Clinging On

As the human world reels under the malign influence of Coronavirus, my thoughts turn to Cretaceous barnacles. 

This sudden interest in extinct cirripedia is prompted by a paper published a month ago by Professor Andy Gale: New thoracican cirripedes (Crustacea) from the Cretaceous of Europe and North Africa.[1] It announces the discovery of new extinct genera and species of barnacle. There are two sorts: the acorn/wart-type (sessile) barnacles familiar from rocky shores and the stalk-type (pedunculate) 'goose barnacles' sometimes found attached to drift wood. 

I have never really thought about these crustacea before. They are easily overlooked - that is until you gash your hands or feet on them at the seaside, or eat them in a Portuguese restaurant. What crystallises my interest in them now is that one of the Zeugmatolepadid family now bears my name: Subsecolepas holtwilsoni. It is a lepadid barnacle - one of the stalked type. My thanks go to Andy for the honour. I think its taxonomic status is:

Phylum - Arthropoda

Clade - Mandibulata

Clade - Pancrustacea

Subphylum - Crustacea

Class - Maxillopoda

Infraclass - Cirripedia

Superorder - Thoracica

Order - Pedunculata

Suborder - Scalpelliformes

Clade - Thoracicalcarea

Family - Zeugmatolepadidae

Subfamily - Martillepadinae

Genus - Subsecolepas

Species - holtwilsoni 

Andy Gale is one of a very small band of palaeontological researchers active in the field of fossil cirripedes. Their most illustrious forebear is Charles Darwin. Thomas Withers was active from 1910 to the 1960s, and catalogued the fossils specimens at the Natural History Museum, London. " There can be no doubt the Wither's 'Catalogues' are to fossil lepadomorph and verrucomorph barnacles what Darwin's 'Monographs' are to Recent barnacles."[2] Andy has been one of the most prolific cirripede researchers in recent decades, focusing on the Cretaceous Chalk and publishing many papers. He says that S.holtwilsoni is common in chalk of the Upper Campanian stage in the UK, and that 400 fossil specimens have been found at various old pits in the Norwich area. He named it after me for helping him dig in these pits and for having been involved in their conservation, including Keswick, Catton, Cringleford and Whitlingham.

Collecting samples at Keswick, 2015

I have not visited any chalk pits lately. Britain today is in emergency 'lock-down', and I feel sorry for city-dwellers cooped up in flats and terraced houses. At least I have an extensive wildlife garden to ramble in, and I also enjoy exploring the meaning of our geological heritage.

Crustaceans of the Campanian seas are a great imaginative diversion - a dépaysement, as the French say. Geology and palaeontology call us out of our own time and down into the profound depths of planetary and biological evolution. I try to imagine the lifeworld of the extinct species that now bears my name.  

Here are photos of the type specimens of S.holtwilsoni, variously sourced from chalk pits at Keswick and Cringleford, and all are now archived in the Natural History Museum. They show elements of the set of hard, calcareous plates which enclose the head of the barnacle. 

Type specimens of Subsecolepas holtwilsoni. Image courtesy Andy Gale [1]

Stalked barnacles from JG Wood: 'The Illustrated Natural History'; Routledge, London, 1863

Darwin's drawing of a Middle Jurassic stalked barnacle Pollicipes concinnus,
as found attached to the shell of an ammonite.[3]

Contemporary stalked barnacles attach themselves to floating objects, particularly driftwood, turtles and ships. According to Andy Gale, S.holtwilsoni and other Zeugmatolepadids probably had a similar lifestyle, attaching to the shells of free-swimming ammonites and seabed-dwelling inoceramid bivalves as well as floating wood.[1, p.245] There must have been a steady rain of their plates falling into the carbonate-rich mud of the sea floor, perhaps 100 to 500 metres down.[4] 

The Campanian stage spans from 83.6 to 72.2 million years ago.[5], and chalk of this age is well-represented in Norfolk and Suffolk. I have visited many quarries of this period in the Gipping valley and Norwich areas. At Keswick and Cringleford I helped clear the chalk exposures so that Andy Gale could record the geological succession and take samples. The samples are treated with glauber's salt and freezing in a repeat process until the miniscule fossil fragments - echinoid spines, bits of coral, fish scale, shell, etc - are freed from their chalky matrix and can be examined under a microscope.  

