Geology Today最新文献

Limestone is a notoriously leaky rock. In many areas that are underlain by limestone, surface rivers are few and disjointed. They disappear into sinks only to reappear, sometimes many kilometres away, at springs. It is not an environment in which lakes are typically found. Some 40 percent of Ireland is underlain by limestone, yet the Irish lowlands are scattered with countless lakes, large and small. In many the limestone beneath is effectively sealed by a cover of glacial till; others have formed where hollows descend below a shallow water table. Around the shores of many, exposed limestone bedrock and boulders support a range of peculiar etched features that are virtually confined to this lakeshore environment.

Travertine is widespread in karst terrains, and less so elsewhere, and some of its varieties constitute spectacular landforms, many of which become popular visitor sites for geologists and non-geologists alike. Among the many forms of travertine, barrages are the most spectacular, especially where they still have streams or rivers cascading over them. Carbonate travertine is polygenetic, both chemical and organic, and both karstic and geothermal, with a full range of sites between those extremes.

Eudialyte is a mineral unfamiliar to most people. This is likely to change in the near future, as this mineral is of increasing economic importance. Eudialyte is now known to be one of a group that has grown in number to a remarkable extent in recent years, and eudialytes are index minerals for a specific category of igneous rocks and are repositories for elements, such as the rare earths, which have become increasingly critical to modern technology. The eudialyte group now comprises about 50 members of which about 29 members are fully recognized, and exploitation of eudialyte group minerals will soon be a reality. The mineral's name comes from Greek: Eu διάλυτος, meaning ‘well decomposable’—a reference to the fact that, unlike the highly refractory zircon (the common source of zirconium), eudialyte is soluble in common acids, making it relatively cheap to work.

The Swiss continue to publish highly detailed 1:25 000 geological maps and memoirs, coupled with informative cross sections. They are presented in attractive plastic wallets with a geological time scale on their back including stage names for deciphering partly abbreviated keys in whichever regional language. Swisstopo has also put free downloads of all their geological maps online, including out of print editions. This makes economic sense, given publication represents a small fraction of the overall costs incurred in surveying each sheet. In addition, they have developed an easy-to-use online data viewer where different layers of cartographic information can be selected and mixed together to produce bespoke, ready-to-print pdf downloads complete with a scale bar. Though, unlike digital data, which may become corrupted, printed material can survive for centuries. The first sheets in this national atlas were published in 1930, and so when their coverage is finally completed within roughly the next decade, policy makers would be wise to start resurveying older editions to keep them up to standard. In this way, Switzerland can maintain enough geologists familiar with regional ground conditions, to provide impartial advice about the impact of climate change on fragile environments vulnerable to flooding, landslides, melting permafrost and other potential geological hazards. Plus, enhancing water supply management, natural resources, radioactive waste disposal, carbon capture and storage, and planning new developments and infrastructure like their futuristic trans-alpine railway tunnels.

The beach is where the ancient, in the shape of diverse erratics, meets the present in the shape of corrosion, encrusting shells and invertebrate borings. Many of us have favourite beach walks, repeated whenever possible, and educating us in the common and rare clasts that might be encountered in such an ever-changing environment. After over 12 years of patrolling the coast of north Norfolk, in eastern England, I found a common Chalk echinoid—so why am I excited?

The use of geological interpretations to better understand features that are observed outside the Earth defines what is known as planetary geology. It is a highly multi-disciplinary field, using concepts from many areas of human knowledge to better understand the many objects of the Universe. Interpretations tend to be based on analogue models, created from observations made on the Earth and extrapolated to the many geological contexts of other celestial bodies. It is assumed that these models can always be used, as long as corrections considering differences in properties such as temperature, mass, atmospheric, crustal and mantel composition, amongst others, are made. In most cases, such correlations are possible, requiring minor to no significant modifications. However, a reasonable number of extra-terrestrial features cannot be explained using the Earth as the unique comparison ground, requiring the use of other analogues as a basis, or even the creation of models and theories from scratch. Here, we present an overview of planetary geology: what it is, the limits of its application, the current state of the art and the meaning of this line of research in the era in which we live, where the exploration of other objects of the Solar System is a reality.

