Dr Trevor Watts (UK) We (my wife Chris and I) enjoyed our fourth visit to Big Island Hawaii in May 2013 so much that we decided to return to the same places in October 2014. We were hoping to see similar events and activities, which we had found particularly interesting and accessible over the years. Every time we visit, something changes or isn’t possible, but this time was a little more changeable than most. The intervention of three ladies altered a few of our plans – Iselle, the hurricane that visited the southeast of Big Island two months before we arrived; Madame Pele, the Hawaiian Goddess of the Volcano; and Ana, the hurricane that hit the area during our stay. The three interventions illustrate the simple fact that we and our little plans have to be adaptable and show that some of the great locations will be discussed in these articles and will be missed if you only make one visit. This is the first of three articles on Big Island in Hawaii. In them, I will talk about the major highlights of our visit in connection with the volcanic activity of this wonderful island. This first part will mostly illustrate the different volcanic concepts that need to be understood to appreciate what can be seen, and will also provide a general background to the location and the significant summer 2014 flow towards Pahoa. About lava Traditionally, lava is described as pahoehoe or a’a. These are taken to mean ropey … Read More
Mark Wilkinson (UK) The Armboth Dyke makes a good half day geology excursion in a scenic but quiet part of the UK Lake District. Parking is on the west shore of Thirlmere, in a pay-and-display car park accessed by the narrow road that winds around that side of the lake (Grid reference NY 305 172). The car park is in an excellent setting, with direct access to the wooded lake shore, and would be a great place for the non-geologically minded to wait while you venture onto the adjacent hill. It is probably worth noting at this point that the dyke itself is mostly exposed on rather featureless rolling moorland at around 400m above sea level (Fig. 1), and might not be a good place to visit in thick mist, unless you are very confident with a map and compass. If you happen to be in the business of teaching students to make geological maps, this site makes a great practise day, without too many problems of recognising weathered rocks in the field. Fig 1. Moorland with the dyke just visible as a slightly lighter patch of rock below the red arrow, where the edge of the dyke is exposed. University of Edinburgh students for scale. So, assuming you have decent weather, leave the car park and take the path uphill from the west side of the minor road, a few metres to the north of the car park. The path is steep-ish, and can be slippery if wet, so … Read More
Dr Trevor Watts (UK) This is the second and final part of an article on the volcanic highlights of Northern Ireland’s Giant’s Causeway and surrounds. For the first part, see Giant’s Causeway (Part 1): An introduction.) We were in the area for several days and the weather was fairly mixed, but there were glorious skies between the showers, and the high winds brought the waves up beautifully. Of the six highlights discussed below, we visited the first three in one day, as all were a few kilometres to the west of The Giant’s Causeway. Those to the east, we visited on another day. Fig. 1. A map of some of the highlights. They are all supremely interesting and give an idea of the range of volcanic features to be seen. You cannot see an actual, traditional volcano in Antrim, with its classic shape. However, you can visit many scattered and varied elements of the area’s vulcanicity, and so gain an appreciation of the overall picture. Fig. 2. Fanciful cross section of highlights. 1. Deep lava flows forming the Causeway Basalts and their columnar basalt features. Found at The Giant’s Causeway and Ballintoy Harbour. 2. Beds of red ‘laterite’ rocks and soils buried by the later lava flows. Seen along the whole coast, especially east of the Giant’s Causeway. 3. Multiple relatively thin lava flows forming the Lower Basaltic Series. Seen at The Giant’s Causeway area and Dunluce Castle. 4. Dykes bringing magma towards the surface through fissures of cracks in … Read More
Dr Trevor Watts (UK) This is the first of two articles on the volcanicity of the Giant’s Causeway and the surrounding area. The Causeway itself is an area of basalt columns, about 100m or so across, jutting into the Irish Sea. A remnant of a vast ancient lava flow, it is located in a coastal strip that is lavishly scattered with other superb volcanic features. The whole area is both beautiful and fascinating, and neither spoilt in any way, nor over-crowded out of season. We (my wife Chris and I) went there because I had a few days’ work in Northern Ireland and it seemed like a good idea to combine this with a short break during an October, half-term school holiday. Fig. 1. The Giant’s Causeway, battered by curling waves, becomes a sunlit wonderland in the evening light of autumn. The geology of the Giant’s Causeway The long-held theory that the Causeway was created by an Irish giant called Finn MacCool in Middle Earth times has – sadly – been discredited. Around 60mya (in early Tertiary times), great masses of molten rock were rising from the depth of the earth’s mantle, probably centred beneath present-day Greenland. These nation-sized ‘lava-lamps’ are collectively considered to be a ‘hot spot’, now known as the ‘Iceland Plume’. They split the earth-wide continent of Pangaea apart in great cracks that were aligned roughly northwest to southeast. This was sufficient to split the land apart on a vast scale, beginning the opening of the Atlantic … Read More
I remember reading and enjoying this book when the first edition came out many years ago. I am also a keen hillwalker and have stood on top of many of the Scottish mountains referred to in the text. In fact, I particularly enjoyed climbing Ben More on the island of Mull, which I remember reading was the last volcano in northwest Europe.
