This is an interesting little booklet and very much a new departure for the Palaeontological Association. You will be aware that I have reviewed several of its many excellent fossil guides in this magazine. However, this recently published tome is somewhat different.
I always wait expectantly for the publication of a new Palaeontological Association guide to fossils and, when they turn up, I am never disappointed. This is undoubtedly another triumph. This guide attempts to bring the diversity of its flora and fauna together in a single work, for the first time.
I sat down to read this over Christmas and what a good read it turned out to be. The appropriate word is ‘eclectic’ – because Measures for Measure is written for all us with an interest in the industrial history of Great Britain, and its impact on the landscape, economy, social history and culture. It’s a great read as it dots about linking places and ideas together, with the link always being the geology.
P W Forster (UK) I have many years of experience collecting and cutting agates. It was my wife who originally had an enthusiasm for these beautiful semi-precious stones and it was because of her enthusiasm that I developed an interest that has now become an obsessive hobby for the both of us. Cabinets in our home evidence the wide range of specimen stones that an amateur collector can discover. Each specimen has identiﬁcation labels and is catalogued to show the date and the region where it was found. Before starting my first collecting foray, I obtained as much information on the subject as was available. To this end, I found the book ‘Agates’ by H G McPherson most useful. (This book, together with ‘Agate collecting in Britain’ by P R Rodgers, has been extensively used in the writing of this article.) From my research, it became apparent that the Midland Valley of Scotland contained many of the best deposits of agates in Great Britain. With this in mind, we paid the ﬁrst of many visits to the region. We started searching along the east coast of Ayrshire. This coast abounds with small coves of pebble beaches and large stretches of andersite larvas that stretch out to sea. During the ﬁrst year, we amassed a large amount of what we thought were agates, but closer examination revealed that we had collected some colourful specimens of jasper as well as some lovely quartz pebbles. This ﬁrst attempt had revealed that those agates … Read More
This book is truly sumptuous, and yet is also a comprehensive discussion of William Smith’s maps (including the revolutionary ‘A Delineation of the Strata of England and Wales, with part of Scotland’) and career. It is beautifully produced, printed on quality paper and the full colour illustrations are outstanding.
Carl Mehling (USA) Things aren’t always what they seem. The fluidity of information and the frailties of human memory allow for a lot of corruption. Innocent assumptions are made. Sloppy mistakes take place. Unforeseeable accidents occur. And deliberate subterfuge is always there as an option when these others fail. Throw a little time at them and mis- and disinformation get lithified, entrenching them in the human psyche and culture. Fighting for accuracy is a continuous battle. A wing and a prayer Once almost considered throw-away parts of the bird, chicken wings have soared to unimaginable heights since their transformation into ubiquitous bar food in the 60s. Buffalo wings are so absurdly popular in the US that possibly-calculated rumours often circulate that a wing drought is coming, causing the requisite panic. Sports bars riot over this dearth, prompting half-serious suggestions of breeding chickens with more than the pathetic pair that their lineage has provided. Anything this popular inevitably spawns feuds over priority: Who gets to claim bragging rights for such a powerful, lasting and lucrative phenomenon? Fig. 1. Were the origins of Buffalo Wings in a science pub or a brew pub? This certainly happened with Buffalo wings. I’ll spare you the gory details, but although hard to prove definitively, most have settled on the idea that the Anchor Bar in Buffalo, NY began this tangy trend in 1964. However, as it turns out, it can be demonstrated that the origin of buffalo wings actually happened elsewhere, and in 1962. Or, … Read More
Robert Sturm The Isle of Skye is a part of the Inner Hebrides in the north-west of Scotland. It has a total area of 174,000 hectares and has an irregularly shaped coastline that is typical of the British Isles. Since the early nineteenth century, the island has become a centre of geological research, because rocks of different geological periods are exposed there. For instance, the gneisses of the Lewisian complex were formed in the Proterizoicum, 2,800Ma and, therefore, are some of the oldest rocks in Europe. On the other hand, intrusive and extrusive igneous rocks can be assigned to magmatic events that covered wide parts of the island during the Tertiary. This event, which took place about 60Ma, resulted in the development of the Atlantic Ocean in its present form. In more recent times, two ice ages, which affected the island 26,000 years ago (the Dimlington glacial) and 11,000 years ago (the Loch Lomond glacial), resulted in the formation of a partly spectacular glacigen landscape (a landscape formed by the ice) with sediments that are of high interest for geological research. Fig. 1. Geological map of the Isle of Skye (modified after Anderson & Dunham 1966) illustrating the high variability of rocks that can be found on the island. Impressive evidence for the Tertiary volcanism is provided by the plateau lava series (these are horizontally stacked layers of lava), mainly exposed in the north and west of the island. These extrusive rock formations probably reached a thickness of 1,200m before … Read More
Scotland has been the source of many important fossil discoveries, from the first ever soft body parts of the conodont animal, to Devonian fishes and early tetrapods. Yet, there has been little published for the popular market on Scottish palaeontology.
