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The world of Stonehenge catalogue by Duncan Garrow and Neil Wilkin (2022)

All the catalogues to British Museum exhibitions come in the same format and style. They are big, heavy and black. The front cover image emerges out of a dead black, matt black background as if from an unfathomable past – the cover of the Nero exhibition had this style, and the Peru exhibition, and in the case of this catalogue it is a collage of a night-time photo of Stonehenge itself dominated by the most striking exhibit in the show, the Nebra sky disk (made in Germany 3,600 years ago).

Front cover of The world of Stonehenge catalogue.

The hardback versions are very heavy and have the dimensions of coffee table books, 13.8 inches tall by 11.5 inches wide. But the classic coffee table book consists of mostly full-page photos or illustrations with captions and minimal text. Whereas, although it has photos on almost every page, beautiful photos of Stonehenge and scores of other prehistoric sites, and hundreds of images of finds and relics, they are what you might call moderate size, and embedded in a great deal of information-rich prose.

Main ideas

I dare say the authors (Duncan Garrow and Neil Wilkin) had numerous ideas they wanted to get across, but three really big ones came over for me:

1. What is a henge?

Ironically Stonehenge is not a henge. A ‘henge’ is a type of Neolithic earthwork which features a ring-shaped bank and ditch, with the ditch inside the bank (the term was coined by British Museum curator Thomas Kendrick in the 1930s). So the ‘henge’ in Stonehenge doesn’t refer to the stone circles at all; it refers to the circular ditch and bank which surrounds the stone circle. There are some 120 henges, or prehistoric circular ditches with a bank, scattered across the British Isles, but there’s a much larger number of stone circles, at over a thousand. Whole passages of the catalogue are devoted to discussing in detail many of these other stone circles, particularly in Ireland and in the Scottish islands of the Orkneys and Hebrides, all accompanied by beautiful photos (pages 95 to 99).

Anyway, even the ditch part of Stonehenge isn’t a ‘true’ henge because its ditch runs outside its bank (Stonehenge catalogue, page 19).

Henges often have entrances i.e. an earth bridge across the ditch, sometimes marked just inside by a pair of flanking wood poles or standing stones – but far from being consistently aligned with astrological features i.e. the sun or moon, there is a wide variety of placement and no consistency or pattern. Henges which are large enough to contain a sizeable central flattened area where structures were subsequently erected are called ‘henge enclosures’.

Because another key thing about henges is that the wooden or stone circles built inside them were often built a lot later so the two might not have had the same purpose or meaning. Maybe stone circles were built within henges because they had become holy sites, but the cultures which built them were separated by up to 1,000 years in time.

2. Packed landscape

Nowadays we see Stonehenge as a strange and mysterious edifice, standing unique and solitary on the windswept Salisbury Plain. But nothing could be further from the archaeological truth. If there’s one thing to take away from the exhibition and the catalogue it is that, in its day, Stonehenge was embedded in a crazily busy, heavily developed landscape.

The Avenue We now know there was a wide ‘avenue’ carved into the chalk which led off northeast from the henge, before bending east, then south to join the River Avon.

Blick Mead This is a chalkland spring about a mile east of Stonehenge and excavation at the site indicates that there was continuous human habitation here from 10,000 to 6,000 years ago, an immense period of time, and covering the early stages of the construction of Stonehenge (p.36).

Bluestonehenge Very recent excavations have discovered that at the landing place from the river there was a flattened area and another circle, 60 feet wide. Excavations have revealed 27 holes which held stones. No stones remain but flakes of stone suggest they were ‘bluestones’ like the ones used at Stonehenge, so archaeologists speculate that some time after it was erected, the circle was taken down and the stones moved to form the middle circle at Stonehenge (p.89).

Bush Barrow less than a mile south-west of Stonehenge is a burial site dating to around 3,900 to 3,700 years ago. The burial chamber contained one individual accompanied by some of the most spectacular grave goods ever found in Britain.

The gold lozenge of the Bush Barrow grave goods, 1950 to 1600 BC Amesbury, Wiltshire, England. Photographs taken by David Bukach. © Wiltshire Museum, Devizes

Car park postholes Just 250 yards north-west of Stonehenge three massive pits have been discovered which held upright wooden poles. The holes and poles date back ten thousand years and mark the earliest known human building activity in the area (p.29). At this point Britain was still fully connected to the continent by the large area of land, subsequently drowned to form the North Sea, and now referred to as Doggerland (p.33).

Coneybury henge A mile south east of Stonehenge is the remains of Coneybury Henge, an oval ditch around 45 metres by 55 metres in diameter, inside which are some pits and stakeholes and an arc of postholes which may have represented a post circle (p.44).

Durrington Walls Two miles north east of Stonehenge is Durrington Walls, which is now known to have been a substantial Neolithic settlement and site of the second-largest Late Neolithic palisaded enclosure known in the UK. Excavations suggest the settlement may once have included 1,000 houses and perhaps 4,000 people, making it the largest settlement in northern Europe, the London of its time (p.86). Durrington was inhabited for about 500 years, from about 4,800 to 4,100 years ago.

Excavations as recent as 2020 revealed a number of pits and holes apparently designed to hold massive timbers, which could be part of a 1.2-mile-wide circuit of 33 foot pits. If this interpretation is correct, this would be Britain’s largest prehistoric monument (p.84). Meat was consumed her in huge quantities. Pig was the most popular source of meat (p.87).

Professor Mike Parker Pearson has proposed the theory that the organic wooden nature of buildings and circles at Durrington may have symbolised food and community and Life, by contrast with Stonehenge, a site dominated by cold, lifeless, hard stones and laced with burials, a site devoted to Death and ancestral spirits, not living people (p.88).

Greater Cursus A mile to the north of Stonehenge is the Greater Cursus, an earthwork 1.9 miles long and between 330 and 490 feet wide. It was built before the stone circle, dated to 5,630 and 5,375 years ago, several hundred years before the earliest phase of Stonehenge 5,000 years ago. Cursus is the Latin word for racetrack, as this is what 18th century antiquarian William Stukeley mistakenly speculated it may have been for (p.57). In fact its exact purpose is unknown. Maybe it was a boundary between sacred and profane territory. Maybe it had a ceremonial purpose.

Lesser Cursus Same uncertainty surrounds the Lesser Cursus to the north-west of the Greater Cursus. The Lesser is  a 400 metres long and 60 metres wide earthwork. Its purpose is utterly unknown. It is mind boggling to learn that both long, deep, wide trenches were dug with reindeer antlers fashioned into basic picks, and ox shoulder blades used as shovels.

Barrows At the eastern terminal of the Cursus is a Neolithic long barrow. To the south-west of the Cursus is the Cursus Barrows Group, a round barrow cemetery which extends 1,200 metres west-to-east along a ridge and measures 250 metres wide (p.54).

In total a staggering 670 burial mounds are known in the landscape around Stonehenge, though the real number may be closer to 1,000 (p.197).

Larkhill enclosure Two miles north of Stonehenge a monumental enclosure has been discovered at the village of Larkhill which seems to be aligned to the solstices and was built 3,750 to 3,650 BC i.e. maybe 500 years before the first stones were erected at Stonehenge. Maybe it acted as a kind of template for the later building? (pages 19 and 56).

Winterbourne Stoke Two miles west of Stonehenge a massive barrow was built in around 5,500 years ago i.e. 500 years before the earliest building at Stonehenge (p.55).

Woodhenge And that’s not all – a short walk from the south of the henge is the structure called Woodhenge, a henge and timber circle dated to between 2,470 and 2,000 BC, about the same time as, or slightly later than, construction of the stone circle at Stonehenge. Radiocarbon dating of artefacts shows that the site was still in use around 1800 BC.

