Friday, 18 August 2017

doomsday scenario

As a former student of geology, I’ve always known about the mass extinction events that have punctuated the Earth’s history, but I recently learned something completely new about the most devastating of these, the Permian–Triassic mass extinction. I was aware that around 96 percent of plant and animal species died out during this event, and I also knew that there were major volcanic eruptions in what is now Siberia but was then part of the supercontinent of Pangaea. These eruptions were of basalt, which is far more fluid than acidic lavas and therefore flows greater distances, and they had been considered the primary cause of the extinction event because the extra carbon dioxide added to the atmosphere by these eruptions resulted in dramatic increases in global temperatures, the so-called ‘greenhouse effect’.

However—and this was probably not known when I graduated 50 years ago—some of the extruded basalt flowed far enough to reach what was at the time the planet’s largest coal basin, and the combination of hot lava and huge quantities of organic matter released vast amounts of methane, which rose to the surface, where it exploded. You might think that this is a highly speculative scenario, but a Norwegian geologist recently discovered evidence of these explosions, the existence of which he must have already suspected in order to look. And the result of the explosions would have been dramatic increases in carbon dioxide in the atmosphere and a massive spike in temperatures around the world.

There is a worrying parallel with the present day here. The basalt that flowed into the coal basin during the Permian–Triassic event burned through organic matter that had been accumulating for many tens of millions of years in a relatively short period of time. And although the Industrial Revolution is barely 300 years old, humans have already burned through a significant proportion of the organic material—coal, petroleum and natural gas—that has accumulated since.

Yet we continue to extract and burn more, egged on by idiots like the current occupant of the White House and former British chancellor of the exchequer Nigel Lawson, who has had the temerity to establish a think tank, the Global Warming Foundation, to promote his view that global warming is no big deal. In fact, Lawson’s argument is an economic one, that global warming—if it exists—is merely a by-product of raising developing countries to the level of developed countries. However, given that Trumplthinskin believes climate change to be some kind of hoax, and that Lawson is on record as saying that he ‘wouldn’t mind if the weather was a bit warmer’, we can deduce that neither man understands the science involved.

Unfortunately, neither do any of their supporters, which accounts for the frequency with which I have to respond to completely specious arguments about the subject. A classic example of such an argument concerns the recent levelling off of global air temperatures over a period of about a decade. This was seized on by climate change deniers as clear evidence that the planet wasn’t warming after all, but anyone who used this argument is clearly unaware that NASA has a network of satellites around the globe whose sole purpose is to monitor incoming and outgoing radiation. And, guess what! More energy is entering the Earth’s atmosphere than is being re-radiated back into space. So where did the surplus energy go if air temperatures remained static? We now know that it went into warming the oceans instead, an inconvenient fact that I expect will be ignored by those who deny the reality of global warming.

The problem is that the UN target of restricting warming to 2 degrees Celsius, which is essentially a compromise given the impossibility of stabilizing global temperatures at their present levels, is probably unattainable, especially now that the United States—one of the world’s biggest producers of carbon dioxide—has decided to pull out of the Paris Agreement on climate change and is in the process of eviscerating its Environmental Protection Agency. Temperatures during the Permian–Triassic mass extinction must have been insufferable, but unless humans stop burning coal, use their cars less often and stop clearing forests, they will soon know the meaning of ‘insufferable’. The planet’s sixth mass extinction will soon be underway, if it hasn’t already started. And the human race will not necessarily be spared.

Wednesday, 2 August 2017

from the archives: dolomite diversion

I travelled abroad for the first time in 1966, when I was still a teenager. My companions were two fellow students from Manchester—the same two students who had introduced me to rock climbing only a few months earlier, which I mention only because climbing was our reason for going abroad in the first place.

Our first intended destination was Innsbruck in Austria. We’d booked tickets for a train that had been organized by the Anglo-Austrian Alpine Club (AAAC), and we got off to a less than auspicious start by boarding the wrong train in Ostend! The carriages of this train were emblazoned with the AAAC logo, which misled us even though we did notice that the destination boards on the sides of the carriages read ‘Wien’. We had no idea at the time that this was the German word for Vienna.

Every seat on the train had been pre-booked, so without a booking for this specific train, we had no option but to sit on our rucksacks in the corridor. This was an overnight train, but sleeping on a train where you don’t even have a seat is not an option. We thought that it was merely our bad luck at first, but our tickets included a list of towns and cities that our train was meant to pass through, and it didn’t take us long to realize that we weren’t passing through any of them. Incidentally, our tickets were supposed to have our names on them, but I can still remember the name that the AAAC had given me. I often used to be complimented on the neatness of my handwriting, so how the club concluded that my name was ‘Downis Hoolison’ is a question to which I shall never find the answer.

