geology

July’s Changing Seasons ~ To Shropshire’s Mysterious Stiperstones

It is a wild and brooding place, one of the strangest in South Shropshire’s hill country. For one thing the Devil has his chair there, and when the mist comes down, this is where he sits – brimming with pent-up malevolence but unseen by us mortals.

We did not encounter mist on Saturday when we ventured there so we assumed the Devil was out. But there were lowering skies, a near absence of light and the threat of rain. Oh yes, and wind, that somehow caused a discontinuity of function between brain and feet, so making the trek over moorland paths strewn with quartzite cobbles somewhat hazardous.

The Stiperstones ridge extends 5 miles (8 km), and at its highest point on Manstone Rock is 1700 feet (536 metres) above sea level. Standing on the top you can look west across the great expanse of Wales, and on clear days see Snowdon and Cader Idris mountains. Turn east, and you can scan across the Long Mynd to north east Shropshire and far, far beyond.

The ridge has ancient origins and half the world away, some 60 degrees south of the equator. It probably began existence as a quartz sand beach laid down by a shallow sea during the Ordovician, some 495-443 million years ago. Thereafter the landmass moved one inch a year for the next 450 million years to reach its present location 50 degrees north of the equator. A slow, slow journey, then, of 7,500 miles.

You might think, as you look at succeeding images, that it doesn’t look much like a beach these days. In fact it has suffered much folding, sending the beach skywards, and tilting it at angles of 80 degrees in places. Along its length are a series of quartzite tors described by the eminent Victorian geologist, Murchison, as ‘rugged Cyclopean ruins’ (The Silurian System 1854). Besides the Devil’s Chair and Manstone Rocks there are also Diamond Rock, Cranberry Rock, Nipstone Rock and several other eye-catching outcrops.

The place is also described as ‘relict landscape’, one that is undergoing continuous weathering. What we see today was mostly shaped during the last Ice Age when the quartzite was locked in permafrost. Moisture seeped into the cracks, and as it froze, expanded, causing the rock to fissure and fragment.

The moors below the ridge-top are rich in whinberries and cowberries, and so provided food and grazing for human populations from at least the Bronze Age. These people from prehistory left us their burial monuments – stone cairns along the hill’s spine. Then around 100 CE the Romans arrived, avidly searching of silver, but mostly mining lead, and smelting it in hillside boles to provide material to line their plunge pools, make water pipes, cover roofs, construct their coffins, and for the craftsmen of Wroxeter Roman City to use in the production of pewter.

Down succeeding centuries lead mining expanded dramatically. The flanks of the Stiperstones are littered with adits and the mine shafts that featured so dramatically in Mary Webb’s Gone To Earth. One of the biggest concerns, Snailbeach Mine, started at the foot of the hill in 1783, employed 500 workers at its height. For a century and more, then, the wild countryside was also a filthy industrial zone of delving, massive spoil heaps, steam-pumping engines and hard-worked men and boys.

Yet somehow this phase too has somehow welded itself into the mythic fabric of the landscape, an impression heightened by the strange visual effect of Stiperstones quartzite – that it somehow looks black against the light, when in fact it is grey and speckled with ice white crystals.

And on that note I’ll leave you with the words of Much Wenlock’s Mary Webb, whose writerly landscape this very much was – and in all senses. This quote is from The Golden Arrow:

The whole countryside was acquiring in his eyes something portentous, apocalyptic. For the personality of a man reacting upon the spirit of a place produces something which is neither the man nor the place, but fiercer or more beautiful than either. This third entity, born of the union, becomes a power and a haunting presence – non-human, non-material.

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Changing Seasons – Please visit Max for this month’s jaw-dropping vistas from his trekking trip to the Romsdalseggen: not for the faint-hearted.

Views From The Silurian Sea

I dare say the farm fields were neither so large nor so orderly when Africa explorer, ‘Livingstone-I-presume’, Henry Morton Stanley looked out on this Shropshire landscape. For looked at it he would have when he came as a guest to The Abbey home of the Milnes-Gaskells of Much Wenlock. Stanley’s hosts were enthusiastic tour guides and brought all their visitors to Wenlock Edge to admire the view.

