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Drought in South Australia creates soil problems

Dr Paul Shand (Australia) In South Australia, the staff of the Commonwealth Scientific and Industrial Research Organisation (CSIRO) Land and Water have recently shown that the River Murray, adjacent wetlands and the Lower Lakes (Alexandrina and Albert) close to the Murray Mouth are being seriously impacted by a combination of low water levels and the presence of acid sulfate soils (ASS). The Lower Lakes and the floodplains below lock 1 at Blanchetown are undergoing their first drought since the introduction of barrages more than 50 years ago. Lakes, such as Lake Bonney and Lake Yatco, as well as several wetlands formed by the River Murray, are being isolated as one option to generate water savings and help mitigate drought-related problems in the Murray-Darling Basin. Field observations and chemical analysis confirm the occurrence of both sulphuric materials (pH <4) and sulphidic materials (high sulphide concentrations and pH >4) in a range of ASS subtypes (Fig. 1). Fig. 1. Acid Sulphate Soil with sulfuric material near Swanport adjacent to the Murray River. In addition, some areas contain ‘monosulphidic black ooze’, that causes rapid oxygen depletion of lake and drainage waters when the ooze is mixed with oxygenated waters during disturbance (Fig. 2). Fig. 2. extensive cracking and accumulation of white and yellow Na-Mg-Fe-Al-sulphate-rich minerals or salt efflorescences. Unpleasant smells (‘rotten eggs’), as a result of rotting vegetable matter and the release of gases, have been experienced in these areas of exposed soils when water levels are extremely low or the lakes have … Read More

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A very brief Introduction to the Quaternary

By Joe Shimmin The Quaternary comprises the Pleistocene and the Holocene and is the youngest of the geological periods. It dates from approximately 1.8 million years ago right up to the present, with the large majority of this time being filled by the Pleistocene. The Holocene spans a geological ‘blink of an eye’, beginning only 10,000 years ago at the start of the present interglacial and continues today. What sets the Quaternary apart from other geological periods is a suite of high frequency climate fluctuations, with very cold stages being interspersed by warmer stages. This type of climate fluctuation is believed to have occurred at various other times in the Earth’s history, but most of the evidence for these has been wiped out over millions of years. However, the glacial/interglacial or warm/cold stages of the Quaternary have, in many cases, left us enough evidence of their existence for the Quaternary scientist to be able to attempt to reconstruct these past environments with some degree of success. Fig. 1. Glacial beds at Benacre, Suffolk Serbian mathematician, Milutin Milanković, formulated the accepted theory for why climate oscillations have occurred in this period, in the first half the twentieth century. According to ‘Milanković, Quaternary climate was, and is, influenced by three factors: Factor 1: the shape or ‘eccentricity’ of the Earth’s orbit around the sun, which varies over a cycle of approximately 100,000 years.Factor 2: The tilt or ‘obliquity, of the Earth’s axis, which varies over a cycle of approximately 41,000 years.Factor 3: … Read More

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SEACHANGE sets sail: Science on the high seas

Jack Wilkin (UK) During April and May 2022, I had the fantastic opportunity to participate in a research expedition to the North Sea and Iceland on the RRS Discovery, as part of the SEACHANGE project. The following article is a brief description of the science that happened on the ship. What is the SEACHANGE Project? SEACHANGE is a six-year research project funded by the ERC Synergy Grant Scheme (part of the EU’s research and innovation programme, Horizon 2020). It is jointly run by the University of Exeter (UK), Johannes Gutenberg University Mainz (Germany) and the University of Copenhagen (Denmark). This is a collaborative project with scientists worldwide, from master’s students to professors working diligently to answer the question: What were the oceans like before large-scale human impact? To answer this question, we need to test the scale and rate of biodiversity loss resulting from fishing, whaling and habitat destruction over the last 2,000 years in the North Sea and around Iceland, eastern Australia and the Antarctic Peninsula. In addition, we need to find out more about the earlier transition from hunter-gatherer to farming communities in northern Europe around 6,000 years ago. However, before answering this question and starting to generate data, we first needed the raw materials. Because we were monitoring the oceans, we needed to go to the sea to gather our samples, so we need a boat … a very big boat. The RRS Discovery. The RRS Discovery (Fig. 1) is one of the most advanced research ships … Read More