Anthony Rybek (UK) Having lived on the Isle of Skye since 2007, I consider myself to be very fortunate to have every day opportunities to fulfil my hunger for the wilderness, natural world and two of my greatest passions, fossil hunting and geology. So, it was of no surprise to me that, during these times immersed in this dramatic and mostly unspoiled landscape, yet another passion would evolve – oil painting. Fig. 1. Anthony Rybek, working on a painting. Like all my pursuits, I am self-taught and, as I began to learn and practice painting techniques, it soon became clear that I had a degree of aptitude for this art form. I found it similar to my earliest fossil hunting trips where, once I tasted success and the thrill of discovering new and amazing fossils, the desire to learn more and improve my skills grew deeper and deeper. My painting is no different. It wouldn’t take long before the subject matter for my landscape paintings would cross paths with fossil hunts and geology. Skye has an abundance of iconic geological landmarks and I feel privileged to have a basic understanding of the geological processes that help shape these formations. And it is these dramatic scenes that are the main influence of many of my paintings. The Trotternish Ridge In the northern half of Skye, this is the dominant feature of the Trotternish Ridge, which runs like the spine of an ancient creature between the islands capital Portree and the infamous … Read More
Mark Wilkinson (UK) Scotland has a number of sites of historical interest to geologists. I described one of these, Hutton’s Unconformity at Siccar Point near Edinburgh (see Hutton’s unconformity and the birth of ‘Deep Time’). James Hutton described several Scottish unconformities in his book of 1795 and, while the one at Siccar Point is easily the most dramatic and most easily accessible, there is another unconformity on the Isle of Arran that is well worth a visit if you are on the island. There is a third unconformity in the Scottish Borders that is sufficiently well known to be actually called ‘Hutton’s Unconformity’, but is on private land and is thought to be presently inaccessible. There are also a number of other locations that Hutton described, but which have sunk in the mists of time back into obscurity. It would make an interesting project to resurrect these. It was on the Isle of Arran that Hutton first observed an actual unconformity surface, in 1787. Arran is the seventh largest Scottish Island at around 32km long, lying in the Firth of Clyde some 64km to the southwest of Glasgow. Sometimes described as ‘Scotland in miniature’ due to the range of scenery, Arran has both highland and lowland landscapes. This is because the varied scenery reflects the underlying geology, with rocks typical of the Highlands of Scotland, and the lowlands. There is a good range of sedimentary, igneous and metamorphic rocks, many of which have well-exposed field relationships, as well as areas … Read More
If you can see past the somewhat robust title (a reference to James Hutton’s discomfort riding around Scotland on horseback during his geological investigations), this is an interesting read, combining both geological science and humour in just about the right measures.
