November 2017

So I’ve been feeling a little stuck. I go out in the dark with a headlamp. It’s really dark. I grew up in Galloway Forest, apparently one of only four Dark Sky Parks in the western world. I know dark. I walk away from the house. I follow the gravel path, past the pond with its sleeping geese. I cross the little footbridge, with its shiny, treacherous planking. I tramp onto the road and round the corner. The house disappears. I switch my headlamp off. It’s so quiet. I can hear the snails in the hedge. I walk, by body memory more than sight. Things take longer in the dark. I squelch left, avoid the thorny thicket, cross an invisible threshold. My boots are really sticking to the earth now. Great clods of clay meeting synthetic fabric. Heavy. I think: sticking is resistance. Heavier still where the rain has pooled in the mud. I switch on my headtorch.

(click on image to view gif)

It is only at night, that marl appears to glitters with such brilliance: a sharp, shock of blue against muddy seams of topsoil and brown clay. In daytime, broad and flat light, marl appears more as a silvery, glinting grey. But torchlight is a different kind of illumination – it revels in the fragmentary and the fractal – offering only a partial grasp on what lurks in the dark.

For the philosopher Michel Serres, in his essay ‘Information and Thinking’, the light of the cave begets a different kind of thought, than that which is produced in the light of day. He cites a passage in Jules Verne’s 1884 novel, The Vanished Diamond:

“Dazzled with the light after so long a darkness … [the two heroes] thought at first they were the prey of some ecstatic illusion, so splendid and unexpected was the sight that greeted their eyes. They were in the centre of an immense grotto. The ground was covered with fine sand bespangled with gold. The vault was as high as that of a Gothic cathedral, and stretched away out of sight into the distant darkness. The walls were covered with stalactites of varied hue and wondrous richness, and from them the light of the torches was reflected, flashing back with all the colors of the rainbow, with the glow of a furnace fire and the wealth of the aurora.”

Verne’s cave is proposed by Serres to be the opposite of Plato’s cave. Plato’s allegory of the cave seeks to show that human perception and knowledge gained through the senses is illusory. Real knowledge must be gained through philosophical reasoning: ‘truth’ therefore is attained by those who leave the darkness of the cave. Vernes’ cave, however, is not a place of obscurity or hallucination: it is the site of the most brilliant light and colour. It is here, in the reflective light of the torch that another way of knowing might emerge.

Michel Serres writes:

“Philosophy loves light and has turned it into the model of excellent knowledge, especially the splash of daytime sunshine. Sparkling with truth, light is supposed to chase away the darkness of obscurantism. […] In fact, thinking is
much less like the day than like the night, where every star shines like a diamond, where every galaxy flows like a river of pearls, where every planet, like a mirror, reflects the light it receives. Thus authentic knowledge overflows
with results and intuitions; it sets up multiple reference points grouped into constellations with forms that are as disparate as those of scholarly disciplines.”

Perhaps the view from the headlamp and the condition of near-darkness, a discovery in the black unknown – is fitting for an investigation of marl.

Over the centuries, as excavated marl holes pockmarked the landscape, often abandoned when they filled with water, folklore and rumour produced dark tales out of their artificial and mysterious topography.

The Irish National Folklore Collection includes a tale of the Largan Ghost, a haunting of a house in County Cavan. Recorded in 1937, and referring to an incident 80 years prior, the story goes:

“The occupants of the house could never get butter off any churning. One night all the strong men gathered to the house to churn. They closed all the air spaces in the house even the key-hole. They started to churn. After some time a clóca [cloak] crept over the floor and under the churn; they then fainted one by one, and the door had to be opened, and they abandoned the work. They then sent for Father John Murray who was C.C. in Drumkilly at the time. He settled the ghost in the “Marl hole” between the froth and the water. Ever afterwards there is light seen at the marl hole.”

The spectre is exorcised from the house and confined to the marl pit – not in the water or bound to the clay, but somewhere inbetween. There, the phantom is contained, but free to generate its own luminescence. The tale, passed down generations into myth, presumably acted as a deterrent, warning against against straying too close to the treacherous pool.

Other tales tell of “marl holes with no bottom“, pits haunted by a banshee (or “bow”), and what became known as “the murdering hole”, after a community took shelter in a marl pit but failed to escape detection from invading Danes.

What these folk histories reveal is the diffraction of knowledge through different bodies over time, in which some stories stick and others slip away. Diffraction is also about light: it is the diffusion and interruption of a light beam. In a way, it might describe the light of a torch, shone into a gleaming, glittering substance, which reflects, differentially, back at the viewer.

For the philosopher Karen Barad, drawing on quantum physics, diffraction means more than this – the torch and the torchbearer are quite literally in the picture. She writes:

“Diffraction is an ethico-onto-epistemological matter. We are not merely differently situated in the world. ‘Each of us’ is part of the intra-active ongoing articulation of the world in its differential mattering.”

Looking at marl – whether by torchlight, through the microscope or shimmering in the light of day – can never be a passive or ‘objective’ observation. It is to glance into a dark mirror, in which human histories of extraction, capital and conquest are reflected, reshaped and retold.


