Geology 2: Rocks

Let’s start off with a bit more about me. I was born in South Wales and at the age of three, my family moved to the Afan Valley and my uncle Roy died of a brain tumour. Growing up, all I ever really knew about Roy was that he had been a caver. He had run his own caving club taking working class London boys up to Yorkshire and down potholes. We inherited his logbooks and scrapbooks and looking at them gave me a passion for caves. I always wanted to be a caver like my Uncle Roy, alas although I did a few potholes in my teens, life takes unexpected turns and now of course I doubt that I’d have the stamina for anything I can’t just walk through. Last year I nearly died just trying to climb Helvellyn.

For some people, being wedged between a half mile long section of two slabs of rock that weigh billions of tonnes just centimetres apart as you inch your way underground in almost complete darkness, with no escape to the surface except back the way you came, where a sudden unseen rainfall on the surface could render you trapped or even underwater in minutes, where suffocating, explosive or radioactive gasses can become trapped in pockets, and where temperatures are either very cold, or unbearably hot if you get far enough down, is probably not the most appealing of hobbies. For others, the attraction can only be explained as pure romance. Pulling yourself through the bowels of the earth, where no forces act apart from gravity, tectonics and water. Coming across natural caverns, potentially never seen by human eyes, or any eyes, ever before. Carved out of rock by water over millions of years, seeing rock layers up close and in the raw, in fact crawling between them. Stalactites and stalagmites and flowstone. In some caves around the world, the mineral crystals have grown bigger than humans. Even in the most well mapped and well explored caves in the world, there are places where no human has ever explored. There might be holes barely a few centimetres wide, the only entrance into cathedral sized caverns.

The Hologram, Going Postal

The Hologram, Going Postal

For me, I was a romantic.

Growing up in the Afan valley was the most wonderful childhood. Most of the British isles were covered by glaciers just a few hundred thousand years ago. Geography, the bastardised subject son of Geology and Orienteering taught you that glaciers carve U valleys through rock. The South Wales valleys are where the glaciers stopped and most of them are pure river V valleys. The Afan is the steepest valley in the country, rising up from Port Talbot. It is relatively sparsely populated with small villages up and down the valley and Richard Burton is our most famous son. Every week my parents would take me down to the Afan country park where we would visit the mining museum, and then walk down to the ‘troll’ bridge and play billy goats gruff. The little river that runs through the park before joining the Afan (Afan/Avon of course means river) is a lovely little shallow tributary that runs over slate. The water itself is brown and full to brim with iron. The iron has leeched into the slate, turning a grey black stone bright red orange. The slate itself is so soft that even at five years old, I could split it apart with my fingers. One day I split a large piece of rock and found a rainbow gradation of colours along the plane. It was beautiful and I kept it for many years. It possibly still resides in the parent’s attic (I hope).

So began my lifelong love of rocks. And of course I am a Welshman.

The Afan was a mining valley, but the mines shut down in the sixties and seventies. In this video, Richard Burton talks about his brothers and the pride of the Welsh miner. Wales has been mined by the Welsh for centuries. Bluestone from Preseli for Stonehenge, Gold, Slate and Coal. The Welsh are literally tied to the land beneath their feet with pride and blood. But I will come back to this.

The Hologram, Going Postal
The Afan Valley – Heaven on Earth

Alas, at the age of seven, my Dad got a job in Coventry and we moved. I still haven’t gotten over it. I’ve spent the past 30 years trying to get back and failing.

There are three different types of rock. Igneous, metamorphic and sedimentary.

Igneous rock is rock formed from magma or lava. Igneous rock contains crystals. If lava solidifies quickly or under pressure, the crystals formed are small, if lava solidifies slowly and without pressure, the crystals grow large. Just like water, a light soft winter will bring large snowflakes, a sudden deep frost solidifies the water in tiny flakes. Water forms snow in the low pressure high atmosphere, but ice when at the higher pressure ground level. It is the same process.

