THE RHAETIC BEDS OF THE NORTH-EAST MIDLANDS

Abstract
Summary: Rhaetic strata of the NE. Midlands are represented by the Westbury Beds (Black Shales) and Cotham Beds, with a possible thin representative of the Langport Beds. The Sully Beds are absent. The evidence does not support suggestions that the Rhaetic sea invaded England from the east, across south Lincolnshire. In north Lincolnshire sandstone beds become important in the Black Shales, and are locally notable in the Upper Rhaetic also. From near Lincoln northwards reddish clays and shales are developed in the Upper Rhaetic, a partial reversion to Keuper conditions. There is a marked increase in thickness in north-west Lincolnshire, moderate thinning in the area immediately south-east of Lincoln, and strong attenuation in the Grantham district. Thickness changes in the Rhaetic are proportionately much greater than in the formations above and below. Regarded regionally, they correspond with major structures in the Carboniferous floor, and reflect movements related to the earliest known development of the Market Weighton uplift.

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