Gravel sheets in the suburbs of Washington, DC

Deborah Painter (USA) If you live in western Prince George’s County, Maryland in the USA, in the towns of Oxon Hill and Suitland and you want to dig to place a water line, plant a garden or excavate to construct a foundation for any building, chances are you will encounter sandy soil with hundreds of cobbles and boulders. Some boulders encountered could be in the form of large flattened slabs. You might be wondering why these are present, since these towns are in a coastal plain, far south and east of the rocky outcrops of the Piedmont area of Virginia and Maryland. For someone like me, who was born and raised in the Coastal Plain area of Virginia, these ubiquitous cobbles and boulders seemed out of character for the region. I discovered these odd boulders and cobbles when I joined a colleague from an office in a northern state to assist him in ecological studies for two small sites not too far from the United States Capital of Washington, in the District of Columbia (DC). Our goal was to help our client know if there were any threatened or endangered species, wetlands, hazardous materials or other site constraints, as this would assist the client to decide whether to purchase the properties. Our first Prince George’s County site for an ecological study was one of a few hectares in size in Suitland, a suburb of Washington, DC and approximately 8km southeast of the border of the capital city near the shore … Read More

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Geomodels in engineering: An introduction

Peter Fookes, Geoff Pettifer and Tony Waltham (UK) This article is based on the introduction to the newly published book Geomodels in Engineering Geology – An Introduction. What, why and when? The Earth is an active planet in a constant state of change. These changes can take place over both long and short periods of geological time (thousands or millions of years) or much more quickly on an engineering timescale (minutes, hours or days). Geological processes continually modify the Earth’s surface, destroying old rocks, creating new ones and adding to the complexity of ground conditions: the so-called ‘geological cycle’. The all-important concept that drives this geological plate tectonics. The benefits geologists bring to construction projects must exceed the cost of their services — that is, they must accurately improve the engineer’s ground knowledge more cheaply and effectively than any other method. They must reduce the risk of geological hazards by anticipating situations perhaps unseen by the engineers and also help to determine effective ways of dealing with risks and any problems arising during design and construction. The main role of the engineer geologist is to interpret the geology and ground correctly. Creating an initial model for the geology of the site is an excellent start. Geology (the study of the Earth) and its closest geo-relative, geomorphology (the study of the Earth’s surface), are concerned with changes over time and any geomodel has to build in any changes likely to occur in the near future, especially when the construction project may … Read More

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Rocks in Roslin Glen: A record of a swampy past

Mark Wilkinson and Claire Jellema (UK) Midlothian is an area of central Scotland that lies to the west of Edinburgh and is an area with strong geological connections due to a history of mining for both coal and oil shale. As a part of the annual Midlothian Science Festival (http://midlothiansciencefestival.com/), the School of GeoSciences at the University of Edinburgh offered a walk to look at some local geology and a talk about climate change research on the Greenland icecap. In addition, a ‘Dino and Rocks Day’ was attended by 380 people, proof (as if it were needed) that dinosaurs continue to fascinate the general public. The Edinburgh Geological Society also contributed with a session about Midlothian Fossils and a local historian talked about the history of coal mining in the area. The geology walk visited local exposures, in this case Carboniferous sediments including what may be the best exposed fluvial sediments in the area. The walk was advertised as “Rocks in Roslin Glen: a Record of a Swampy Past” and all 25 spaces were quickly booked. The location was Roslin Glen, which may sound familiar if you’ve seen the film, The Da Vinci Code, based on the novel by Dan Brown. We have not misspelled the name of the glen incidentally. For some reason, Rosslyn Chapel lies on the edge of Roslin Glen and the country park of the same spelling. The glen itself is a steep-sided valley of around 20m in depth, which carries the River North Esk roughly … Read More

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Colourful bluffs in Long Island recall the most recent ice age

