A MID-CARBONIFEROUS UNCONFORMITY IN THE SKIPTON ANTICLINE

Abstract

From Skipton to Bolton Abbey, Carboniferous rocks are broadly folded into an anticline known as the Skipton Anticline. The greater part of the succession exposed in the anticline is mainly composed of dark-grey argillaceous limestones and shales, a Carboniferous facies usually referred to as the Culm facies. These beds are of Lower Carboniferous (Dinantian) age. The upper beds exposed on the flanks of the anticline are mainly felspathic sandstones and shales of Millstone Grit facies and Namurian in age. At three levels in the Dinantian, the rocks are limestones with little or no shale. These limestones are fossili-ferous and their position in the Lower Carboniferous zonal sequence with an estimate of their very variable thickness was given in 1926, as follows[*][1]:— | Namurian | { | | Basement Grits | | | || | E1 | Upper Bolland Shales | } | 700 ft. | | Dinantian | { | P | Lower Bolland Shales | | | D1 | Eastby Limestone | | 250 ft. | | | Shales with Limestone | | 1400 ft. | | S | Embsay Limestone | | 400ft. | | | Shales with Limestone | | 1600 ft. | | C | Haw Bank Limestone | | 800 ft.+ | The Skipton-Bolton Abbey area is part of the Craven Lowland basin of sedimentation which existed in Dinantian and Namurian times south of the Craven Highland massif. As the rocks of the Skipton anticline are almost entirely of Culm facies, the area has therefore been considered as part of a mid-basin facies belt, one of the series of facies-belts into which the Craven Lowlands have been divided.[†][2] In no part of the succession of the Skipton anticline is there any development of reef limestone, characteristic of a marginal facies belt. Whereas … [1]: #fn-1 [2]: #fn-2