Rocky Rambles: 10 Remarkable Geosites

This is a scheduled post. I am currently walking the Wales Coast Path to raise money for the Llanberis Mountain Rescue Team. (Update: I completed the Wales Coast Path on 7th February 2022 and raised £1,300)

It seems everyone last year, myself included, went to Skye and went about making the Old Man of Storr into the Kim Kardashian of the natural world. I therefore think it’s safe to say that the people of the UK definitely appreciate the strange, otherworldly, stone formations that collision, eruption, freezing, cleaving, earthquaking and landslips have thrown up, down or twisted around.

But maybe this year we can give the Old Man of Storr a rest. It is an old man after all and he’s probably quite fed up. Luckily, we are hardly lacking for alternatives. It’s really no surprise our islands bred so many superstar fantasy writers seeing as we have corners of our country just as visually bonkers as Mordor, Narnia, Bolvangor and Hogwarts. Possibly not at Discworld level; a world that rides on the back of a turtle balanced on the back of four elephants is fabulous but I’d be lying if I said it was relatable.

The Geological Society did us a solid back in 2014. For Earth Science Day that year they launched an awesome list of 100 Great Geosites, voted for by the enthusiastic public, and then put them into categories. There are geosites of historical importance, geosites of industrial relevance, incredible geosite landscapes, geosites formed by humans, fiery geosites, icy geosites, folded and faulted geosites, outcropped geosites, coastal geosites, educational geosites and, the category I will be covering here (less scientifically and probably with more irrelevance); geosites for adventurers.

Oh yeah, a whole list just for next year’s plans; for the clamberers, scramblers, cavers and canyoners, for the hiking and biking whole damn curious, cabin-fevered lot of us. Chuck the Christmas jammies and the slipper socks aside, get out your ropes, your poles, your wetsuits, your crampons and your cameras and pull up them bootstraps; get ready for a new adventure.

Porth yr Ogof Caves, Brecon Beacons, Wales

Credit: Martyn Ferry

The Afon Mellte, ‘lightning river’, breaks away from a cluster of rivers churning south towards the Vale of Neath. Out of the steep sided gorges, clustered with ash and alder trees, it heads off on its own, soon burrowing under the limestone to create the formidable entrance to labyrinthian caves.

The Afon Mellte rises and falls dramatically in response to rainfall; and these fickle tantrums have carved out the Porth yr Ogof entrance into a cavernous 20 metre wide and eight metre tall maw that swallows down into nearly a mile and a half of stony, subterranean passageways. Usually entered via a leftside ledge or wading to the right into the ‘wormhole’; a curling crawl tube before finding one’s way past the rectangular ‘letterbox’ and somehow negotiating the two ‘washing machines’. Along the way one would pass the scalloped walls of the ‘grotto’ into the intricate and constricted maze.

Contrariness brought the river through the relatively narrow band of carboniferous limestone to create the caves. This limestone, formed in far warmer seas from the compressed shells of millions of sea creatures over 325 million years ago, holds many curled fossils between its horizontal layers mentioned in the writings of Welsh naturalist Edward Lhuyd. The brittleness makes it open to the same shaping seen in its other limestone caves and structures; the warped bend hiding the riddled caves of Malham Cove, the massive swoops of White Scar Cave, and the tinged walls of Aillwee Cave (the last bear den in Ireland – there’s a story for another time).

Despite its main use as a training cave, Porth yr Ogof has seen eleven recorded fatalities. Ten of these occurred at the far end of the passage, in the resurgence pool full of fast flowing and icy cold water seven metres deep.

There is no record of its discovery. It seems Porth yr Ogof has been known to man since before established writing and cartography though, unsurprising considering the frequency of flooding, it has never been a settlement.

If you are venturing to the Brecon Beacons with all intention to head up, maybe take half a day to investigate the draw of heading down. Porth yr Ogof is not the only entrance to the cave system and each entrance will lead to a different choose-your-own-adventure. To ensure you choose the right one for you, look at the official site.

Gaping Ghyll, Ingleborough, North Yorkshire

Credit: The Guardian (Danny Lawson)

Another limestone region of the UK, the Dales, consists of a top layer 200 metres thick known as the Askrigg Block. The Ingleborough area is an uplifted part of the block with the Dent Fault securing it to the west and the Craven Fault to the East. The easy sculpting of the limestone is what gives the Dales their distinctive smoothness and giant, wide sweeping valleys. Its brittleness also creates potholes.

