Coastal Musings

During two weeks in June 2009, the British Geological Survey will carry out a low level airborne survey of Anglesey and north east Gwynedd around Bangor and Caernarfon, North Wales. The aircraft used will be a De Havilland Twin Otter with a distinctive red and white striped tail-plane and registration OH-KOG. It will fly along a regular series of lines 200 metres (656 ft) apart, oriented north-south and at a height no lower than 56 metres (185 ft) as it gathers information on the local geology and environment. The aircraft will be based at Caernarfon Airfield for the duration of the 2-week long survey.

The most important measurements in this particular survey will be made with an electromagnetic system; this records variations of electrical conductivity in the shallow earth which may reflect land quality. The plane’s other sensors measure magnetism, which can indicate rock type and structure, and natural gamma spectrometry, which reflects mainly the type and condition of the soils.

David Schofield, senior geologist at the British Geological Survey said: “Anglesey has been the subject of geological controversy from the earliest days of the geological sciences. Some of the oldest rock in the British Isles, south of the Scottish Highlands are preserved on Anglesey and the island has long been considered by scientists as a ‘test-bed’ for understanding the processes by which the fundamental building blocks of southern Britain were assembled.”

“The most recent geological survey was published in 1920, however significant advances in geological sciences and a large body of research carried out on the island have necessitated this new survey. Our mapping team will be using all the modern techniques available to bring the map up to a modern standard. Of these, the airborne survey will probably provide one of the most significant new datasets for interpreting the geology.”