Romancing the Stone Workshop

Well, it has been a long hard slog but we have managed to break the back of it. Yesterday we went live with our new website, www.oldcanvasexpeditions.com. Now Old Canvas is the provider of some of the top specialist safaris in Southern Africa. More than just a game drive is our slogan and that is exactly what we hope to achieve.

Old Canvas Expedition's flagship geology workshop is out of the town of Clarens in the Eastern Free State - at an altitude of 1800 metres it is the second highest town in the country. The beautiful sandstone cliffs which surround the town and provide the magnificent backdrops for which it is famous, are fossilised sand dunes, harking back to a time 180 million years ago when the area was a desert, the realm of dinosaurs and small mammals.

Gondwana was stilled joined; a vast supercontinent including Africa, India, Australia, Antarctica and South America. Incontestable forces began to play out at the end of Gondwana times, and the supercontinent began to tear itself apart. As these ruptures took place, thousands of metres of red hot, incandescent lavas flooded out onto the Gondwana landscape, burying all in a fiery embrace.

Walking through the town of Clarens gives no inkling of this cataclysmic history, but looking south one can see the blue Maluti Mountains - a remnant of those thousands of metres of lava which burned everything before it. Dinosaur bones protrude out of rocky road cuttings, the ancient desert dunes lie preserved in the cliff faces, faults form large dislocations in Earth's crust and dykes traverse the landscape for tens of kilometres, once feeder pipes to the overlying basaltic outpourings.

We will marvel at the geological history of the region and the story of both wandering continents and wandering dinosaurs. We will drive the highest road in Africa to the Letseng Diamond Mine - the highest on Earth and the source of 4 of the 20 largest diamonds ever found. On the final day we will fly past the Tugela Falls, the second highest on Earth at 947 metres and enjoy views of the Drakensberg. This range is a proclaimed World Heritage Site - the uKhahlamba. From the air we will also be able to see the post-Gondwana landscape and the phenomenal gorges that the eastward-flowing rivers have cut into the ancient African bedrock.

Join us then on a journey through 300 million years of Earth history, witness the breakup of Gondwana, the outpourings of lava and see the highest diamond mine on Earth. Perhaps the highlight will be to fly along the Eastern Escarpment past the Tugela Falls and the towering ramparts of the Drakensberg.

These are experiences which cannot be missed, and so we invite you to journey not only to one of the most picturesque towns in South Africa with its art galleries and restaurants, but on a journey down through the aeons, to a time when dinosaurs once ruled the Earth and Clarens was at the heart of a vast continent called Gondwana.

The Ancient of Days - Barberton

Romancing the Stone

There is a piece of land on South Africa’s eastern escarpment so ancient that it beggars the imagination. We as humans work on another time scale entirely - our short lives are measured in decades and a time span of 2000 years seems so very very long ago. Five million years spans all of human evolution and even those numbers seem improbable. So to now tell you that rocks which underlie this piece of land have been dated at 3 538 000 000 years might indeed stretch your imagination. That number does indeed read as “three billion, five hundred and thirty eight thousand million years”. Whew! To set our own lives against this kind of timescale makes them appear entirely insignificant, and the history of mankind not much more so. But there is worse to come – they have discovered ancient gneisses in the Slave Province of Canada 4 billion years old, and a single zircon crystal from Australia has been dated at 4.3 billion years. But this is no dent to our national pride – we are still up there with the front runners and Barberton remains an earth scientist’s Mecca.

It is one of the few places on Earth where the Archaean (rocks of 2500 million years and older) is so well preserved and so easily accessible and at one stage we held the record for the oldest rocks on Earth. But let us not indulge in hubris here, remembering the insignificance of our allotted three score and ten years when compared against the background of this vast sweep of geological time.

The Barberton Mountain Land is characterised by rugged topography and deeply incised river valleys. It is shaped roughly like a giant ice-cream cone, with the mandatory cherry on top located at Badplaas and Komatipoort forming the tip of the cone (well, almost). It extends from the high African hinterland down to the Lowveld, including a portion of northwest Swaziland in its sweep.

The towns of Steynsdorp, Havelock, Horo, Kaapmuiden, Louw’s Creek and of course Barberton have the honour of being founded on this veritable Methuselah of the Earth’s crust and those who walk on it are treading on hallowed ground. Moving swiftly from the realm of the metaphor to that of the mundane, the limits of the zone and its simplified geology are shown in the accompanying figure.