Those of you who come here often will know that Wenlock Edge is an 18-mile limestone ridge that runs across southern Shropshire. It is very much a local landmark, and its geology is of international scientific interest. The Edge as we know it now was formed by the uptilt of fossilized strata that were once the bed of the Silurian Sea.

Some 400 million years ago, this shallow tropical sea, that pre-dated even the advent of fish, and long before terrestrial life had evolved, once lay off East Africa near today’s Comoros Islands. You can find out more about it in an earlier post: Old Stones of Wenlock: Repurposing the Silurian Sea

On Sunday I posted an African landscape. Today is my ‘Out of Africa’ landscape, both of itself (because this chunk of Britain once lay in African waters), and on account of the photographer (that would be me) who has yet to get over leaving that continent.

But it goes to show how landscape intimately affects who we are, both physically and spiritually. It feeds our imagination, and shapes the lives we lead in a multitude of ways. Its resources may provide the basis for our livelihoods, and will have shaped communities and culture over countless generations before us. If we fail to value it, we will ultimately lose the best of ourselves, our true heritage. In Shropshire we owe great thanks to the National Trust and Shropshire Hills Area Of Outstanding Beauty, organizations that strive to creatively engage and reconnect people with the earth beneath their feet, and the natural beauty around them. More power to their purpose.

Day 7 of my Nature Photo Challenge shots. Thanks once more to Anna at Una Vista di San Fermo who started me off on this jaunt.

And view 2 in the Daily Post weekly photo challenge: Landscape

giant gwendol makes the wrekin

As hills go, The Wrekin (pronounced REE-kin) in my home county of Shropshire is not very high – just over 400 metres (1300 feet) . But then, as estate agents say, location is all, and this is the only big hill for miles around. It rises over a county of farm fields and the flatness of the Shropshire Plain beyond, and thus is a useful landmark when navigating the county’s ancient network of sunken rural roads. It has also long loomed large in local imagination. As with significant natural features the world over, it gives people something to think by, prompting many a tale and joke.

For instance, we have a saying whose usage extends into neighbouring counties. To go all round The Wrekin means to ramble on for hours before arriving at the point. Hopefully not exemplified in this post. Because yes, I will get around to Giant Gwendol before too much longer. But first some geology. Please don’t groan. I’ll make it snappy.

Looking at the photograph above, the first thing that strikes you is that the hill looks like an old volcano, and I seem to remember being told that it was in year 3 geography at secondary school. This apparently is not the case, although it is composed of volcanic rock. The vent that spewed it out is no longer around or visible. This is perhaps worrying. One has to put faith in notions of volcanic dormancy and, since the spewing forth of rhyolites, tuffs and agglomerates took place in the Precambrian some 680 million years ago, we can perhaps rest easy in our beds: Shropshire has had long enough to get over its hot phase.

This is also good because as you can see from the second photo, the place where I live, Much Wenlock, is rather close to The Wrekin. The yellow wheat field in the middle ground is behind my house.

But now for the Gwendol story.

There once was a Welsh giant called Gwendol. For reasons unknown he had conceived a grudge against the mayor and townsfolk of Shrewsbury, in the neighbouring county of Shropshire. Since the town lay within a nearly closed loop of the River Severn, Gwendol came up with a dastardly plan. He would dam the river and so drown the town and all who lived there.

He set off from Wales with a great spadeful of earth to do the deed, and headed for Shrewsbury. He tramped for mile after mile, but somehow lost his way, ending up instead near the town of Wellington. Weary with the search, and from carrying a heavy load, he sat down to rest.

After a time, an itinerant cobbler came walking by. He had walked from Shrewsbury and was heading for Wellington. Over his shoulder he carried a big sack of used shoes for mending.

Gwendol stopped the man and asked for directions. He even told the cobbler his plan to fill in the River Severn and so drown Shrewsbury and all who lived there.

The cobbler was horrified, and especially appalled at the prospect of losing so much trade.

He thought fast.

“Oh dear me,” he told the giant, “that town is so far away. Many days’ walk.” Then he opened his sack of old shoes. “See,” he said. “I have worn out all these shoes and boots walking from Shrewsbury.”