Anyway, by the time we reached Nuremberg, we’d decided that our best option would be to leave this train, with all our gear, and catch a train to Munich, which our intended train was scheduled to pass through. So that’s what we did. No tickets. We didn’t think we needed them.

Of course, we did encounter a ticket inspector on this early-morning train. I’ve often wondered what he made of whatever feeble explanations we offered for being on his train without tickets.

“Stupid Englanders!” he probably thought.

Fortunately, he didn’t ask to check my ticket against my passport, or he might have spotted the discrepancy in names. And he did allow us to continue our journey without paying. And we did manage to join the train we should have caught in the first place in Munich. After all that, the remainder of the journey was utterly unmemorable.

However, Innsbruck turned out to be a mistake. We had thought of stopping off there for a few days to do some ‘mountaineering’ before continuing to our ultimate destination, the Dolomites in northern Italy, but we quickly realized that this was overly optimistic. You may detect a lack of planning on this excursion to date.

The following day, we caught the first available train to Bolzano and trekked up into a steeply rising valley flanked by towering walls of magnesian limestone. Conventional limestone consists of the mineral calcite (calcium carbonate), which is soluble in a weak solution of carbonic acid, another term for rainwater. Magnesian limestone, on the other hand, is made up of the mineral dolomite, which differs from calcite in that half the calcium atoms have been replaced by magnesium, and these are arranged in precisely alternating positions in the lattice. This makes dolomite more resistant to weathering than calcite, hence the towers and spires that I was seeing all around me. Our ‘plan’ was to reach a small rifugio (‘refuge’), or mountain hut, where we would spend the night before continuing. And this is what faced us the following morning:

The sunlit spire on the right is a profile of the three Vajolet Towers, which we aspired to climb. But first we had to reach the next rifugio, which is up to the left and out of sight but was ideally located for our ‘planned’ assault on the towers. I haven’t mentioned it before, but as a first-timer abroad, I hadn’t cottoned on to the need to travel light. In addition to my climber’s rucksack, which was a crude affair compared with what you can buy nowadays, I’d brought a holdall. As you can imagine, lugging all that up that hill was not pretty.

Anyway, this is what the towers look like from the rifugio:

We had intended to tackle the left-hand tower first, but we came under the watchful eye of an Austrian climber, several years older than me, who appeared to be alone. He noted that there were three of us, and a rope of three will take almost twice as long to complete a given climb than a rope of two. Would one of us like to climb with him? I was always going to be the odd man out here, because my friends had known each other before they knew me, so we arranged to meet the next morning to climb the central tower.

“Too many mousquetons!” said Max imperiously, as he watched me walk towards him.

I had half a dozen rope slings around my neck, each with a metal snaplink attached. I remember thinking at the time: how strange; someone whose native tongue is German (presumably) chooses to use a French word. Perhaps he thinks we won’t know what a karabiner is.

Anyway, we set off, and I quickly noticed that Max was using a ‘direct belay’ protection method, a primitive safety precaution that involves temporarily allowing the rope to run behind a flake or spike of rock, so that if Max, in this case, happened to slip, he wouldn’t fall as far as he would have done without the protection. There’s just one snag! Allowing the rope to run over potentially sharp edges is not a smart idea. When it was my turn to lead, if I came to a suitable spike or flake, I placed a sling over it and clipped the rope to the sling using the attached karabiner, which allowed the rope to run freely, away from those edges. Of course, a sharp edge can still cut through the sling if it comes under load, but all you lose is a sling. The rope remains intact. And Max did have the grace to confess, later, that he now understood why I carried so many mousquetons.

The ascent wasn’t particularly interesting. Rock climbing is only ever interesting when you have to think how to proceed (and if you’ve read Rigor Mortis, you’ll know that I once spent 45 minutes in one place on a climb trying to work out what to do next). And this climb wasn’t even hard.

But there was only one word to describe the descent: harrowing. I’m not sure whether I’d any previous experience of abseiling (American usage: rappelling), but it would have been sketchy at best. By the way, I purposely included the word ‘usage’ above because it points to another linguistic confusion in climbing terminology. While an American will rappel (a French word) down a steep cliff, his British counterpart will abseil (a German word) down the same cliff. Max abseiled too.