On a fellwalk up Ingleborough, a scurry around the southern slope along Fell Beck will reveal such a pothole. The waters of the stream suddenly tumble away into the Gaping Ghyll and slam down 98 metres from moor to floor. It is the highest unbroken waterfall in England. It used to be the deepest, but Titan in Derbyshire came in and nabbed that title.

The cavern below is far larger than appears from the height; a nifty industrial tool called a laser rangefinder has shown the volume to be the same as the whole of York Minster. The first recorded attempt at descent was in 1842 by John Birkbeck, a ‘banker and alpinist’ (as you do). He made it to a ledge around 55 metres down, but in these days before geophysics and nifty industrial tools he did not know yet what came deeper and cautiously barred his further descent. That ledge is named for him.

The first full descent was made by Édouard-Alfred Martel, the ‘father of modern speleology’, in 1895. It was realised that the underground cavern was huge around this point. I am finding numerous throwaway lines stating that, in an effort to show how big it was, there was once an attempt to fly a hot air balloon inside it. I cannot find any solid references to confirm this. It may well just be local lore, but it’s far too fantastic not to include, and a hot air balloon inside a cave is just the kind of nutty showman shenanigans that the Victorians adored.

You would normally have to be potholing or caving at an experienced level to attempt to descend Gaping Ghyll yourself to see what all the fuss is about but, lucky for us, that isn’t always the case; twice a year newbies can descend. Over the week of the May Bank Holiday, the Bradford Pothole Club secure a winch to the top and drop down any old member of the public (as long as you weigh under 125kg). The Craven Pothole Club does the same in August.

The 2022 dates for the winch are:

26th May – 3rd June (Bradford Pothole Club)

12th -19th August (Craven Pothole Club)

There is no pre-booking. Turn up, hand over £15, nab a numbered ring, and soon see yourself travelling down into the spectacular cavern (getting just slightly soaked by the plummeting ghyll in the process)

Staffa, Inner Hebrides, Scotland

Credit: National Trust for Scotland

The Island of Staffa, formed from two periods of volcanic activity, sits like a cake that has burst its tin; top heavy and heaving over a tall and rigidly formed base.

The columns of basalt that make up the lower layer were the result of the earliest eruptions from the Mull volcanoes, occurring after the last of the ice retreated. On a basement layer of volcanic ash (known in the rock world as ‘tuff’), the basalt flows formed the six sided colonnades of black stone. The high silica content of the lava that enabled this formation to happen, was lacking from the third layer (not such tuff stuff); a slow moving, slow cooling, slaggy basalt that flopped on top and sighed dramatically. It bulged around the edges and slowed to a halt with the imprints of its flow captured in the surface.

The island is only two thirds of a mile long, and half that wide, and whilst a shore is dipped to the northeast, the boundary of the island is mostly rugged, rough and studded with caves. The most famous of these is Fingal’s Cave, formed in the cliffs of the south; its large, dark yawn being the inspiration for Mendelsohn’s Hebrides Overture . In fact it was visited by many creative types – John Keats, Sir Walter Scott, Jules Verne and Robert Louis Stevenson. Wordsworth was disappointed by the amount of tourism which feels pretty rich coming from someone that lived in the Lake District.

Among its admirers was David Livingstone, the explorer, who would go on to try and find the source of the Nile and disappear (but not really) in the process.

It’s not an easy place to live or stay for any great period of time. The one family living there in the 1700s, existing on a diet of barley oats, abandoned it due to the ferocity of the winter storms and now the only surviving building on the island is, ironically, the ruin of an 1800s travellers’ shelter. It is now owned by The National Trust for Scotland which has cleared it of all livestock (farmers from Iona used to dump their cows, sheep and goats there for grazing) and allowed the natural vegetation and birdlife to come into its own.

Whilst Staffa lacks an anchorage, it can still be accessed by ferries and boat tours from Fionnphort, Ulva, Iona, Tobermory, Oban and Kilchoan. There is no formal accomodation on the island, but due to the relative permissiveness of Scotland’s access code, wildcamping is permitted. Just don’t be an arsehole about it.

The Cuillin, Isle of Skye, Inner Hebrides

I blathered on an awful lot about the Cuillin in my report on the Skye Trail, especially considering I wasn’t even climbing it.

Dramatic and almost inaccessible, the Cuillin Hills are divided into two ranges. To the east are the Red Cuillin; formed of a pale, red-tinged granite; smooth and rounded with grassy summits and slides of scree. A typical highlands scene. To the west, however, is the pinnacled ridge of the foreboding Black Cuillin; formed of basalt and coarse gabbro. Both the Cuillins were formed in the aftermath of volcanic activity; the Black Cuillin rose out of the magma chambers itself whilst the mountains to the east came later in acidic, granite flows.

