinsen & Collinson (2002), Martinsen et al. (2003), and Strachann and Alsop (2006) suggest the the base of the Fisherstreet Slump within the Gull Island Formation on the basis of the Goniatites in the marine band R. dubium (R1a5).
Strachann and Alsop, (2006) report that the Gull Island Formation is 140 m thick in the Burren region though it reaches 550 m in the vicinity to the Shannon Estuary.
The outcrops in the image gallery are fine-grained sandstones and siltstone
s and where they occur towards the base of the formation are characterized the slumped structures of the Fisherstreet Slide. Strachann and Alsop, (2006) indicate that the slide is overlain by a rippled sandstone bed
that contains flute marks, tool marks, and sand volcanoes that they interpret formed during late-stage dewatering of the slumped beds. As in the outcrops to the south the formation represents tubiditic deposition on an unstable shelf margin, possibly a pro-deltaic slope, that prograded eastwards into the Shannon Trough (Collinson et al, 1991).
Bibliography and References
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Collinson, J.D., Martinsen, O., Bakken, B. & Kloster, A.(1991), Early ¢ll of the Western Irish Namurian Basin: a complex relationship between turbidite
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Williams, W. (1966), Limestone pavements with special reference to Western Ireland. Transactions of the Institute of British Geographers 40, p. 155