Geology Today最新文献

Recent discoveries of trackways and trails on ancient tidal flats at Blackberry Hill, Wisconsin, USA, have transformed our understanding of the initial invasion of land, 500 Ma. Huge slug-like molluscs grazed on microbial mats. Euthycarcinoid (stem myriapod) death traces (mortichnia) suggest that they did not come onto land to feed or breed, but simply to survive; Moon was closer to Earth then, and massive tides stranded animals in tidal pools that gradually dried up.

The elevation of the mountains in Norway is geologically young. Much of the present-day land surface was buried below a thick cover of relatively young sediments in the early Miocene, 23 Ma, when Scandinavia started to be uplifted. Big river systems eroded deeply into the rising landscape and transported sand and gravel from Norway and Sweden to Denmark where the detritus was deposited in a large delta. In Norway, the erosion formed an extensive plain near sea level that included the present-day mountain plateau of Hardangervidda and extended across a thick pile of sediments that covered the present-day coastal areas of Norway. Hardangervidda was uplifted to its present elevation of about 1200 m after a second phase of uplift that began about 5 Ma, in the early Pliocene. The hard bedrock of Hardangervidda has preserved this part of the plain as an elevated plateau, but the part of the plain that extended across the sediments has been eroded away, exposing the underlying basement rocks. That re-exposed basement surface was shaped in the Jurassic when the climate was warm and humid. The basement rocks were weathered where rainwater seeped into fracture zones. Erosion of the weathered rocks has left a terrain of fracture valleys and hilly relief that contrasts with the sub-horizontal plain of Hardangervidda. This weathered landscape is today exposed on the slope between the west coast and Hardangervidda. While the elevation of the mountains is young, today's landscape has a long history.

This article highlights key moments in the history of the development of loose material micromorphological analysis, analysing its current position in the context of lithological facies studies. This method was developed to reconstruct the conditions of transport and deposition of Quaternary deposits. Since the 1970s, the study of grain surfaces has been used to study the features of cryogenesis formation in deposits. The development of the method was facilitated by the technical progress of the twentieth century, and the development of electron microscopy has brought the method to a completely new level. Currently, micromorphological analysis remains the most widely used method of analysing the surface of grains. However, modern methods for studying the surface of particles, such as computed tomography, are now being introduced into the research methodology. This in turn significantly expands the research scope: in recent years, the shape and degree of roundness of grains has been used to analyse the properties of soils for construction. As of today, the volume of publications abroad significantly exceeds the number of publications in Russia.

On the afternoon of Christmas Eve 1965, the village of Barwell, in Leicestershire, England, was the scene of an extraterrestrial invasion. Rocks rained down from the sky causing damage to buildings and vehicles, and consternation among the locals. It was soon established that these stones were actually meteorites and, with more than 40 kg falling in total, it proved to be the largest meteorite fall in UK history. Analysis showed the Barwell meteorites to be stone meteorites of a particular type known as ordinary chondrites. More specifically, they were a variety called L chondrites, which are among the most common type of stony meteorite so it might be assumed that its story prior to arrival in Barwell might not be especially interesting. In fact, nothing could be further from the truth. Common as they might be (by meteorite standards), the Barwell meteorites and other L chondrites are ‘ordinary’ only in name and they actually record some truly astonishing events in the history of the Solar System.

For those interested in the Solar System, 1969 was a momentous year. Rock samples collected during the first Moon landing, and on subsequent missions, contributed enormously to understanding our nearest neighbour, but several meteorite falls that same year also had a profound influence on our wider understanding of the Solar System. Fortuitously, two of these falls, which by their very nature are unplanned events, also played a significant role in the analysis of samples brought back from the Moon by the Apollo astronauts. In this article, I will outline how meteorites have contributed to our understanding of the Moon, and how the Moon also has provided information on meteorites.

Meteorites are natural lumps of rock and/or metal that fall to Earth from Space. Most meteorites are from the Asteroid Belt, with a few from the Moon or from Mars, but their ultimate origins extend more widely through the Solar System. More than 150 parent bodies are represented among more than 65 000 meteorites known. Certain meteorite components provide an age for the Solar System of 4567 million years. Various meteorite classifications have been proposed based on composition, texture and inferred formation processes, but the most informative of these encompasses aspects of all of these properties.

The fall to the Earth of a meteorite—a piece of rock or metal from Space—is a rare event with fewer than 30 recovered from Britain and Ireland in more than two centuries. Museum curators like myself acquire meteorites mainly through purchases or sample exchange with other museums. Meteorites are so rare that, unlike many rocks and minerals, I cannot reasonably expect to go out and find one, at least not in the UK or Ireland. Or so it seemed until 2021.

Dead shells are common allochthonous clasts on British beaches. How much information of relevance to palaeontology can be gleaned from such bioclasts? One exceptional shell, a common Buccinum, is described, which preserves an array of borings and other ichnological evidence. It provides confirmation that we need to look harder at fossil gastropods, too.

A thin layer of Middle Triassic Otter Sandstone recently exposed on south-west England's East Devon coast produced abundant and diverse vertebrate fossils, including previously unrecorded taxa. Some of the remains are remarkably complete, allowing CT scanning of Otter Sandstone fossils for the first time. Here we discuss the formation of this assemblage and summarize the preserved fauna, which provides an important insight into the recovery of terrestrial ecosystems following the Earth's greatest mass extinction.