Category: climate

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climate fossils geology palaeontology south america

Diatoms: the jewels of palaeoclimatology

Jack Wilkin (UK) My PhD at the University of Exeter focuses on using micropalaeontology and various geochemical methods from Holocene marine sediment cores, to try to find out how the climate of South Georgia has changed over the past 15,000 years. One of the microfossil groups I’m using to achieve this is diatoms (Fig. 1). Fig. 1. Some of the different diatoms I’m working on from the Southern Ocean:(a) Actinocyclus actinochilus; (b) Thalassiosira lentiginosa (the thick hexagonal microfossil is a silicoflagellate) (c) Eucampia antarctica; (d) Navicula sp.; e). Fragilariopsis kerguelensis; (f) Rhizosolenia antennata f. antennata.(Photographs courtesy of Dr Claire Allen (British Antarctic Survey). (a)-(c), (f) = centrics, (d)-(e) = pennates (only raphed forms are pictured here).) Diatoms are microscopic algae that play a vital role in marine ecosystems. They have circular or elliptical to rod-like shapes and are perforated by minute apertures called areola. They are divided into two orders: the Pennales and the Centrales. Diatoms can reproduce both sexually and asexually, using a unique “shrinking division” form of a sexual reproduction called binary fission. They are photosynthetic and form the basis of food chains in many aquatic ecosystems. Diatoms also have a wide range of geological applications, especially in palaeoclimate studies. What do diatoms look like? Diatoms are usually colonial, photosynthetic, single-celled algae, made of biogenic silica, with an estimated 20,000 to two million species. One could imagine them as microscopic plants that live inside tiny glass greenhouses, stacked on top of each other. They form as iliceous shell, … Read More

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Book review: Cro-Magnon: The Story of the Last Ice Age People of Europe, by Trenton W Holliday

The Cro-Magnons were a population of early modern humans (that is, they were physically indistinguishable from us, today), who lived in Europe between about 40,000 and 10,000 years ago, during the Upper Palaeolithic period. This information comes from Trenton Holliday’s excellent book, which tells the story of these people in the context of recent scientific advances. However, while it does not shy away from complex scientific issues, the book is written with a light, understandable touch.

climate geology historical / biographies minerals scotland urban, art, anthropology

Shetland – an archipelago on the edge

Allen Fraser (UK) Shetland is a spectacular group of islands with a varied geology, a wonderful landscape and a special flora and fauna, peopled by a culture distinct within the British Isles. Shetland remains one of Britain’s natural treasures.” (J. Laughton Johnston) Fig. 1. St Ninian’s Isle. The islands Shetland sits on the edge of the European continental shelf and is sinking. Since the end of the last glaciation about 10,000 years ago, relative sea level has risen by about 120m and has fashioned an archipelago of over 100 islands. The island group extends over a distance of 110km from Muckle Flugga (Fig. 2) in the north to Fair Isle in the south, and a convoluted coastline, over 2,700km in length, means that no point on land here is more than 5km from the sea. Fig. 2. Muckle Flugga, a small rocky island north of Unst in the Shetland Islands. The landmasses of the larger islands are generally in the form of roughly north-south ridges of hills forming the ‘spine’ of Shetland. The hills, mainly composed of acidic granite, schists and gneisses, are treeless and are generally covered by peat or blanket bog. The valley floors between the hills of the central Mainland (the largest island) are composed of crystalline limestone and are generally more fertile. Together with sandy coastal areas, they form the best agricultural land. Fig. 3. The fertile valley of Tingwall. Fig. 4. The port of Scalloway, the largest settlement on the west coast of the Mainland, … Read More

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climate geology historical / biographies museums, societies north america

Ice, dykes and tectonics: the Plattsburgh story

Deborah Painter (USA) As our small passenger jet began its descent into the Plattsburgh, New York International Airport on a cool November day, I admired Lake Champlain to the east from my window and noticed that the small aircraft, once it touched the very long runway, continued rolling down it for ten whole minutes. When the jet came at long last to the gate area, I noted that the size of the attractive terminal was small – quite out of proportion for that enormous runway. On returning to the terminal and dropping off my rental car two days later, following completion of an environmental compliance project, I noticed that the young lady who checked my bags and took my ticket at the gate was the same person who loaded the plane’s baggage compartment. Why should such a tiny airport with such a tiny staff and only a few arrivals and departures daily need such a long runway and taxiway? Later, I learned that this had been an Air Force base in the past and the runway had been intended to serve as an alternate runway for NASA’s Space Shuttle in case of an aborted mission. Less than three years later, I had the good fortune to have another project in Plattsburgh. This time, I took a passenger train and, since the rail line runs parallel to and very close to Lake Champlain through much of its service through New York north of Albany, I was able to see the lake … Read More

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africa / middle east climate fossils geology palaeontology

From sea to sand – ancient marine reptiles from the deserts of Saudi Arabia

Benjamin Kear (Australia) The hot, dry deserts of modern Saudi Arabia are not renowned as a source of ancient marine reptile fossils. Indeed, only a few years ago, virtually nothing was known beyond a few unidentified scraps of bone recovered by petroleum geologists searching for oil. However, recent exploration by teams of both Saudi and international palaeontologists have led to some exciting new finds that are helping to piece together the 190 million year long story of marine reptile evolution in the Arabian Peninsula. Fig. 1. A map of the modern Arabian Peninsula (with Saudi Arabian borders) showing the extent of the Arabian Shield (lilac) and successive Mesozoic-Cainozoic sedimentary rock exposures: Late Permian to Triassic (violet); Jurassic (blue); Cretaceous (green); Cainozoic (brown). What are marine reptiles? The term ‘marine reptile’ is actually rather ambiguous and does not refer to a specific group. Rather, it applies to any wholly or partly aquatic reptile that makes, or has made, its home in the ocean. Examples of modern marine reptiles include sea turtles (chelonioids), sea snakes (related to terrestrial venomous snakes or elapids), the marine iguana (Amblyrhynchus cristatus) and the salt-water crocodile (Crocodylus porosus). The latter is typically estuarine, but commonly ventures into coastal marine areas. However, the zenith of marine reptile diversity occurred during the Mesozoic or ‘Age of Dinosaurs’, when in excess of ten major radiations, including representatives of those living today (that is, turtles, snakes, lizards and crocodiles), made the transition to life in the sea. Despite having quite different … Read More

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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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climate fossils geology museums, societies palaeontology

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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Book review: 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.

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Book review: 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.

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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.

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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.

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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.

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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.