A Handful of Stones By John S Watson
A Handful of Stones Essays on the the Scottish Landscape
By John S Watson
Cir Mhor on Arran - The Rosa Pinnacle
Hutton's Arran
In my palm, I roll around three small stones taken from the waters. One is a blue schist pebble, slightly chipped, another a perfect egg of sandstone conglomerate and the last a pink and white granite sphere. When I force my brain onto the rack of geological time, exploding it out into a thousand ‘civilizations’ or so (my attempt at imagining a million years), then multiply this by, say, 50, I just about get an idea of each stone’s provenance. I feel I am rolling around three small planets in untouchable orbits; three lost worlds of breathtaking shape and form; elegant worlds which have been crushed, eroded and rolled into one another and, briefly, given this current page of our pop-up book of time: there you go, this is your planet for now. Turn the page another million years and another world pops up. Stones are border guards of the unknown, of secretive territories; they are bureaucratic knots in our understanding of deep time. The island of Arran is one place where this understanding began. I am visiting some of James Hutton’s field sites for his Theory of the Earth which he collated in the last decades of the 18th century. Today, stepping out of the Arran bus, doors popping with a pressurised swish, is effectively a step into a geological library; specifically, into a heavily annotated text that is North Glen Sannox. The bus heaves off in dusty billlows of diesel fumes, leaving me in a world of rock and water and fragile skylark song. I wander the hotbed of 18th century geology which is exampled in this Scottish burn. There is a long wait between geological buses and here you can see their arrivals, departures and brief traffic jams. I marvel at the slow sculptures of water and rock, the vertigo of the unconformity between clashing geologies. I love the aura of rock, its vibrant meditative state, its philosophical resistance. ‘All is lithogenesis,’ as MacDiarmid pondered, wandering a pebble beach and astounding himself with
Granite erratics on Old Red Sandstone
rolled marbles of words and time. Without my own three, small pebbles, I would be unable to imagine my world, it wouldn’t exist. These three geologies, separated by about 500 million years (500,000 ‘civilizations’, as it were) inform my understanding of what a patient universe we inhabit, how impatient our reasoning, and how vastly inadequate our imagination. On the geological map, Arran is a distorted dartboard with a swollen, red bulls-eye: the Arran batholith. This rock is young, geologically speaking, around 60 million years, and part of the ‘recent’ Tertiary volcanic period (geology insists on inverting commas). This spired cirque of impressive granite peaks is surrounded by slim, flattened beds of older geologies, such as the old red sandstones of the Carboniferous era, which sweated out an equatorial period between 360 and 280 million years ago; or older-still ‘Moine’ rocks of schist which formed in the Caledonian Orogeny - a folding of continents that created the Highlands on a fulcrum of 520 million years ago, now they are just the worn stumps of a once-grand mountain range. The higher granite peaks of Arran are the youngest rocks, around 60 million years old. One can walk the rim of this giant ‘batholith’ of granite, tracing the edge of its existence and touching the ragged remnants of its time exposed to the elements. A batholith is a dome of igneous rock, a solid body of ‘plutons’ of depth-cystallised magma, large extrusions of granite eventually escaping the crust like rocky hernias. There are some giant batholiths on the planet, the most famous being the Yosemite domes, themselves small, plutonic pimples in the grandiloquent swathe of the Sierra Nevada. This one is closer to home in Scotland, an hour’s ferry journey from the anthill of Glasgow. In the summer of 1787, a curious Edinburgh geologist was roaming Arran, seeking evidence for a theory much closer to the physics of the real world than the anthropocentric scales of pre-enlightenment philosophy. Hutton meandered
Intrusive igneous granite veins
on horseback from Brodick to Lochranza, watering his horse at various burns along the way, seeking proof of his tehories in the rocks. He was in a dispute with a Freiberg geologist called Abraham Gottlob Werner, who had proposed that the rocks of the world were simple watery precipitates and nothing but crushed layers of soil laid down one upon another in recent times (the theory called ‘Neptunism’). To Hutton’s Plutonic convictions, this seemed simplistic and unrepresentative of the deeper, hotter complexities of the earth’s processes. Hutton was sure, somewhere in his homeland, there were markers, or traces of a fire-borne geology. Werner's watery tale of crytallised origins came crashing down in some simple, deductive reasoning that seems clear on hindsight but took a distinct mind to make the first leap of intuition through some astute and minute readings of a Scottish landscape. Hutton's case for a volcanic driving force meant he was looking for evidence that older rocks – what he termed 'alpine schistus' – would show deformation by heat or intrusion by molten rocks. His horse may have looked up momentarily at his sudden sparks of enlightenment in North Glen Sannox and Newton Point. Here he found where geologies met and understood that there were serious implications in the unconformity between the rocks; such as twisted injections of intruded, once molten, rock in sedimentary beds; or simple, field examples of two rocks exposed their incompatibility in terms of continuous formation. They often exhibited violently different habitats of time. It was not only on Arran that he hunted down these ‘unconformities’, which stressed the visible abysses in time between rock layers rather than a timeline of continual deposition. The schist and granite unconformity in North Glen Sannox, together with the Carboniferous/Cambrian unconformity at Newton Point, speak of two geologies separated by hundreds of millions of years. Indeed in 1888, with his companion John Playfair, he found the most dramatic example of this dislocation at Siccar Point in Berwickshire. Here,
Arran - the granite batholith tors
Silurian greywacke layers (425 million years old) show signs of having been baked and lithified in the bowels of the earth, uplifted, eroded, tilted on end by tectonic collisions, before being covered, much later in the geological spin cycle, by a horizontal layer of Devonian sandstones, which were themselves water-borne erosional deposits from a continent existing around 345 million years ago. To intuit the depth of time needed for this process, without modern-day laboratory dating, made the perspicacious geologists giddy with excitement, so much so the findings were published and presented to the newly formed Royal Society of Edinburgh in 1788. John Playfair wrote of the event:
On us who saw these phenomenon for the first time the impression will not easily be forgotten. . . . we felt necessarily carried back to a time when the schistus on which we stood was yet at the bottom of the sea, and when the sandstone before us was only beginning to be deposited, in the shape of sand or mud, from the waters of the supercontinent ocean... the mind seemed to grow giddy by looking so far back into the abyss of time; and whilst we listened with earnestness and admiration to the philosopher who was now unfolding to us the order and series of these wonderful events, we became sensible how much further reason may sometimes go than imagination may venture to follow. Back on Arran, I continue my walk up Coire nan Ceum, hiking through boulder clusters to the serrated granite ridge of Caisteal Abhail. On Arran, granite is predominant to the eye, but treacherous to reason. It is in fact the youngest rock rather than, as one might assume, the basal tray of time. The full Arran cirque is visible from the summit – four or five corries pinched into the vaguely circular scalp of the batholith. Wandering the wind-sculpted granite ridges and tors, marvelling at the scooped corries of the ice ages, meandering amongst the spires and plated armour of the crags, a crystal emptiness of mind
North Glen Sannox unconformity site
is attained, the present becomes time-lapsed and it is tempting to lose all thought in awe and flow. But the geology is never far from question and the batholith’s gravity pulls at my reasoning. My puzzled attempts at scale erode my understanding, my towers of complacency come tumbling down. I sit down for a rest, for some sustenance, some cool draughts of mountain water. The burns run over my bare feet, the raven barks, mineral flakes turn in the stream’s eddies and settle, and I dream of knowing. The batholith remains, unknowable. Time, at whatever pace it chooses, or knows, moves on.