Intra-Carboniferous deformation and unconformity at Gilnockie Bridge, SW Scotland, reinterpreted as the result of multiple channel-bank collapse

Abstract

The unconformity and deformation in Pennsylvanian strata seen at Gilnockie Bridge have previously been taken as being illustrative of the erosion and break in sedimentation between the Pennine Lower Coal Measures and Stainmore formations on nearby syndepositional anticlinal crestal areas in the Canonbie Coalfield, SW Scotland. However, Gilnockie Bridge is located in a synclinal position, and re-examination of the exposures suggests that the complex deformation seen there is a localized synsedimentary feature, resulting from multiple phases of river channel-bank collapse. This bank failure was possibly associated with contemporary movement on the nearby Gilnockie Fault, but not necessarily related to the unconformity on the nearby anticlines.