Neale Monks (UK) Alongside trilobites, ammonites are by far the most popular invertebrate fossils. Whether you’re an enthusiastic fieldworker or more of an armchair geologist, chances are that your collection includes a fair number of ammonites of one sort or another. These may well have names and localities, but details on the ecology of ammonites is often lacking, and relatively few popular books on geology say much about how ammonites lived beyond the fact they were marine invertebrates related to modern squids and octopuses. As it happens, British geologists are well served when it comes to ammonites, with extensive exposures of Jurassic and Cretaceous strata accessible across the country, from the Kent coast to the Isle of Skye. Coastal exposures are the ideal, of course, but old quarries and other inland sites can be fruitful too, and the UKGE website is there to help anyone wanting to build up their own ammonite collection (see https://www.ukge.com/). Belemnites are often found alongside ammonites, and being cephalopods as well, resembled ammonites in many ways. The biggest difference was that they were more squid-shaped animals, with the buoyant shell inside the animal instead of outside. They were probably quite good swimmers, but whether they foraged close to the seafloor like cuttlefish, or high up the water column like squid, remains unclear. It may well be that different belemnites did different things, and the variation we see in belemnite fossils reflects this. But what, if anything, is the quintessential British ammonite? And if such a … Read More
Rosalind Jones (France) In Part 1 (Mull’s famous fossil tree (Part 1): Chrissie and the tree), I described the events surrounding the unique fossilisation of an Eocene redwood tree in Mull’s famous Staffa suite of volcanic rocks. In this part, I will take you on a walk to the fossil tree. As enjoying Mull’s magnificent scenery is one of those ‘never to be forgotten’ experiences, choose a fine day to visit and come prepared with a camera and picnic. Fig. 1. The view across Loch Scridain from Ardtun towards the fossil tree location at Rubha na h Uamha. But, be advised, Mull’s weather is very changeable, as acknowledged in two Mull sayings: If you don’t like Mull’s weather, just wait twenty minutes’ and ‘In Mull you can experience all four seasons in one day”. Both sayings are true, so sturdy shoes or boots and wet-weather clothes are essential, unless you are blessed by a Mull heat wave and drought. If staying on Mull, make your way to Tiroran but, if over just for the day, drive from Craignure or Fishnish ferry ports, via Glen More to Kinloch. Fig. 2. An autumnal view of Ben More from Tiroran, taken at the start of the walk to Burg and the tree. Turn right onto the B8035 for the pretty hamlet of Tiroran, then left at the converted Kilfinichen chapel. Cross the bridge over the River Abhainn Bail’ a Mhuilin to enter Ardmeanach – where it feels as though you’ve entered a time-warp. … Read More
This is a very ambitious work. The authors discuss the geology of Britain as a “geological legacy”, that is, they believe it is “an inheritance bequeathed to 11 millennia or so of its post-glacial inhabitants”.
I reviewed some excellent previous guides in this series (Classic Geology in Europe 3: Iceland in Issue 39 and Classic Geology in Europe 12: Almeria in Issue 48), but this one is closer to home and covers an area that I have fond memories of from my Munro-bagging days.
I love the Highlands of Scotland and I am proud to say that I have climbed many of the mountains covered in the glossy hardback. But, as I say in the other book review on this page, it is more than a picture book. It contains some excellent and fascinating science explaining their outstanding beauty.
Mark Wilkinson (UK) Concretions are a common feature in many sedimentary rocks, yet they seem sometimes to be misunderstood. So, how do concretions form? As well-studied examples, let’s look at the ones found in some of the sandstones of the Scottish Inner Hebrides, notably the islands of Eigg and Skye. The concretions are found in several formations, but perhaps the largest and most spectacular are in the Valtos Sandstone Formation of the Great Estuarine Group. This was originally named the Concretionary Sandstone Series after the prominent metre-scale concretions. It is Bathonian in age (Middle Jurassic) and is interpreted as having been deposited in a coastal environment. The Great Estuarine Group is becoming famous for its abundant dinosaur footprints and much rarer skeletal material. The concretions themselves vary from spherical to elongate volumes of rock and are typically from around 50cm to one metre or more in diameter. They are also often coalesced into groups (Fig. 1). Inside the concretions, the spaces between the sand grains are filled completely with a calcite cement. The concretions are resistant to weathering compared to the host sandstone, which is fairly soft, so stick out from the cliff in a sometimes rather alarming manner as you walk below them. I’ve been visiting the concretions sporadically for around 30 years and some of the ones that I photographed in the cliffs in the 1980s are now lying loose on the beach. None of them have fallen while I’ve been there, touch wood. Fig 1. Concretions on … Read More