Fossil residues from the Chalk (40x magnification)

  

The contrast between the physical reality of an old chalk pit, with its crumbly, scrub-infested chaos, and the clarified world of knowledge compiled by over 150 years of scientific research into the Chalk is remarkable. We now know much about the Earth's geography during the Campanian, for example that Europe was an archipelago of islands.[6] We know much about biodiversity and details of climate and chemistry.[7; 8]  

 

The world as it was in the late Cretaceous. Image courtesy Andy Gale [1]

All this is wonderful, radical stuff to explore during COVID-19 lock-down. Like astronomy, geology has the power to frame human life against an almost infinite scale of time and space. Like pedunculate cirripedes, we cling for a few seasons to our floating attachment points and then - like them - our debris will inevitably find its way to the metaphorical sea floor. Perhaps only our names, inscriptions and genetic coding will survive us, for a century or two at most. The history of taxonomic revision makes clear that not even species names backed up with diligent taxonomic description may be proof against time. 

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REFERENCES

[1] - Gale, A.S. New thoracican cirripedes (Crustacea) from the Cretaceous of Europe and North Africa. Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen Band 295 Heft 3 (2020), pp.243-282. [Link accessed May 2020]
[2] - Southward, AJ. Barnacle Biology. CRC Press, 1987; chapters 2.1 and 2.2.
[3] - Darwin, CR. A monograph on the fossil Lepadidæ, or pedunculated cirripedes of Great Britain. Palæontographical Society, London, 1851 Plate 3, Fig.1. Downloadable here. [Link accessed May 2020]
[4] - Rawson, PF. Cretaceous: Sea Levels peak as the North Atlantic Opens, in: Brenchley, PJ & Rawson, PF (eds). The Geology of England and Wales. The Geological Society, 2006; 2nd Edition. 
[5] - Lee, JR, et al (eds). British Regional Geology. East Anglia. British Geological Survey, Fifth Edition, 2015.
[6] - Csiki-Sava, Z et al. Island life in the Cretaceous - faunal composition, biogeography, evolution, and extinction of land-living vertebrates on the Late Cretaceous European archipelago. Zookeys, no.469, January 2015, pp.1-161. [Link accessed May 2020]
[7] - Jarvis, I, et al. Late Cretaceous (Campanian) carbon isotope events, sea-level change and correlation of the Tethyan and Boreal realms. Palaeogeography, Palaeoclimatology, Palaeoecology, no.188, 2002, pp.215-248.
[8] - Skelton, PF et al (eds). The Cretaceous World. The Open University / Cambridge University Press, 2003.

THANKS TO

• Andy Gale, for naming the extinct beastie.
• Gilbert Addison, for suggesting the title of this article.

A Blackthorn Spring

Cold winds easterly have been blowing across East Anglia for the past week, though temperatures are set to rise this weekend.  Blackthorn blossoms are flourishing in this 'blackthorn spring': their froth of cold, white flowers starting out of the rattling, winter blackness of branch and twig.

Prunus spinosa, is respected by country dwellers for its fruit (sloe gin), its hard, durable wood and particularly for its long, piercing thorns like stiletti. They are able to pass straight through clothing, gloves and even boot soles and car tyres - things I know from experience.

I now have a terrible story to relate. It was told me by my friend C. and began about a month ago when her boyfriend D. was working in a Suffolk wood. Blackthorns make bristling thickets that require careful handling. Even though he was wearing goggles, a chance branch whipped his forehead and embedded a spine in his brow down to the bone. Naturally he pulled it out, but that evening redness and swelling set in, followed later by deep inflammation. Over the following days his condition worsened as his head swelled up and he became very unwell, with symptoms similar to sepsis (blood poisoning). Luckily neighbours noticed his silent home and telephoned C. She drove over immediately and what she found appalled her; a man in delirium, shivering with fever, with a necrotic lesion on his forehead. He was taken to hospital by ambulance and given intensive care. Over the next few days the hallucinations faded - at one time he said he thought his bed was surrounded by tall trees - and his temperature subsided. It was evident that he would need a skin graft to repair the damage, but this would have to be delayed because the hospital had started dealing with a flood of Coronavirus casualties. That is the situation now: D. is waiting and convalescing, wearing a head bandage and lucky to be alive.

What is it about blackthorn that makes it wound so grievously?

A look through my bookshelf did not turn up much useful information.