To peer through the swirling mists of the deep abyss of geological time in an attempt to unravel what went before is an almost impossible task. To have remnant samples from this deep abyss preserved relatively unaltered is a gift in the process of unravelling the complexities of Earth history.

Without boring you unduly with lessons in geology, suffice it to say that the earth is in a constant state of flux. Mountains are thrust upward and then ground down by the inexorable mill of erosion. The crust beneath the ocean basins is created by fire at the mid-oceanic ridges and is then carried away towards destructive plate margins on massive convection cells at a rate ranging from 2.5 (the rate at which your finger nails grow) to 15 cm per year. There is no hurried agenda to the slow grind of Earth’s workings – she has all the time in the world to crank the workings of her machine. On average, oceanic plates will last no longer than 100 million years - they will be carried back down into Earth’s mantle along subduction zones – known as destructive margins - the most famous of which is the Ring of Fire encircling the Pacific. Similarly mountain ranges such as the Alps and the even mightier Himalaya were thrust skyward approximately 65 to 40 million years ago – the mountain building process in these regions is still ongoing. But they are being worn down by the agents of erosion, and in 100 million years will be reduced remnants of their former glory, nothing more than a detritus of sand and mud. Throw another hundred million years into the pot and there will be little left of the world which we currently know.

Two hundred million years may seem an immense span of time, but considering how crust, both continental and oceanic, will doubtless be destroyed and recycled in this time, then to have a 3.5 billion year remnant preserved right here in our own back yard is miraculous indeed.

The Barberton Mountain Land is indeed a remnant – a remnant adrift in a sea of granite, cast to the sharks of time and erosion, leaving her chewed and frayed around the edges. Two geologist brothers, Viljoen and Viljoen, wrote a paper in 1969 titled grandly “The Geology and Geochemistry of the Lower Ultramafic Unit of the Overwacht Group and a proposed new class of igneous rocks Komatiite, Upper Mantle Project.“ This if course all sounds very esoteric to most of us, but one has to read a little between the lines to understand the significance of what they had found. Some of you might remember in the mid 1990’s the discovery of a 90 kg, cowlike animal called a Saola in the jungles between Vietnam and Laos. This was the first land vertebrate of this size to be discovered for more than fifty years. Well, the discovery of a new type of igneous rock in the Komati Valley, and an extruded lava at that, was perhaps the geological equivalent of the discovery of the Saola, although it didn’t get anywhere near as much coverage in the popular press. The exciting thing is that the chemistry and mode of occurrence of this rock shed light on the geological conditions prevailing during the formation of Earth’s crust way back then, which until this discovery had been open to nothing but pure conjecture. Appropriately this rock was called a komatiite and several other occurrences have since been found elsewhere on the planet’s face, but it was here near Barberton that this ancient rock type was first brought to the attention of the geological world.

And what were conditions like 3.5 billion years ago? Well, we must add a little more flesh to the geological skeleton, otherwise we will be getting ahead of ourselves. Sitting on top of the ancient komatiites is an accumulation of volcanic lavas, limestones and shales. These rocks make up the Onverwacht Group, the first of three broad subdivisions of the geology of the Barberton Mountain Land. Overlying the Onverwacht is the Fig Tree Group; a sedimentary pile of material laid down in submarine conditions. Finally all is overlain by the Moodies Group which comprises quartzite (metamorphosed sandstone), sandstone and shales with occasional volcanic lavas.

The interpretation of conditions prevailing in the Archaean has been made based on studies of the BML and other greenstone belts around the world. Mantle heat flows were higher then than now. The chemistry and mineralogy of the komatiites indicate that they were erupted at relatively high temperatures compared to those associated with the eruption of younger basaltic lavas. Richard Fortey in his recent book titled Earth: An Intimate History, sums things up beautifully, describing prevailing Archaean conditions thus: “The nascent masses of continental crust had not yet congealed to their present size. Instead, smaller rafts of lighter rocks formed the nuclei of what would become more stable continental areas..…. The sea – and there was certainly an ocean – was whipped up by storms, reducing all land newly elevated by tectonics to sedimentary waste. Slabs of oceanic rock were covered with sediments derived from the rapid weathering of the protocontinents. Unprotected by any cloak of plants, the wind and rain worked fast upon the naked rocks. This was a world of tempests and flash floods, of jagged crags and dunes. Clays and grits, the mucky progeny of erosion, slumped down into deep water. Volcanic rocks were erupted over the sea floor….. Buoyed up by their less dense composition, the growing continents bobbed onwards, as would rafts of cork on a mill pool, while heavy ocean crust was created and then destroyed in the early cycles of plate tectonics.”