The site consists of six concentric oval rings of postholes, 168 holes in total. Most of these held wooden posts but excavations in 2006 indicated that there were at least five standing stones on the site arranged in a ‘cove’. The deepest post holes measured up to 6 feet and are believed to have held posts which reached as high as 25 feet above ground. Those posts would have weighed up to 5 tons, and their arrangement was similar to that of the bluestones at Stonehenge.

Some theorists speculate that woodhenge maybe symbolised the organic transient world of Life, while the huge stone circle a mile away, which was also a burial ground, symbolised the cold eternity of Death (60 cremation burials dating between 5,000 and 4,800 years ago have been found in or just next to the henge, containing up to 120 bodies; p.67).

Seahenge at the time of excavation © Wendy George

Durrington South timber memorial And just 20 metres away from the periphery of Woodhenge is a completely separate edifice, the Durrington South timber memorial (p.100).

Summary

So what emerges is a picture of Stonehenge the opposite of how we see it today. Far from rising in splendid isolation from a flat plain, it would have been surrounded by numerous other circles of stone or wood, plus the long ditches of the cursuses and the dramatic wide Avenue leading down to another circle by the river. Maybe there were more paths or tracks between these various sites. Maybe pilgrims to the sites had to process around them in a ritual order, as Muslim pilgrims do at the sites of Mecca. Certainly the more we discover, the more densely packed the prehistoric terrain becomes and the more puzzlingly dense with long lost meanings and rituals.

Prehistoric sites around Stonehenge Ordnance Survey (source: Wikipedia) compare with the map on page 90 of the catalogue.

Avebury stone circle Not that much further afield, at Avebury just 25 miles north of Stonehenge, is another, huge stone circle with multiple associated henges and circles and causewayed enclosures and barrows.

Silbury Hill Between the two is Silbury Hill, the largest artificial mound in Europe, 30 metres high and 160 metres across, in the construction of which an estimated half a million tons of chalk were moved requiring about 4 million man hours of labour (p.94).

3. Speculation

It’s not surprising but it is noticeable how much of what the exhibition and the catalogue describe is pure speculation. Obviously it’s speculation by highly experienced experts in their field but, nonetheless, it is speculation, informed guesswork. This really struck home in a paragraph of six sentences on page 101, every one of which hinged on the verb ‘may’. ‘May’, along with ‘maybe’, ‘perhaps’, ‘probably’ and ‘likely’ do a lot of work in this text. Maybe this, perhaps that, possibly the other. This carving could indicate, that dating might suggest…The reader moves from one conditional speculation to another.

On this same page the authors speculate freely that the close proximity of the two massive complexes at Stonehenge and Avebury may have played a part in social rivalry and competition (p.101). Maybe. Maybe not.

The entire chapter 3, about the possible religious beliefs of the henge builders, is a high point of speculation. Just about every relevant object is subjected to flurries of conditionality – these rock carvings may indicate some form of mythological story, these objects might have taken part in religious ceremonies, perhaps these sites had resonant astronomical significance.

  • The sight of flames baking the solar images to the bottoms of these special pots may have added an extra layer of meaning to their production and use. (p.129)
  • Lunulae may have been regarded as too powerful or special to be grave goods associated with any one individual. (p.129)
  • Perhaps the role or identity they conveyed on their wearer was fleeting or part of a rite of passage or ceremony. (p.130)
  • The bronze axe may have been a product of both Ireland and Cornwall. (p.130)
  • It may be impossible to divorce the benefits of trade from beliefs about the cosmos and the role and origin of the sun itself. (p.131)
  • In a ceremony with all kinds of sensory stimuli, from fire, smoke, sounds and spectacle, the movement of the cart may have enacted the passage of the sun through the heavens… (p.133)
  • The bird-sun-boat motif may symbolise a myth or story distinct from but related to the Scandinavian version… (p.135)
  • The chariot might have played a part in ceremonies that did not require a fixed temple… (p.135)
  • Two bronze horses from Scania, Sweden, may have come from a similar model, their glowing amber eyes, again, perhaps representing the sun. (p.137)
  • Sacrificing valuable objects that represented the sun to supernatural forces may be an example of exhortations to the powers of spirits or ancestors, perhaps perceived as the best way to guarantee fertility, regrowth and regeneration. (p.138)
  • [The Amesbury Archer] may have been a specialist metalworker, bringing knowledge of this new, apparently magical, craft… (p.165)

As I read on I became increasingly sceptical about such claims, for the simple reason that the experts  and their theories often radically contradict each other. The authors candidly explain the two or three theories about the meaning and purpose of every site and ditch and stone circle and passage tomb and bronze object and rock carving, and they are often interesting and stimulating speculations.

But the net effect is that a moderately intelligent layman like myself soon comes to realise that there are two utterly distinct levels at play here: on the basic level are the objects themselves, the sites and henges and stones and carvings and axes and metal objects, together with concrete, factual information about the sites where they were discovered – and then, completely separate, is a distinct second layer of speculation, initially tied to these objects but often roaming off into misty worlds of speculation, fantastic descriptions of night-time ceremonies, of the multi-sensual impact of religious rites, for which there is no evidence beyond the authors’ imaginations.

It is also noticeable that many of the conditional speculations are in the direction of current academic and modishly woke concerns: in other words, the academics tend, often without any evidence whatsoever, to rope in ideas about ‘gender’ and ‘identity’ and ‘ethnicity’ as if they were writing a Guardian article or a BBC documentary or a Tate gallery label.

I was particularly struck by the half dozen times they speculate that pots and beakers may have contained ‘intoxicating substances’ to help participate in cult rituals. This sounds cool and modish but there is absolutely no evidence at all of any such substances, after thousands of years there couldn’t be. It’s just a cool Channel 4-type guess or speculation that fits the mood of our drug-soaked times, that gives otherwise dry scholarly articles a rakish, rebel air.

A hundred and fifty years ago the Victorians superimposed their ideas of race and history and religion onto these objects, and now contemporary archaeologists are projecting our values onto them, in turn. The artifacts are like Rorschach tests, complex but unknowable objects onto which scholars project very vividly the concerns and clichés of our own day.

So reading the book tells us about its subject, an encyclopedic overview of the archaeological knowledge of the years 8,000 to 800 BC. But it’s also like looking in a mirror at the values and issues uppermost in the mind of the academic community of archaeologists and ethnographers and ancient historians.

What this aspect of the book displays in spades is the human need for narrative and explanation and causation, all subsets of the fundamental human need for meaning and purpose. A woman friend of mine goes to as many exhibitions as I do, but rarely reads the big wall labels explaining the detailed historical context, or the small labels describing individual exhibits. She just enjoys the objects for what they are, here and now, enjoys them as necklaces, earrings, pendants, figurines, whose presence ennobles and enriches your life, even for a few moments, as you walk among them, with no straining after meaning or context. Just for their beauty alone. I wish I had her courage.

Plain v-perforated jet buttons from Harehope Cairn, Peeblesshire, Early Bronze Age, 2200 to 1750 BC. On display at The world of Stonehenge exhibition at the British Museum (Photo © National Museums, Scotland)

Prehistoric trivia

Impossible to summarise such an encyclopedic text, but certain facts stood out:

– Stonehenge was built between 5,000 and 4,000 years ago, roughly contemporary with the construction of the great pyramid at Giza, the Sphinx (4,500 years ago) and the royal cemetery at Ur in Iraq.

– The first modern to carry out fieldwork, map and describe Stonehenge was antiquarian and founding trustee of the British Museum William Stukeley, during the 1720s. He was instrumental in popularising the notion that Stonehenge was built by the Druids which is wildly incorrect, out by a period of some 3,000 years (Stonehenge started construction 3,000 BC, Druids active when the Romans landed in 43 AD).