"A scratch from the thorns would cause blood poisoning. This was thought to be because Christ's crown of thorns was made from it".(1)

"Long associated with dark forces".(2) 

"Other tannin-rich barks were also used [for making inks] particularly those of blackthorn ...".(3)

A trawl through the WWW was more promising.

"On Tuesday evening I was scratched on the hand by a blackthorn, not deeply, but enough to draw blood. Fortunately, I know about blackthorn poisoning: it can be very unpleasant. A piece of blackthorn burying itself under the skin might cause severe infection, blood poisoning, swelling and pain. If left too long before treatment, amputation might be the result. Blackthorns are covered in unpleasant bacteria. If you have a piece buried in your flesh, the best course of action is to get yourself off to the hospital if you have a rapidly escalating and unpleasant reaction; don’t leave it until the area around the wound turns black. My light scratch was reacting badly to the blackthorn toxins within 5 minutes. I sprayed the area liberally with surgical spirits on my return home, which quickly reduced the angry redness and swelling. I woke in night with the swelling raging ... ".(4) 

A comment was appended to this blog post: "Our friend has just died from black thorn poisoning. Thought it was flu …".(5)

"Years ago I ignored a blackthorn wound. Within a week I had a red line running from the inside of my wrist to my elbow warning of the onset of sepsis".(6) 

"Blackthorn injury can give rise to a wide variety of manifestations ranging from mechanical dermatitis, cellulitis, abscess, foreign body granuloma, peritendinitis, tendinitis, pericapsulitis, synovitis to acute septic arthritis. Human synovial tissue is very prone to react to organic substances like blackthorns. Removal of the blackthorn fragments causes prompt resolution of the inflammation".(7)

It is clear that blackthorn wounds can be dangerous, particularly if remnants of thorn are left in the wound. I think D.'s injury was down to more than just a bad-luck thorn-prick.

"Why do [blackthorns] cause so much trouble? Clinical research undertaken at Oakham suggests that the painful tissue reaction to blackthorn injury is not caused by infection. In fact, contrary to popular belief among the equine veterinary community, the joint is sterile after a thorn penetration. The substances that make blackthorns black are alkaloids, and this thorn contains more alkaloids than other plants. Our research indicates it is this that causes the severe tissue reactions".(8)

The website 'Botanical Online' in its 'Blackthorn Toxicity' page states that the toxic principles of blackthorn are: prussic acid (seeds, bark, leaves); hydrogen cyanide (seeds); tannins. Anecdotal evidence from online discussion forums suggests that the blackthorn is particularly poisonous during the growing season.

So, I suggest that what makes a blackthorn wound so grievous is that the bark and thorns at this time of the year are exuding small quantities of plant toxins known as cyanogenic glycosides, notably hydrocyanic acid (HCN, aka prussic acid), "one of the most toxic of all plant compounds. ... The occurrence of cyanogenic glycosides is widespread. Amygdalin and prunasin are very common among plants of the Rosaceae, particularly the Prunus genus".(9) Oakham Veterinary Hospital is probably wrong about alkaloid poisoning: the blackness is caused by tannins, and the toxicity is caused by HCN. The presence of other pathogens such as bacteria from bird muck may play a secondary role, although I imagine most humans and other animals have a measure of immunity against them.

HCN has been tested as a chemical weapon to be absorbed through the skin. According to a Wikipedia, a concentration of 2000 ppm will kill a human in about one minute. "The toxicity is caused by the cyanide ion, which halts cellular respiration by acting as a non-competitive inhibitor for an enzyme in mitochondria called cytochrome c oxidase".  Basically, it kills cells. No wonder D. suffered toxic shock and now has a necrotic lesion on his head.

According to the University of Maryland, "All 400-plus Prunus species are toxic to livestock. ... The most commonly recognized species are the stone fruits: cherries, peaches, plums, almonds, apricots, and nectarines. All parts of the plant are toxic except the mature fruits. ... Hydrogen cyanide acts as a poison by preventing red blood cells from releasing oxygen".(10)

I think I now understand how D. came to be so badly affected by a single puncture wound. Fragments of thorn are likely to have released HCN which led to localised cell death, followed by toxic shock from sepsis and a dermal necrosis. His immune system struggled to cope with the chemical arsenal of Prunus spinosa, and also probably the effects of some bacteria and algal detritus.