The two main igneous rocks are Granite and Basalt. Granite forms continental plate and Basalt forms Oceanic plate. Granite and Basalt are formed of the same material. Mica, Quartz and Feldspar. Differing percentages of these minerals form different variations of these rocks. But Basalt solidifies quickly, with tiny crystals, because it generally erupts into water. The Basalt is subducted; melts, and then rises through volcanoes to the surface, where it solidifies again, this time as Granite which solidifies slowly, has larger crystals and is therefore less dense in the same way that snow is less dense than ice. Other igneous rocks range from Obsidian, basically lava cooled so quickly it forms glass, to Pumice, which is magmatic, cooling underground where gasses cannot escape, leaving bubbles in the rock.

Metamorphic rock is rock that gets buried deep in the crust, typically under mountains, and is subjected to huge pressures and temperatures. When a material is placed under that kind of pressure, the melting point goes up and so it remains a solid, but nevertheless is transformed into a new form of the material as the molecular bonds are broken by sheer pressure and reformed. Marble, Slate and Diamonds are formed in this way, as are the plainer Schist and Gneiss.

Sedimentary rock is formed from sediment. At the surface of the planet, rocks are eroded by the natural process of water and wind, they are chipped away and broken up and then glued back together. This process forms Sandstone, Mudstone, Shale, Millstone Grit and Conglomerate. There is a second process of sedimentation, formed from biological material. This creates Coal from dead wood, or Limestone formed from the calcite extrusions of oceanic life, from shells to coral. If you have seen the limestone pavements at Malham or the Derbyshire Dales, it is quite astonishing to think that every vertical centimetre of limestone represents centuries, if not millennia of tiny marine life. The remains of trillions of living beings forever made a part of the life cycle of the planet.

There are many, many more types of rock than I mention here, and geochemists will break them down even further depending on increasingly complicated factors. There are at least a dozen basic characteristics to work your way through when identifying a rock; ranging from colour, crystal appearance, composition and size, hardness, shape, cleavage (how a rock splits apart), roughness and even taste. Yes some geologists do go around licking rocks to determine if they taste of salt or not.

But what is the point of knowing all of this? Well even the basics of these rocks tell us things. A Limestone pavement tells us that the area used to be a shallow sea, likely tropical. A coal seam indicates an ancient forest. Granite indicates that there was a lava flow, or a former volcano. If you look at Edinburgh Castle; it is sat on top of a huge Granitic ball of rock that was once the magma chamber of an ancient volcano. The rest of the mountain has disappeared, the granite, being harder rock than anything around it, has survived. Sandstone obviously likely denotes a former desert. Anything metamorphic has probably been beneath a mountain at some point. It all gives us a window back into the history of the planet and as the geochemistry and geophysics get more complicated, gets very accurate.

Of course it isn’t as simple as that. One of my favourite parts of Geology was cross sections.

The Hologram, Going Postal

Cross sections in Geology are like getting to spend your day job doing logic puzzles. Using the above diagram, can you work out the sequence of events from oldest to youngest? Solution next paragraph.

It’s basically pick up sticks, where you cannot pick up a stick if it is covered by something else, so on the above, relatively easy cross section, the magmatic extrusion M (It’s magmatic because it is a ball or line of magma rising to the surface rather than neatly layered rock formed by gravity) is younger than fault line N (caused by an earthquake) because it crosses over it. But N and M must be older than G, the rock which cuts both of them off and fault line O must be younger still, as must magmatic extrusion L.

Easy right? But then you get out into the field.

The Hologram, Going Postal

In this picture we can see what looks at first glance, like one very large reasonably homogenous hill. It is one big solid lump of rock. At this distance it is difficult to spot smaller differences in the rock, but what we can see is different colours and striations, moreover striations that don’t lie flat as the bedrock in the diagram does, but are clearly folded. Because yes, massive layers of bedrock weighing millions of tonnes, can be folded up like paper, and even turned upside down under the tectonic forces of the earth. That hill used to be flat as a pancake. We can see at least three different types of rock: red, white and black. The black is likely to be a magmatic igneous intrusion into the white rock as there is white above and below and the black peters out, though the vegetation and scree obscures the view, but it also appears to have a white mineral vein within it. Each striation likely indicates a new layer of bedrock which could conceivably represent anything from a few thousand to a few million years, so we can see here a climate which favoured this red rock for millennia, before a change led to the white rock. Let’s assume the red is sandstone and the white is chalk, that would mean a change from desert to sea (chalk being sedimentary sea life). The fold likely represents a ‘syncline’ where the younger rocks are at the centre of the fold, but if it was an ‘anticline’, where the younger rocks were on the outside of the fold, it would mean that the whole structure has at some point been turned upside down and the sea came first before moving to desert. But it definitely is an ‘antiform’, where the fold points upwards, as opposed to a ‘synform’ where the fold would point downwards. The fold indicates that this hill has gone through some extreme tectonic pressures at some point. Then, after all of that, it has been weathered into what we see today with half the left side just gone which indicates that that side is more exposed to the elements, wind and/or water.