The relevant periods are:

  • the Mesolithic: c. 12,000 to 6,000 years ago
  • the Neolithic: c. 6,000 to 4,500 years ago
  • the Bronze Age: c.4,500 to 2,800 years ago

– Collective monuments to house the dead were built in Britain and Ireland for the first time around 6,000 years ago (p.21).

– The period 6,000 to 5,000 years ago i.e. the millennium before Stonehenge was the era of burial chambers and tombs and chambered graves which occur all across the British Isles which often contain numbers of dead, particularly in the period 5,750 to 5,400 years ago (pages 60 and 62). After 5,400 these developed into ‘passage tombs’ with passageways leading into one or more connected burial chambers all covered by stone lintels themselves covered in earth and grass (p.61).

All of the art and decorative work (on stone) from the early Stonehenge period (6,000 to 4,500 years ago) is abstract and non-figurative: lots of circles, whorls and lozenges (p.119).

– 4,500 years ago a major cultural change. The sarsen stone phase of Stonehenge was completed and stone circle building across Britain came to an end. Maybe due to the immigration from the continent of people who brought metal working, the Beaker People. Instead of communal activity or worship, Stonehenge became the focal point of scores of individual burial mounds. Offerings of weapons and tools start to be made at natural places, for example springs and rivers, miles away from man-made henges and circles, as if religion became more personalised, local and easy. Again and again the curators speak of ‘the waning influence of Stonehenge commencing with the arrival of the metal smelting people 4,500 years ago’.

– The last person to be buried at Stonehenge was interred between 4,400 and 4,200 years ago, an adult male aged 25 to 30 who had been shot by several arrows. It is widespread evidence like this which leads experts to suggest that, with the arrival of the Beaker People, society became more individualistic and violent (p.161).

– The agricultural revolution spread from the Middle East from about 9,000 years ago. By about 7,000 years ago it had reached most of north-west France. But then there was an epic delay, and evidence of the farming revolution in lifestyle (fixed settlements, agricultural implements, seeds, domesticated animal bones) didn’t appear until a millennium later, around 6,000 years ago. Why the huge delay? Nobody knows (p.41).

– Knowledge of domesticating plants and animals wasn’t transported to Britain in the abstract. Neither the plants nor the animals naturally existed in Britain. Wheat and corn, cows and sheep and goats and pigs and chicken had to be physically transported across the Channel in primitive boats (p.43).

– A thousand years after the first stones were erected, and several hundred years after the last reconfiguration of the stones, some of the big sarsen stones were decorated with carvings. A total of 119 carvings have been identified, 115 axes and four daggers (p.195). In the curators’ opinion this shows the Beaker People-era shift from communal edifices to the veneration of the new, metal, portable objects. Presumably it indicates the way axes and daggers had not just practical utility but some kind of numinous power.

– In the late 3,000s the emphasis switched from communal effort to create a vast edifice like Stonehenge towards numerous burials of individuals, indicating a switch towards the prioritisation of families and individuals. No fewer than 670 burial mounds are known in the vicinity of Stonehenge (p.197).

– About 3,500 years ago bronze artifacts become so common across Europe, implying a step change in trade routes and exchange of metal ores and finished products, that some scholars refer to it as the ‘bronzisation’ of Europe, comparable to modern ‘globalisation’ (p.209).

– The focus of society moved away from the heartlands of the Wessex chalkland towards the coasts. Analysis of bronze and gold objects shows that the original ore was imported across the Channel. Bronze Age ships and their cargoes have been discovered. It is at this period that precious objects begin to be deposited in waterways, springs and lakes, presumably to propitiate spirits. The huge communal effort required to build Stonehenge belongs to a long distant past.

– There was an increased shift to living close to water, reflect in and permitted by advances in boat and canoe building. In a landscape with few if any roads, waterways were the easiest way to travel and to tap into what all the evidence suggests were farflung networks of trade and connectivity (p.238).

– The closer we come to historic times, the more violent societies all across Europe became. Metal means weapons and armour. The late second millennium BC refers to 1300 or 1200 BC and the authors repeatedly compare the design and use of decorated axes, helmets, maces and armour with that described by Homer in his epics about Troy, set at a legendary epoch often dated to 1300 to 1200 BC.

– The Bronze Age, which is said to have commenced about 2,500 BC, is said to end about 800 BC with the relatively quick introduction of the much more durable, useful medium of iron, having lasted about 1,700 years.

– Not only iron but glass begins to be found in the record from 800 BC and a new type of complex interwoven zoomorphic designs which we nowadays call ‘Celtic’. It was a big revelation to me to see Celtic patterns, designs and culture as the end point of all the previous changes, as a relatively brief phase barely even a thousand years long before the arrival of the Romans in 43 AD.

– And that the late Iron Age also saw the advent of a completely new kind of edifice, the hill fort, which quickly became very widespread across the British Isles, and characterised the Britain the Romans discovered much more than the – by now – ancient and often ruined stone circles, chambered tombs, causeways and circular ditches which littered the countryside (p.243).

Video

The best video I can find consists of an interview with Mike Parker Pearson, Professor of Archaeology at University College London, who not only explains the sequence of building at Stonehenge but relates it a) in spatial terms, to the construction the huge nearby site at Durrington Walls (Pearson’s speciality) and b) in time, to the big cultural shift which took place with the arrival of the Beaker People about 4,500 years ago, which swept away the communal ethos – and, if the DNA evidence is to be believed – the actual populations responsible for the construction of Stonehenge and the many other henges and circles and chambers and barrows which are the subject of this big, beautifully illustrated and fascinating book.

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Posted by Simon on February 24, 2022

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Prehistoric timelines

Texts about prehistory are liable to use three different timelines or naming systems interchangeably so it’s as well to be absolutely clear about them. What follows isn’t definitive, it’s the opposite. It’s my attempt to make sense of the timelines and period-related terminology used in the Stonehenge exhibition at the British Museum. As far as I can tell there are three systems:

  1. the geological eras
  2. the sequence of ice ages
  3. the archaeological periods relating to human culture

1. Geological eras

The geologic time scale is the very high level division of earth history into units called — in descending order of duration — eons, eras, periods, epochs and ages. We are interested in just two epochs:

a) The Pleistocene epoch: 2,580,000 to 11,700 years ago

This long period includes all the earth’s most recent periods of glaciations. It ends with the end of the most recent ice age and general climate warming.

b) The Holocene epoch: 11,650 to now

The Holocene is said to have started about 11,650 years ago, at the end of the most recent maximal glaciation or ice age, and we are still living in it today (although see the note at the end about the possible creation of a new epoch, Anthropocene).

Human figurines carved from yew wood with quartzite eyes from Roos Carr, East Yorkshire, 1000 to 500 BC © Hull Museums

2. Ice ages

The Quaternary glaciation: 2,588,00 YA to the present

The Quaternary glaciation started around 2,588,000 years ago (YA) and is ongoing. The dating of its start is based on the formation of the Arctic ice cap. The Quaternary glaciation itself consists of a sequence of glacial and interglacial periods and we are living in the most recent of its interglacial periods i.e. a warm spell between ice ages.

The Last Glacial Period (LGP): 115,000 to 12,000 YA

The Last Glacial Period (LGP), known colloquially as the last ice age, covers the period 115,000 to 12,000 years ago. The LGP is just part of the larger sequence of glacial and interglacial periods known as the Quaternary glaciation (see above). During this last glacial period there have been alternating episodes of glacier advance and retreat.