I think it would be worth somebody researching more about HCN in blackthorn For instance, I'd like to know whether it is the live or dead thorns that do the most damage. The results would be worth publicising for farmers, gardeners and any other outdoors people likely to encounter this baleful, though attractive and interesting, bush. 

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SOURCES

(1) - R. Vickery (ed.). 'Unlucky Plants - a folklore survey'. Folklore Society, 1985.
(2) - Tess Darwin. 'The Scots Herbal'. Mercat Press, 1996.
(3)  - Richard Mabey. 'Plants with a Purpose'. Collins, 1977.
(4)  - Michael Griffiths. 'Blackthorn Poisoning. A warning'. The Wilden Marsh Blog, 3-12-2015.
(5) - Ibid, comment from 'Debra', April 17, 2018.
(6) - John Shelley. 'Nature. A Thorny Issue'. The Mayo News, 1 April, 2014.
(7) - H Sharma & AD Meredith: 'Blackthorn injury: a report of three interesting cases'. Emergency Medical Journal, vol.21, no.3, April 2004.
(8) - Oakham Veterinary Hospital, online: 'Blackthorn injury in hunters / sport horses'.
(9) - Andrew Pengelly. 'The Constituents of Medicinal Plants'. Allen & Unwin, 2009; pp.44-45.
(10) - Sara BhaduriHauck. 'Toxic Plant Profile: Prunus Species'. University of Maryland Extension, 3-8-2015.

All online sources accessed April 2020.

Text and pictures © TD Holt-Wilson, April 4th 2020.

Islay

4th June 2018

I'm back from staying with my uncle on the Isle of Islay. This is the most southerly large island of the Inner Hebrides. It looks northwards to Colonsay, eastwards to Jura, southwards to Ulster and westwards to nowhere - or rather into the vastness of the Atlantic Ocean and beyond, to the chilly coast of Labrador. For better or worse, its climate and weather are intimately connected with the ocean.

A misty, eventide view looking south from Ben Cladville, with Donegal in the distance

Spacious Islay - open to the elements. It's a marked contrast to my cramped Suffolk homeland, with its woods, hedged fields and clustered villages. Houses on Islay are white-painted and built of stone and slate; they are strung in rows through 19th century settlement towns such as Bowmore and Port Charlotte, or scattered in farmsteads with strange, hybrid Gaelic, Norse and English names. Many of them have fine views over rough pastureland or boggy moorland, greenish-grey, brown and dotted with rocky outcrops and boulders, and a backdrop of mountains. Many of them have fine views over the sea, which is never far away with its stormy grey or shades of passionate blue and green. The inlets of Loch Indaal and Loch Gruinart almost divide the island in two.

View across Loch Indaal towards the distant Paps of Jura.</ font>

My uncle lives in the Rinns of Islay, a broad peninsula ten miles long at the south-western end of the island. The family farm is perched on a south-facing hillside with spectacular panoramic views to Portnahaven and a scattering of islets. The place is buffeted by wind and rain for many months of the year. The land includes over half a mile of sea cliffs, with caves, precipices and a natural arch, and even a prehistoric dun (promontory fort) and a cleit (burial mound). There are choughs and ravens, peregrines and curlews, stonechats and skylarks. Starlings bubble and squeak from the chimney pots. Sparrows and siskins jostle for space at the bird table.

View over Cladville and the south-western tip of the Rinns.

Rinns rock

The Rinns is founded on very ancient bedrock: gneiss dated to about 1.8 billion years old (by way of comparison the Earth is 4.6 billion years old). Chemical analysis tells us the gneiss originated in the roots of a volcanic mountain range[1], perhaps 20 miles down. Tectonic processes over eons of time have since brought it to the surface. The rocks of the Rinns Complex, as it is called, lie all round Cladville and Portnahaven in the form of the pinkish-coloured gneiss and a greenish-grey amphibolite. The one looks rather like frozen sausage meat; the other like frozen salt and pepper. Both are very hard, and were created through metamorphism of the deep crustal rocks syenite and gabbro respectively. 

A boulder of syenitic gneiss
with a quartz vein and lichen, Claddach

Sea-smoothed gabbroic amphibolite, Lossit

These rocks are the oldest thing I have ever contemplated. They originated in the late Palaeoproterozoic Era of the Precambrian Supereon. They are thought to have formed deep within a volcanic arc where the crust of the Columbia Supercontinent was being subducted.  Today - risen from the depths - they form the cliffs and underlie the boggy moorland of the Rinns.

