Geology of the Newquay district : a brief explanation of the geological map Sheet 346 Newquay

This Sheet Explanation presents an account of the geology of the district covered by the Geological 1:50 000 Sheet 346 Newquay, published in 2012. The district is mainly underlain by Upper Palaeozoic rocks of Devonian age. These have undergone deformation in the Variscan Orogeny, a northward propagating mountain building event which commenced in the Devonian in this area, and are variably folded and faulted. Minor granite intrusions of latest Carboniferous to early Permian age occur near the coast and Cenozoic deposits are present locally around St Agnes, in the west. The regional strike in the district, and across the Cornish peninsula, is east–west, so coastal exposures afford a structural crosssection that is almost at right-angles to strike. Several notable early workers commented on aspects of the geology in the district, among them Borlase (1758), Conybeare (1817) and Sedgwick (1820), though the earliest detailed geological notes were published in 1839 by Sir Henry De la Beche, to accompany a geological map published in the same year. Further metalliferous lodes were added subsequently to De la Beche’s map by Sir W W Smyth (1858), and the work was republished in 1866. Survey at the same scale (1:10 560) by Clement Reid, J B Scrivenor and D A MacAlister was carried out around 1900–1905 and published in 1906 at a scale of 1:63 360. A reprint of the Newquay geological sheet, based predominantly on previous work, but converted to the modern 1:50 000 scale, was published in 1974.