Not only do you need an anchor point to abseil from, you need to be able to retrieve the rope once you’ve descended. And the only suitable anchor point on the top of the tower was a groove less than an inch deep that had been chipped into the rock adjoining one edge of the tower. There were no friction devices in those days, so it would have been necessary to run the rope over my shoulder and across my back to generate the friction needed to control the descent, but all I can remember is how hard it was to get over the edge. I kept expecting the rope to lift out of its groove if I couldn’t keep my weight below it. The problem was starting with my weight above the anchor. The remainder of the descent was much less alarming. And we eventually made it back to the rifugio.

We decided to return to the lower hut the following morning, probably because the accommodation there was cheaper. The next photo is a view down towards that lower hut, which is out of sight in the picture:

And that was the end of the climbing. The weather deteriorated badly over the next few days, and after those few days, with no end in sight, my erstwhile companions decided to bugger off back to Blighty. I wanted to stay, but I was running short of cash. However, after my friends had left, I became friendly with a couple of students from Oxford who, amazingly, had a spare tent I could use. It was more like a bivouac, to be honest, but it did mean I could afford to hang around a while longer. And I did learn how to play contract bridge. The next photo shows a rescue helicopter and provides some idea of how bad the weather was (snow is a rarity in summer in the Dolomites).

The two Oxford students had driven from England in an Austin A35 van, and when we’d all finally had enough of the weather, they offered me a lift back home in exchange for a share of the fuel costs. There was just one final problem: the bad weather had triggered a landslide that had wiped out about 100 metres of the local access road, and we were on the uphill side. And the word was that the road would not be repaired until next season.

However, there were five or six other vehicles that had been trapped by the slide, 15–20 people altogether, and we decided to build a temporary roadway across the debris. I’ve no idea where we got all the timber (see following photo), but we spent most of the day shifting huge quantities of rubble, soil and boulders and then laying a narrow causeway across the slide. I’ve had some extreme endurance experiences during my life, but I don’t think I ever worked physically as hard as I did that day. When we were finally ready, we pushed the cars across one by one, not without considerable anxiety that one might suddenly career off downhill.

One of the Italians in the ad hoc labour gang brought out a bottle of wine. Just enough for a quick swig each, but a nice gesture—after all, we had achieved our objectice by working as a team. And then we were on our way home, nursing memories of huge bowls of spaghetti with tiny dollops of Bolognese sauce. I didn’t try spaghetti again for many years, and even now, the pasta:sauce ratio has to be close to 50:50.

Anyway, we reached England without further alarm or exertion. I said farewell to my two new friends and proceeded to hitch-hike north to Penrith. I can’t remember much about that journey north, but I can’t forget one encounter. I’ve no idea from where and to where the person giving me the lift was travelling, but at one point he slid his hand lightly down the top of my thigh.

“Nice material,” he said.

I used to wear corduroy climbing britches in those days, and I didn’t interpret this move as a sexual advance, because there was no squeezing or unseemly pressure. Mind you, his next remark should have left me in no doubt, but I took the question literally and merely thought that my questioner was a bit odd. It was 1966 after all, and homosexual acts were still illegal.

“Do you ever go looking for fairies?” he asked.

“There are no such things as fairies!” I replied.

Damn! Another poor fairy has just dropped down stone dead. It tends to happen, or so I’ve been led to believe. The driver didn’t say another word until he dropped me off where he’d said he would drop me off, and the rest of the journey home was uneventful.

Thursday, 27 July 2017

new red sandstone #2

Last summer, I posted an account of some of the sandstone buildings in Penrith under the title New Red Sandstone. By no stretch of the imagination could this be considered a comprehensive account, as the following series of photographs illustrates. However, please refer to the earlier account for technical details of the geology.

The first photo is of the Station Hotel, the nearest public house to Penrith’s railway station. Sixty years ago, the left-hand section of this building—the section with double rather than triple windows—was a temperance hotel, but it has since been converted into residential accommodation. At the height of the Victorian temperance movement, there were no fewer than four such hotels on this street, which connects the station with the town centre.

Just across the road from the Station Hotel is the Agricultural Hotel (‘the Aggie’). The left-hand section of this building once housed the auction ring for a thriving livestock market (behind and to the left of the hotel, there used to be a large area of pens where animals could be held prior to being sold). However, increasing traffic after the section of the M6 that bypassed Penrith was opened in 1969 meant that this site was no longer a practical location for a livestock market, which subsequently moved to an out-of-town site.

