Geological investigations of the Lizard District, Cornwall, England: 1818–1883

Abstract. A lower Paleozoic slab of oceanic lithosphere was obducted onto the southern margin of Avalonia during the Variscan orogeny and is now exposed throughout the Lizard District of Cornwall, England. This complexly faulted and metamorphosed region of mafic and ultramafic rocks has been the subject of geological investigation for over two hundred years. Herein the most significant scientific contributions made over a sixty-five-year interval from 1818 to 1883 are reviewed. Early workers, including Ashurst Majendie, Adam Sedgwick, John Rodgers, and Henry De la Beche, conducted field-based studies of the region, making lithologic observations and mapping contacts between the major rock units. Subsequently, an intense phase of investigation into the processes and products of contact and regional metamorphism in Cornwall and the Lake District informed and inspired the field and microscopical studies of the Lizard District by Thomas G. Bonney. Detailed consideration of the pioneering work of these 19th century geologists provides insights into their methodologies as well as an evolving understanding of the complex and enigmatic rocks of the Lizard.