Geological Curiosity in Western Ireland

November 07, 2017

Fanmore_IMG_3053 (2)

Aral_Islands_IMG_3002 (2)

Photographer: Jim Bucko 
Summary Authors: Jim Bucko; Jim Foster 

The photos above show limestone erosion patterns observed in western Ireland. The top photo was taken on the coast, near Fanore, and the bottom photo was captured on the Aran Island of Inisheer. Limestone on the Aran Islands is an extension of the limestone hills found in the Burren region, on the mainland of western Ireland. In both locales it erodes in a curiously consistent manner; in squares or rectangles. The cracks are called grikes and the resulting blocks are called clints. Evidently, preexisting vertical joints in underlying rock types have contributed to the formation of the fissures and pavement-like slabs in the limestone here. Note that the bright green substance coating the blocks closest to the shore in the foreground is a type of marine algae.

Photo Details: Top - Camera: Canon PowerShot SD1200 IS; Focal Length: 6.2mm; Aperture: ƒ/2.8; Exposure Time: 0.0025 s (1/400); ISO equiv: 80; Bottom - same except: Exposure Time: 0.0016 s (1/640).