Just to the left of the previous photo, there used to be a group of five warehouses. They had no particular architectural qualities, but given that they were demolished around the time that the livestock market closed to make way for a supermarket, and that I’ve just discovered the next image among my collection of old photographs, I thought that I’d include it here:

You will have noticed the name of James and John Graham on the side of the nearest warehouse, where they are identified as ‘agricultural merchants’, but these men also founded a grocery store in the town centre in 1793, and this is shown in the next photo (the date 1880 in this photograph probably refers to when the building depicted here was built).

Staying with the warehouse theme, the next photo shows what is now universally known as the ‘clint mill’, but when I was growing up, I thought of it as Pattinson and Winter’s warehouse. According to my research, it was originally built for this grocery firm, which once had a shop in Cornmarket but no longer has a presence in the town. The building has now been converted into offices.

A short walk from Graham’s shop brings you to the Penrith Building Society building in King Street:

…while an even shorter walk in the opposite direction brings you to the George Hotel:

Prince Charles Edward Stuart, otherwise known as the Young Pretender in a reference to his claim to the British throne, or as Bonnie Prince Charlie, is reputed to have stayed here overnight on his way south in 1745 in his ultimately futile attempt to claim the throne. His forces were engaged a few miles south of Penrith in the Battle of Clifton Moor, the last battle to be fought on English soil, although historians have subsequently downgraded this encounter to a mere skirmish.

The nearby parish church of St Andrew is flanked by churchyards. On one side are the church’s parish rooms, built in 1894:

…while on the other side, you will find the original Queen Elizabeth Grammar School, which was founded in 1564. Although the grammar school moved to a new location in 1917, this building was still in use as part of the school until 1958:

The final photograph shows Hutton Hall at the top end of Friargate. It was built in the eighteenth century, although I’ve been unable to come up with a more precise date. It was formerly the local lodge of the freemasons, but I don’t know anything about its current use. Note the partial balustrades just above the eaves. The inner ends of both balustrades appear to be new, leading me to suspect that there was once a continuous balustrade across the entire building, although this is a conjecture that I’ve so far been unable to confirm.

Friday, 21 July 2017

tough stuff

I described the local building stone in my home town in New Red Sandstone, but there is another stone, obtained from a quarry about 12 miles south of Penrith, that is used around town for purely decorative purposes. This is Shap granite, which I propose to describe in detail and provide examples of where it has been used around town.

Igneous rocks—that is, rocks that started out as molten magma—are classified according to two criteria: their chemical composition and where they end up. Taking the second criterion first, a rock that has been extruded onto the surface is described as ‘volcanic’ or ‘extrusive’, while a rock that solidified before it reached the surface is described as ‘intrusive’. There are two types of intrusive igneous rock: hypabyssal and plutonic. The first of these terms describes shallow intrusions, usually along bedding planes (a ‘sill’) or up near-vertical faults, cracks and joints (a ‘dyke’), while granite is a typical plutonic rock and is often intruded at great depth, hence the reference to the Roman god of the underworld.

You might think it necessary to perform some kind of analysis to determine the chemical composition of a rock, but you can get an approximate idea of that composition from the minerals present. There are five main groups of rock-forming minerals, and the relative abundance of each is a pointer to a rock’s chemistry. The first group are the feldspars, in which the silicon atoms in a crystal are arranged in a three-dimensional lattice, which places severe constraints on what other elements can fit into the gaps. In practice, all feldspars contain aluminium in a fixed ratio with the silicon, and differences between minerals are determined by the relative proportions of sodium, potassium and calcium, all of whose atoms are similar in size to the silicon, aluminium and oxygen of the main crystal lattice.

In minerals classified as micas, the silicon atoms form flat sheets, meaning that there are obvious lines of cleavage through a crystal, and a typical specimen will appear flaky, like puff pastry. In pyroxenes and amphiboles, the silicon atoms are arranged in single and double chains, respectively, meaning that the structure can accommodate larger atoms such as iron and magnesium, but I don’t intend to discuss these minerals in more detail, because they rarely occur in granite. The fifth rock-forming mineral is olivine, which is an iron/magnesium silicate that never occurs in granite.

The relative abundance of these minerals reflects the amount of silica (silicon dioxide) in a rock. Rocks with the most silica are classed as ‘acid’, and with progressively less and less silica, rocks are classed as intermediate, basic or ultrabasic (there are no ultrabasic rocks in the Lake District). Granite is an acid igneous rock, with a silica content in excess of 66 percent, while the best-known example of a basic igneous rock is probably basalt, perhaps because most people have heard that the Giant’s Causeway in Northern Ireland and Fingal’s Cave on the island of Staffa in the Inner Hebrides are basalt.