Deborah Painter (USA) Imagine a tremendous piece of land moving equipment that scraped up the soil and some of the surface bedrock from four states within the United States’ Eastern Seaboard, carrying and dragging it all the way, before dumping it on a ridge off the shoreline. That is what essentially occurred with the final advance of the Wisconsinian ice sheet, the only one which left glacial deposits visible in New York State today. Long Island is a ridge of Cretaceous bedrock with glacial deposition. The moraines there have not been ground into sandbars and spits along the western end of the north shore as much as elsewhere, because of the sheltered nature of the Long Island Sound. Therefore, shoreline bluffs expose rocks as well as glacial loess. Fig. 1. Fishermen’s Drive takes you to the loess deposits. To park at the beach requires a permit. (Photo by JB Steadman.) If you find that your journeys take you to New York City, one of the world’s largest metropolitan areas, try to make time to visit Caumsett State Park at Long Island Sound. My own visit began when planning a visit to New York State’s Long Island to see my friend, Joyce Raber. She suggested various things that we might do: go to a Broadway play, go shopping and so forth. However, my list of things to do was typically “eco-tourist”. I wanted to visit the famed American Museum of Natural History in Manhattan, then see nearby Central Park, where the … Read More

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Volcanism in the ancient world

Dr Robert Sturm (Austria) In the ancient Greek and Roman world, volcanism was recognised as a divine phenomenon standing in close connection with the fire god, Hephaestus or Vulcan. Although there did not exist any term corresponding to the modern word “volcano”, people were aware of the destructive power arising from volcanic eruptions. Some early natural philosophers were already able to identify individual volcanic processes, such as lava flow and the generation of huge and extremely hot dust clouds. In the ancient Greek language, lava masses streaming downhill were simply named “rhea” (ῥύαξ or flow), whereas the Latin words “Vulcanius amnis” (Vulcanic stream), “saxa liquefacta” (liquefied rocks) and “massa ardens” (blazing mass) were used for the same phenomenon. Volcanoes were of enormous importance for the ancient Mediterranean world, because their eruptions caused the destruction of adjacent settlements and even the annihilation of entire civilizations. According to our present historical and archaeological knowledge, three volcanoes had an immense influence on the development of Mediterranean cultures: (1) the volcano of Thira-Santorini, which left behind the huge caldera visible today; (2) Vesuvius near the city of Naples; and (3) Etna on the island of Sicily (Fig. 1). Fig. 1. A satellite map of the Mediterranean region, including the position of the three volcanoes covered in this article. Despite the Thira-Santorini volcano being situated in the Aegean Sea, Vesuvius near Naples and Etna on Sicily, they are all considered to be part of the western Mediterranean Sea. (Photo: ©NASA.) In this article, I intend … Read More

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Urban geology: Gabions in the Dutch townscape

Stephen K Donovan (The Netherlands) Gabions are tools of the engineering geologist, facing elements that are used to stabilize over-steep slopes, such as sea cliffs or railway/roadway cuttings; they also have military applications. The word is derived from the French, gabion, and Italian, gabbione, and originally referred to “A wicker basket, of cylindrical form, usually open at both ends, to be filled with earth, for use in fortification and engineering” (Little et al., 1983, p. 823). A modern gabion used in engineering geology is a cage, box or cylinder, commonly infilled by rocks or concrete, and sometimes sand or soil (https://en.wikipedia.org/wiki/Gabion). Fig. 1. A gabion wall, lacking subtlety, outside the restaurant, ‘De Blausse Engel’, at Amsterdam Zuid railway station. A: General view of castellated wall, separating restaurant patrons (chairs and tables to left) from passers-by. B: Detail of one cobble in the gabion, showing a vein (sphalerite?). Essentially, gabions provide a stable retaining wall that is semi-permanent. That is, they can be more easily removed, modified or replaced than a permanent structure made in concrete, brick or steel. Although they may be aesthetically unpleasing, gabions provide stability in situations where serious erosion problems may exist, which cannot be controlled by alternatives such as re-vegetation (Freeman and Fischenich, 2000). This is a simplification and studies such as that of Druse (2015) explain something of the complexities. So, in the low-lying Netherlands, what uses might be and are found for gabions? It is reasonable to suggest that they might be used in … Read More

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Urban micrometeorites: A myth?