These interpretations of the processes which formed these ancient greenstone belts might quicken the pulse of earth scientists everywhere, but these events took place so far back in Earth’s history to be almost irrelevant to most of us here in the early part of the 21st Century. But two really important conditions prevailed which do affect us all. Firstly sedimentary structures in the form of sand ripples within the sandstones of the Moodies Group indicate deposition on tidal flats, and to have a tide, we must have a moon. So this is the first evidence of for the existence of the moon in orbit early on in our geological history. Secondly, and perhaps most importantly, on pondering our origins and our significance on this small blue planet of ours, it may be useful to remember that some of the first evidence of unicellular life occurs within the Onverwacht and Fig Tree Groups. Spheroidal or rod-shaped micro-organisms formed algal mats called stromatolites – a form of blue-green algae which changed the world forever. Back then the atmosphere was almost devoid of oxygen with hydrogen sulphide and methane being the dominant gases. Blue green algae, stromatolites included, added via the process of photosynthesis oxygen to the atmosphere, molecule by tiny molecule to create an atmosphere which sustains us all. But the evolution of life must have predated the deposition of the Fig Tree sediments and currently it is thought to have occurred around 3.2 billion years ago.

Having said all that, other than being of interest in terms of the origin of life and the fact that the moon was winging its elliptical path around our Earth 3.5 billion years ago, what other relevance does all this have to our lives? Well, internationally, Archaean Greenstone belts, as they are also known, are home to many of the world’s gold mines.

The four operating in the Barberton region are have the romantic names of Sheba, Consort, Fairview and a somewhat more down to earth name, Agnes. Gold was discovered in the headwaters of the Blyde Rivier in 1873 by “Wheelbarrow” Patterson which led to a gold rush and the founding of the town of Pilgrim’s Rest. The largest gold nugget (perhaps the term boulder would be more appropriate here), discovered in 1875, weighed in at 8.02 kilograms. But the gold rush days soon passed by when gold was discovered in the Witwatersrand gold fields 12 years later.

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Vredefort Impact Site - Ground Zero

Romancing the Stone

Winging its way in at 70 km per second from somewhere in the asteroid belt, the meteorite, at 15 km in diameter is the largest and deadliest object to ever strike Earth. At ground zero the destruction is unimaginable, as a concentric shock wave propagates outwards at supersonic speed for a distance of over 300 km. The ground heaves, and where there was once solid rock, now there is molten glass, where there was once stable atmosphere, there is now a column of dust and ejecta towering thousands of metres into the afternoon sky. Ejecta and ash billow in vast, debris laden clouds, casting a doom-black pall across the land. The sun, as if bending down to look onto the face of the Earth, gazes impassively at her blighted face, while hot winds toss the dark clouds across the crimson disk before going out with the light.

Wandering through the long grass around the village of Vredefort, Free State, South Africa, the casual observer would not have the slightest inkling that this is Ground Zero of the largest meteorite impact on Earth. Low quartzite ridges provide the topographical interest with valleys in between. From the air the picture becomes somewhat clearer; as a series of concentric topographic ridges with intervening valleys become apparent, best developed in the northwest of the area. In geological parlance this is a “dome” – an approximately circular area of Earth’s uplifted crust, dipping away from the centre, and in our case 80 km in diameter. To explain the enormity of this event a little stratigraphy is necessary at this point and perhaps a good analogy is a multicoloured cake. The adventurous chef has placed pink sponge at the base, and then covered with alternating layers of chocolate and vanilla sponge. The pink represents the ancient granite which underlies 1000’s of square kilometres of real estate around the dome, and the alternating coloured sponge layers the younger sedimentary cover. At Vredefort the layers of the cake are stood on end, with the pink granite sponge protruding through the overlying layers. Returning to the scale of the real world, this is the equivalent of 20 km thickness of rock being upturned and the granite punching through to the surface. This is, to use an overused but appropriate word, awesome. Back on the ground, evidence of some kind of cataclysmic event having occurred here is to be found in the form of two rock types known as pseudotachylite and granophyre. Shatter cones and spectacular fracturing the rocks also are witness to this event. Tachylite is a form of glass found in volcanic environments, which the material in the dome resembles, although this is clearly not a volcanic environment, hence the prefix ‘pseudo’. Pseudotachylite is almost ubiquitous throughout the dome and occurs in veins from less than 1 mm to up to 100 metres thick. The Vredefort granophyre, a brecciated rock, has as part of its composition a glassy matrix indicating instant melting and rapid cooling. In fact both of these rock types are the product of shock-induced melting. The granophyre occurs as large dykes, several kilometres long and many metres wide with a composition different to any other known rock and containing fragments of extraterrestrial material. Then there are the shatter cones – concentric, conical structures the result of the almost instantaneous shock wave so intense as to shatter and melt hard, competent rock. And in the process to overturn a thickness of 20 km of granite and lithified material.

