The origin of Ot Moor, Oxfordshire, England

Abstract

Ot Moor, a sub-basin of the River Ray catchment, developed during the late Wolstonian to Devensian period. Previously, water drained at various times through four gaps, three westward into the River Cherwell and the fourth southwards into the River Thame. Up to the late Devensian, the area was drained by at least two major streams which deposited lithologically distinct sediments, thus enabling their former courses to be defined. The southerly gaps were abandoned before the deposition of the First Terrace deposits. During the late Devensian, Ot Moor was drained by the Eastern Ray which flowed out of the basin through the Oddington Gap-Islip ‘Gorge’ features. The Eastern ray subsequently captured the Northern Ray diverting it into Ot Moor and abandoning the Hampton Poyle Gap. The Ray catchment has a rapid run-off and is subject to frequent flooding. As the base level of erosion was lowered, three gaps were abandoned leaving only the Islip ‘Gorge’-Oddington Gap outlet. Further downcutting revealed resistant Cornbrash thereby restricting the escape of flood waters. The consequent back-ponding led to the deposition of a wide tract of alluvium, which encompasses Ot Moor and extends up the tributary streams, locally enclosing outcrops of older drift deposits and Jurassic strata.