At this, the giant groaned. “I am too tired,” he said, “to carry my load of dirt that far. I had better leave it here.” And so he emptied it out there and then and, as a parting shot, before setting off back to Wales, he cleaned the mud from his own boots, and so left behind little Ercall, the small hill that stands nearby.

And so now you have the true story of how The Wrekin was born. In fact, for a not very bright giant, I think Gwendol did a pretty good job, landscaping-wise. Also the damming plan would never have worked. Old Shrewsbury town may sit inside the loop of the River Severn, but it is also on a very steep hill. Just as well, though, that Giant Gwendol trudged back into Wales and was never heard of more in Shropshire.

SOURCE: This tale appears in Charlotte Burne’s Shropshire Folklore 1883. In other versions the Devil is the hill-builder.

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Vulcanicity ~ Welcome to the hot zone

I have long had a fearful fascination with volcanoes – probably ever since, as a young child in the 1950s, I saw a newsreel item of Mount Etna erupting. It seemed like a living nightmare. I remember especially the unstoppable flows of boiling lava that rolled over everything in their path. Even in places where it had cooled I seem to remember people who walked on it found their shoes smouldering. It was perhaps my first apprehension of the fact that the earth could do things that mankind was incapable dealing with. I remember having a dream afterwards where the ground beneath my feet kept cracking open into ever widening fissures: my first anxiety dream perhaps.

With this in mind, you will understand how very deeply impressed I was when I first set eyes on Africa’s Great Rift Valley.

NASA non-copyright image

Here, on the surface of the earth, we have a 4,000 mile chain of connected fissures that extends from Lebanon in the Middle East to Mozambique in south east Africa. It comprises the Jordan Rift Valley, Red Sea Rift and the East African Rift, which itself divides into eastern and western arms with Lake Victoria Nyanza in between. The entire system has been described as a world wonder, the biggest rupture in the planet’s land surface, and the only geological feature that can be seen clearly from the moon. The East African Rift of course includes the great ice-topped volcanoes of Kilimanjaro and Mount Kenya that are mere remnants of their formerly gargantuan fiery selves.

So however you look at it, moon- or otherwise, the Great Rift is definitely a case of EXTREME geology. All that seismic shunt and shift. And it is still happening and at this very moment. One day the Horn of Africa and littoral East Africa will be an island.

The East African Rift is thought to have begun to pull apart around 40 million years ago. Scientists surmise that the environmental changes associated with fissuring may have had a significant impact on the evolution of humankind. So far, very many of the earliest fossils of (potential) human ancestors have been found in the Rift – Olduvai Gorge, and in the vicinity of Lakes Baringo, Turkana and Omo. On the other hand, this could simply be a reflection of the decades of systematic searching in these areas, instigated largely by the Leakey dynasty of palaeontologists. But whether a good case of careful looking or not, I’m still prepared to believe that humans could have evolved here.

The photograph at the start of this post is of the old volcano, Longonot. It lies in the Rift between Nairobi and Naivasha in Kenya. In the next shot you can see it from Lake Naivasha (hippo added for purposes of scale Smile ). Part of this lake is also formed within a submerged crater.

One key side effects of volcanic activity is highly fertile soil. In Kenya and Tanzania the Rift Valley floor supports the Serengeti grasslands that in turn are home to millions of herbivores, their following of big cat predators, and the whole wonderful species-rich eco-system. These plains also have long been the grazing grounds of the best known nomadic pastoralists on the planet, the Maasai.

Before the British invaded East Africa in the late nineteenth century (intent on setting up the Imperial British East Africa Company) and concluded that any land not occupied by people at that point in time was EMPTY and thus FREELY AVAILABLE, the Maasai ranged over vast tracts of the Rift grassland system. It is believed that their ancestors moved out from the Horn of Africa about four thousand years ago.

This means that the Maasai lived a life that suited them and apparently with little cost to the environment for 4,000 years before the British came along and herded them into a reserve where the land is least fertile and watered for human purposes, and otherwise known as the Maasai Mara. Europeans then set about destroying the plains’ wildlife on a breathtakingly ugly scale. The invaders, or their activities also became vectors for deadly disease – rinderpest that decimated native cattle, and smallpox and syphilis that took their toll on the human populations.

Smallholder farms at Escarpment just north of Nairobi. Mount Longonot beyond.