Dr Trevor Watts (UK) Lanzarote is the easternmost island of the Canaries, less than 100 miles (about 150km) off the coast of Morocco. It is part of Spain, but not officially in the European Union and Pico Partido is a sharp, prominent peak near the centre of the island, between the small town of Mancha Blanca and the volcano of Timanfaya. The name means “divided mountain”, so called because the high peak is split by a deep fissure that seems to chop it in two. And it is enthralling. It is a basket of volcanic jewels to be treasured, particularly after the disappointment of the lack of access to Timanfaya itself (of which, more later). And Pico Partido is accessible, unlike much of the island where too many roads have no lay-bys or even a patch of cinder where you can pull in and explore. The geology of Lanzarote Lanzarote, with its volcanoes, is sitting on the tectonic plate that forms most of Africa. It is not near the edge, so it is not formed by one plate sinking under the other. Nor is it above a rising mass of magma, a hot spot. A little surprisingly, it is on a line of fractured rocks that stretches to the Atlas Mountains in North Africa, and further over to the European Alps. Fig. 1. The “Devil” sign that marks the start of the National Park, and the site of a parking space. The fractures formed, and are still moving, as a … Read More
RMW Musson (UK) For millions of people in the western part of Sichuan province in China, the morning of 12 May 2008 started out as a day like any other. People left their homes for work as usual, saying goodbye to family members without any thought that they would never see them again. Children packed into their school classrooms, their minds on lessons and games. It seemed like just another busy day. Fig. 1. Damage from the 2008 Wenchuan, China, earthquake. Photo by Raymond Koo, courtesy of EEFIT, UK. At 28 minutes past two in the afternoon, catastrophe struck. There was no warning – just a sudden terrific roaring sound, as buildings bucked violently, sending down clouds of plaster dust, and then giving way completely, as the heavy ceilings came crashing down. People outside were the lucky ones. For them, the ground itself rocked violently like the deck of a boat in a storm. All around, clouds of dust arose from collapsing buildings, amid the sounds of roaring, of crashing masonry and of screaming people fleeing into the streets. These scenes were repeated in the same instant across a huge area, nearly 300km long, at the edge of the Sichuan plain where the mountains of Longmen Shan rise up abruptly from the flat farmland. In the narrow mountain valleys, steep, rocky slopes came tumbling down, as massive rockslides added to the devastation and blocked the roads. In a matter of a couple of minutes, over 70,000 people were killed and … Read More
Dr Trevor Watts (UK) In 2012, my wife Chris and I booked a volcano tour around the north of Iceland. At the time, it was our third visit to the country, so we knew of extra things we wanted to do. Before joining the group with Volcanic Experiences of Bromsgrove, in the UK (www.volcanicexperiences.co.uk), we decided to have three extra days on our own. An hour on the Internet allowed me to book three unforgettable events. That really is all it took – and, incredibly, every company sent an email confirmation of my booking before the afternoon was finished. Fig. 1. The high point of Eyjafyallajokull’s rim – still steaming and too hot to sit down for long. The first was a 4 x 4 ride and then a three and a bit kilometre hike to the top of the now-famous Eyjafjallajokull volcano – still so hot underfoot that a dog with another group fled howling from the top of the ridge (Iceland Rovers: icelandrovers.is or http://www.2iceland.is).The second was a two-hour ‘Ice and Fire’ flight over the central part of the island, especially over the multi-coloured landscape of Landmannalaugar, with the campsite right at the edge of a lava flow (Eagle Airline, booked using Nordic Visitor: iceland.nordicvisitor.com).And the third was a trip down inside the emptied-out magma chamber of a volcano – Thrihnukagigur (insidethevolcano.com). And this is the subject matter of this article.Fig. 2. A view in the central highlands of Landmannalaugar, with multi-coloured hillsides, steaming vents, glaciers and a … Read More
Allen Fraser (UK) For a land area of just 1,468km2, yet within a staggering 2,731km of coastline, Shetland has probably the most complex and diverse geology and geomorphology to be found anywhere in the World. Part of Shetland’s Geopark plan was a suggestion from the community of Northmavine that a geological gateway be established to their area at Mavis Grind, and a volcano trail be set up around the dramatically beautiful Eshaness. Fig. 1. Map of Eshaness. Although it is hard to imagine today, some 350Ma ago, the peninsula of Eshaness was a fire and lava-belching volcano. In fact, the name “Esha Ness” comes from the Old Norse language and means the “Headland of Volcanic Ashes”. The beaches and cliffs of Eshaness show many fine examples of the rocks that formed in this ancient volcano and tell us something of the environment in which the volcano grew. Fig. 2. The Eshaness peninsula. Setting the scene Eshaness’ story begins some 400Ma (in the Devonian period) when three of the Earth’s tectonic plates converged and eventually formed a huge continent now referred to as Pangaea. This collision threw up the Caledonian Mountain chain that was originally of Himalayan proportions but which rapidly began to erode. Rivers carried the erosion products (sediments) into lakes that formed in valleys between the mountains and on the plains below the foothills of the mountain chain. At this time ‘Britain’ lay in equatorial latitudes so the rocks we see exposed today were often laid down in environments … Read More
