The Tectonic Structure of the Howardian Hills and Adjacent Areas

Yorkshire can be subdived into structural units based on the control exerted by various fold-lines or block-faulting movements. Certain difficulties are encountered when the structures in the eastern part of the county are examined. The north-eastern unit, the Cleveland Hills, is dominated by the large east-west anticline which passes out to sea at Robin Hood’s Bay. The influence of this fold is felt as far south as the Wolds, where it has impressed a southerly dip on the Chalk. The Upper Cretaceous rocks have, however, been influenced by other lines of movement for the quarter-basin structure they show involves the effect of a fold with Malvernian trend—presumably the Pennine fold. North-west of the Wolds and south-east of Cleveland lie the Howardian Hills, “one of the most intricate pieces of geology in N.E. Yorkshire.”1 The hills are crossed by a complicated network of faults, while folding- is apparently non-existent. According to Fox-Strangways, these faults represent a great east-west dislocation “which, finding the strata thinnest and weakest along the Howardian range of hills, has shattered them, causing the irregularity of outcrop.”2 The present paper is an attempt to elucidate and explaim the structures and to show their bearing on the tectonice structure of the areas. The Faulting. The northern boundary of the area is marked by two important faults forming the Coxwold-Gilling valley. Starting in the Magnesian Limestone north of Ripon, they continue in an east-west direction across the Vale of York maintaining parallelism for a considerable distance, but near Coxwold ...