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Take a Walk Back Into Our Volcanic Past

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Take a Walk Back Into Our Volcanic Past Take a walk Back InTo our volcanIc pasT Journey through the British Isles with this unique guide to nine walks that take you to the heart of our volcanic origins INSPIRED BY BBC2’S VOLCANO LIVE volcano lIve introduction volcano lIve introduction contents glossary england volcanoes? The phrases and Hadrian’s Wall 4 descriptions you Side Pike 6 right here! need to know wales MagMa Rocks of the Snowdon 8 they’re not abouT to erupt any time soon, Earth’s crust and/or Llanddwyn Island 10 sayS professor IaIn sTewarT, BuT OuR mantle (the layer between Our Active Land 12 ancient volcanoes Offer clues to the the crust and the core) that have melted or scoTland earth-shattering past Of THE BRITISH isles Arthur’s Seat 14 semi-melted Ben Nevis 16 wonder and peril that make pyroclasTIc erupTIon Talisker Bay 18 volcanoes the most thrilling A violent eruption where norThern Ireland natural phenomena on Earth. the magma is blasted out as fragments, rather than The Giant’s Causeway 20 But live volcanoes are also flowing out as lava Portrush Rocks 22 windows into our planet. Whatever your perspective, pyroclasTIc flow The history of the they are places where you can The hottest, most violent world — in a year 24 olcano Live on BBC2 really sense that the Earth type of pyroclastic eruption celebrates the seething beneath your feet is shifting caldera A large molten world of active — places that make you think depression (about 15km v volcanoes, which have got to very differently about the long and 10km wide) be some of the most exciting world around you. created during a The walks have been places on the planet. In the uK, of course, we pyroclastic flow eruption written by Dr Kathryn for a start, their barren have no active volcanoes. Goodenough of the British sIll Magma that doesn’t rocky wastelands look like They occur at the edge of the Geological Survey, Dr Mark reach the surface, but another planet. The sights, tectonic plates that make up Cooper of the Geological cools down when smells and sounds, too, are the surface of the Earth and ancIenT edIfIces centres erupted colossal country. One of the best places Church Stretton in the Survey of Northern squeezed between layers alien, from superheated at the moment — indeed for a view of the lakes of glaslyn quantities of magma. to see that is Edinburgh. Welsh borderland are Ireland, Clair Drew, who of the bedrock. This is gurgling mud pools to noxious the next few million years — and llydaw from near the Over millions of years, the Clamber up to the top of the outpourings of leads guided walks along summit of snowdown known as “intrusive” rock gases. Menacing craters burst we remain some distance spreading of the Atlantic Arthur’s Seat and you can 600-million-year-old lavas. Hadrian’s Wall, and Paul Igneous Any rock into action with fiery showers from any plate boundaries. seaway has shunted eastward see isolated rocky pinnacles Gannon, a science and formed from cooled of incandescent magma or those volcanic centres — scattered along the forth lthough lacking the technology writer and magma, whether streams of molten lava. he last hurrah of the Arran, Mull, Skye — away from estuary, each the eroded fireworks of live author of guidebooks intrusive or erupted Some eruptions are so big British volcano was the well of superheated rock neck of a former volcano. volcanoes, our volcanic a BasalT Rock formed on the geology of that they drive plumes of hot about 60 million years “in the uK, you that originally fed them, so The jagged peaks of heritage, fashioned by Britain’s hills. T from magma that usually rock and ash high into the ago, when an extraordinary that, today, that upwelling Snowdonia and the Lake millions of years of erosion, Please note: maps do not walk on flows easily to form lavas atmosphere, playing havoc fiery outburst accompanied now feeds the craters and District are even older reveals the inner workings of are illustrative and suBducTIon zone with global aviation and the wrenching open of the volcanoes, you geysers of Iceland. volcanic edifices, while Ben these natural furnaces. not to scale. The area where an spawning lethal clouds of North Atlantic Ocean. The uK’s volcanic fires may Nevis is the disembowelled for, as the following pages walk within them” oceanic plate “subducts” scalding debris that obliterate All along what is now be no more, but remnants of remains of a massive show, in the uK you do not COvER IMAGE: GETTy prof IaIn sTewarT below a continental plate, anything in their path. the western shores of an enduring eruptive past collapsed volcano. Even walk on volcanoes, you walk Art direction AND MAP leading