The 80 km diameter of the dome represents only the uplifted, central part of the impact crater and by extrapolating from other known impact craters on the Earth and the moon, a figure of 300 km diameter for the Vredefort crater is arrived at – the largest impact crater on Earth. As a student in the late 1980’s there was much speculation as to its origin, and geologists, being essentially romantics at heart, adopted the meteorite impact theory. However, absolute, conclusive evidence was lacking but thanks to the careful work of Uwe Reimold and his team from the University of the Witwatersrand, conclusive evidence was provided to sustain this theory, enough for it to be declared a World Heritage Site in 2005, as Earth’s oldest and largest meteorite impact crater. How old is it? Just over 2 billion years, which is just under half the age of Earth. Fortunately life was still in its infancy then and the impact, although cataclysmic, did not cause the damage that better known and more recent collision events had on the biosphere.

Romancing the Stone

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The Age of the Earth - Episode 3

Newton then swept away Descartes’ imprecise theories with his Principia – the laws governing the motions of the heavenly bodies were now defined in minute detail. However his seems to have wasted his intellect and the latter years of his life trying to tie the history of ancient kingdoms and biblical chronology into the record of astronomical events – eclipses and the arrival of comets – but with extremely limited success.

Isaac Newton

His friend Edmond Halley then came up with the theory that the age of the Earth could be estimated by the amount of salt in the sea. By measuring the rate of increase of the sea’s salinity, and assuming that salt had been washed into the oceans at a constant rate, it would be possible to work backward to a time when the seas contained no salt at all, which would then give the age of the Earth. In 1715, this was a fantastic idea, but no one, least of all Edmond Halley, knew how to measure increases in salinity year on year, and he concluded that the observations would need to be made a century apart to be meaningful. However Methuselah, in spite of his famed longevity, was no longer alive, so this was impossibility.

Georges Louis Leclerc Buffon was the next to estimate the age of the Earth. He was well connected with the French court and had the ear of several of the crowned heads of Europe. Clever, hard working, and somewhat eccentric, he proposed the idea that the Earth’s age could be estimated by the rate at which it cooled.

Georges Leclerc Buffon

He heated up metal spheres and then estimated the rate of heat loss as they cooled, and then extrapolated this to the larger Earth, settling on the age of 75 000 to 168 000 years. This was a quantum leap from the 6000 year old theory and he nearly got excommunicated for his troubles. Being a politically astute animal, he recanted his heresies but then proceeded to repeat his assertions for the rest of his days.

Charles Darwin, apparently unhappy with creating controversy, but brave enough to do so anyway, suggested that the Earth was 300 million years old. This date proved so contentious that he actually withdrew it from his Origin of the Species. The great Lord Kelvin, who towered over Victorian science like a colossus, took Darwin to task for some of his assertions, and declared that the Earth cold be no older than 24 million years, which were downward revisions of an original figure of 400 million. However, in spite of Kelvin’s phenomenal intellect, he was not aware of the invisible heat source deep with the Earth – radioactivity – which drives the engine of our planet. Radioactivity is a concept to which we have become accustomed to thanks to the popular press, nuclear power and its use in the medical field. But is Kelvin’s day it was still unknown, and it was thanks to the pioneering work by Marie and Pierre Curie that radioactive material was first recognised and isolated. Earnest Rutherford then provided the world with an explanation of how it all worked, and of the energies released in the process – which then provided a mechanism for keeping the interior of the Earth at elevated temperatures. Other great names of nuclear physics come from this time – Bohr, Heisenberg, Thompson, Chadwick and of course Einstein. The properties of the atom and the elements became increasingly understood as well as the chemistry and isotopes of radioactive elements.