Once the British had staked their claim in British East Africa, the Bantu farming communities that inhabited the higher hillside zones of Kenya were also enclosed in Reserves. The occupants could only leave to work for Europeans. The justification for creating reserves with designated boundaries (and they were quite large areas) was to protect tribal land holdings from the incoming white settlers.

African farmers, being the successful cultivators they had been for several millennia, were naturally inhabiting the best and most covetable land. So in this sense, the British administration had a point. The early settlers were British aristocrats like Lord Delamere and the sons of the Earl of Enniskillen, and thus the kind of men who expected to own vast acreages and begin farming/ranching on an industrial/landed gentry scale.

Meanwhile from 1896-1902, and as a result of military paranoia of epic proportions, the British had built a very expensive 600-mile railway from Mombasa to Lake Victoria. It was called the Lunatic Line even at the time of its building. But as the strategic objective receded in importance during the early 20th century, so the Colonial Office needed settlers – well-heeled, gentlemen of means who would grow produce for export and so help pay for the railway.

First page of Lord Cranworth’s A Colony in the Making: Or Sport and Profit in British East Africa, Macmillan 1912. A guidebook and general sales pitch to attract gentleman settlers. (Out of copyright).

Thus, in the wake of the adventure-aristocrats came retired military men, among them individuals who were variously set on nation-building, knocking the natives into shape and, in the process, getting rich from flax, ostrich feathers and coffee. The country’s fine shooting and fishing were definite lures, and made much of in the publicity brochures sent out from British East Africa. Other attractions included the notion of plentiful cheap farm labour and house servants, and thus the preservation of social status that was already well on the wane for the middle classes back in Blighty.

But now we come to the rub. Or in fact two rubs. Firstly, when the monsoon winds are blowing in the right direction, Kenya has the most benign climate imaginable, providing two rainy seasons, and thus two and sometimes three growing seasons for some crops. The elevated plateau of Central Province in particular, and its Aberdares highlands are rarely too hot. The beauty of the great forests suggested Scotland or Wales rather than Africa to the newcomers. They set about building mini-baronial lodges and laying out English lawns and rose beds.

But then comes the other rub. The soil. As I’ve said, volcanic soils are very fertile, but they are also very fragile. Wholesale clearance of trees and bush will quickly create desert. The late, great Kenyan environmentalist, Wangari Maathai, has maintained that felling deeply rooting forest trees ultimately leads to desertification for a whole range of reasons.

The forests not only attract rain but the trees shelter, stabilize and feed the soil (many tropical species fix nitrogen). Most importantly, she pointed out, the deep roots open up underground aquifers to water the land.

Traditional farmers of course made gardens within the forest rather than large fields. They cleared trees certainly, but they did not clear all trees. Some had sacred meaning, like the wild fig, and were protected. Others were valued for cropping purposes – for animal fodder, medicine, bee forage etc.

When the old colonials set out for Africa on a cash-cropping spree, full of the notions that they knew best how to farm, they singularly failed to understand that indigenous peoples, far from being ‘undeveloped’, had very good reasons for doing things the way they did them. Their objectives were more about living well than getting rich.

Pre-colonial accounts by explorers and missionaries show that the Bantu peoples were very successful farmers. They planned their planting to take into account the possible vagaries of climate. For instance, drought resistant millet might be the mainstay crop, and cultivated on the drier soils in their territory. Squashes and beans would be grown near stream beds, and water-hungry maize would be the risk crop, planted on a river bank on the off chance that seasonal floods would be small enough not to wash the crop away, but good enough to provide a bonus to the annual harvest.

The other important contingency depended on kinship and clan ties. As the Bantu communities moved out across the African continent over many centuries, pioneering into new territories as population growth or failing soil fertility dictated, networks of clan relationships became extended over quite large territories. If drought, disease or invaders struck, people would take their possessions and seek refuge with distant relatives until the threat had passed.

Pastoralists like the Maasai also relied on being able to move over large distances to secure grazing for their herds in times of drought. But once people were confined to reserves, bound by European constructs of land ownership, they could not move. Land in the Native Reserves where people farmed thus became overcrowded, degraded and overgrazed. Under colonial rule Africans were not allowed to acquire fresh land. This was one of the chief reasons for the uprising in 1950s Kenya when the Land and Freedom Army (dubbed Mau Mau) went to war against British rule.