These rocks push my understanding into a new dimension: they take me as far back in time as I can go in British geology. The only life-forms on Earth then were bacteria and algae.[2] They belong to a world dominated by physical processes in which micro-organisms had a precarious foothold. Today, 1.8 billion years later, the same natural processes continue but micro-organisms are everywhere, forming the foundations for the pyramid of complex life which surrounds me, and of which I am a tiny part. Apparently I may well have more micro-organisms inside me than there are cells in my body.[3] Elements of the Palaeoproterozoic world survive, and not just on Islay.


Snowball Earth

A week ago today I took a bus trip up to Port Askaig, crossing the island diagonally. On the way, I stopped at the Islay Natural History Trust centre in Port Charlotte, where there are displays about geology as well as wildlife. It was an opportunity to get a better overview of local Earth history. Among the specimens on display were samples of the Port Askaig tillite.

Tillite from Port an t-Seilich, near Port Askaig.

Seen here, the specimen has a grey, sandy mudstone matrix containing pebbles of granite. The mudstone is a lithified example of glacial till (hence 'tillite') deposited in very shallow sea water, with its matrix derived from the erosion of shales and granites[4]. The pebbles dropped into it either from melting ice floes or - more likely - melt-out from the grounded base of a wasting ice sheet.[5]

The tillite is exposed along the coast at Port Askaig and also in the road cutting next to the ferry terminal. On arrival, I knew only had two hours before my bus returned so decided to focus on the cutting, which has recently been extended. I soon found examples of granite and other pebbles embedded in mudstone.

A granite pebble in mudstone matrix.

This tillite has a special place in geology. It was first recognised as a glacial rock formation as far back as the 1870s, and attributed to the early Cambrian.[6] Where does it fit in the geological timescale today? It is classified lithostratigraphically as part of the Islay Subgroup within the Dalradian Supergroup, and deposited during the Cryogenian Period of the Neoproterozoic Era of the Precambrian. Evidence from remnant magnetism and carbonate chemistry in these rocks suggests that Britain lay close to the Equator at this time, however the fact that we have clear evidence for glaciation at this very low latitude has suggested that the Earth may have undergone periods of very extensive ice cover. This has given rise to the 'Snowball Earth' concept, which envisaged prolonged periods in the Neoproterozoic when the Earth was frozen as far south as the Equator. The Port Askaig tillite is most likely attributable to the Sturtian Glaciation, part of which has recently been dated to 716.5 million years ago.[7]. Back in Victorian times, Thomson speculated about the origin of the granite clasts. He found he couldn't relate their mineralogy to any extant granites in Scotland:

‘If ... we compare the embedded boulders of granite with the granites found in situ throughout the Highlands, we feel the necessity of tracing them to another source, and hope we do not overstep the bounds of prudent speculation in suggesting that those erratics are the reassorted materials of some great Northern Continent that has yielded to the ceaseless gnawing tooth of time, leaving scattered fragments as wreckage of its former greatness, and that the material of which the mass is composed have in time, deeper than we have hitherto suspected, been transported by the agency of ice.’

We now know that the mudstone matrix was derived from some now-vanished source rocks somewhere south-east of Islay.[4] The granites may well have been derived from rocks related to the syenites of the Rinns Complex, probably an eroding part of the 'igneous province' of tectonically mobile crust which then spanned Scandinavia, Greenland and north-west Canada as part of the Neoproterozoic Rodinia Supercontinent.[8] I touch my hat to Thomson for his scientific insight.

Image courtesy Fitches et al, 1996.

An ice age legacy

Jumping forward 716,250,000 years in time, Islay was covered with ice at the height of the last cold glacial period, the Devensian Stage of the late Pleistocene.  The limits of the ice sheet are thought to have lain many miles to westward at this time.

Devensian ice limits about 23,000 years ago.
Image courtesy Clark et al, 2012, fig.18.

The Devensian, and presumably earlier glaciations, have left traces everywhere on Islay. There is ice-scratched and -scoured bedrock and other glacially-sculpted topography; there are eskers and moraines, sub-glacial meltwater channels; layers of till and outwash gravel. The general direction of ice flow was towards the Atlantic. The till is unevenly distributed, and underlies the most fertile parts of Islay. My cousin William has noticed that his best farmland lies to the south-west side of Ben Cladville, and speculates that the till was deposited more thickly in the lee of the hill as the ice flowed over it. This seems very plausible to me.

