Intra-Jurassic Movements and the Underground Structure of the Southern Midlands

Abstract

Summary1. The occurrence of anticlinal folding during Jurassic times has been demonstrated by Mr. Buckman's detailed zonal work in the Vale of Moreton and in the North Cotteswolds. These anticlines are indicated on the map by marked bends in the outcrops of the Lower Jurassic formations.2. Similar bendings of outcrops are seen at several localities in the Eastern and Southern Midlands, and the structure at one such locality—Melton Mowbray—has recently proved to be anticlinal.3. Intra-Jurassic folding betrays itself by non-sequences and reduced thicknesses of Lower Jurassic zones along anticlinal axes. Such evidence suggests the existence of anticlinal structures in the neighbourhood of Banbury, Weedon, and perhaps also Market Harborough, in addition to the cases mentioned above.4. Movement was probably almost continuous along some or all of these axes, at least from Rhætic to Bajocian times. Outcrops of post-Bathonian formations are not affected by the flexures, although the folding was perhaps renewed in later Jurassic or even Tertiary times.5. Several of these lines of Jurassic folding probably follow the lines of earlier and more powerful movements. The bearing of such flexures on the structure of the Palæozoic floor is discussed.6. Attention is called to a curious symmetry in the disposition of the Palæozoic formations on either side of a prolongation of the Pennine axis.