Last Glacial Maximum (LGM): 33,000 to 12,000 YA

The most recent period of glacier advance, when ice reached its furthest extent, is called the Last Glacial Maximum (LGM). Ice sheets covered much of North America and Northern Europe leading to a large drop in sea levels. The ice sheets began to grow 33,000 years ago and maximum coverage was reached between 26,500 and 20,000 years ago. At this point all of Scotland, most of Ireland and Wales and England north of a line from the Wash to the Bristol Channel was under ice. South of the ice the land was covered by permafrost with scattered glaciers and ice sheets at high points further south.

During the last glacial maximum, 26,500 and 20,000 years ago, the sea level was about 125 meters (about 410 feet) lower than it is today. After about 20,000 years ago deglaciation commenced in the Northern Hemisphere, and the ice cap began to retreat north, causing sea levels to rise.

The Holocene: 11,650 YA to the present day

Relevant both as a geological epoch and in the timeline of glaciation, the Holocene is the most recent geological epoch and the one we’re all still living in today. In Britain it correlates to the withdrawal of the ice sheets from the entire country.

As the ice sheets withdrew, Britain continued to be part of the continent of Europe, joined by an extensive area referred to as Doggerland. With the withdrawal of the ice and the rise of sea levels, Doggerland was flooded, creating what we now call the North Sea and the English Channel, a process which was complete by about 8,000 years ago.

Bone-bead necklace, part of the finds from Skara Brae, c. 3100 to 2500 BC Skara Brae, Orkney, Scotland © The Trustees of the British Museum

3. Human culture timelines

Human archaeology and ethnography uses what is called the ‘three age’ system, dividing the prehistory of humans into three broad categories – stone age, bronze age, iron age – according to the type of tools found in find sites.

It’s surprising to learn that this schema is 200 years old. It was developed by Christian Thomsen, director of the Royal Museum of Nordic Antiquities in Copenhagen, Denmark, in the 1820s. Thomsen wanted to categorise objects in his collection chronologically according to the main medium used for tool making in each era, and his collection suggested that stone tools came first, then bronze, then iron.

In 1865 the British archaeologist and ethnographer John Lubbock sub-divided the stone age into two, the old stone age or paleolithic (from the Greek paleo meaning old and lithos meaning stone) and the new stone age or neolithic (from the Greek neo meaning new and lithos). Almost immediately the British archaeologist Hodder Westropp suggested an intermediary stage, the middle stone age or mesolithic (from the Greek meso meaning middle and lithos meaning stone), which is still used but is a little more controversial.

Finally, it was realised that the huge extent of the so-called ‘paleolithic’ itself needed to be subdivided, eventually into 3 stages, the lower, middle and upper, which were proposed in the 1880s. And so we find ourselves with the following schema:

  1. Stone Age: 
    • Paleolithic 3.3 million years ago to 15,000 YA
      • Lower Paleolithic: 3 million to 300,000 years ago
      • Middle Paleolithic: 300,000 to 30,000 years ago
      • Upper Paleolithic 50,000 to 12,000 YA
    • Mesolithic: 15,000 to 5,000 years ago
    • Neolithic: 5,000 to
  2. Bronze Age 5300 years ago to 3200 YA
  3. Iron Age to (depends on region)

Two reservations

1. It’s worth emphasising that this entire system works well in Europe and some parts of Asia but doesn’t far at all with human developments in Africa, the Americas or far Asia. In many parts of the world there was no Iron Age at all, for example in Pre-Columbian America and the prehistory of Australia.

2. The term Megalithic does not refer to a period of time, but only describes the use of large stones by ancient peoples from any period.

Now let’s look at the ages in a bit more detail:

Fine jadeitite axe-head made from material quarried in the high Italian Alps, c. 4500 to 3500 BC © The Trustees of the British Museum

Paleolithic or Old Stone Age: 3.3 million years ago to 15,000 YA

Paleolithic indicates the fact that from the dawn of the first proto-humans who used any kinds of tools through to the discovery of metal smelting, all human species used tools made from stone, particularly flint blades and axes. The paleolithic covers a vast period of time, from the earliest known use of stone tools by hominids c. 3.3 million years ago to the start of the Holocene era, about 12,000 years ago. It covers 99% of the period of human technological prehistory. For that entire period humans appear to have been roaming bands of hunter-gatherers living off the land.

As mentioned, as long ago as the 1880s it was found necessary to subdivide the Paleolithic into three:

Lower Paleolithic: 3 million to 300,000 years ago

The Lower Paleolithic is the earliest subdivision of the Paleolithic or Old Stone Age. It spans the period from around 3 million years ago when the first evidence for stone tool production and use by hominids appears in the archaeological record until around 300,000 years ago.

I was a bit puzzled by use of lower and upper until I equated this with the physical location of the finds with the older findings being literally lower down in the earth, and more recent findings being less deep or uppermost.

Middle Paleolithic: 300,000 to 30,000 years ago

The Middle Paleolithic is the second subdivision of the Paleolithic or Old Stone Age as it is understood in Europe, Africa and Asia. Anatomically modern humans (i.e. Homo sapiens) are believed to have emerged in Africa around 300,000 years ago. Around 125,000 years ago they began migrating out of Africa and slowly replaced earlier pre-existent Homo species such as the Neanderthals and Homo erectus.

The use of fire became widespread for the first time in human prehistory during the Middle Paleolithic and humans began to cook their food about 250,000 years ago.

The later part of the period saw the development of a range of new tools: about 90,000 years ago harpoons were invented which brought fish into human diets. Microliths or small stone tools or points were invented around 70,000 to 65,000 YA and were essential to the invention of bows and spear throwers.

Upper Paleolithic 50,000 to 12,000 years ago

The Upper Paleolithic or Late Stone Age is the third and last subdivision of the Paleolithic or Old Stone Age. About 50,000 years ago there was a marked increase in the diversity of artifacts. In Africa, bone artifacts and the first art appear in the archaeological record.

The early modern humans who migrated out of Africa and into Europe about 50,000 years ago, commonly referred to as the Cro-Magnons, left sophisticated stone tools, carved and engraved pieces on bone, ivory and antler, cave paintings and Venus figurines.

The distinct species Homo neanderthalensis, which had first emerged in the fossil record 400,000 years ago and lived widely across Europe and Asia, continued to live for a very long time – as long as 10,000 years – alongside the new incomers Homo sapiens. Then, abruptly, Neanderthals disappear completely from the fossil record 40,000 years ago, leaving archaeologists to speculate about the reasons for their sudden disappearance to this day.

This upper paleolithic revolution which kicked off 50,000 years ago saw many innovations. It witnessed the first evidence of human fishing. New implements were invented: for example, the spear thrower (30,000 years ago), the net (around 29,000 YA), the bolas, the bow and arrow (30,000 to 25,000 YA). From this period date the oldest examples of ceramic art, for example, the Venus of Dolní Věstonice (about 29,000 YA). Members of the European early Upper Paleolithic culture known as the Aurignacian had even developed lunar calendars by 30,000 YA.

Human populations

A really important fact to grasp is that human populations during this period were tiny. The entire population of Europe between 40,000 and 16,000 years ago was probably somewhere 4,000 and 6,000 individuals.

Bronze Age sun pendant, 1000 to 800 BC © The Trustees of the British Museum

The Mesolithic (in Britain): 12,000 to 6,000 years ago

The Paleolithic is said to end with the end of the last ice age and the spread back into Europe of human communities which developed new tools and techniques. The period from the end of the ice age to the arrival of metal smelting 4,500 years ago was initially simply referred to as the Neolithic or new stone age because of the proliferation of new techniques.

But, as we’ve seen, archaeologists almost immediately felt the need to define an interim period between the end of the Old Stone Age and the final period of innovation – hence the creation of the term mesolithic, which refers to the final period of hunter-gatherer cultures in Europe and Western Asia, between the end of the Last Glacial Maximum and the Neolithic Revolution. In Europe it spans roughly 15,000 to 5,000 years ago.