to volcanic activity ILLustration: Jacob Howard It is that mix of natural Scotland, huge volcanic can be found throughout the the gentle summits above within them. alamy 2 3 volcano lIve england volcano lIve england & the great Whin sill, roMan road The route of hadrian’s wall hadrian’s Wall northumberland follows the geological line of the great whin sill HIKE THE roman way across OuR volcanic past adrian’s Wall is an iconic hadrian’s historical monument, wall hugging the natural FACT File h features from one side of the highshield island to the other. winshield crags housesteads The central section of the crags Wall is the most impressive, incorporating natural defences formed by the steep face of cawfield an undulating line of hills. crags These hills are the product of volcanic activity under the land surface about 300 million years ago. The Earth’s internal convection currents caused A bus service from Carlisle WALK Hadrian chose the narrowest the underlying tectonic plate takes 40 minutes. duraTIon 3 hours route across northern England to stretch, crack and thin. vast Walk north up to the ridge, dIsTance 6–7 miles (10k) for his 73 mile-long wall, which quantities of molten magma skirting the eastern side of grade Moderate to ran from Wallsend on Tyne in the started to rise up. But rather the fort to reach the Wall. hilly terrain east to Solwayf irth in the west. than erupting onto the The walk finishes at the Map OS Explorer OL 43 In choosing the route he surface, the magma was Cawfield Quarry car park. To consciously used the geology squeezed between layers of catch the AD122 bus back to it hugs the top of the sill to of the landscape and the natural existing rock and cooled down Housesteads, follow the road Highshield Crags. At the defences provided by the crags there, forming large south to the Milecastle Inn on western end a good example that mark the outcrop of the horizontal sheets called sills. the B6318. In places the walk of columnar jointing can Whin Sill. The Great Whin Sill, on can be slippery, so suitable be seen. This prominent The Sill has been quarried which the Wall stands, is the clothing and footwear are feature of the Great Whin since Roman times and today, largest of the swarm of sills recommended. Sill is common in igneous many of the disused quarries that help define the landscape rocks and results from the have become places that of northern England. FEATURES To way the magma cools and harbour wildlife and rare plants. where To sTarT LOOK ouT FOR contracts slightly, producing Start off from the car park Take the western path vertical cracks. columnar jointing can be seen of Housesteads fort, near following the Wall up the Continue along the ridge, here together with vesicles, Haydon Bridge, Hexham. gentle rise of Housesteads over Winshield Crags, which mineral-filled cavities formed Today it’s an English Heritage Crags. The steep angle of the is the highest point at 345m, by gas bubbles trapped in the site but 1,800 years ago it was scarp slope of the sill is very before finally descending molten rock. They are usually home to 800 Roman soldiers. impressive. follow the Wall as into Cawfield Quarry. More no larger than a penny coin. pa getty; 4 5 volcano lIve england volcano lIve england side PiKe langdale, laKe district ENJOy A landscape lovED By walkers AND created By vIOLENT ERuptions he head of Langdale is old greaT one of England’s finest dungeon langdale other Places ghyll T mountain landscapes. nT The knobbly fells that campsite oF interest surround the dale are the product of violent eruptions side pike that occurred in the same lingmoor subduction zone that affected Tarn Snowdonia (see p8). But while those eruptions happened under the sea, Blea Tarn in the Lakes they took place on land. Massive lava flows were High Rigg, keswIck followed by explosive views of lava flows FEATURES To WALK stacked on top of one pyroclastic eruptions from 1 LOOK ouT FOR duraTIon Short walk 2 /2 fissure vents, forming various another from St John’s in The first few rock outcrops hours; long walk 5 hours plus types of a rock known as tuff. the vale and from summit. are welded tuffs — created in dIsTance Short walk These eruptions also the very hottest type of 2m (3k); long walk 5m (8k) sough Top, peak created large depressions or pyroclastic eruption and grade Short walk moderate; dIsTrIcT Lavas and calderas, which rapidly filled distinguishable by the thin long walk hard pyroclastic rocks form a with rainwater, turning them streaks of flattened lumps of Map OS Explorer OL 6 convoluted line of grassy into lakes (though not the pumice ripped away by the hills rising above this part same lakes as today, which eruption of an incandescent coarse tuffs with visible of the White Peak.
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