Marl, in the height of its use in agriculture, was commonly described as a treatment for ‘exhausted soil’. It was not therefore recommended as a general accelerant or helpful addition to healthy, fertile land. It was rather, applied in times of desperation, when the soil, overused and depleted, was becoming less and less productive.

In the eighteenth century, soil fertility was a critical issue across Europe. From 1660-1750, agricultural practices underwent significant changes. New species of vegetable, many drawn from the newly “discovered” Americas, were introduced to Britain. Clover and turnips were two of these alien crops, grown as fodder for wintering farm animals. This practice had an accelerating feedback effect: as more animals could be kept, more dung was produced. Dung was used to manure the land, and thus produce more fodder crops. Along with the increasing irrigation techniques and the formation of water meadows, this led to the output of the soil and the use of land gradually increasing and intensifying.

As a result of this accelerated exploitation of agricultural land, the depletion of soil become a chief concern of the growing capitalist societies of Europe (a concern only matched by that with the loss of forests, urban pollution and overpopulation). Governments, early scientists and enterprising landowners hunted for potential fertilisers everywhere: resulting in transnational endeavours such as the guano trade, phosphorus mining and even (as recounted to me in a wonderful anecdote from RDS librarian Gerard Whelan) the powdering of mummified Egyptian cats to be sprinkled on English soil!

Marl could be found much closer to home, and unsurprisingly, features in many accounts of methods of soil improvement. The rural economist John Wynn Baker published a series of Experiments in Agriculture for the Dublin Royal Society, in which he tried and – to some extent – trialled dozens of potential soil improvers. In the 1764 report, he wrote:

“The Experiment with the Shell Marle, proves that to be a very high, and excellent Manure, for, as it will produce Turneps upon poor Ground, it may be safely relied upon for any other Crop.”

Soil depletion was such a fundamental issue that it inspired Karl Marx’s metabolic rift, a theory developed to understand the emergence of capitalism as ecological crisis. In Capital, vol.1, Marx writes:

“Capitalist production collects the population together in great centres, and causes the urban population to achieve an ever-growing preponderance. This has two results. On the one hand it concentrates the historical motive force of society; on the other hand, it disturbs the metabolic interaction between man and the earth, i.e. it prevents the return to the soil of its constituent elements consumed by man in the form of food and clothing; hence it hinders the operation of the eternal natural condition for the lasting fertility of the soil.

Marx then connects the exploitation of workers with the exploitation of the earth:

All progress in capitalist agriculture is a progress in the art, not only of robbing the worker, but of robbing the soil; all progress in increasing the fertility of the soil for a given time is a progress toward ruining the more long-lasting sources of that fertility. Capitalist production, therefore, only develops the techniques and the degree of combination of the social process of production by simultaneously undermining the original sources of all wealth—the soil and the worker.”

The invention of artificial fertilisers (as by-products of research developing chemical warfare) in the twentieth century somewhat sated the appetite of agriculture, vastly increasing the yield of farming globally. Two German chemists, Fritz Haber and Carl Bosch, devised a way to transform nitrogen in the air into fertiliser: what they described as: “Brot aus Luft” or “Bread from air”. Despite this monicker, the process of generating nitrogen fertiliser requires vast amounts of natural gas and coal, and even today, accounts for more than 50% of total energy use in commercial agriculture, as well as being a significant pollutant in itself.

Moreover, synthetic fertilisers have not solved the problem of overproduction and exhausted earth. Scientists noted in 2015 that soil erosion and nutrient depletion was the biggest threat to global food security and a contributor to climate change, as carbon once sequestered in soil is gradually released into the atmosphere.  Alternatives to dominant modes of food production have always existed – and waxed and waned in popularity – but it is the drive for consistent growth and productivity that continues to take precedence (and investment) over other ‘slower’ and more labour-intensive ways of growing.

In her article ‘Making time for soil’, feminist scholar Maria Puig de la Bellacasa argues that rethinking our relationship to soil away from “productionism” requires recalibration towards temporalities of care and labour. She suggests:

“[T]he time of soil is not ‘one’; it exposes multifarious speeds of growth becoming ecologically significant to each other. To argue for a disruption of futuristic time through making care time is therefore not so much about a slowing or redirection of timelines but an invitation to rearrange and rebalance the relations between a diversity of coexisting temporalities that inhabit the worlds of soil and other interdependent ecologies.”

In the time of marl’s popularity in Ireland, it was championed by colonial administrators and landowners, keen to turn a quick profit. Over decades, with marling widespread, farmers began to see the real fruit of their labour. The forcing of the land into perpetual productivity eventually depleted the soil beyond easy repair. It gave rise to the peasant proverb: “Marl makes rich fathers and poor sons.”

I opened an exhibition last year with a looping gif displayed on a small screen. It showed a second or so of the processing of marl as clay: a lump of marl is repeatedly turned by hand in water. In the animation, marl becomes a blue-grey planet rotating in a translucent bath, turning without tiring: it is the fantasy of capitalist acceleration, that the earth might beget its rewards interminably. But as the human history of marl teaches us, this was always, already, a disintegrating delusion.