Precise dating of the Mesolithic varies between areas because they were impacted by a) deglaciation and the creation of newly habitable land and b) the arrival of the agricultural revolution, at widely varying times. Thus the mesolithic is said to start in warm Greece around 15,000 years ago but in chilly Britain only around 12,000 YA.

Broadly speaking the Mesolithic is associated with a decline in the group hunting of large animals in favour of a broader hunter-gatherer way of life, and the development of more sophisticated and typically smaller lithic tools and weapons than the heavy-chipped equivalents typical of the Paleolithic.

The Neolithic (in Britain): 6,000 to 4,500 years ago (2,500 BC)

The Neolithic is now used to refer to the period after the ice age when human society was transformed by the advent of agriculture with its enormous cultural, social and economic consequences, but most tools continued to be made of stone, albeit of high levels of sophistication.

The advent of agriculture is sometimes referred to as the Neolithic Revolution. It saw the wide-scale transition of many human cultures from a lifestyle of hunting and gathering to one of agriculture and settlement, with the domestication and breeding of edible grasses and farm animals. With settlement came villages and then towns. We have religious records which point to polytheism.

Some archaeologists refer to a ‘Neolithic package’ in which they include farming, herding, polished stone axes, timber longhouses and pottery. Farming formed the basis for centralised administrations and political structures, hierarchical ideologies, depersonalised systems of knowledge (that’s to say, writing), densely populated settlements, specialisation and division of labour, more trade, the development of non-portable art and architecture and greater property ownership.

The agricultural revolution spread from its origins in the Middle East, through Turkey, across Greece and slowly into central and western Europe. Different sites in the Middle East point to different dates for the domestication of different plants or animals but the process was underway by as long ago as 12,000 years ago.

The diffusion across Europe, from the Fertile Crescent through Anatolia, across the Aegean and central Europe to Britain, took some 3,000 years (9500 to 6000 years ago). It is calculated to have spread at a speed of about 1 kilometre a year, but it was patchy, spreading to some (fertile) areas, moving round mountains, stalling, then suddenly jumping again.

Interestingly, there is evidence of some communities keeping to the mesolithic hunter-gatherer lifestyle for very long periods after the neolithic package arrived, for as long as a thousand years! Archaeologists call such societies are called ‘subneolithic’, the ‘sub’ just meaning hanging on after the main era had ended.

One of the mind-blowing aspects of the neolithic revolution is that all the evidence suggests it made human beings measurably worse off! Many of the cultivated crops (wheat, barley, maize) are deficient in vitamins and minerals and relying on them and cow or goat milk to the exclusion of other elements in a diet can be very harmful. All the archaeological evidence suggests that the Neolithic Revolution led to much more limited diets and poorer nutrition. Human height decreased by an average of 5 inches! Apparently human height didn’t return to pre-neolithic levels until the 20th century.

In addition, close habitation with animals led infectious diseases to jump the species boundary. Smallpox and influenza are just two diseases we got from animals. And higher population densities, living with poor sanitation led to tainted water supplies and the usual diseases of diarrhoea and dysentery, typhoid and cholera.

Jared Diamond suggests that the status of women declined with the adoption of agriculture because women in farming societies typically have more pregnancies and are expected to do more demanding work than women in hunter-gatherer societies.

Having read widely about it, it’s hard to avoid the conclusion that the Neolithic Revolution was a catastrophe for most humans.

The Bronze Age (in Britain): 2,500 BC to 800 BC

Bronze is produced by smelting copper and alloying it with tin, arsenic, or other metals to strengthen it i.e. use it to make stronger, more durable tools or weapons.

In Eurasia the development of bronze tools definitely follows the final refinement of stone ones, and supersedes them. When exactly this happened varies largely from region to region and even from site to site within regions.

In Britain the advent of the Bronze Age is generally agreed to be marked by the arrival of the so-called Beaker culture, so named for the sudden appearance of beaker- or bell-shaped bowls in graves. In Britain the Bronze Age is subdivided into an earlier phase (2500 to 1200 BC) and a later one (1200 to 700 BC).

The Beaker people appear to have known how to smelt copper from their first arrival but it is only around 2150 BC that there is evidence of them smelting copper with other metals (generally tin) to make bronze.

A 2017 study suggests that the Beaker People almost completely replaced the island’s earlier inhabitants, with an estimated 90% of Britain’s neolithic gene pool being replaced! That’s to say, the people who built Stonehenge were substantially wiped out and superseded.

Primarily the Bronze Age is characterised by the widespread use of bronze tools and implements. It is usually accompanied by most of the traits of ‘civilisation’, including craft, urban centres, crafting of precious objects, widespread trade. In the Middle East and Greece we know it was accompanied by the worship of ethnic gods.

Devon and Cornwall were major sources of tin for much of western Europe and the earliest Greek and Roman historians refer to trade with these remote islands which brought the ore to the Mediterranean heartlands.

Bronze twin horse-snake hybrid from hoard, 1200 to 1000 BC. Kallerup, Thy, Jutland, Denmark © National Museum of Denmark

The Iron Age (in Britain): 800 BC to 43 AD

The Iron Age in Britain is dated by the first finds of iron tools in burial sites (around 800 BC) to the arrival of the Romans (43 AD).

The Iron Age is characterised by substantial population growth which allowed increasing social specialisation in societies living in large settlements. In Britain there was a proliferation of large hill forts. There is sophisticated social organisation, for example a class system overseen by a king and the implementation of taxation. There is extensive trade, nationally and internationally, leading to burial sites rich in high value goods, sometimes transported across great distances.

Also a good deal of immigration with entire tribes moving into and settling territories. Whether this involved conquest or peaceful ‘diffusion’ is debated to this day. When the Romans arrived they found a land divided among tribes with a highly developed sense of identity, regional allegiance, names and kings.

The Iron Age is said to end when writing begins. Even though the same kinds of tools are used, a culture has clearly entered a new phase when it enters the historical record. But obviously this happened at different times in different regions.

Thus in the Ancient Near East the Iron Age is taken to end with the start of the Achaemenid Empire in the 6th century BC, as it enters history in the writings of the Greek historian Herodotus. In Western Europe the Iron Age is ended by the Roman conquest, which was established by 100 AD. By contrast in Scandinavia and other parts of northern Europe that the Romans did not reach, the Iron Age is said to have continued until the start of the Viking Age in about 800 AD.

As the Stonehenge exhibition at the British Museum strongly indicates, the later Iron Age was characterised by increasing warfare and social strife. Skeletons show signs of multiple injuries. Average life expectancy at birth was around 25. Into this culture arrived the Romans with their writing, education, towns, roads and laws.

P.S. A new geological era – the Anthropocene?

Remember how I said we’re only interested in two geological epochs, the Pleistocene and the Holocene. Well, there is a new, third category: many scientists are pushing for the scientific community to recognise that the Holocene has ended and we have entered a new epoch, to be named the Anthropocene.

The idea is that this new era should be dated to mark the commencement of significant human impact on Earth’s geology and ecosystems. With widespread acceptance that manmade global warming is having (and will continue to have) a significant effect on the world’s ecosystems, you can see the logic of arguing that we live in an entirely unprecedented era. But to date, none of the official bodies which recognise the geological eras have accepted the anthropocene and there is ongoing debate about when  it should be said to have started.

The problem with our over-documented, over-determined time is that too much has happened. Since Hiroshima we live in The Atomic Age. And since the end of the Second World War we are also all living in an age of rapid technological and social change, which some historians call the Great Acceleration.

Or should we be going further back, should the start of the anthropocene be lined up with the start of the Industrial Revolution in 1710 or 1770 (depending on which precise technical discoveries you prioritise)?

