Northern Rocks: Shetland
Neville Martin (UK)
Shetland is famous for many things including ponies, knitwear, sheep and sheepdogs, birdlife and fishing. It is less well known for being an excellent attraction for the geologist or that it is currently going through the process of qualifying for European and World Geopark recognition. The rocks of Shetland are too old for fossils with the exception of some fish and aquatic plant fossils at the southern and western extremities. However, what it lacks in fossils it more than makes up for in an abundant variety of minerals and geological structures and, while looking for minerals, the geologist can enjoy some of the most spectacular seascape in the UK. In addition, the islands have a long history of mineral extraction and there has been talk of possible, future platinum and gold mining.
One of the reasons for the geological diversity is that the Great Glen Fault, which formed Loch Ness, also manifests itself in Shetland. This gives rise to a displacement of some 60 to 80km, such that there is a distinct difference between East and West Shetland. The landscape is also the result of sculpturing by glaciers and the sea. The many submerged, glacial valleys are called “voes”, the largest of which is Sullom Voe, the site of the oil terminal where oil from north, east and west of Shetland is landed. The shelter provided by such a large voe (which is sea loch) made it an important flying boat base and airfield during the Second World War and remnants of these days are still evident.
Getting to Shetland in the past was a challenge with all links being through Scotland, mainly via Aberdeen (a one hour flight or 12 hours overnight sailing). However, over the last few years, things have got easier with sea links to the European mainland (Denmark and Norway) and direct summer airlinks to Stansted (by the Faeroese Atlantic Airlines).
The islands are much larger than many realise, covering 1,426km2 and consisting of over 100 islands (with 15 being inhabited). Arriving at Sumburgh Airport at the southern tip of mainland Shetland, you have a 100km drive and two ferries to reach the northernmost tip of the island of Unst. At the airport, you will notice the Shetland flag, which is based on the Scandinavian Cross, indicating where much of Shetland’s cultural identity lies.
The rest of this article takes the form of a guided tour. Obviously, one can pick and choose where to go and what to see in Shetland but, hopefully, it will give you some idea of the places one can visit.
When leaving the airport, one should start by driving up to the Sumburgh Lighthouse that sits on top of a massive, red sandstone promontory with spectacular cliffs. Then drive north via Bigton to see St. Ninian’s Isle that is connected to the mainland by a sand tombolo. A few miles further north and on the east side is Sandwick. This was the major, copper-mining area up to the 1920s and limonite and hematite can also be found here. Samples of malachite can sometimes be found by the cliffs at Sandsayre. One of the mineshafts went under the Mousa Sound that is the body of water separating the mainland from the island of Mousa and home of the famous 2,000-year-old Mousa Broch (an Iron Age, dry stone, defensive structure). The island was the location of a quarry for hardwearing, sandstone flags used in Lerwick. Another mile north at Catpund, the remains of Viking quarrying activities for talc (soapstone) can be found.
On reaching the Shetland capital of Lerwick, you should head to the new museum where there is a large collection of the sort of minerals you can look for (see the pictures accompanying this article). The collection was assembled by Professor Derek Flinn of Liverpool University. At Lerwick, there are also some excellent examples of conglomerate rock that originate from the build-up of alluvial fans onto an ancient braid-plain.
From Lerwick, there is a variety of locations and geology to see. For the sake of this article, we will continue north to the islands of Yell and Unst. However, if you have time, you should detour to Northmavine to see the magnificent stacks off Eshaness and the granite cliffs of Ronas Voe that provide evidence of a volcanic past. At the Back of Ollaberry, there is a magnificent exposure of the Walls Boundary Fault that is likely to have been linked to the Great Glen Fault. Evidence can also be found at various locations of sand and rocks washed up from a tsunami as a result of a massive underwater landslide off Norway.
Half a kilometre west of the Loch of Girlsta can be found the second highest gold concentration in Shetland. In addition, copper in the South Nesting area, lead and zinc ores can be found close to the major fault line. Crossing over by ferry to Yell, you should head towards Houlland for deposits of galena. Geologically, Yell is relatively uniform gneiss. However, the two neighbouring islands of Unst and Fetlar cannot be accused of uniformity.
The island of Unst probably holds the most interest to the amateur geologist as recent surveys have shown significant quantities of gold, platinum and palladium – there have been numerous reports of gold being panned in the Muness area. Further north, at Hagdale, are the remains of a chromate mine. The crushing circle or “horse mill”, where a horse went round all day grinding the ore, has now been restored. There are also remnants of the longest railway that was ever constructed in Shetland on which horses pulled the ore-ladened wagons down to the pier. Further north still, at Clibberswick, is a still-functioning talc quarry.
This article is only a brief description of the wide variety of geology that can be found in Shetland. If visiting, a vehicle is essential to cover the large distances although the more adventurous could try bikes. For an introduction to Shetland, it is recommended that you contact the Shetland Tourist Centre (01595 693434) that can give you details of guided tours by Shetland Geotours (www.shetlandgeotours.com).