A full traverse of the ridge that runs the length of the Black Cuillin will take anything from 15 to 20 hours to journey only seven miles from sea level at Glenbrittle, to the bar at the Sligachan Hotel. Oddly, there is no real record of anyone trying to climb any of the Black Cuillin mountains prior to the Victorian era rise of leisure mountaineering. They had no names before then.

Some believe the ultimate mountaineering experience of the UK is the full traverse of the Cuillin Ridge. Some others agree, but only if its done in winter when a 24 hour traverse is hindered by short days and the terrain by snow and ice. These types of people are likely really annoying to be around and are probably one-uppers.

Any climbers wishing to explore the Cuillin have many options from which to do so on Skye, be it from the Sligachan Hotel, the Glenbrittle Campsite or after a rest at the Camusanary Bothy.

Walk Highlands can give hikers the nitty gritty for boot based exploring, for the rock jocks, UK Climbing has some words of advice.

Yr Wyddfa/Snowdon, Eryri/Snowdonia, Wales

Credit: BBC

Fossils are embedded in the summit of Yr Wyddfa. It might be the tallest mountain in Wales today, but once upon a time its land was submerged beneath the Ordovician Iapetus Ocean. Around 457,000 years ago, a volcanic caldera formed and slammed up the sleepy seabed to stunning heights before layering on its rain of tuff (remember tuff?) up to 500 metres thick. The northern edge of that ancient caldera sits where the modern day summit has risen.

More recently, the last ice age scooped out the cwms (corries) upon its retreat, dappling the uplands with cold mountain lakes and plunging waterfalls. Where two cwms formed back to back, the arête of Crib Goch was formed; the knife edge route to the top.

Yr Wyddfa forms the northern edge of the Harlech Dome; a geological doming of the volcanic creations that extends to Cadair Idris in the south. The Rhinogydd stand in the middle, it’s composition altered away from its neighbours by later geological activity into the sands and slates that the area is known for.

No one knows who first climbed the mountain, but today it is the busiest mountain in Britain with over half a million visiting the summit each year. With a variety of ways to go up and down, these visits could have been as easy as taking the train, or as gruelling as the Crib Goch horseshoe.

In order to avoid the crowds, start your climb early and choose the route to suit you.

Mixon Hole Deep Water Gully, English Channel, West Sussex, England

Off of Selsey Bill, a 30 metre deep gully is carved into the seabed. This underwater trench was once a river; used by the Romans to transport goods, but has now been claimed by the rising sea.

The gully is kept in place by the strong tidal currents; its walls formed of limestone overlaying softer, dark clay. The limestone cap juts at the top, having formed a reef that is now overhanging the blue cliff descending deeper into the waters. Clay and limestone that has fallen, collects far down at the base in great boulders, scattered around with crabs, lobsters, and empty limpet shells. Rays, cat-sharks and smoothhounds also dot the sands.

Back in the roman days, this particular outcrop of limestone rock became a desired building material, with Mixon rock still adorning the floors and walls of ruined villas all over the country.

A number of diving schools in Selsey will take you out to the reef-topped gully, though many will only do so on neap tides due to the strong currents.

Uyea, Unst, Shetland Isles, Scotland

Credit: Shetland Times (Shetland Flyer)

The many layers of stone that make up the Shetland Islands are a perfect geologist’s storybook. The very oldest can be found at the very base of the island of Uyea and were formed 2,900 million years ago; at a time before the atmosphere contained oxygen and the sky was red. These granitic layers still stay almost a secret, rarely seen apart from occasions where erosion has taken the top layers or the rough process of mountain formation pushed them to the surface. Later layers of magma, rich in iron and magnesium, poured over the granite and cooled to form dark, crystalline gabbro.

As the continents shifted, moved and collided, these layers were buried and baked forming the Lewisian Gneisses, typical of, but isolated to, this small area far off the Scottish coast. The Caledonian Orogeny saw landmasses collide and the pieces that would become the countries of the UK thrust together for the first time. Many of the nation’s mountains were raised in this collision as the seam smashed together somewhere along where the north of England is now – The Lake District, Snowdonia and the Scottish Highlands were all forced into their more modern topographies though through the time since, land has broken away until only our islands remain together. The westward extension of the Highlands became The Appalachians when they broke away and floated to be part of a whole new land.