This understanding of radioactive half lives became fundamental to the dating of rocks, Professor Arthur Holmes of Durham University took up the cudgels and pioneered the methods which are used to this day. The technique was based on Rutherford’s 1904 work, when he discovered that atoms decay from one element into another at a rate predictable enough to allow them to be used as clocks.

Arthur Holmes

Holmes measured the rate of decay of uranium to lead, and used this to calculate the age of the Earth. In spite of a lack of funds and sophisticated equipment, he announced in 1946 that the Earth was at least 3 billion years old. His methods met with praise, but his date was not. But he was far closer to the mark than Kelvin had been.

Building on Holmes' pioneering work, Clair Patterson of the University of Chicago took up the challenge. The problem with dating the Earth is that one needs rocks almost that old, and these are rare thanks to the ongoing cycling of crust due to plate tectonics. In addition one needs uranium-bearing crystals within these rocks. Patterson made the assumption that if all the lead on Earth came from radioactive decay, then it would be easy to find the age of the Earth. The more lead a rock contained, the older it had to be. In reality all the lead on Earth did not come from uranium and it was impossible to separate out the ‘primordial’ lead – that which had been around from the creation of the Earth, from that derived from radioactive decay. To sidestep this thorny issue, another brilliant assumption was made, that meteorites were left over building material dating back to the early days of the solar system, and thus their lead content would be the same as that of the early Earth. Perhaps more importantly they contained no uranium to upset the clock. None of the lead in meteorites then would have come from radioactive decay. Harrison Brown, Patterson’s doctoral supervisor said this to him:

“Pat, you just go in and get an iron meteorite – I’ll get it for you. We’ll get the lead out of the iron meteorite. You measure its isotopic composition and you stick it into the equation. And you’ll be famous, because you have will have measured the age of the Earth.”

Clair Patterson

It took Patterson 7 years to build a completely lead free laboratory and to obtain a result, which dated the Earth at 4550 million years. After three hundred years we had at last a date for the beginning of the World. And that figure still stands to this day.

The Age of the Earth - Episode 2

Firmly entrenched and supported by the church, Ussher’s date seemed impregnable. However, some sceptics put forward their own versions. A French Calvinist and lawyer, La Peyrere in 1641 postulated that there had been people on Earth before Adam. This was heresy and of course was banned by Cardinal Richelieu, the prime minister of France. Essentially a pragmatic and fair man, he however realised what effect La Peyrereses manuscript might have in France. La Peyrere kep this freedom, but he did not desist with his theories, eventually in 1655 invoking the wrath of the Catholic Church. He was arrested, interred and forced to recant his heretical views – in short he got off lightly. Enter another player on this grand stage – a Jesuit missionary, Farther Martino Martini, who was carrying out missionary work in China.

Martino Martini

On telling the Chinese that mankind had been destroyed by God in a great deluge, they greeted his pronouncements with great hilarity and disbelief. Their own history stretched well beyond the so-called date of the Flood, and they had records to prove it. A reversal of roles took place, with Martini realising that the ancient Chinese chronology posed a serious challenge to the authority of the bible. In 1654 he returned to Europe, where he published an account of Chinese history, receiving of course the usual disbelief and hostility which marked all other controversial ideas perpetuated at the time. However arrest and persecution was out of the question as Martini had returned to China to further his missionary work. Europe continued her dyed-in-the-wool approach, but slowly thinking was evolving, with crucial intellectual shift away from biblical textual authority towards an enquiry based on scientific principles. Throughout Europe the cry was the same: rocks, not books were believed to hold the secrets of the past. And indeed they did, and still do, and it was left to the natural philosophers to prove the age of the world.

One of the more interesting notions of the 17th Century was that the Earth had been created fully formed; flat, beautiful, unblemished, with no disease, famine, mountains or deserts to blemish her perfect face. A golden age had existed before the Flood, and age when all God’s blessings were poured out onto the world – in short a perfect God had created a perfect world. But now things were in decline – the Earth had become old and wrinkled, volcanoes and deserts were carbuncles and scars on the face of the Earth. An old prophecy that the world would last only 6000 years was being confirmed by nature. The thinking was that the Earth had run most of its days, and doomsday was not far off, perhaps only 350 years in the future (taking of course the date of 4004 BC as the day of creation).