Neville Martin (UK) Shetland is famous for many things including ponies, knitwear, sheep and sheepdogs, birdlife and fishing. It is less well known for being an excellent attraction for the geologist or that it is currently going through the process of qualifying for European and World Geopark recognition. The rocks of Shetland are too old for fossils with the exception of some fish and aquatic plant fossils at the southern and western extremities. However, what it lacks in fossils it more than makes up for in an abundant variety of minerals and geological structures and, while looking for minerals, the geologist can enjoy some of the most spectacular seascape in the UK. In addition, the islands have a long history of mineral extraction and there has been talk of possible, future platinum and gold mining. Fig. 1. Old Red Sandstone Cliffs, Bard Bressay and Noss. One of the reasons for the geological diversity is that the Great Glen Fault, which formed Loch Ness, also manifests itself in Shetland. This gives rise to a displacement of some 60 to 80km, such that there is a distinct difference between East and West Shetland. The landscape is also the result of sculpturing by glaciers and the sea. The many submerged, glacial valleys are called “voes”, the largest of which is Sullom Voe, the site of the oil terminal where oil from north, east and west of Shetland is landed. The shelter provided by such a large voe (which is sea loch) made it … Read More
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
As the author, John McManus, writes: “The East Neuk of Fife was blessed with a mineral resource that was relatively easy to access”. This resource was coal – the driver of the industrial revolution and, even before then, a crucial element to the area’s industrial development from medieval times (or even Roman times) to the late twentieth century.
I’ve been waiting for a book like this for a very long time and am delighted that a publication of this quality has now arrived. New books covering British palaeontology are always welcomed by this magazine and we published an article a while ago by the founder of the publisher of this book – David Penney – explaining the need for such guides.
Bob Davidson (UK) The north of Scotland is famous to scientists and amateur collectors for its wealth of localities where fossil fish of Devonian age can be collected. From plate tectonics, we know that in Devonian times Scotland was situated just below the equator, as part of a continent that was largely arid desert and where land plants were only just emerging. Most life on earth was still aquatic and fishes were the most successful backboned animals. The fossil fish of the area are unique in many ways. They present a window on the development of vertebrates, in which many of the innovations necessary to pave the way for the next great evolutionary step (the invasion by tetrapods of the land) were already in place. The fauna contains the acanthodians, one of the first group of vertebrates to evolve jaws, and the lobe finned fishes, so called because of their fleshy lobes supporting their pectoral and pelvic fins. The lobe fins also include the lungfish. Their fleshy fin lobes played an important role in the development of the limbs of early four-legged animals (tetrapods) and ultimately to all terrestrial vertebrates today – including ourselves. The classic Middle Devonian (380 to 375Ma old) locality is Achanarras Quarry in Caithness, where exquisitely preserved fish can be collected in an old roof tile quarry. Many such quarries existed in the past and fish have been widely collected from several localities over the years. The fish are preserved in thinly laminated siltstones and limestones, … Read More
Dean R Lomax (UK) Palaeontology and Britain In its simplest form, palaeontology is the study of prehistoric life, through examination of fossils. Palaeontology is, however, not just dinosaurs. Dinosaurs constitute a miniscule portion of what palaeontology is. After all, a myriad of different, and often down-right bizarre, organisms lived long before the dinosaurs and ended up as fossils under their feet. Regardless, the imagination and wonderment that dinosaurs create are why they are considered a symbol for palaeontology – they are a gateway into this most incredible of sciences. The geology and palaeontology in Britain is incredibly diverse. Rocks of almost every geological period are exposed and have been studied for hundreds of years. This provided a platform for geology and palaeontology to flourish and evolve. Some rather notable individuals include the