An acclaimed international collection of earth science articles and book reviews on palaeontology, geology, minerals and more
Michael C Mackiewicz (USA) Almost every mineral collector owns a mica specimen, whether they realise it or not. Silvery muscovite books from pegmatites, dark biotite flakes in granite, honey‑coloured phlogopite crystals from marble deposits, and lilac lepidolite from lithium‑rich pegmatites appear in collections, museums and geology classrooms around the world. … Read More
Jon Trevelyan (UK) This is the first in my series of short articles on fossils of the Silurian. Few British fossils have achieved the cultural visibility of Calymene blumenbachii, the famous “Dudley Bug”. Found in abundance in the Wenlock limestones of the English Midlands, this trilobite has charmed collectors, inspired … Read More
Jon Trevelyan (UK) I have previously reviewed Donald R Prothero’s The Story of Earth’s Climate in 25 Discoveries for Deposits, and one of the things that particularly impressed me about that book was his ability to explain complicated scientific ideas in straightforward, entertaining language. I am pleased to say that … Read More
Regular readers of Deposits will know that we have never regarded geology as something that stops at national borders. The rocks beneath our feet are parts of much larger stories: continents assembled and torn apart, oceans opened and closed, mountains raised and destroyed, ice sheets advanced and retreated, and rivers … Read More
Few coastal landscapes in Britain are as instantly recognisable as the Seven Sisters. Along this stretch of the Sussex coast, brilliant white chalk cliffs rise and fall in a rhythmic sequence of headlands and valleys, before plunging abruptly into the English Channel. Seen from the cliff tops or from the air, the landscape appears almost sculpted: seven sweeping ridges, separated by deep green folds in the downs.
Jon Trevelyan (UK) This is the twelfth and last in my series of short articles on fossils of the Ordovician. Trinucleus fimbriatus is one of the most distinctive and instructive trilobites of the Late Ordovician, especially familiar from the mudstone successions of Wales and the Welsh Borderlands. Dating to roughly … Read More
Jon Trevelyan (UK) A museum unlike any other There are natural history museums in which the building is little more than a container for the collections it houses. The Oxford University Museum of Natural History is emphatically not one of them. Here, architecture, geology and the history of science are … Read More
If the lycopsids built the forests and the tree ferns reclaimed the drowned ground, then the seed ferns – particularly Neuropteris, Odontopteris and Alethopteris – tell the story of how the Carboniferous landscape diversified beyond the swamp. These plants, long extinct but abundantly preserved in the roof shales in the West Cumberland Coalfield, flourished on levees, raised mudbanks and floodplain surfaces that were too dry for lycopsids, but too unstable for true forest soils. Their fossils show how the environment shifted from a drowned swamp, back towards a mixed floodplain-wetland mosaic.
Jon Trevelyan (UK) This is the eleventh in my series of short articles on fossils of the Ordovician. Brachiopods flourished during the Ordovician, undergoing rapid diversification as part of the Great Ordovician Biodiversification Event. Among them, Strophomena planumbona stands out for its distinctive shell architecture and ecological adaptability, making it … Read More
Jon Trevelyan (UK) From natural history to Earth history In Part 1, we considered a deceptively simple question: what should a great natural-history museum do with a great collection? The Natural History Museum provided no simple answer. In some galleries, magnificent specimens dominate; elsewhere, screens, models, reconstructions and interactive displays … Read More
In the dry valleys of the Anti-Atlas Mountains, some of the oldest sedimentary rocks in North Africa are exposed in spectacular detail. Along winding desert roads near the village of Tizaghte, folded bands of dark and pale rock emerge from the hillsides in sweeping patterns visible even from satellite imagery. Closer inspection reveals something potentially even more intriguing: structures that may preserve traces of ancient microbial communities that once lived in shallow seas during the latest Precambrian or earliest Cambrian.