Or, in a massive leap, should we go right back to the start of the neolithic revolution described above, which is when human beings first began to have a measurable impact on their environment? Which would make it identical the current term, the Holocene?

The debate is ongoing and there’s no shortage of candidates but if we stick to permanent markers which are being laid down now and which geologists will find in a million years time, then apparently radioactivity from the nuclear tests is now embedded in ice cores and a thin layer of microplastics has been laid down on the ocean beds, the kind of thing which 100% fulfil the geological criteria.

Personally I think it should be the 1780s and the invention of new, more efficient steam engines, as it was this breakthrough – more than agriculture itself – which set us on the course of greater and greater reliance on energy, first coal, then oil and gas whose use, we all now know, has led to our runaway proliferation, our destruction of every ecosystem we come into contact with, and what looks likely to be massive and irreversible effects on the entire global climate.

Will Stonehenge, built as a result of the neolithic agricultural revolution, survive long enough to see the world transformed by the manmade global warming which is that revolution’s long-term legacy? (Photo © English Heritage)

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The Periodic Kingdom: A Journey Into the Land of the Chemical Elements by Peter Atkins (1995)

Chemistry is the science of changes in matter. (p.37)

At just under 150 pages long, A Journey Into the Land of the Chemical Elements is intended as a novel and imaginative introduction to the 118 or so chemical elements which are the basic components of chemistry, and which, for the past 100 years or so, have been laid out in the grid arrangement known as the periodic table.

The periodic table explained

Just to refresh your memory, it’s called the periodic table because it is arranged into rows called ‘periods’. These are numbered 1 to 7 down the left-hand side.

What is a period? The ‘period number’ of an element signifies ‘the highest energy level an electron in that element occupies (in the unexcited state)’. To put it another way, the ‘period number’ of an element is its number of atomic orbitals. An orbital is the number of orbital positions an electron can take around the nucleus. Think of it like the orbit of the earth round the sun.

For each element there is a limited number of these ‘orbits’ which electrons can take up. Hydrogen, in row one, can only have one electron because it only has one possible orbital for an electron to take up around its nucleus. All the elements in row 2 have two orbitals for their electrons, and so on.

Sodium, for instance, sits in the third period, which means a sodium atom typically has electrons in the first three energy levels. Moving down the table, periods are longer because it takes more electrons to fill the larger and more complex outer levels.

The columns of the table are arranged into ‘groups’ from 1 to 18 along the top. Elements that occupy the same column or group have the same number of electrons in their outer orbital. These outer electrons are called ‘valence electrons’. The electrons in the outer orbital are the first ones to be involved in chemical bonds with other elements; they are relatively easy to dislodge, the ones in the lower orbitals progressively harder.

Elements with identical ‘valance electron configurations’ tend to behave in a similar fashion chemically. For example, all the elements in group or column 18 are gases which are slow to interact with other chemicals and so are known as the inert gases – helium, neon etc. Atkins describes the amazing achievement of the Scottish chemist William Ramsey in discovering almost all the inert gases in the 1890s.

Although there are 18 columns, the actual number of electrons in the outer orbital only goes up to 8. Take nitrogen in row 2 column 15. Nitrogen has the atomic number seven. The atomic number means there are seven electrons in a neutral atom of nitrogen. How many electrons are in its outer orbital? Although nitrogen is in the fifteenth column, that column is actually labelled ‘5A’. 5 represents the number of electrons in the outer orbital. So all this tells you that nitrogen has seven electrons in two orbitals around the nucleus, two in the first orbital and five in the second (2-5).

 

The Periodic Table. Karl Tate © LiveScience.com

Note that each element has two numbers in its cell. The one at the top is the atomic number. This is the number of protons in the nucleus of the element. Note how the atomic number increases in a regular, linear manner, from 1 for hydrogen at the top left, to 118 for Oganesson at the bottom right. After number 83, bismuth, all the elements are radioactive.

(N.B. When Atkins’s book was published in 1995 the table stopped at number 109, Meitnerium. As I write this, 24 years later, it has been extended to number 118, Oganesson. These later elements have been created in minute quantities in laboratories and some of them only exist for a few moments.)

Beneath the element name is the atomic weight. This is the mass of a given atom, measured on a scale in which the hydrogen atom has the weight of one. Because most of the mass in an atom is in the nucleus, and each proton and neutron has an atomic weight near one, the atomic weight is very nearly equal to the number of protons and neutrons in the nucleus.

Note the freestanding pair of rows at the bottom, coloured in purple and orange. These are the lanthanides and actinides. We’ll come to them in a moment.

Not only are the elements arranged into periods and groups but they are also categorised into groupings according to their qualities. In this diagram (taken from LiveScience.com) the different groupings are colour-coded. The groupings are, moving from left to right:

Alkali metals The alkali metals make up most of Group 1, the table’s first column. Shiny and soft enough to cut with a knife, these metals start with lithium (Li) and end with francium (Fr), among the rarest elements on earth: Atkins tells us that at any one moment there are only seventeen atoms of francium on the entire planet. The alkali metals are extremely reactive and burst into flame or even explode on contact with water, so chemists store them in oils or inert gases. Hydrogen, with its single electron, also lives in Group 1, but is considered a non-metal.

Alkaline-earth metals The alkaline-earth metals make up Group 2 of the periodic table, from beryllium (Be) through radium (Ra). Each of these elements has two electrons in its outermost energy level, which makes the alkaline earths reactive enough that they’re rarely found in pure form in nature. But they’re not as reactive as the alkali metals. Their chemical reactions typically occur more slowly and produce less heat compared to the alkali metals.

Lanthanides The third group is much too long to fit into the third column, so it is broken out and flipped sideways to become the top row of what Atkins calls ‘the Southern Island’ that floats at the bottom of the table. This is the lanthanides, elements 57 through 71, lanthanum (La) to lutetium (Lu). The elements in this group have a silvery white color and tarnish on contact with air.

Actinides The actinides line forms the bottom row of the Southern Island and comprise elements 89, actinium (Ac) to 103, lawrencium (Lr). Of these elements, only thorium (Th) and uranium (U) occur naturally on earth in substantial amounts. All are radioactive. The actinides and the lanthanides together form a group called the inner transition metals.

Transition metals Returning to the main body of the table, the remainder of Groups 3 through 12 represent the rest of the transition metals. Hard but malleable, shiny, and possessing good conductivity, these elements are what you normally associate with the word metal. This is the location of many of the best known metals, including gold, silver, iron and platinum.

Post-transition metals Ahead of the jump into the non-metal world, shared characteristics aren’t neatly divided along vertical group lines. The post-transition metals are aluminum (Al), gallium (Ga), indium (In), thallium (Tl), tin (Sn), lead (Pb) and bismuth (Bi), and they span Group 13 to Group 17. These elements have some of the classic characteristics of the transition metals, but they tend to be softer and conduct more poorly than other transition metals. Many periodic tables will feature a highlighted ‘staircase’ line below the diagonal connecting boron with astatine. The post-transition metals cluster to the lower left of this line. Atkins points out that all the elements beyond bismuth (row 6, column 15) are radioactive. Here be skull-and-crossbones warning signs.

Metalloids The metalloids are boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te) and polonium (Po). They form the staircase that represents the gradual transition from metals to non-metals. These elements sometimes behave as semiconductors (B, Si, Ge) rather than as conductors. Metalloids are also called ‘semi-metals’ or ‘poor metals’.

Non-metals Everything else to the upper right of the staircase (plus hydrogen (H), stranded way back in Group 1) is a non-metal. These include the crucial elements for life on earth, carbon (C), nitrogen (N), phosphorus (P), oxygen (O), sulfur (S) and selenium (Se).