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Lake District: Landscape and Geology, by Ian Francis, Stuart Holmes and Bruce Yardley

I recently reviewed another of the guides in Crowood Press’s excellent “Landscape and Geology” guides, which was undoubtedly a great read. And this one is equally good, with great, full colour pictures, maps and diagrams, and easy to read text, with descriptions of interesting walks and what can be seen on them.That is, there are easy-to-understand explanations of how the rocks formed and how the geology affects the landscape, and there is also an n exploration of the long human story of the landscapes.

Iceland: Classic Geology in Europe (3rd edition), by Thor Thordarson and Ármann Höskuldsson

reviewed the 2nd edition of this guide a while ago and, as I said then, Iceland seems to set the hearts of certain geologists racing and, reading this field guide and that previous incarnation, it is abundantly clear why. Iceland’s fascinating geology is clearly set out in this concise and authoritative book. The island, astride the Mid-Atlantic Ridge, is a ‘natural laboratory’ where the earth sciences can be watched in real-time. Rifting of the crust, volcanic eruptions and glacial activity are among a host of processes and features that can be observed in this fascinating land.

Book review: Introducing Geomorphology: A Guide to Landforms and Processes (2nd edition), by Adrian Harvey

As I said in my review of the first edition of this guide, I love geomorphology. In fact, I have loved it since my school days and deeply regret not having studied it at university. However, as I said in that review, I suspect many people are discouraged by its scientific name, but all it means is the study of the earth’s landforms and the processes that create the landscapes we see today.

Book review: River Planet: Rivers from Deep Time to the Modern Crisis, by Martin Gibling

I think the reason why this book is such a success is that River Planet not only introduces readers to the fascinating palaeo-history of the world’s rivers (both existing and disappeared), but also reveals the author’s personal account of his experience of rivers, together with a bit of history and interesting (and relevant) anecdotes, in the most entertaining of ways.

Book review: Inscriptions of Nature: Geology and the Naturalization of Antiquity, by Pratik Chakrabarti

Maybe it’s a result of my social anthropology and geological background, but I found this difficult but fascinating book a great read. It’s about nineteenth century India. It is not about the modern geological science or social anthropology of the subcontinent, but rather, the geological imagination of India, as well as its landscapes and people, and its history.

Book review: Hutton’s Arse: 3 billion years of extraordinary geology in Scotland’s Northern Highlands (2nd edition), by Malcolm Rider and Peter Harrison

If you can see past the somewhat robust title (a reference to James Hutton’s discomfort riding around Scotland on horseback during his geological investigations), this is an interesting read, combining both geological science and humour in just about the right measures.

Clarkia Flora: 16-million-year-old plants offer a window into the past

Margret Steinthorsdottir and Helen K Coxall (Sweden) Near the small town of Clarkia in Shoshone County, Idaho in the USA, exists a rich and unique fossil deposit. The Clarkia fossils, or Clarkia Flora, as the deposit is mostly called due to the abundance of fossil plants, is so well preserved … Read More

Colourful bluffs in Long Island recall the most recent ice age

Deborah Painter (USA) Imagine a tremendous piece of land moving equipment that scraped up the soil and some of the surface bedrock from four states within the United States’ Eastern Seaboard, carrying and dragging it all the way, before dumping it on a ridge off the shoreline. That is what … Read More

Whitby Jet and the Toarcian Oceanic Anoxic Event

Arthur Speed (UK) One hundred and eighty million years ago in the Toarcian Stage of the Lower Jurassic Period, the Earth was very different from the world we know today. The continents were all clumped together in a supercontinent called Pangaea, which was just beginning to split apart. Sea level … Read More