Jon Trevelyan (UK) This is the tenth in my series of short articles on fossils of the Ordovician. Few Ordovician fossils are as instantly recognisable as Receptaculites oweni, commonly known as the “sunflower fossil” for its strikingly geometric appearance. Despite long-standing debates about its biological affinities, this enigmatic organism provides … Read More
Jon Trevelyan (UK) A museum like no other This is the first part of a two-part article on the Natural History Museum in London. And there are few museums whose buildings announce their ambitions quite as emphatically as this museum does. Approaching from Cromwell Road, Alfred Waterhouse’s great Romanesque building … Read More
Dr Maria Trotteyn (Argentina) and Dr Julia Desojo (Argentina) Although the most famous and intensely studied fossilised vertebrate (backboned) animals are dinosaurs, these reptiles coexisted during a segment of geologic time -the Triassic Period – with numerous groups of equally interesting, but less well-known species. Most of these fossilised animal … Read More
Jon Trevelyan (UK) This is the ninth in my series of short articles on fossils of the Ordovician. The long, tapering shells of Orthoceras are among the most evocative fossils of the Ordovician. As straight-shelled nautiloids inhabiting the open oceans, these cephalopods represent early experiments in mobility, buoyancy control and … Read More
Jon Trevelyan (UK) Robert Westwood is no stranger to the pages of Deposits. Over the years, I have reviewed several of his geological guides, covering subjects ranging from the Jurassic Coast to Cornwall and the Lake District (ee below). What has always appealed to me about his publications is their … Read More
Jon Trevelyan (UK) Maidstone Museum and an unexpectedly substantial geology gallery Maidstone Museum is not primarily a geological museum. Its collections range across archaeology, natural history, fine and decorative art, costume, ethnography, and local history, with more than 600,000 objects in its care. Yet, tucked away on the first floor … Read More
This final part of the series brings together the two very different lake worlds explored so far. In Part 1, we reconstructed the long-lived Devonian lakes of the Orcadian Basin; in Part 2, we examined the short-lived but dramatic ice-dammed lakes of Glen Roy. Here, we broaden the view to consider the wider pattern of lost lakes across Britain – how they formed, how they drained, and how their influence persists in modern landscapes, particularly in the behaviour of rivers and the shape of valleys.
Jon Trevelyan (UK) This is the eighth in my series of short articles on fossils of the Ordovician. Nemagraptus gracilis is one of the most important and visually distinctive graptolites of the Middle Ordovician, widely known from the black shales of Britain, Scandinavia and North America. Dating to around 463-460 … Read More
Jon Trevelyan (UK) There can be few places in Britain better suited to a geological field guide than the Isle of Wight. Its relatively small area contains an extraordinary range of rocks and fossils, while its eroding cliffs and beaches have produced discoveries ranging from ammonites and molluscs to plants, … Read More
Jon Trevelyan (UK) A geological museum in the heart of the Black Country Dudley is one of those places where geology is difficult to separate from almost everything that followed. The rocks beneath the town and the surrounding Black Country provided coal, ironstone, limestone and fireclay; their exploitation transformed the … Read More
When a Carboniferous swamp drowned, its towering lycopsids collapsed, its peat surface disappeared beneath mud, and the forest that had stood for decades, or at most a few generations, abruptly ceased to exist. Yet within surprisingly little time, new vegetation reclaimed the abandoned lake floor. The first wave of this recovery is written across the roof shales of the West Cumberland Coalfield district in thousands of beautifully preserved fronds, most commonly those of Pecopteris, the characteristic tree ferns of the Westphalian wetlands.
Jon Trevelyan (UK) This is the seventh in my series of short articles on fossils of the Ordovician. Of all the Ordovician gastropods, few are as visually striking as Maclurites bigsbyi. With its large, open-coiled shell and broad, planispiral whorls, the species represents a unique experiment in molluscan shell architecture … Read More
One of the great advantages of publishing Deposits online is that an article does not disappear once the next issue comes along. Everything we publish remains available on the website, creating an ever-growing archive of articles, covering geology, palaeontology and the wider Earth sciences. However, as that archive grows, there … Read More
Jon Trevelyan (UK) A museum built on fossils Hastings is usually associated with history rather than prehistory. Its name is inseparable from 1066, while its fishing beach, old town and cliffs are familiar features of the modern resort. Yet the rocks beneath and around the town preserve evidence of a … Read More
In Part 1, we reconstructed the long-lived Devonian lakes of the Orcadian Basin from their sedimentary record. Here, we turn to a much more recent and far more fleeting landscape. At the end of the last Ice Age, ice-dammed lakes formed across parts of Britain, leaving behind traces that are often subtle – but in Glen Roy, they are spectacular. The famous ‘parallel roads’ provide one of the clearest records of changing lake levels anywhere in the country, preserving the story of a landscape shaped over centuries, rather than millions of years.
Jon Trevelyan (UK) This is the sixth in my series of short articles on fossils of the Ordovician. Trilobites reached their zenith in diversity during the Ordovician, but few species are as impressive as Isotelus maximus. Renowned for producing some of the largest articulated trilobite specimens ever found, this North … Read More
Jon Trevelyan (UK) A museum unlike any other Perched above Scarborough’s South Bay, the Rotunda Museum occupies a unique place in the history of geology (Fig. 1). Opened in 1829, it is one of the world’s earliest purpose-built geological museums and remains one of Britain’s most historically significant centres for … Read More
Stephen K. Donovan (UK) One of the first volumes that I bought when I first took up palaeontology over 50 years ago was the very excellent Directory of British Fossiliferous Localities (Arkell et al., 1954; Donovan, 2025a), a tome full of meat. It was published in the same year as … Read More
Jon Trevelyan (UK) This is the fifth in my series of short articles on fossils of the Ordovician. If one fossil trilobite has achieved near-universal recognition among collectors, it is Flexicalymene meeki. Abundant, beautifully articulated and famous for its perfectly enrolled specimens, this species offers a remarkably complete view of … Read More