Halogens The top four elements of Group 17, from fluorine (F) through astatine (At), represent one of two subsets of the non-metals. The halogens are quite chemically reactive and tend to pair up with alkali metals to produce various types of salt. Common salt is a marriage between the alkali metal sodium and the halogen chlorine.

Noble gases Colorless, odourless and almost completely non-reactive, the inert, or noble gases round out the table in Group 18. The low boiling point of helium makes it a useful refrigerant when exceptionally low temperatures are required; most of them give off a colourful display when electric current is passed through them, hence the generic name of neon lights, invented in 1910 by Georges Claude.

The metaphor of the Periodic Kingdom

In fact the summary I’ve given above isn’t at all how Atkins’s book sounds. It is the way I have had to make notes to myself to understand the table.

Atkins’ book is far from being so clear and straightforward. The Periodic Kingdom is dominated by the central conceit that Atkins treats the periodic table as if it were an actual country. His book is not a comprehensive encyclopedia of biochemistry, mineralogy and industrial chemistry; it is a light-hearted ‘traveller’s guide’ (p.27) to the table which he never refers to as a table, but as a kingdom, complete with its own geography, layout, mountain peaks and ravines, and surrounded by a sea of nothingness.

Hence, from start to finish of the book, Atkins uses metaphors from landscape and exploration to describe the kingdom, talking about ‘the Western desert’, ‘the Southern Shore’ and so on. Here’s a characteristic sentence:

The general disposition of the land is one of metals in the west, giving way, as you travel eastward, to a varied landscape of nonmetals, which terminates in largely inert elements at the eastern shoreline. (p.9)

I guess the idea is to help us memorise the table by describing its characteristics and the changes in atomic weight, physical character, alkalinity, reactivity and so on of the various elements, in terms of geography. Presumably he thinks it’s easier to remember geography than raw information. His approach certainly gives rise to striking analogies:

North of the mainland, situated rather like Iceland off the northwestern edge of Europe, lies a single, isolated region – hydrogen. This simple but gifted element is an essential outpost of the kingdom, for despite its simplicity it is rich in chemical personality. It is also the most abundant element in the universe and the fuel of the stars. (p.9)

Above all the extended metaphor (the periodic table imagined as a country) frees Atkins not to have to lay out the subject in either a technical nor a chronological order but to take a pleasant stroll across the landscape, pointing out interesting features and making a wide variety of linkages, pointing out the secret patterns and subterranean connections between elements in the same ‘regions’ of the table.

There are quite a few of these, for example the way iron can easily form alliances with the metals close to it such as cobalt, nickel and manganese to produce steel. Or the way the march of civilisation progressed from ‘east’ to ‘west’ through the metals, i.e. moving from copper, to iron and steel, each representing a new level of culture and technology.

The kingdom metaphor also allows him to get straight to core facts about each element without getting tangled in pedantic introductions: thus we learn there would be no life without nitrogen which is a key building block of all proteins, not to mention the DNA molecule; or that sodium and potassium (both alkali metals) are vital in the functioning of brain and nervous system cells.

And hence the generally light-hearted, whimsical tone allows him to make fanciful connections: calcium is a key ingredient in the bones of endoskeletons and the shells of exoskeletons, compacted dead shells made chalk, but in another format made the limestone which the Romans and others ground up to make the mortar which held their houses together.

Then there is magnesium. I didn’t think magnesium was particularly special, but learned from Atkins that a single magnesium atom is at the heart of the chlorophyll molecule, and:

Without chlorophyll, the world would be a damp warm rock instead of the softly green haven of life that we know, for chlorophyll holds its magnesium eye to the sun and captures the energy of sunlight, in the first step of photosynthesis. (p.16)

You see how the writing is aspiring to an evocative, poetic quality- a deliberate antidote to the dry and factual way chemistry was taught to us at school. He means to convey the sense of wonder, the strange patterns and secret linkages underlying these wonderful entities. I liked it when he tells us that life is about capturing, storing and deploying energy.

Life is a controlled unwinding of energy.

Or about how phosphorus, in the form of adenosine triphosphate (ATP) is a perfect vector for the deployment of energy, common to all living cells. Hence the importance of phosphates as fertiliser to grow the plants we need to survive. Arsenic is such an effective poison because it is a neighbour of phosphorus, shares some of its qualities, and so inserts itself into chemical reactions usually carried out by phosphorus but blocking them, nulling them, killing the host organism.

All the facts I explained in the first half of this post (mostly cribbed from the LiveScience.com website) are not reached or explained until about page 100 of this 150-page-long book. Personally, I felt I needed them earlier. As soon as I looked at the big diagram of the table he gives right at the end of the book I became intrigued by the layout and the numbers and couldn’t wait for him to get round to explaining them, which is why I went on the internet to find out more, more quickly, and why Istarted my review with a factual summary.

And eventually, the very extended conceit of ‘the kingdom’ gets rather tiresome. Whether intentional or not, the continual references to ‘the kingdom’ begin to sound Biblical and pretentious.

Now the kingdom is virtually fully formed. It rises above the sea of nonbeing and will remain substantially the same almost forever. The kingdom was formed in and among the stars.. (p.75)

The chapter on the scientists who first isolated the elements and began sketching out the table continues the metaphor by referring to them as ‘cartographers’, and the kingdom as made of islands and archipelagos.

As an assistant professor of chemistry at the University of Jena, [Johann Döbereiner] noticed that reports of some of the kingdom’s islands – reports brought back by their chemical explorers – suggested a brotherhood of sorts between the regions. (p.79)

For me, the obsessive use of the geographical metaphor teeters on the border between being useful, and becoming irritating. He introduces me to the names of the great pioneers – I was particularly interested in Dalton, Michael Faraday, Humphrey Davy (who isolated a bunch of elements in the early 1800s) and then William Ramsey – but I had to go to Wikipedia to really understand their achievements.

Atkins speculates that some day we might find another bunch or set of elements, which might even form an entire new ‘continent’, though it is unlikely. This use of a metaphor is sort of useful for spatially imagining how this might happen, but I quickly got bored of him calling this possible set of new discoveries ‘Atlantis’, and of the poetic language as a whole.

Is the kingdom eternal, or will it slip beneath the waves? There is a good chance that one day – in a few years, or a few hundred years at most – Atlantis will be found, which will be an intellectual achievement but probably not one of great practical significance…

A likely (but not certain) scenario is that in that distant time, perhaps 10100 years into the future, all matter will have decayed into radiation, it is even possible to imagine the process. Gradually the peaks and dales of the kingdom will slip away and Mount Iron will rise higher, as elements collapse into its lazy, low-energy form. Provided that matter does not decay into radiation first (which is one possibility), the kingdom will become a lonely pinnacle, with iron the only protuberance from the sea of nonbeing… (p.77)

And I felt the tone sometimes bordered on the patronising.

The second chemical squabble is in the far North, and concerns the location of the offshore Northern Island of hydrogen. To those who do not like offshore islands, there is the problem of where to put it on the mainland. This is the war of the Big-Endians versus the Little-Endians. Big-Endians want to tow the island ashore to form a new Northwestern Cape, immediately north of lithium and beryllium and across from the Northeastern Cape of helium… (p.90)

Hard core chemistry

Unfortunately, none of these imaginative metaphors can help when you come to chapter 9, an unexpectedly brutal bombardment of uncompromising hard core information about the quantum mechanics underlying the structure of the elements.

In quick succession this introduces us to a blizzard of ideas: orbitals, energy levels, Pauli’s law of exclusion, and then the three imaginary lobes of orbitals.