Allen Fraser (UK) In September 2009, the Shetland Islands were awarded the accolade of becoming the thirty-fifth European Geopark. This is fantastic news for the isles. It acknowledges the importance of Shetland’s incredible geology and creates opportunities to promote it to an international market and develop partnerships with other members. When visiting, the best place to start your journey into Shetland’s ancient past is at Shetland Museum, in Lerwick. Here, displays take you back into the mists of time, revealing vanished landscapes and the amazing events behind them. All across Shetland, the rocks and landscapes tell an endless story – of oceans opening and closing, of mountain building and erosion, of ice ages and tropical seas, volcanoes, deserts and ancient rivers, of land use, climate change and sea level rise, and of minerals and miners. Around 360mya, a walk through where Lerwick is now, would have meant a wade across fast-flowing rivers, in a climate like that in Death Valley, California. How do we know? Well, if you take a stroll around Lerwick, and walk from the Knabb to the Sletts and out to the Sands of Sound, you can see for yourself. Here, flat-lying beds of thick, buff-coloured sandstone begin to acquire rounded pebbles and cobbles of pink and white quartz. These sandstone beds tell us that fast flowing rivers once deposited their loads in the area and that flash floods occasionally scoured the riverbed, leaving trains of far-travelled cobbles and pebbles embedded in the sandy layers. These rivers … Read More
Phil Stone (UK) Plate tectonics have produced some surprising juxtapositions, as the earth’s continental fragments have drifted and jostled over the eons. Microplates seem to have enjoyed most freedom of movement and none more so than that supporting the Falkland Islands. Though this archipelago is situated in the south-west corner of the South Atlantic Ocean, about 650km east from Tierra del Fuego and the Strait of Magellan, its geology tells of an African heritage. Charles Darwin provided the first evidence for that – although he didn’t appreciate it at the time. Fig. 1. A reconstruction of the Gondwana supercontinent at about 300mya. (© BGS/NERC.) HMS Beagle visited the Falkland Islands twice, in 1833 and 1834, and during the first visit Darwin discovered fossil shells, mostly brachiopods. His first impression had been unfavourable, but, after that discovery, he noted in his diary: “The whole aspect of the Falkland Islands were however changed to my eyes … for I found a rock abounding with shells; and these of the most interesting age.” Darwin published his account of Falklands’ geology in 1846. The “interesting age” proved to be Devonian and, as more data were acquired, a close and surprising similarity was established with the fauna of equivalent age in South Africa. This similarity was soon extended to other aspects of the Falklands rock succession, while the geology of neighbouring Patagonia proved to be quite different. These relationships were not readily explicable without recourse to continental drift, so were largely ignored for many years, … Read More
Robert Broughton (UK) The end Permian mass extinction occurred 251mya and marked the end of the Palaeozoic era. The loss of life is currently estimated to consist of 95% of the marine fauna and around 70 to 77% of the known terrestrial fauna (where the fossil record is inevitably less complete). This article will provide an overview of the many events and processes that played a part and a discussion whether they can all be attributed to a single, root cause. Reef evidence At this time, the landmass was united into the single, super-continent of Pangea, surrounded by warm shallow seas with abundant reef systems. This extensive reef fauna supported a variety of suspension feeders (for example, crinoids, rugose and tabulate corals, and so on), which were the most heavily hit by the extinction event, with all the known corals dying out. Modern scleractinian corals only appeared in the Triassic and there is a considerable gap in the coral fossil record at this time. Other reef inhabitants, such as the last phillipsid trilobites also became extinct. All these creatures were sessile or relatively immobile inhabitants of the reefs that occupied a relatively narrow zone on the continental shelf. This habitat must have been destroyed almost globally by a number of factors, but importantly, the single shelf margin around Pangea meant there was no other shallow reef environment for the fauna to migrate to. Fig. 1. Reef evidence. Tectonic activity The single continent of Pangea was always doomed to split apart. … Read More