However this idea of an ageing Earth brought the notion of a world in flux and a constant state of change to the fore, and it was Rene Descartes who lead the break with the literal interpretation of the bible. Reason was the reason de etre. Paris, 1625, and our clever and sociable Descartes had become the leading light of Parisian intellectual life – a time when libertine free thinkers were making their mark. Caution was always necessary and a weather eye was kept open for gathering storm clouds in the direction or Rome. One Giulio Vanini, a ‘heretic’ doctor, had had his tongue cut out before being strangled and burned six years before for voicing some anti religious views. Inevitably the storm broke and Descartes moved to Holland, a country which has always had a tradition of tolerance and liberalism which endures to this day. He began his philosophical treatise, The World, which was to be a completer revision of philosophy which he eventually published in 1641.

Rene Descartes

However it was a watered-down version of his original manuscript as it was a bad time for liberal thinkers. Galileo had recently been arrested and forced to recant his heretical views that the Earth went around the Sun. Descartes’ view of the world was essentially that a few simple laws governed the universe, and these laws were what created the complex world around us. The world had the same relationship to God as a clock had to the clock maker – once it had been carefully constructed and set in motion, there was little more involvement from the creator. His ultimate achievement was to remove God from the day to day running of the world. Until then the belief was that God was intimately involved in the day to day, minute to minute running of the world. God may have created the world, but it was then governed by the laws of nature.

To be continued.......................

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The Age of the Earth – Episode 1

All this frantic subdividing and classifying based on rock types and fossil assemblages allowed for a systematic assessment of the order of the ancient strata. Relatively, those early geologists knew which rocks preceded others, but no one had the faintest idea how old they were in absolute terms. Which brings us to some of the other great controversies of the geology which raged from 1650 to the middle of the 20th Century. Two thousand years ago the idea that the world might have a starting point was inconceivable. Most of the ancients believed that the Universe had existed forever, and that recurring cycles of creation and destruction were part of the clockwork which was so evidently displayed in the endless cycling of the heavenly bodies overhead – clear manifestations of the cyclical machinations of the Universe. The Hindus believed that the shortest cycle, the Maha Yuga, lasted 4320 000 years. A thousand Maha Yugas made up one Kalpa, and two Kalpas completed a single day in the life of Brahma. After this, eveyone was reincarnated and the cycle repeated.

Similar ideas were manifest in ancient Greece, and Plato suggested that the length of a cycle was defined by the time it took for all the planets to return to their same relative positions in their orbits, which they had occupied at an earlier time. This time period of 36 000 years was known as the magnus annus – the great year. However just one civilisation in the ancient world ascribed to a different idea – that the heavens and the Earth had been created by God, and that there was a beginning. This Jewish notion was adopted by Christianity, and with the concept of a beginning now firmly planted in the thinking of the Christian world, it was only a matter of time before someone attempted to set a date to it.

The most influential was Bishop Ussher who set it at 6 pm on Saturday, October 22, 4004 BC. We may well pour scorn on this date but there are those who still subscribe to this improbably precise reckoning and it may still be seen in the margins of some old bibles printed around the turn of the last century. Bishop Ussher was no fool mind you. The genealogy of the book of Genesis, the biblical account of creation of the world, runs to 21 generations. Precise dates of the lengths of the lives of the various protagonists are also given, and by totting up the numbers on can arrive at a precise date of creation. This is exactly what Ussher did. No one was more qualified than he, having learned Latin as a boy, and after joining Trinity College in Dublin in 1593, he pursued the date relentlessly, teaching himself Hebrew and Greek so as to better understand the ancient texts from which he was working. He built up Trinity College’s library into what was probably the largest collection of learned works in the world at the time – a total of 4000 volumes. He himself owned 10 000 at the end of his life. He had access to the libraries of London, Cambridge and Oxford, and rubbed shoulders with the free thinkers of the time – Frances Bacon and Ben Jonson.

In 1624 at the age of 44 he was appointed Bishop of Armagh, the most senior position in the Church of Ireland. Issues of which version of the Bible to use in determining this date – for example the Greek-derived Septuagint Bible used by the Orthodox church gave dates which stretched back almost 1000 years earlier than the Hebrew-derived Bible. Adding to the difficulties was the fact that different nations had different ideas as to how long a year actually was, and different dates for the beginning of the year. In addition, astronomical records were used to help tie down dates. For example the date of the birth of Christ was based on the following account:

“As for the other Mathias who had stirred up the sedition, Herod had him burnt alive, together with his companions. And that very night there was an eclipse of the moon.”