There is a group of small islands in the east of Hong Kong, all of which are surrounded by impressive cliffs. One of these islands is called Basalt Island, presumably, by analogy with the Giant’s Causeway and Fingal’s Cave, because of the columnar jointing displayed on these cliffs. However, the rock here is rhyolite, the volcanic equivalent of granite, and what this shows is how easy it is to make mistakes when you jump to conclusions about a subject you know nothing about. Hexagonal columnar jointing is found in all volcanic rocks and is merely an artefact of shrinkage during cooling.

There is no basalt in Cumbria, but there is a small intrusion of gabbro, the plutonic equivalent of basalt, that forms a mountain—Carrock Fell—in the northeast of the Lake District; and there is a sill of dolerite, the hypabyssal equivalent of basalt, in the north Pennines, a dozen miles east of Penrith. This is the Whin Sill, which I believe to be the largest sill in Britain.

Returning to Shap granite, the first photograph shows the use of this stone to form four pillars framing the side entrance to Penrith’s town hall (the town’s library is no longer housed here).

Reflections on the pillars are an indication that Shap granite polishes up extremely well, mainly because of its crystalline nature. Notice too the black spot near the base of the left-hand pillar, indicated by a red circle. This is a xenolith (‘foreign stone’), a piece of the surrounding rock—probably an intermediate volcanic rock called andesite—that fell into the magma before it had cooled and was not completely assimilated. And this is a closer view:

This photo also provides a good indication of the rock’s structure. The large pinkish crystals scattered throughout the rock are orthoclase, which is a potassium aluminium silicate and a type of feldspar. As you can see, these crystals are much bigger than the crystals of minerals in the groundmass, and as such they are known as phenocrysts. If you look closely at the groundmass, you will see a white mineral. This is plagioclase, also a type of feldspar but with a varying composition in which either sodium or calcium replaces the potassium of orthoclase. Plagioclase is in fact what is known as a solid solution series, meaning that all possible ratios of sodium and calcium are theoretically possible, including 100:0 and 0:100.

There is also a semi-transparent mineral, quartz, which is a crystalline form of silica that occurs mostly in acid igneous rocks, reflecting the high silica content of the magma, but never in basic and ultrabasic rocks. Most of the black specks are biotite, a type of mica, but a small proportion are magnetite, an oxide of iron that was the basis of the original Chinese magnetic compass.

There are in fact two types of Shap granite—light and dark—both obtained from the same quarry, and the next two photos illustrate the difference. The first shows the offices of Banco Santander in Market Square, where Shap granite has been used for the pilasters on each side, while the second is a close-up of part of the right-hand pilaster. Note the small xenolith near the top of the second picture.

I’m not sure what causes the difference between the light and dark forms of the granite, but I’m inclined to think that it reflects localized variations in the iron content of the magma. This element is present in only trace quantities here, but the plagioclase in the dark variety is definitely reddish rather than white, and iron is the most likely culprit.

I used to think that there were many more places around town where Shap granite had been used, but I was able to find only three other locations during a recent survey. The first is the town’s main post office, which was rebuilt circa 1960 on the site of an earlier post office (I’ve been unable to find the exact date). The second is a close-up.

The next photo is of an optician’s shop in King Street, where Shap granite has been used for the pediment below the windows, followed by a close-up. This was a newsagent’s and tobacconist’s shop when I was growing up.

The final two photos are of a second optician’s shop. This one was a greengrocer’s shop when I was growing up. Not many shops around town retain their original use now, and many traditional shop fronts have been vandalized by rebuilding, but I’m pleased to see that both these shops retain the original design.

The Dayson Building, which I featured in Windows Ten, can be see beyond the shop in the first of the two previous photos.

Shap granite has another important use, although you wouldn’t necessarily be aware of it unless somebody told you. It is an extremely hard rock, so when it is crushed into an aggregate and mixed with bitumen, it is ideal for use as a wearing course on motorways and other major roads. Locally obtained Carboniferous limestone is often used on the area’s minor roads, but this rock is far too soft to use on any surface where the traffic density is high.

Finally, Shap granite was formed towards the end of the Caledonian orogeny, the mountain-building event that produced the mountains of the Lake District, which makes it approximately 400 million years old.