Cnoc Bhi Bhuirn, a glacially-sculpted rocky knoll in the classic shape of
a roche moutonée, The direction of ice flow was from the right (north-east).
Ben Cladville is in the far distance.

A glacially-scoured outcrop of gneiss bedrock, with accentuated jointing.  

An erratic boulder of dolerite in glacial till at Claddach.
Dolerite is found on Islay as intrusive igneous dykes of early Tertiary age.

A distinctive ridge of glacial moraine (the 'Blackrock Moraine') at the head of Loch Indaal.
It is thought to have developed in a retreat phase of the last ice sheet.[10]

Another legacy of the last ice age is a suite of raised beaches on Islay. They were formed at a time when the land was depressed by its overburden of ice, but were raised up as the land rebounded after the ice sheets melted and retreated. These are well displayed as a series of planed surfaces in the coastal landscape around Portnahaven.

Raised beaches on two levels at Orsay island, Portnahaven:
c.+ 15 m OD near the lighthouse and c.+10 m OD at St Oran's Chapel (right).

A raised beach at c. +15 m OD behind the houses at Portnahaven.
(Snoozing grey seals in the foreground.)

Coastal deposits on a raised beach at Portnahaven, at the +10 m OD level.

After the ice

The ice sheets have retreated, but seemingly only just. The blanket of meadowland, bog and heather can scarcely cover the the bare bones of the recently glaciated landscape. I say recently, but the ice sheets vanished from Islay between 16,000 and 17,000 years ago.[9]

There is a pass called Bealach Froige on the north side of Ben Cladville. It looks like a glacial overspill channel through which meltwater once flowed westwards. It has a gently sloping long profile and a level, boggy floor which terminates abruptly in a steep declivity, breaking down to a narrow, rocky inlet called Port Froige. The level floor may be the remnant of a raised beach or - more likely - a moraine-dammed lake, as there appears to be a bar of glacial till defining the steep break of slope and marking the still-stand of a small retreating lobe of ice. 

Bealach Froige, a likely glacial meltwater channel - view looking west.

Reddish-brown till exposed at the seaward lip of Bealach Froige

In the 1980s the valley's sediments were cored to a depth of 7.5 metres and analysed for fossil pollen. The results have provided information about the environmental history of Islay in the early post-glacial period.[11]

Far from being the treeless moorland we see in the Rinns today, the pollen record shows that the Cladville area was once forested with birch, Scots pine, elm, oak, alder, hazel and willow. The Bealach Froige profile is undated, but comparison with dated profiles from nearby Loch a' Bhogaidh suggests the expansion of forest took place about 9,000 years ago.[11] There is oak and hazel woodland elsewhere in sheltered parts of Islay, no doubt directly descended from the first colonising trees.

Oak woodland at Kildalton in south-east Islay.

The earliest evidence of human life on Islay after the ice sheets retreated is flint tools of the Ahrensburgian industry, product of late glacial and early post-glacial horse and reindeer hunters. Ahrensburgian-type chipped stone tools have been found beneath Mesolithic layers at Port an t-Seilich.[12] The excavators speculated as to whether these people may have been seal hunters.

The Mesolithic site of Bolsay Farm, close to Loch a' Bhogaidh, has yielded large quantities of microlithic flintwork,[12] and is dated to about 7,930 years BP. David has found a single worked flint flake on his cliff top, so perhaps there is a prehistoric campsite under the peat close by. It could be Mesolithic or equally Neolithic, as there is evidence of Neolithic activity at Loch a' Bhogaidh in the form of stone tools and pollen profiles that indicate forest clearance.[13]

For peat's sake

Peat is found everywhere where there is poorly-drained land on Islay. Initially formed over wet patches and hollows, it spread and coalesced to form a blanket over areas of level moorland. Dead plant debris marinades in a deoxygenated stew of its own decay, becomes compacted, turns into layers of peat. It has been forming across Islay for millennia, but received a boost 4,000 years ago in the early Bronze Age when the climate became wetter and forest clearance was well advanced.[13]

I first came to Islay in the summer of 1968, and remember seeing drying stacks of peat dotted across the landscape near Porthahaven. It was a picturesque sight. Today, fifty years on, very few people continue the practice; David tells me that the struggle to cut the stuff, dry it and cart it away are now beyond most people's patience and endurance. The trenches near Portnahaven are now healing over. Elsewhere, it seems the only large-scale peat cutting still carried out on Islay is destined for the whisky distilleries. They rely on peat smoke to lend its distinctive aroma to the drying barley used in the malting process. The barley itself was originally grown on local areas of loamy soil, though today most of it is imported.

