An acclaimed international collection of earth science articles and book reviews on palaeontology, geology, minerals and more
Jon Trevelyan (UK) In the dry valleys of the Anti-Atlas Mountains of southern Morocco, 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 … Read More
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
Jon Trevelyan (UK) A landscape full of holes Grime’s Graves does not announce itself with the drama of a great cliff, cave or quarry. On a low Chalk ridge in the Breckland of Norfolk, the most immediately striking feature is instead the ground itself. Across the grassland are hundreds of … Read More
This is the first of a three-part series exploring Britain’s lost lakes – landscapes that once existed across very different timescales, from the Devonian world of the Orcadian Basin to the fleeting ice-dammed lakes of the last Ice Age. In this opening article, we go deep into the Devonian, reconstructing the Orcadian lakes from the evidence preserved in Caithness and Orkney. Here, finely layered sediments, exceptional fossil preservation and subtle environmental clues allow us to rebuild not just the organisms that lived there, but the structure and behaviour of the lakes themselves.
Jon Trevelyan (UK) This is the fourth in my series of short articles on fossils of the Ordovician. Among the diverse and often bizarre echinoderms that flourished during this period, Echinosphaerites aurantium is one of the most distinctive. A rhombiferan cystoid with a rounded, grapefruit-like body, it embodies the experimental … Read More
Jon Trevelyan (UK) A small museum with a remarkable geological story Tucked away behind the parish church in the centre of Cromer, Cromer Museum occupies a modest site that visitors could easily overlook. Entering through a modern reception building, the museum opens into a narrow courtyard surrounded by a terrace … Read More
Every coal seam in the West Cumberland Coalfield district records the accumulation of peat in a mature lycopsid swamp. But just as revealing as the coal itself is what lies immediately above it – the roof shales. These fine-grained sediments record the moment when the forest drowned, the swamp surface subsided or flooded, and a new ecological phase unfolded above the buried peat. In the West Cumberland Coalfield, roof shales are exceptionally well developed and preserve a full sequence of the events that followed each catastrophic rise in water level.
Jon Trevelyan (UK) This is the third in my series of short articles on fossils of the Ordovician. Although the famous Pterygotus of Silurian and Devonian fame had not yet reached their iconic size in the Ordovician, their ancestors were already present in the marine ecosystems of the period. These … Read More
Jon Trevelyan (UK) Rising above the hills near the town of Blaenavon is the distinctive headgear of Big Pit, one of the most recognisable symbols of the South Wales Coalfield (Fig. 1). Today, the site forms part of the National Coal Museum of Wales, but for nearly a century it … Read More
Deborah Painter (USA) There is a fault zone that trends southwest to northeast from Stafford County, Virginia USA and joins a fault that extends through the capital of the United States. It is a high-angle reverse fault. Cambrian and Ordovician mylonites, schists and phyllites lie unconformably atop Cretaceous gravels or … Read More
Jon Trevelyan (UK) This is the second in my series of short articles on fossils of the Ordovician. Among the many colonial organisms that chart the course of Ordovician seas, Didymograptus murchisoni remains one of the most recognisable. A key graptolite of the Middle Ordovician, it combines elegant morphology with … Read More
Jon Trevelyan (UK) The ruined furnaces of Blaenavon rise unexpectedly from the Welsh hillsides like the remains of some vast industrial fortress. Massive retaining walls, towering masonry structures and steep charging ramps still dominate the landscape, despite the silence that now surrounds them. Grass and wild flowers spread across terraces … Read More