There are two things I’ve left out in that analysis. Can you spot them?

Two horizontal fault lines. The first at the height of the lamp post and the second just cutting into the white. Slightly difficult to spot because from this angle they look like human made paths across the hill, but if you look to the left you can see clear disparities in where the striations line up. The fault lines cross the folds, so they are likely to be the youngest geological features in this scene except for the erosion. Both caused by earthquakes.

This hill is an aberration. The vast majority of bedrock at any given location is concealed under vegetation and other bedrock. Imagine grass covering that entire side of the hill and we would have to work much harder to find out what was going on underneath. Field geologists have to work to build pictures from what is exposed at the surface, what can be found in caves and mines, and limited boreholes. Physical field geology is an incredible jigsaw and logic puzzle in four dimensions, where you only get to see a tenth of the pieces, the clues are hidden and you have no box art to help you on your way.

Here’s something a little more difficult. Have fun.

The Hologram, Going Postal

As an aside, as someone commented on my last article, it’s no wonder that Geologists are usually anthropological climate change sceptics. The change of colour on that hill is likely prima facie evidence of a radical shift in climate. It did not destroy the planet, nor wipe out life. It is evidence that climate change is a natural and ongoing part of the earth. Life will survive. Also we’re still in an ice age anyway, geologists define the ice age as ‘ice at the poles’. For most of Earth’s history the poles were ice free. We are in an interglacial period. That means one day we will either have a new glacial period where it will get very cold, or exit the ice age where it will get very hot and the polar ice will melt and the polar bears will suffer the consequences of evolving in a geologically temporary biome. Neither of these occurrences will have anything to do with humans.

There is one final part to this essay on rocks. The best paid Geologists in the world are those who search for oil. Oil isn’t a rock obviously, but it still counts. Oil is what powers the modern world. Before oil, it was coal. These are energy sources that gave us the modern world. Ore is where we get most of our resources. Elements, mostly metals, that are held in rocks. The most well known is Haematite – Iron Ore. And so Geologists are responsible for keeping us going with resources, especially finding them, but here I’m going to advance a theory.

There is an anthropological theory that says that Homo Sapiens only started moving forwards once we discovered agriculture, meaning we didn’t need to migrate following animals, leaving us more time to start developing humanity. I disagree. It wasn’t an agricultural revolution that kickstarted Homo Sapiens, it was a mining revolution. Agriculture provides three things, food, textiles and wood. But humanity did not advance through the wood age, the wheat age and the cotton age. We went through the Stone Age, the Bronze Age, the Iron Age, the Coal Age and now the Oil Age. All these things came out of the ground, from Egyptians mining clay from the Nile, to the Bluestone of Preseli for Stonehenge. Even the Aztecs and Maya had mines. They built Macchu Picchu and Tecnoctitlan with quarried stone, they had gold and jade, but they never developed iron working. There is a huge difference between a civilisation that has access to flint they picked up off the ground for their knives and a civilisation that is smelting iron into swords and shields.

Agriculture can happen almost anywhere, but to get things out of the ground, you have to go to where things are in the ground. Some North American tribes were fishermen and so had static villages, they never advanced in technology one inch. The civilisations that advanced were not those that developed farming, but those which headed to good mining sites and settled there, giving themselves access to clay, stone, and then metals. It is civilisations which did not have access to mines and metals which died. In the final battle (and discounting the smallpox which wiped out the last surviving Aztecs in the last days of the battle) between the Aztecs and the Spaniards, which raged for roughly 100 days over the causeways of Tecnoctitlan, the Aztecs sent out tens of thousands of warriors and although they carved their way through the other tribes who had allied themselves to Cortez against the Aztec tyranny, they barely made a dent in the Spanish army, which numbered less than 100. The Spanish had iron armour, swords and cannon, the Aztecs fought in loincloths with stone spears.