Mark Wilkinson (UK) From much of the coast along the Firth of Forth in southeast Scotland, and from coastal hills such as Arthur’s Seat in Edinburgh, the impressive piece of rock called the Bass Rock forms a prominent landmark. This steep island is the neck of a Lower Carboniferous volcano, rising 107m above sea level. Scuba divers, on the north side of the island, have shown the sea bed to be around 40m in depth, so the neck would be 150m high if we could see it all. The rock is made of phonolitic trachyte, that is, an alkali igneous rock with less silica content than a ‘normal’ trachyte, so the alkali feldspar is accompanied by one of the silica-deficient feldspathoid minerals, such as analcime. Unfortunately, this interesting mineral assemblage is too fine-grained to see easily, except in thin sections under a microscope. In winter, Bass Rock is a dark brown as might be expected, but, in summer, it turns white from both the seabirds that crowd every available surface and their accumulated guano. The shape of the island is significant – clearly the igneous rock was more resistant to erosion than the surrounding sediments into which it was intruded. These country rocks are not visible now, having been eroded away to below water level, with an estimated one kilometre or more of overlying rock removed since the time of intrusion, along with any surface eruption products, such as lavas and pyroclastic rocks. Fig. 1. The Bass Rock from the west. … Read More
Dr Steve Koppes (USA) Hikers visiting the Kilauea Iki crater in Hawaii today walk along a mostly flat surface of sparsely vegetated basalt. It looks like parking lot asphalt, but, in November and December 1959, it emitted the orange glow of newly erupted lava. Now, a precision analysis of lava samples taken from the crater is giving scientists a new tool for reconstructing planetary origins. The results of the analysis, by the University of Chicago’s Nicolas Dauphas and his associates, were published in the 20 June 2008 issue of the journal Science. Fig. 1. Eruption Hill in Kilauea Iki crater on the Big Island of Hawaii. In December 1959, lava spurted 580m feet high from this location. Working with lava samples from the crater, scientists at the University of Chicago and elsewhere have devised a new tool for reconstructing planetary origins. (Photo: Steve Koppes.) The researchers selected Kilauea Iki for their study because scientists have drilled it for samples many times over the years as it cooled. This sequence of samples makes the lava lake a perfect site for studying differentiation – the separation of minerals and elements as magma cools and hardens. In particular, a close examination of iron isotopes – the slight variations the element displays at the subatomic level – can tell planetary scientists more about the formation of crust than they previously thought, according to Dauphas and co-authors, Fang-Zhen Teng of the University of Arkansas and Rosalind T Helz of the US Geological Survey. Dauphas informed … Read More
Dr Robert Sturm (Austria) Compared to the geological architecture of other European countries not exceeding a total area of 100,000km², the geology of Scotland is characterised by an unusual diversity of geological features. Due to its tectono-metamorphic complexity Scotland attracted numerous earth scientists in the eighteenth and nineteenth centuries, whose main aim was the development of theories about, on the one hand, rock formation and, on the other, metamorphic alteration of initial lithologies. Besides being the preferred target of foreign scientists, the country has also produced its own important figures in the history of geological research. In this context, James Hutton – the “father of modern geology”, after whom, for example, ‘Hutton’s Unconformity’ at Siccar Point in Berwickshire is named – has to be mentioned, but also Hugh Miller and Archibald Geikie provided valuable contributions to the enlightenment of various geological problems. Fig. 1. Geological subdivision of Scotland into four main units. Returning to the geology of Scotland, it is possible to subdivide the country into four main geological and geographical units. The Southern Uplands, which extend south of the Southern Uplands Fault, are mainly composed of sedimentary rocks dating back to the Silurian and the Devonian. The Central Lowlands or Midland Valley, which border the Southern Uplands Fault on the north, represent a rift zone that chiefly comprises Palaeozoic rocks of both sedimentary and volcanic origin. North and west of the Highland Boundary Fault lies the Highlands and Islands, which, due to their geological diversity, can be further subdivided … Read More
Iceland seems to set the hearts of certain geologists racing and, reading this field guide, it is abundantly clear why. Set out in this concise and authoritative book is the evidence of how this strange piece of rock – astride the Mid-Atlantic Ridge – is a “natural laboratory”, where the earth sciences can be watched in dramatic real-time.
This is the fourth book in a series published by Dunedin that I have been lucky enough to review – the others being on palaeontology, geology and volcanology. And this is as good as the others. However, it is not an easy book to read.
Nowadays, people don’t do geology – they do ‘earth sciences’ – and this book is very much in that mould. That’s not to say this is a problem.
The Scottish Borders region is famed for its frontier history and attendant myths and ballads. This book concerns its more ancient geological history that is revealed by its rocks. These indicate that the area was once on the edge of a huge ocean.