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
Steven Marquez (USA) Amethyst is the violet to purple variety of quartz. It is often associated with albite and orthoclase in pegmatites. Fine specimens of amethyst can be classified as semiprecious gemstones. This specimen was found in Cripple Creek Colorado, as a near surface deposit on the David Leighton gold mine, owned by Steven Wade Veatch across from the hardware and grocery store on Teller County 1. The short, stubby amethyst crystals formed gas pockets in a hot, welded ash deposit that once covered the landscape of Cripple Creek. Amethyst is also mined in great quantities from the state of Minas Gerais in Brazil. A deep purple amethyst is commonly found in Uruguay. The colour purple is a royal colour, which is why amethyst is often used in jewellery for kings and queens. It was highly valued by Egyptians and the ancient Greeks believed that it protected against intoxication. Amethyst is the birthstone for February. Fig. 2. Note the faint crosswise striations on the surface of the amethyst crystal. This is one of the diagnostic features of quartz. The specimen is from the Steven Veatch collection. Photo by Steven Marquez. Facts on fileChemical formula: SiO2Composition: silicon dioxide; the colour is caused by iron or manganese impuritiesColour: purple, greasy lustreStreak: whiteHardness: 7Crystal system: hexagonalTransparency: transparent to translucentSpecific gravity: 2.65Lustre: vitreousCleavage: noneFracture: conchoidalTenacity: brittleGroup: silicates, tectosilicatesHaiku Brilliant purple Never ceasing to amaze Glowing like the stars About the author Fig. 2. Steven Marquez, seen working on the curation and cataloguing of the … Read More
I have been fortunate enough to review for this magazine a large number of books from the Dunedin series of guides introducing aspects of the different sciences, especially the earth sciences. And Introducing Mineralogy continues the high standard set by its predecessors. It is slightly larger than some of the other guides in the series, but is still beautifully illustrated, nicely written and very informative.
These three guides by Robert Westwood are in the same simple format. All are local geological guides to specific areas of the UK and all are illustrated by lovely full colour photographs. They all contain simple, introductory geological introductions for the uninitiated, and then more detailed expositions of what makes the regions so special.
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.
Normally, I wouldn’t be interested in semi-precious stones and other pretty things. Personally, I prefer grubbing around in the dirt, perhaps for those far more beautiful, elusive and perfectly formed Cretaceous terebratulids or Silurian trilobites. However, some semi-precious stones have the advantage of also providing a tangible link to the ancient history of life.
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.
Deposits magazine has covered the science and appeal of agate in some detail over the last few years. Indeed, this issue has another in Wayne Sukow’s excellent series on the science of Lake Superior agate formation.
Here at Deposits, we like our amber and this certainly isn’t the first book on the subject I have reviewed. In fact, over the years, we have published many articles on the fossilised sap and its inclusions, and have just finished publishing a short, two-article series by the authors of this excellent little publication.
Over a period of 20 years, Ian Tyler has written a series of books on the metalliferous mining industry of the English Lake District and this has clearly been a significant labour of love for him.
Terry Moxon likes his agates. It is easy to see his enthusiasm and it is just as easy to appreciate it from this short book on the science of these colourful minerals. However, his is not just a casual interest.
For many years, the Geologists’ Association has published some of the best geological guides to the UK (and a few other places). This new one, the 67th in the series, covers the Dalradian of Scotland.
The island of Cyprus is a truly classic area of geology in Europe. Perhaps nowhere else on Earth does so small an area provide such an excellent illustration of the dynamics of Earth processes through abundant exposures of spectacular and diverse geology.
The Caithness area of Scotland is important for its geology, but is also well known for its palaeontology. The area even once had its own ‘gold rush’ and you can still try your luck at panning there today at Kildonan.
For a long time Watchet has been known to be a superb location for those interested in both fossils and geology but surprisingly, the location has had little in the way of media attention. However, within the last couple of years, this area has begun to attract a lot of interest and this book will further increase its growing popularity.
Minerals of Britain and Ireland is a comprehensive account of the minerals found in Britain, Ireland and the surrounding islands. At over 600 pages and illustrated throughout by over 550 images (mostly in colour), the book provides exhaustive coverage of the remarkably wide range of minerals found in this part of the world.
Dorling Kindersley (DK) are well-known for producing popular reference media for beginners and enthusiasts. No doubt, most readers will be familiar with their ‘Eyewitness Guides’. The Eyewitness Handbook of fossils, certainly makes a useful starting point for anyone new to geology or palaeontology.