The thinking was that Jesus must have been born before this date, and that the great astronomer Keppler leant his weight to this argument, opting for the date of March 14th 4 BC, which is in fact the accepted year of Jesus’ birth today. Ussher’s consulted far and wide, had agents in the Near East buying up ancient texts, and devoted his entire life to the quest. Secular problems also intruded into his world, including rebellion in Ireland and dodgy political connections in England which led to his arrest during the English Civil War. If Cromwell was ready to behead King Charles I, what qualms would he have about severing the head of a mere bishop? Ussher managed to weather these storms to the extent that he was given a state burial by Cromwell, so esteemed was he in Irish and English society. Certainly he was a formidable scholar and made maximum use of the resources available to him, and although we can look on at his date with faint amusement, we must remember that he was a product of his age.

The 4004 BC date may have fallen into obscurity if it hadn’t been added to the bible by a bookseller and printer, Thomas Guy. In 1675, in a simple marketing ploy to boost sales, Guy added the date into the margins of his bibles, which worked fantastically, making him a rich man. The subtle twists of fate are in fact quite breathtaking, for Thomas Guy bequeathed his fortune to Guy’s Hospital – an institution which has provided medical care for over 300 years. In 1701, the date received the official blessing of the Church of England.

The Origins of the Science of Geology

Romancing the Stone

Humankind has had an intimate association with the Earth from the first tentative footsteps of those early hominids to our current insatiable need for minerals and fossil fuels. Undoubtedly our early ancestors were aware of geological deposits, whether they were a source of flint for hand tools or clay for cave paintings or body adornment. Once the origins of the science stretch way back into the early history of man. Adobe to build dwellings or the source of ochre for cave paintings may have been the first venture into sources of materials for the use of mankind. Later stones and clay would have become important as building materials or for brick making. Certainly the ancient Egyptians were using bricks in their less ambitious constructions. And to deny that there was no understanding of the local geology when it came to the quarrying of stone for the Egyptian pyramids would have been naive indeed.

Herodotus, 484 to 426 BC, made many significant geological observations, speculating about the effect of earthquakes on landscapes, but ascribed their causes to Poseidon. Pliny the Elder (AD 23 to 79) lost his life tramping around the slopes of Vesuvius during the eruption that destroyed Pompeii. His reasoning was that earthquakes were a result of Earth’s resentment against those that mutilated and plundered her for gain. Christianity put scientific enquiry literally into the dark ages due to an all encompassing theory for the cause of everything, and besides it was thought that the Earth was a very young place, doomsday was nigh, and therefore the study of the machinations of the planet would be a pointless exercise. Inconsiderately doomsday did not arrive which got some individuals wondering about the natural world. In addition the increasing preoccupation during the Middle Ages with alchemy kick started a scientific process which continues to this day. Leonardo da Vinci, Nicholas Copernicus, Galileo Galilei, brave and brilliant philosophers and scientists all, drove some of the first nails into the coffin of ignorance, holding high the light of knowledge for those who would see.

However the first real attempt on a treatise on geology was made by Scottish farmer James Hutton in an inaccessible 1795 tome titled ‘A Theory of the Earth with Proofs and Illustrations.’ He might have passed into geological obscurity if it wasn’t for a certain John Playfair who rewrote the book on Hutton’s death, making it possible for mere mortals to grasp the concepts that Hutton had so obscurely written about. At that time natural philosophers were divided into two camps – the Neptunists, who believed that everything on Earth, including sea shells on lofty peaks, were due to rising and falling sea levels, and the Plutonists, who noted that volcanoes and earthquakes continually changed the face of the planet and that seas were not the agents which the Neptunists believed. Plutonists also raised difficult questions such to the whereabouts of all the water during periods of tranquillity, a period we are experiencing now.

Hutton’s insights threw some light on the matter, thanks to his keen eye and a close identification with the land thanks to his farming background. He observed the formation of soils, and their erosion and transport to other locales. He realised that over time this erosion of the high ground and the infilling of the lows would leave a planet smooth and devoid of topography. However everywhere he looked there were hills and mountains, particularly so in his native Scotland. He realised that there had to be some process that renewed and uplifted the landscape the keep the cycle going. Those pesky fossils on the mountain tops had not been deposited by floods, but had been lifted there, along with the mountains themselves. Heat within the Earth was the driving force of all this activity, or so ran the thoughts of Mr Hutton. Interestingly some of these thoughts have only been vindicated in the last 40 years or so. More importantly however was the idea that these processes required immense periods of time – far more than anyone had as yet ever conceived.