As I understood it, the Pauli exclusion principle states that no two electrons can inhabit a particular orbital or ‘layer’ or shell. But what complicates the picture is that these orbitals come in three lobes conceived as lying along imaginary x, y and z axes. This overlapped with the information that there are four types of orbitals – s, p, d and f orbitals. In addition, there are three p-orbitals, five d-orbitals, seven f-orbitals. And the two lobes of a p-orbital are on either side of an imaginary plane cutting through the nucleus, there are two such planes in a d-orbital and three in an f-orbital.

After pages of amiable waffle about kingdoms and Atlantis, this was like being smacked in the face with a wet towel. Even rereading the chapter three times, I still found it impossible to process and understand this information.

I understand Atkins when he says it is the nature of the orbitals, and which lobes they lie along, which dictates an element’s place in the table, but he lost me when he said a number of electrons lie inside the nucleus – which is the opposite of everything I was ever taught – and then when described the way electrons fly across or through the nucleus, something to do with the processes of ‘shielding’ and ‘penetration’.

The conspiracy of shielding and penetration ensure that the 2s-orbital is somewhat lower in energy than the p-orbitals of the same rank. By extension, where other types of orbitals are possible, ns- and np-orbitals both lie lower in energy than nd-orbitals, and nd-orbitals in turn have lower energy than nf-orbitals. An s-orbital has no nodal plane, and electrons can be found at the nucleus. A p-orbital has one plane, and the electron is excluded from the nucleus. A d-orbital has two intersecting planes, and the exclusion of the electron is greater. An f-orbital has three planes, and the exclusion is correspondingly greater still. (p.118)

Note how all the chummy metaphors of kingdoms and deserts and mountains have disappeared. This is the hard-core quantum mechanical basis of the elements, and at least part of the reason it is so difficult to understand is because he has made the weird decision to throw half a dozen complex ideas at the reader at the same time. I read the chapter three times, still didn’t get it, and eventually wanted to cry with frustration.

This online lecture gives you a flavour of the subject, although it doesn’t mention ‘lobes’ or penetration or shielding.

In the next chapter, Atkins, briskly assuming  his readers have processed and understood all of this information, goes on to combine the stuff about lobes and orbitals with a passage from earlier in the book, where he had introduced the concept of ions, cations, and anions:

  • ion an atom or molecule with a net electric charge due to the loss or gain of one or more electrons
  • cation a positively charged ion
  • anion a negatively charged ion

He had also explained the concept of electron affinity –

The electron affinity (Eea) of an atom or molecule is defined as the amount of energy released or spent when an electron is added to a neutral atom or molecule in the gaseous state to form a negative ion.

Isn’t ‘affinity’ a really bad word to describe this? ‘Affinity’ usually means ‘a natural liking for and understanding of someone or something’. If it is the amount of energy released, why don’t they call it something useful like the ‘energy release’? I felt the same about the terms ‘cation’ and ‘anion’ – that they had been deliberately coined to mystify and confuse. I kept having to stop and look up what they meant since the name is absolutely no use whatsoever.

And the electronvolt – ‘An electronvolt (eV) is the amount of kinetic energy gained or lost by a single electron accelerating from rest through an electric potential difference of one volt in vacuum.’

Combining the not-very-easily understandable material about electron volts with the incomprehensible stuff about orbitals means that the final 30 pages or so of The Periodic Kingdom is thirty pages of this sort of thing:

Take sodium: it has a single electron outside a compact, noble-gaslike core (its structure is [Ne]3s¹). The first electron is quite easy to remove (its removal requires an investment of 5.1 eV), but removal of the second, which has come from the core that lies close to the nucleus, requires an enormous energy – nearly ten times as much, in fact (47.3 eV). (p.130)

This reminds me of the comparable moment in John Allen Paulos’s book Innumeracy where I ceased to follow the argument. After rereading the passage where I stumbled and fell I eventually realised it was because Paulos had introduced three or so important facts about probability theory very, very quickly, without fully explaining them or letting them bed in – and then had spun a fancy variation on them…. leaving me standing gaping on the shore.

Same thing happens here. I almost but don’t quite understand what [Ne]3s¹ means, and almost but don’t quite grasp the scale of electronvolts, so when he goes on to say that releasing the second electron requires ten times as much energy, of course I understand the words, but I cannot quite grasp why it should be so because I have not understood the first two premises.

As with Paulos, the author has gone too fast. These are not simple ideas you can whistle through and expect your readers to lap up. These are very, very difficult ideas most readers will be completely unused to.

I felt the sub-atomic structure chapter should almost have been written twice, approached from entirely different points of view. Even the diagrams were no use because I didn’t understand what they were illustrating because I didn’t understand his swift introduction of half a dozen impenetrable concepts in half a page.

Once through, briskly, is simply not enough. The more I tried to reread the chapter, the more the words started to float in front of my eyes and my brain began to hurt. It is packed with sentences like these:

Now imagine a 2 p-electron… (an electron that occupies a 2 p-orbital). Such an electron is banished from the nucleus on account of the existence of the nodal plane. This electron is more completely shielded from the pull of the nucleus, and so it is not gripped as tightly.In other words, because of the interplay of shielding and penetration, a 2 s-orbital has a lower energy (an electron in it is gripped more tightly) than a 2 p-orbital… Thus the third and final electron of lithium enters the 2 s-orbital, and its overall structure is 1s²2s¹. (p.118)

I very nearly understand what some of these words meant, but the cumulative impact of sentences like these was like being punched to the ground and then given a good kicking. And when the last thirty pages went on to add the subtleties of electronvoltages and micro-electric charges into the mix, to produce ever-more complex explanations for the sub-atomic interactivity of different elements, I gave up.

Summary

The first 90 or so pages of The Periodic Kingdom do manage to give you a feel for the size and shape and underlying patterns of the periodic table. Although it eventually becomes irritating, the ruling metaphor of seeing the whole place as a country with different regions and terrains works – up to a point – to explain or suggest the patterns of size, weight, reactivity and so on underlying the elements.

When he introduced ions was when he first lost me, but I stumbled on through the entertaining trivia and titbits surrounding the chemistry pioneers who first isolated and named many of the elements and the first tentative attempts to create a table for another thirty pages or so.

But the chapter about the sub-atomic structure of chemical elements comprehensively lost me. I was already staggering, and this finished me off.

If Atkins’s aim was to explain the basics of chemistry to an educated layman, then the book was, for me, a complete failure. I sort of quarter understood the orbitals, lobes, nodes section but anything less than 100% understanding means you won’t be able to follow him to the next level of complexity.

As with the Paulos book, I don’t think I failed because I am stupid – I think that, on both occasions, the author failed to understand how challenging his subject matter is, and introduced a flurry of concepts far too quickly, at far too advanced a level.

Looking really closely I realise it is on the same page (page 111) that Atkins introduces the concepts of energy levels, orbitals, the fact that there are three two-lobed orbitals, and the vital existence of nodal planes. On the same page! Why the rush?

An interesting and seemingly trivial feature of a p-orbital, but a feature on which the structure of the kingdom will later be seen to hinge, is that the electron will never be found on the imaginary plane passing through the nucleus and dividing the two lobes of the orbital. This plane is called a nodal plane. An s-orbital does not have such a nodal plane, and the electron it describes may be found at the nucleus. Every p-orbital has a nodal plane of this kind, and therefore an electron that occupies a p-orbital will never be found at the nucleus. (p.111)

Do you understand that? Because if you don’t, you won’t understand the last 40 or so pages of the book, because this is the ‘feature on which the structure of the kingdom will later be seen to hinge’.

I struggled through the final 40 pages weeping tears of frustration, and flushed with anger at having the thing explained to me so badly. Exactly how I felt during my chemistry lessons at school forty years ago.

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by Simon on April 14, 2019  •  Permalink
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Posted by Simon on April 14, 2019

https://astrofella.wordpress.com/2019/04/14/the-periodic-kingdom-peter-atkins/

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