What does that mean? That means that civilisations have risen and fallen, that populations have moved across the globe and settled in most areas based on rocks in the ground. Rocks that were laid down millions and millions of years ago. Everything that humanity is today, was literally laid into stone eons before we can even imagine. The people who propelled humanity forward were the miners. Hundreds of thousands of unknown men women and children over twenty five thousand years who have dug things out of the ground, mostly with their bare hands, and many who will have paid for it with their lives. Right up until last century, almost everyone, everywhere in the civilisations that developed mining; lived where they lived because of the proximity to some kind of mine and the resources that came out of it that were put there maybe a billion years ago. Whether stone, sand, salt, clay, tin, iron, copper, gold, silver, precious stones, coal, oil. The settlements that had no access to these resources, may as well have never escaped the stone age.

Go back and watch that Richard Burton video on mining one more time.

I said the Welsh were tied to their land with blood and pride. The Welsh remember and idolised their miners, perhaps more so than anywhere else. But all people are tied to their land with blood and pride. I think many people just forgot it. When the land is covered by cities, asphalt and tarmac, we forget the rock beneath our feet which literally gave us everything.

In 2016 I visited the Bluejohn mine in Derbyshire. It has been producing Bluejohn stones for two hundred years. Our guide that day told us that there was only two years work left in the mine, so it will now be closing as a working mine, there is no other known Bluejohn seam in the UK although there is in the US, China and perhaps other places. It’s a precious stone, nice to look at, expensive, not so much practical value, but it’s an omen, no more Bluejohn out of the UK. Ever. As I say, civilisations have risen and fallen based on what they can pull out of the ground. Those resources are limited. Once they are gone, they are gone. The Earth is a big, big place. For all our mines, for all those natural caves, 99% of the resources under the ground will never be accessible to us. I said last time that Mars and the Moon are uninhabitable geologically speaking. One day we might have the technology to over come that, but the resources we have now, we need to spend on getting us into space. One day the Earth will run out of those resources and if we are not moving off Earth and able to mine other bodies by that point, we never will. And five billion years from now, all known life in the universe gets extinguished as Sol goes nova. In order to save life, we need to mine and use those resources properly.

You might also consider this an argument for fracking. And an argument against using precious lithium on pointless electric cars.

Next time we shall look at Palaeontology. Fossils.


Lugosi has already done an excellent article on diabetes and I don’t wish to repeat that, suffice to say that I very slowly started to become diabetic from 2009, in January 2014 I was diagnosed with T2 diabetes. The GP forgot to refer me to hospital and refused to send me when I asked for the referral. I was not sent to hospital until August 2016 where I was diagnosed with T1 diabetes. Life expectancy without insulin is 14 days. I survived approximately 56 weeks without insulin. I had almost complete amnesia, lost the ability to read and write and was on the verge of losing the ability to talk. My body cannibalised itself because it couldn’t process food and I went from 14 stone to 9 stone in just a few months, once I cannibalised every ounce of fat on my body, I had at least 8 weeks of it eating away my muscles and organs. I was bleeding out of places you do not ever want to bleed from, but was so far gone mentally, it didn’t even register.

I should be dead from at least half a dozen ways. I do not know why I am not dead. In 2013 I was commissioned to write my first professional play. I was already so far gone, I only delivered it 3 days before the actors were due on stage. After that, I could no longer read or write because I had zero ability to concentrate. I haven’t written anything long form since then until now, in the past three years I have read just three books, short paperbacks under 200 pages, each of which took me 6 months. My mental and physical health is pretty appalling, but this is now likely the best I will ever be again. I struggle to look after myself. I am about to turn 37 and spent the past decade slowly losing my mind. I might do an article on the farce of my life for the past decade at some point, but I don’t want to come across as self indulgent.

So after my first article, I made a point of not reading any of the comments. All the kind words meant an awful lot to me, especially those from people clearly more qualified and experienced in Geology than I. Also, spending half a decade near death has made me a sap with making sure I say things that are important. Thank you all, you gave me the confidence to move on to part two.

© The Hologram 2018

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