At the same time, down south, William Smith was building canals and draining bogs for a range of clients as part of the expanding infrastructure driven by the Industrial Revolution. During his daily work he uncovered a myriad of fossils, and realised that each succeeding geological bed or formation had its own particular assemblage of preserved organisms. Spending huge amounts of time and money, he travelled widely across vast swathes of England and to some extent Scotland, mapping the various outcrops of the various strata wherever he went. His exertions damaged his health had his finances to the extent that he even spent time in a debtors gaol, and perhaps even more galling for him, his work was discounted and ridiculed by the supercilious aristocrats who had formed the Geological Society of London in 1807.


However an examination of the map that Smith produced and now hangs in the Society’s headquarters in London reveals his genius. His map shows in amazingly accurate detail the geology of the British Isles and was the first ever geological map. Singlehandedly Smith had mapped out what the British Geological Survey, with hordes of geologists and government funding, couldn’t really improve on except by adding detail. And in a true Hollywood ending, Smith was eventually accepted and then lauded by the Society, and was granted a pension in his latter years, putting off forever the spectre of a debtor's prison and a difficult retirement.


Charles Lyell then enters the stage. He had managed to wade through chunks of Hutton’s book, and was eternally grateful to Playfair for rewriting the work into something approaching readable. Lyell was the most influential geologist of his century, which was a time incidentally when the world was in thrall to all things geological. Geology was the central science and the older Royal Society was in danger of being eclipsed by the upstart Geological Society as the premier scientific society of the country, which at that time also meant the world. So popular was the science that when Charles Lyell travelled to America to lecture, 3000 people showed up to be enlightened on ponderous subjects such as marine zeolites and seismic perturbations in Campania. Back home, modern, thinking men would venture forth to do fieldwork dressed in top hats and dark suits, except for a Reverend Buckland of Oxford who preferred an academic gown. Lyell produced his masterpiece, The Principles of Geology, which built on the works of Hutton of a previous century and made his reputation. Charles Darwin carried a copy of his book on the Beagle voyage, writing afterwards “the greatest merit of the Principles was that it altered the whole tone of one’s mind, and therefore that, when seeing a thing never seen by Lyell, one yet saw it partially through his eyes.”

Between the time of Hutton and Lyell there arose another controversy that followed on from the great Neptunist-Plutonist debate. New lines were drawn between the Catastrophism and Uniformitarianism camps. The former adhered to the idea that the Earth was shaped by cataclysmic events – floods, mainly, while the latter camp believed that changes on Earth took place over immense periods of time. The Catastrophists found that their theory worked in well with the Noachian deluge and therefore did not fly in the face of any biblical beliefs. Lyell was a Uniformitarian and his influence remains right down to the present day. As an interesting aside however, rude Catastrophist brickbats still whizz down the passage of 2 centuries to strike at the very heart of Uniformitarian belief. These brickbats comprise meteorite impacts which are widely believed to have brought to a close the Cretaceous Period and the demise of the dinosaurs, and have been invoked as the cause of a number of other extinctions in Earth history.

Because the Brits were the most active in the early years of the science, British names were assigned to the geological time scale. The Devonian Period is named after Devon, the Cambrian after the Roman name for Wales, and the Ordovician and Silurian after ancient Welsh tribes, the Ordovices and the Silures. However other names began to creep in from practitioners elsewhere – Jurassic from the Jura Mountains of southern France, Permian from the Russian province of Perm while the Cretaceous was named by a certain J.J. d’Omalius d’ Halloy of Belgium.

Initially the geological time scale was divided into 4 spans – Primary, Secondary, Tertiary and Quaternary. The Tertiary is the last surviving member of this initial subdivision, although Quaternary does get a period outing. Lyell introduced additional units known as epochs or series to cover the period since the end of the Cretaceous. These were the Pleistocene, meaning ‘most recent’ Pliocene, the ‘more recent’, Miocene, ‘moderately recent’ and Oligocene ‘but a little recent.’ Nowadays geological time is divided into four great chunks known as eras – Precambrian, Palaeozoic, Mesozoic and Cainozoic, which in turn are divided into Periods which some of you may be familiar with, viz., Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian, Triassic, Jurassic, and Cretaceous. (Camels Often Sit Down Carefully Perhaps Their Joints Creak is a useful acronym for remembering them).

Romancing the Stone