geologist, William Smith – the ‘Father of Geology’. In 1815, Smith created the very first geological map of England, Wales and part of Scotland, a ground-breaking achievement. Incredible fossil discoveries found along the beach at Lyme Regis, by the greatest fossil hunter ever, Mary Anning, paved the way for the first scientific descriptions of large, extinct reptiles – the ichthyosaurs and plesiosaurs. The Rev William Buckland provided the very first scientific description of a dinosaur – this would change the world. Fig. 1. The author pictured with dinosaur footprints at Hanover Point, Brook, Isle of Wight (2014). Our fascination and intrigue in studying and examining the rocks and fossils within has unlocked an ancient, alien world. If you … Read More
Dr Mark Wilkinson (UK) I sometimes ask a question to students in an introductory class about geology: “What is the most famous geological site in the world?” For students from the western hemisphere, the Grand Canyon in the USA is a popular choice. However, if you were to ask the same question to a group of geologists, you might get a different answer, and one option is Siccar Point on the coast some 65km southeast of Edinburgh in Scotland. Although the site itself is relatively modest, a gently sloping platform of rock partly washed by the sea at high tide, and it lacks the spectacular grandeur of the Grand Canyon, the historical significance easily outweighs the lack of scenic drama. I’ve taken several groups of visiting geologists to the site, and so far only one of them has knelt and kissed the ground, but the site could be considered to be one of the ‘holy’ sites of our science. It is difficult for most modern geologists to imagine the world when any interpretation of the geological record had to be constrained by the literal interpretation of the Bible. A particular problem is the short timescale of the account of the creation of the Earth in Genesis, and the age of the Earth as calculated by Bishop Ussher, who allowed only some 6,000 years for the whole of geological time. The person who is frequently credited with expanding geological time to the ‘deep time’ we know of today is James Hutton. … Read More
Mark Wilkinson (UK) If you think of dinosaur hunting, you probably imagine trekking through a parched landscape, reaching the crest of a low hill and catching the first glimpse of a complete skeleton lying half exposed in the next depression. While this might just be true in some parts of the world, the reality of hunting for dinosaurs in Scotland could not be much more different. Hence, a cold and damp day in April 2015 found a small group of geologists from the University of Edinburgh on a slippery foreshore on the northwest extremity of the Isle of Skye. We were hoping not for complete skeletons but, if we were lucky, an occasional bone or tooth – well, perhaps we were hoping, but plenty of geologists have been here before, so the chances of a large find seemed pretty slim. Having said that, the total number of dinosaur bones that have been found in Scotland is still small, so that any bone is likely to be of interest – and could well be a new species, or evidence that a larger taxonomic group known from elsewhere was present on the island in the Jurassic. To add extra scientific interest, the exposures on Skye include a thick Middle Jurassic sequence, representing a time of a rapid dinosaur evolution, but with a poor fossil record worldwide. So any find might be of great importance. We visited several locations on the excursion. There are well-known dinosaur footprints at Staffin Bay on the east … Read More
Rosalind Jones (UK) There’s a saying on the Isle of Mull – “If you come to Mull the once you return again for sure” – and it’s not an idle boast, as those who have visited and subsequently revisited this ‘geological Mecca’ will agree. Second largest of the Inner Hebrides, Mull is famous for its Tertiary igneous geology – 6,000 feet of basalt lavas intruded by a complex of concentric bodies, ringed about three igneous centres. With its unique ring dyke of mixed acid and basic magma, Tertiary granites yielding Lewisian dates, and magnetic reversals in the lavas that make compass bearings untrustworthy, Mull is an enigmatic venue for geologists. The island’s best-known fossils are plant remains, including Ginkgo, Platinus, Corylites and Quercus, all preserved in Tertiary lake sediments deposited between lava flows. Once over collected, fossils from the famous Leaf Beds at Ardtun are now protected, as the site is an SSSI. But the biggest and most noteworthy fossil is ‘Macculloch’s Tree’. Remotely situated opposite Ardtun, on the tip of the Ardmeanach peninsula, it is a phenomenon that, if you visit Mull, you really should see. Fig. 1. Burg House. © Pete McHugh.I first came across Mull’s fossil tree as a geology student in 1966. Its location was pointed out while I was in the Ardtun Leaf Beds gully, so I scrambled over slippery rocks, past hexagonal columns of basalt and down to the shore to see. The panorama I beheld took my breath away. Fig. 2. Goat track … Read More