Vegetated former peat cutting scars near Claddach, Portnahaven.

Some small-scale peat cutting near Airigh Sgallaidh, north-east of Ben Cladville.

Peat cutting at Duich Lots. Perhaps the peat is going to one of the nearby distilleries 
at Ardbeg, Bowmore, Lagavulin, Laphroaig or Port Ellen.

As compacted plant remains, peat contains the layered history of the successive plant communities of which it was formed. Its twigs, leaves and pollen are an immediate archive of plant history in the landscape. The deepest peat contains the longest archive. Yes - this means that peat on the fire is part of an ancient landscape library going up in smoke.

But we needn't worry too much, as each volume - each shelf even - is pretty much the same for a given patch of landscape: small variations on a theme in a repetitive music score; a few changed words in otherwise identical paragraphs. Only when we have research questions to answer, as at Bealach Froige and Loch a' Bhogaidh, is it worth the time and trouble to play the score or decipher the text.

Life goes on, oblivious, over and within the Holocene peat bogs of Islay. They hum with insects of all kinds, from infuriating midges to serene damselflies; from gadding cleggs to bumbling bees. Bacterial and fungal action as ever carries out its dark alchemy. Cotton grass flurries in the Atlantic wind which almost constantly buffets the island. Sphagnum moss absorbs water, swells and dies; provides nutrients for its neighbours and descendants. Sundews clasp flies and draw them down into dissolving liquors.

Out on a bog near Airigh Sgallaidh a cuckoo calls incessantly from the echoing walls of a forestry plantation. Palaeoproterozoic rocks continue their unimaginably long journey to becoming grains of sand. It is a Monday morning, and everything has its special place in the world's story.

Blanket bog on Islay, springtime. 

Variations on a theme of peat.

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REFERENCES

1. Muir, RJ. The Precambrian Basement and Related Rocks of the Southern Inner Hebrides, Scotland. PhD thesis, University of Wales, Aberystwyth, 1990.
2. Conway Morris, S.. The Early Evolution of Life. In: Brown, GC, Hawkesworth, CJ & Wilson, RCL (eds). Understanding the Earth. Cambridge University Press, 1992.
3. Sender, R, Fuchs, S, & Milo, R. Revised estimates for the number of human and bacteria cells in the body. PLoS Biol 14(8), 2016. Online at https://doi.org/10.1371/journal.pbio.1002533. [Accessed June 2018]
4. Panahi, A & Young, GM. A geochemical investigation into the provenance of the Neoproterozoic Port Askaig Tillite, Dalradian Supergroup, western Scotland. Precambrian Research, Vol.85 (1–2), 1997.
5. Spencer, AM. Late Pre-Cambrian glaciation in Scotland. Geological Society of London Memoir, no. 6, 1971.
6. Thomson, J. On the stratified rocks of Islay. Report of the 41st Meeting of the British Association for the Advancement of Science, Edinburgh, John Murray, London, 1871.
7. Macdonald, FA et al. Calibrating the Cryogenian. Science, 327 (5970), 2010.
8. Fitches, WR et al. Provenance of late Proterozoic Dalradian tillite clasts, Inner Hebrides, Scotland. In: In: Brewer, TS (ed.) (1996). Precambrian Crustal Evolution in the North Atlantic Region. Geological Society Special Publication No. 112, 1996. 
9. Clark, CD et al. Pattern and timing of retreat of the last British-Irish Ice Sheet. Quaternary Science Reviews Vol. 44, 2012.
10. Peacock, JD. Late Devensian palaeoenvironmental changes in the sea area adjacent to Islay, SW Scotland: implications for the deglacial history of the island. Scottish Journal of Geology, 44, 2008.
11. Edwards, K. Vegetation History of the Southern Inner Hebrides during the Mesolithic Period. In Mithen, S (ed). Hunter-gatherer Landscape Archaeology: The Southern Hebrides Mesolithic Project 1988-1998. McDonald Institute, Cambridge, 2000.
12. Mithen, S, Finlayson, B, Finlay, N & Lake, M. Excavations at Bolsay Farm, a Mesolithic Settlement on Islay. Cambridge Archaeological Journal, no. 2, 1992. 
13. Edwards. KJ & Berridge, JMA. The Late-Quaternary vegetational history of Loch a'Bhogaidh, Rinns of Islay SSSI, Scotland. New Phytologist, no.128, 1994.