It is well known that James Hutton's approach to the study of what would later be known as Earth science was significantly influenced by the work of Isaac Newton. But it is hardly appreciated, except perhaps in continental Europe, that Gottfried Leibniz had as much or greater influence on Hutton's ‘natural philosophy’ and even his methods of research and analysis. Nowhere is this more apparent than in the shaping of Hutton's understanding of the nature of time itself.

In 1987, authors P. Yadagiri and K. Ayyasami described a giant dinosaur, Bruhathkayosaurus matleyi, from the Late Cretaceous beds of the Cauvery Basin, India. Unfortunately, the fossil remains of this giant had disintegrated into dust before they reached the repository, making B. matleyi a dubious species. Gigantism is one of the many characteristic features of dinosaurs that grab public attention, and there is much fossil evidence that suggests gigantism was not limited to any specific group of dinosaurs. Nevertheless, this characteristic feature was very advanced and extensive among sauropod dinosaurs, which belonged to a group of long necked herbivorous dinosaurs. Sauropods evolved from basal saurischian dinosaurs about 200 Ma and survived until the K/Pg (Cretaceous–Palaeogene) mass extinction event, about 66 Ma. By the Late Jurassic period, many colossal size sauropods had evolved, such as Supersaurus, Diplodocus, Barosaurus, etc. but together with other Diplodocidae, they went extinct by the end of the Late Jurassic. During the Cretaceous, a new clade of sauropod dinosaurs evolved, the Titanosauria. The Titanosauria diversified into various genera, and in terms of size, they ranged from a 6-m-long Magyarosaurus, to the 35-m-long Argentinosaurus. Most of these giant titanosaurs, including Argentinosaurus, alongside Patagotitan, Dreadnoughtus, Puertasaurus, and Futalognkosaurus, are known from South America, making this continent truly a ‘land of giants’ during the Cretaceous. However, the latest discoveries of this group indicate that supersized titanosaurs were not just restricted to South America, with Paralititan from Africa and Australotitan from Australia. Loss of the fossil remains of B. matleyi has raised not only questions upon the validity of the species, but also questions the notion that any supersized dinosaur lived in India. Here we critically review pieces of evidence in support of supersize dinosaur remains from Southern India.

Almost exactly half a century after the eruption of the Teneguía Volcano on La Palma (26 October to 28 November 1971), a new eruption occurred on the island and lasted for 85 days from 19 September until 13 December 2021. This new eruption opened a volcanic vent complex on the western flank of the Cumbre Vieja rift zone, the N-S elongated polygenetic volcanic ridge that has developed on La Palma over the last c. 125 ka. The Cumbre Vieja ridge is the volcanically active region of the island and the most active one of the Canary Islands, hosting half of all the historically recorded eruptive events in the archipelago. The 2021 La Palma eruption has seen no direct loss of human life, thanks to efficient early detection and sensible management of the volcanic crisis by the authorities, but more than 2800 buildings and almost 1000 hectares of plantations and farmland were affected by lava flows and pyroclastic deposits. Satellite surveillance enabled accurate mapping of the progressive buildup of the extensive and complex basaltic lava field, which together with monitoring of gas emissions informed the timely evacuation of local populations from affected areas. Lava flows that reached the sea constructed an extensive system of lava deltas and platforms, similar to events during earlier historical eruptions such as in 1712, 1949 and 1971. Long-term challenges in the aftermath of the eruption include protection of drainage systems from potential redistribution of tephra during high rainfall events, the use of the large surplus quantities of ash in reconstruction of buildings and in agriculture, and the crucial concerns of where and how rebuilding should and could occur in the aftermath of the eruption. Finally, there remain strong financial concerns over insurance for properties consumed or damaged by the eruption in the light of future volcanic hazards from the Cumbre Vieja volcanic ridge.