But back on Uyea, so much of it was already made. The new layers thrown on top were just icing. It has existed for most of its life already before Bronze Age settlers built their first cairn there, or when the 12th century came along and Saint Olaf’s chapel was built. In the early 1700s two Uyea girls were caught in a storm as they rowed around the island and found themselves in southwest Norway. Instead of finding a way to return, they married local men and their descendants can still be found in Karmøy.

Uyea has been described as a beachcomber’s paradise, caught as it is between the Atlantic, the Norwegian basin, and the North Sea. Sea beans from South America, mermaid’s purses, rolls of bark from North American forests and a whole rainbowed plethora of shells are not uncommon finds. If you’re lucky you might find a bottle with a message inside; Captain Hunter Brown dropped 1,890 such bottles in the area in 1914 promising a sixpence to anyone that returned a found bottle to the Director of the Fishery Board for Scotland. The intention was to discover the direction of the deep currents of the North Sea, but only a few hundred have ever been found.

Despite having Bronze Age settlers buried here, chapels built here, and young girls swept away, Uyea today is uninhabited. It is a tidal island that can be walked to from Unst at low tide. A perfect place to visit for someone that enjoys a lonely treasure hunt on the ancient edge of the world.

Be sure where you’re going when you head on up to get the ferry to Unst; there are two uninhabited tidal islands called Uyea in the Shetlands (the word means ‘sacred place’). The Unst Uyea may be extremely ancient and endorsed by the Geological Society, but the Northmavine Uyea was also voted the top wild beauty spot in the whole of the UK last year in a survey by Mini. So it seems wherever you end up, you’re in for a treat.

For more on Uyea, visit the Unst and Shetlands websites. For ferry times to Unst, see the timetable.

St. Kilda, Outer Hebrides, Scotland

Credit: Visit Scotland

The St Kilda archipelago sits to the west side of the Outer Hebrides. The eroded remnants of a volcano; these small islands are formed from the intrusive igneous rocks; the gabbros and the granites, that dominate the Hebrides. The four islands of Hirta, Dùn, Soay and Boreray rise their formidable cliffs dramatically from the churning sea, surrounded by pinnacled stacks and squat tumbles of smaller islets. Baxter and Chumley observed in the 80s that St Kilda ‘….is a mad, imperfect God’s hoard of all unnecessary lavish landscape luxuries he ever devised in his madness’.

High rainfall and wind gusts of over 115mph are frequent and the ocean ocean swells are up to five metres high. It might be shocking then to hear that the archipelago was inhabited for four millennia, though never at more than 180 people, until the 1930s when the last inhabitants were evacuated during the second world war. The origin of the name St. Kilda is debated. There’s no actual saint by that name. In keeping with the Norse origin of many of the Hebridean place names, it is possibly a derivation of sunt kelda (‘sweet wellwater’), it could be a corruption of the name of Hirta’s spring, Chirder, or a mishearing of the Hebridean dialect that would pronounce Hirta as Kilta. It could just be some sort of adaption of the Gaelic for westward. My personal favourite theory was that it was named for a long time hermit occupant of the islands called Kilder; the idea that he goes somewhere super remote to get away from everyone, but then ends up living on in cartographical infamy inviting others to his erstwhile home just tickles me.

Throughout the island stand 1,400 ruins, in various stages of decay, of incredibly unique megalithic storehouses called cleits and a medieval village still stands at the base of Conachair For such a weatherbeaten place, many over the years have retreated here for shelter; from those original iron age settlers to travelling Icelanders escaping storms. The isolation of the islands allow them to today be the only home of two different ancient breeds of sheep and for the culture to have remained almost unchanged up until the late 1800s. It was a several day journey of storm-riddled rowing for many, many centuries in order to get there.

Today, St Kilda is recognised for its birdlife; having the Europe’s most important seabird colony, and one of the major seabird breeding stations in the North Atlantic. It also has its own taxa of two birds and a mouse, native to the islands, but it terms of flora and fauna, St Kilda has more in common with the Westmann Islands of Iceland than to the Scottish mainland; the weather does not permit trees to grow, but hunkered down to the earth are 162 types of fungi and 182 lichen. The waters that surround the islands host an unusual collection of marine life.

For a reflective time hiking, adapting to the spontaneous and tempestuous climate, first you must get to the Isle of Harris which can be done by plane, or by ferry from the Isle of Skye. From there a private boat will need to be booked to take you the 3-6 hours across to Hirta. There is no accommodation on the island, though in non-pandemic times, the National Trust for Scotland runs a small campsite. Boats generally only run between June and October; the weather is too unpredictable after then.