Joe Shimmin and Stephen Day (UK) Picture yourself strolling through lush, green woodland, on an Earth unspoiled by man and yet to witness the rise of the dinosaurs. You’d be forgiven for feeling at peace with the world, even slightly euphoric – that is until you stumbled across the giant Arthropleura, a millipede relation as long as a park bench. This encounter might make even the most enthusiastic creepy-crawly hater think twice before squashing the bug in front of them under foot! I (JS) had a slightly less dramatic (but still very exciting) experience involving the creature while on a recent fossil hunting trip to Crail in Fife. On investigating some sandstone ledges that ran across the shore to the south-west of this pretty little fishing village in western Scotland, my eyes were drawn to what could only be a huge set of fossil tracks in the rock. The stratum in which they had been preserved also contained plant remains such as Stigmaria roots, as well as sections of tree trunks and branches. Fig. 1. The pretty fishing village of Crail, Fife as seen from the Arthropleura track find site. I took numerous photographs of the track, which measured about 3m long by 30cm wide and also of other, similar tracks nearby, in the hope that someone might be able to identify what kind of creature had created them. My guess was that it was some sort of amphibian, but I wasn’t sure. All I knew was the thing that … Read More
I remember reading and enjoying this book when the first edition came out many years ago. I am also a keen hillwalker and have stood on top of many of the Scottish mountains referred to in the text. In fact, I particularly enjoyed climbing Ben More on the island of Mull, which I remember reading was the last volcano in northwest Europe.
Allen Fraser (UK) For a land area of just 1,468km2, yet within a staggering 2,731km of coastline, Shetland has probably the most complex and diverse geology and geomorphology to be found anywhere in the World. Part of Shetland’s Geopark plan was a suggestion from the community of Northmavine that a geological gateway be established to their area at Mavis Grind, and a volcano trail be set up around the dramatically beautiful Eshaness. Fig. 1. Map of Eshaness. Although it is hard to imagine today, some 350Ma ago, the peninsula of Eshaness was a fire and lava-belching volcano. In fact, the name “Esha Ness” comes from the Old Norse language and means the “Headland of Volcanic Ashes”. The beaches and cliffs of Eshaness show many fine examples of the rocks that formed in this ancient volcano and tell us something of the environment in which the volcano grew. Fig. 2. The Eshaness peninsula. Setting the scene Eshaness’ story begins some 400Ma (in the Devonian period) when three of the Earth’s tectonic plates converged and eventually formed a huge continent now referred to as Pangaea. This collision threw up the Caledonian Mountain chain that was originally of Himalayan proportions but which rapidly began to erode. Rivers carried the erosion products (sediments) into lakes that formed in valleys between the mountains and on the plains below the foothills of the mountain chain. At this time ‘Britain’ lay in equatorial latitudes so the rocks we see exposed today were often laid down in environments … Read More
Allen Fraser (UK) In September 2009, the Shetland Islands were awarded the accolade of becoming the thirty-fifth European Geopark. This is fantastic news for the isles. It acknowledges the importance of Shetland’s incredible geology and creates opportunities to promote it to an international market and develop partnerships with other members. When visiting, the best place to start your journey into Shetland’s ancient past is at Shetland Museum, in Lerwick. Here, displays take you back into the mists of time, revealing vanished landscapes and the amazing events behind them. All across Shetland, the rocks and landscapes tell an endless story – of oceans opening and closing, of mountain building and erosion, of ice ages and tropical seas, volcanoes, deserts and ancient rivers, of land use, climate change and sea level rise, and of minerals and miners. Around 360mya, a walk through where Lerwick is now, would have meant a wade across fast-flowing rivers, in a climate like that in Death Valley, California. How do we know? Well, if you take a stroll around Lerwick, and walk from the Knabb to the Sletts and out to the Sands of Sound, you can see for yourself. Here, flat-lying beds of thick, buff-coloured sandstone begin to acquire rounded pebbles and cobbles of pink and white quartz. These sandstone beds tell us that fast flowing rivers once deposited their loads in the area and that flash floods occasionally scoured the riverbed, leaving trains of far-travelled cobbles and pebbles embedded in the sandy layers. These rivers … Read More