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. Fig. 1. Old Red Sandstone Cliffs, Bard Bressay and Noss. 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 … Read More

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Fossil folklore: Fish

Paul D Taylor and Mike Smith (UK) Fish are the most diverse animals with backbones – that is, vertebrates – living today. Bone and teeth of fishes abound in the fossil record, from the armour-plated, primitive fishes of the Devonian, through the cartilaginous sharks with their shiny dagger-like teeth, to the bones of advanced ray-finned teleosts related to modern carp and cod. Along with other marine fossils, fossil fishes were once used as ‘proof’ of the biblical deluge, for example, the fabulous Cretaceous fossil fish deposits of Lebanon. Gayet et al. (2012) recorded that, in the third century, the Bishop of Palestine wrote: That Noah’s Flood covered the highest mountains is for me the truth, and I say that the witness of my eyes confirms it: for I have seen certain fishes, which were found in my lifetime on the highest peaks in Lebanon. They took stones from there for construction, and discovered many kinds of sea fishes which were held together in the quarry with mud, and as if pickled in brine were preserved until our times, so that the mere sight of them should testify to the truth of Noah’s Flood”. Petrified nails Hugh Miller, in his book Foot-prints of the Creator (Miller, 1849), mentioned that amateur geologists of Caithness and Orkney would refer to one particular fossil in the Old Red Sandstone, presumably relatively common, as ‘petrified nails’ (Fig. 1). Fig. 1. A so-called ‘petrified nail’, about 150mm long, as depicted by Hugh Miller. These fossils represent … Read More

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Hutton’s unconformity and the birth of ‘Deep Time’

Dr Mark Wilkinson (UK) I sometimes ask a question to students in an introductory class about geology: “What is the most famous geological site in the world?” For students from the western hemisphere, the Grand Canyon in the USA is a popular choice. However, if you were to ask the same question to a group of geologists, you might get a different answer, and one option is Siccar Point on the coast some 65km southeast of Edinburgh in Scotland. Although the site itself is relatively modest, a gently sloping platform of rock partly washed by the sea at high tide, and it lacks the spectacular grandeur of the Grand Canyon, the historical significance easily outweighs the lack of scenic drama. I’ve taken several groups of visiting geologists to the site, and so far only one of them has knelt and kissed the ground, but the site could be considered to be one of the ‘holy’ sites of our science. It is difficult for most modern geologists to imagine the world when any interpretation of the geological record had to be constrained by the literal interpretation of the Bible. A particular problem is the short timescale of the account of the creation of the Earth in Genesis, and the age of the Earth as calculated by Bishop Ussher, who allowed only some 6,000 years for the whole of geological time. The person who is frequently credited with expanding geological time to the ‘deep time’ we know of today is James Hutton. … Read More

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Urban geology: New Red Sandstone at Amsterdam Airport

Stephen K Donovan (The Netherlands) In a country with a limited resource of pre-Quaternary geology in outcrop, the Netherlands nevertheless has a wealth of rock types in building stones (Donovan, 2015a; Donovan and Madern, in press), street furniture (Donovan, 2015b) and artificial ‘outcrops’ (Donovan, 2014). Perhaps the commonest rock type seen in Dutch cities is limestone, particularly imported Mississippian (Lower Carboniferous) limestones (van Roekel, 2007; Donovan and Madern, in press), but also Upper Cretaceous limestones from the province of Limburg in the south of the country (van Staalduinen et al., 1979, p. 47). Less common are massive sandstones, both used as building stones and occurring as boulders (Donovan, 2015b) – most of these that I have seen are, presumably, Pennsylvanian (Upper Carboniferous). The area of outcrop of Carboniferous rocks in the Netherlands, again in the province of Limburg, is limited. Carboniferous rocks used for buildings or street furniture are assumed to come largely, probably entirely, from the more extensive outcrops that are quarried elsewhere. One rock type that is not commonly encountered is red siliciclastic rocks such as siltstones, sandstones and conglomerates. This is despite the broad distribution of the Permo-Triassic New Red Sandstone (NRS) in northern Europe (Hounslow and Ruffell, 2006, fig. 13.2). In my pursuit of river-rounded boulders in the human environment of the Netherlands, I have only seen one NRS specimen of note – a coarse-grained sandstone with abundant gravel-sized fragments truncated by a scoured, erosive contact with an overlying conglomerate (Fig. 1). This is at the … Read More

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