Jon Larsen (Norway) Is it possible to find micrometeorites in populated areas? The question has been raised for nearly a century and, despite numerous attempts to find them, the answer up to this day has been a very short “no”. Meanwhile, our knowledge about these amazing stones has gradually increased. There is a continuous evolutionary line in the research on micrometeorites, from the early pioneers, John Murray and Adolf Erik Nordenskiöld in the nineteenth century, to Lucien Rudaux and Harvey H Nininger. With Donald E Brownlee and Michel Maurette in the 1960s, micrometeoritics became real science. During the past two decades, this research has accelerated thanks to, among others, Susan Taylor, who extracted micrometeorites from the water well at the South Pole, Matthew Genge, who figured out the classification, and other splendid researchers, in addition to the space probes that have returned to Earth with dust samples from comets and asteroids. Today, there is a growing literature about micrometeorites, but still the answer to the initial question is “no” and urban micrometeorites have been considered an urban myth. Micrometeorites have been found in the Antarctic, but also, to some extent, in prehistoric sediments, remote deserts and in glaciers – places that are clear of the confusing anthropogenic influence. The wall of contamination has been considered insurmountable. It is therefore with pride and joy that I can report here about a project involving the systematic examination of all sorts of anthropogenic and naturally occurring spherules in an empirical search for micrometeorites … Read More

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Fake fossils by the hundred: Johann Beringer’s ‘lying-stones’

Paul D Taylor (UK) The sorry tale of Johann Beringer has been part of the folklore of palaeontology for almost 200 years. In 1726, Beringer published a book illustrating some extraordinary ‘fossils’ reputedly found in the rocks close to Würzburg in southern Germany. However, very soon after its publication, Beringer realised that he had been tricked and that the specimens were fakes. The truth about the deception – and its perpetrators – is still shrouded in mystery, and the story of Beringer’s Lügensteine (’lying-stones’) ranks with Piltdown Man as the greatest of all fossil frauds. Who was Beringer? No portrait exists of Johann Bartholomew Adam Beringer (1667–1740) despite the fact that he was an important figure in Würzburg during the early eighteenth century. The son of an academic, Beringer became Chief Physician to the Prince Bishop of Würzburg and Duke of Franconia (Christoph Franz von Hutten) and to the Julian Hospital, and was also the Dean of the Faculty of Medicine at Würzburg University. Like other learned men of the time, Beringer kept a ‘cabinet of curiosities’ said to contain ammonites, belemnites and sharks’ teeth. He seems to have led a conventional life for someone of his high standing until May 1725, when an unfortunate train of events was set in motion. Three young men employed by Beringer to supply him with fossils delivered the first of a truly remarkable series of specimens purported to have been found at Mount Eibelstadt, a few kilometres south of Würzburg. These are the … Read More

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Humble flint sea urchins and the stories they tell

Joe Shimmin (UK) Flint is a very hard-wearing rock from the chalk of the Upper Cretaceous. Whole beaches made of flint pebbles can be found many miles away from the chalk strata that the nodules originated in, owing to the rock’s ability to withstand the processes that destroy other rocks quickly. Flint sea urchins are especially hard-wearing, as their rounded shapes require a lot of force to damage, while less-rounded flints tend to break up over time if subjected to high-energy environments, such as beaches and fast-flowing rivers. Because of this robustness, it is possible to find flint urchins, which have undergone some very interesting journeys before being collected, adding to their interest for fossil hunters. Fig. 1. The hardness of flint and the rounded shape of flint urchins make them extremely robust fossils. All flints start off within chalk strata. Where these strata are exposed at the coast or in quarries and cuttings, it is possible to collect flint sea urchins, which, at first, look very much as if they are preserved like every other urchin found in chalk. They have a white calcite-replaced test and all that can be seen of the flint within is a slight blueish tint or maybe a glimpse of the nodule through the anal or oral apertures. Of course, flints can also be found that partially or fully envelop an urchin and, in these cases, highly aesthetic display pieces can sometimes occur. Fig. 2. Two of these pristine fossil urchins, extracted straight from … Read More

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