Then there were the colonial agriculture officers trying to dictate the way the people on the Reserves grew their crops, pressing for mono-culture rather than the traditional way of mixing crops which helps to fool insect pests and utilizes advantages of companion planting.

As we left Kenya in 2000 I was interested to learn that some European agricultural aid project was actually advocating that smallholder farmers (which means most Kenyans) should use ‘kitchen-garden’ planting techniques to reduce crop pest damage and/or the need for pesticides. It had only taken a hundred years for outsiders to teach Africans what they had known all along, but doubtless been told to forget in the interim because their methods were considered primitive.

Sometimes the hypocrisy of rich world tinkering is enough to make this particular writer’s blood boil up in seismic fury. Time to cool down with a view of snow-topped Kilimanjaro. Who’d have thought it: ice on a volcano. When in the 1840s German explorers and missionaries, Johann Ludwig Krapf and Johannes Rebmann, out exploring from their Mombasa mission, claimed to have seen snow-capped mountains at the Equator, no one back home believed them. Thought they were barking. There’s a lot, we outside Africa do not know about this vast, extraordinary continent even though its nations provide us with so many of our essential raw materials, fairly and otherwise; mostly otherwise…

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Weekly Photo Challenge: Change

Change, what change? All seems so still in this shot of Kenya’s Great Rift Valley. The day is fine. The short rains have brought on the maize and pyrethrum crops on the small escarpment farms. The distant volcano, Longonot, appears dormant and suggests no kind of threat. It is hard to imagine, then, that this peaceful scene is a site of great seismic upheaval, and has been for the last 30 million years. Likewise it is hard to accept that even as I took the photo, the tectonic plates beneath the Rift floor were v-e-r-y slowly pulling apart. In another million or so years you might stand in the spot where I stood and look out on the Indian Ocean; the ground beneath your feet will be a brand new island, and the low Rift terrace where Kikuyu farm wives presently toil, lost under the sea.

The thought is unnerving. For it’s an interesting paradox: while we accept and embrace increasingly rapid changes in the man-made environment, we’re not too keen to confront the reality of a planet that transforms itself beneath our feet and in ways we cannot control. It is interesting then to think, as scientists have been doing, that our very origins as humankind, could well derive from the creation of the Rift Valley.

The argument runs like this. The Rift has long been referred to as “The Cradle of Mankind”. The earliest remains of human ancestors have so far been found along its length (in Ethiopia, Kenya and Tanzania), but the time when we see the big leap in hominid development coincides with the time of maximum uplift in the Rift. This happened around 7 million years ago when the so-called Wall of Africa was created and Africa’s climate thereafter began to change. The rain shadow created by the upthrust highlands caused the forests, the preferred habitat of our primate predecessors, to give way to the more arid savannah we see today.

Without trees for cover and look-out posts our ancestors became vulnerable; food would have become less easy to find, and so in order to hunt and not to be hunted they had to stand up on two feet in order to see over the tall plains grasses. Thus began the long march to cell phone, app and PC that much of humanity apparently cannot now live without. It’s interesting to think how things end up.

As to what created the 3,700 mile-long Rift, then that comes down to plumes of hot semi-molten rock surging up beneath the earth’s crust. In Kenya this surging has also left behind chains of dead and dormant volcanos, including Mount Kenya which, at 17,000 snow-capped feet, is only a vestige of its former unexploded vastness. The pulling apart of the Rift plates has also created the famous soda lakes of Magadi, Nakuru and Baringo, and the deep freshwater Lake Victoria.

Personally, though, I prefer the old Kenyan story that says the Rift was created by termites. It goes like this. Once there was a marauding giant abroad. He preyed on all the animals and none of them was strong enough to finish him off. In the end it took the cunning of many tiny insects to burrow away under the ground and create a well hidden ambush. The next time the giant came rampaging by, the ground gave way beneath his feet and he plummeted into the great trench that the termites had created and so was killed. It was doubtless a fitting end for a troublesome giant, while the hitherto disregarded insects could look forward to greater respect from their fellow creatures.

©2013 Tish Farrell