ACKNOWLEDGEMENTS

• To William for interesting local details, and to David and Morven for making it all possible.

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A Red Crag whale

A fossil whale vertebra can be a beautiful thing. I was delighted when a friend gave me one he'd found on Landguard beach, near Felixstowe, south-east Suffolk.

The front (anterior) side of the specimen still has its flat articular surface, but the back (posterior) side has been worn away by the sea. There are two projections on either side. These are the eroded bases of the bony projections supporting the neural arch.

Thoracic vertebrae of Greenland right whale, showing
centrum and bones of the neural arch.
Image courtesy Eschricht & Reinhardt (1866)

Given its findspot, a Red Crag origin for the specimen is likely. It must have been washed out of the Red Crag strata which outcrop in the Felixstowe area. The town is founded on these reddish-yellow, sandy, fossiliferous sediments of Pliocene age about 2.5 million years old. They also outcrop to the north at Bawdsey and to the south at Walton-on-the-Naze, Essex.

My first exposure to whale fossils was when I was working on the geological collections at Ipswich Museum in 2004/05. There were racks and boxes full of Crag specimens like this, but very few of them had any firm identification. Spencer (1970) recounts everything known about the Crag cetaceans in Ipswich Museum.


I contacted the Natural History Museum in London to see whether I could find out more. Dr Travis Park, a fossil cetacean specialist, gave helpful replies to my questions.

It is a partial thoracic vertebra from either a small baleen whale or a big toothed whale... it's likely [to be] either an anterior or mid-thoracic. ... 

In terms of size, it’s probably closer to something in the 5-10 metre range. That’s a very rough estimate given the degree of wear of the specimen. So it could be a small sperm whale or one of the beaked whales which easily get that size and even bigger. If it’s a baleen whale then a minke whale would be a good proxy although there was quite possibly other small baleen whale lineages around at that time too. 

It's unfortunate that the specimen is so worn as to make it impossible to narrow down to Order level (mysticete or odontocete), let alone Family. Still, it's an attractive thing to have on my shelf, and it prompts me to find out more about the cetaceans of our beautiful 'Blue Planet' as they were in the Pliocene.

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References

• Eschricht, DF & Reinhardt, J. 'On the Greenland Right Whale Balaena Mysticetus. In: Flower, WH (ed). Recent Memoirs of the Cetacea. Ray Society, London, 1866.
• Spencer, HEP (1970). A Contribution to the Geological History of Suffolk. Part 5. The Early Pleistocene. The Crag Epochs and their Mammals. Transactions of the Suffolk Naturalists’ Society, vol.15, pt. 4.

For further information about the geology of the Suffolk coast see my booklet 'Tides of Change' (2015).

Land gulls

Two 80-acre fields at Cookley, near Halesworth, with winter wheat

(shades of yellowish green, blueish green)

on clayland, undulating, empty - just the crop, the soil, the flint.

Setting for a cold wind.

January the last.

Beyond me in space: white gulls.

Gulls in flight, over the field's face, roving. A few standing, breasting the sun.

White owls over a green sea.

A skylark sings, aloft. 

The gulls think downward. Raised on ocean-space and sprats, they turn to terrestrial matters: beetles and worms. 

All beneath a milky, blue and infinite sky.

They flutter to and fro: staring, stopping, turning to drop and rise - a mere second or two. Focused then refocusing. Steady meditation. Body thinking. Time.

How many are there – forty or fifty? 

But who watches gulls - those dustbins of the bird world!?

One could map their delicate trajectories: a script of white on green. Their nodes and lines, objectified. 

Instead, each bird enters my vision, enters my thoughts. 

In this moment each one enters my heart.

Their wavering flights criss-cross my sight in a ceaseless, white-winged ballet. 

They catch the sun, like dew on wheat and roof-lines in distant villages. 

Land gulls.