The local geology is complex ; the area lies astride the Church Stretton Fault and atop some of the oldest rocks in England – formed over 560 million years ago . On 2 April 1990 , another nearby fault – the Pontesford-Linley Fault – registered an earthquake with a magnitude of 5.1 on the Richter scale , known as the Bishop 's Castle earthquake . The area also plays a part in the history of geology ; the three major subdivisions of the Lower Paleozoic are named from local celtic tribes : Cambrian , Ordovician and Silurian . Also , Comley Quarry is about from the town and the first site in the British Isles where trilobites were recorded
Bishop 's Castle earthquake
1990 Bishop's Castle earthquake
Church Stretton