The Old Man of Hoy, Hoy, Orkney, Scotland

Credit: Ultima Thule

I may have encouraged you to venture further away from the Old Man of Storr this year, but here’s a different Old Man to visit. This photogenic and towering sea stack rises a nervous 137 metres high balanced on a base that is only 30 metres wide. Red sandstone from the Devonian era gives it its ochre tinge that gets deeper and more vivid as the sun sets. It has been held as such a magnetic place for so many years that the shaping of it can be traced through old paintings and maps that attempted to capture its odd character.

As recently as 1750 it was an extension of the headland, but by the 1820s the stone had carved away to sit as a precarious stack. An arch at the base had been created; forming the two legs of the old man figure. One of the legs is no more.

Different lava flows over the earlier years of its formation created the faulting and stacking that the rectangular blocks of sandstone build.

Unlike many other landscape features that will confidently be here for millennia to come; the Old Man of Hoy is surely not long for this world. A crack has already started to run vertically from the top threatening the upper reaches, whilst erosion at the fragile base will sometime soon cause total collapse.

The first recorded climb was in 1966, with an ascent the following year filmed by the BBC for a three part documentary. The stack was then climbed solo by mountaineer Catherine Destivelle (this ascent is often wrongly claimed to be the first solo ascent) in 1998, then in 2013 blind climber, Red Széll, successfully reached the top. In 2018 the youngest climber, 8 year old Edward Mills completed the ascent to raise money for Breast Cancer Research. Not to rain on Eddie’s parade, but some might say the record for youngest climber might actually have been in Catherine Destivelle’s abdomen; she was four months pregnant at the time of her climb.

There are seven routes up the stack; the most common being landward facing which is still rated Extremely Severe. A log book is buried in a cairn at the summit for all who complete the height. Base jumpers have also taken advantage of the stack and one highline walker gave it a successful crack in 2017.

Whether you are an enthusiastic climber out for a new challenge, or just a regular hiker that would like to see the precarious pinnacle before it falls for good, you can fly direct to Kirkwall in Orkney from Aberdeen, Glasgow, Inverness and Sumbburgh (Shetland) on LoganAir. Or both CityLink buses and ScotsRail trains can take you right up to where you begin a succession of ferries. Orkney is nowhere near as remote as St Kildas or Uyea and accommodation and food are easy to come by,

The Needles, Isle of Wight, English Channel

Credit: Country Living

The final inspiration for an adventurous 2022 geosite exploration, is another climber’s magnet. The Needles are probably the most recognisable feature on the Isle of Wight; three chonky, chalky sea stacks drifting out like sailing cliffs with a lighthouse perched on the very end.

It’s likely that these chalk outcrops once formed a continuous ring with similar stacks in Dorset, but breaching by the ocean eventually eroded away the soft clays that mottled the ridge to the north within the last 100,000 years.

The sheer sides of the stacks are 30 metres high, and they look nothing like needles. The name came from a fourth stack that was, indeed, needle-like, known as ‘Lot’s Wife’. Ironically she was the first to crumble. The three remaining may be far more squat, but the sides are sheer and nearly vertical coming up to a ridged point. Their strange geology is a result of the heavy folding that took place during the Alpine Orogeny (the mountain-building geological phase that created the Alps, Pyrennees, Atlas and Himalayas). This Orogeny was caused by what are now Africa and India colliding with Eurasia from the south. The faulted chalk continues to run under the sea and is also part of the lovely Durdle Door and Lulworth Cover until, at Harry’s Old Door, the strata lines fall almost horizontal from their previous vertical position.

The Skeleton Ridge climbing route is probably the most well televised climb in the country and traverses the extremely narrow, jagged tops of the stacks. In order to climb The Needles, ask for permission from the National Trust and the Lee on Solent Coastguard. To get there, get the Wightlink ferry from Southampton. Both private and public boat trips can be booked depending on whether you just want a close up view and some decent local info, or if you want an all day, hands on affair.


Whilst it may still be cold and wet and dark and at that stage where it seems we’ll never see light nor feel the heat of the sun ever again, take the opportunity to plan out your next challenge. It may be for next week, or it might be for July, but I hope this has offered you some inspiration. If not, take a gander over to the The Geological Society website and have a look at the other categories. If nothing grabs you then, then maybe you’re just moping. Go for a walk.

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