You sit on the beach and grasp a handful of sand. Peering closely, you focus on one tiny grain. It is small, white and smooth. Bringing it closer to the eye, you notice tiny worn ridges and grooves, with even smaller silty grains in between. It’s quite unremarkable, this miniscule grain with its infinitesimal debris. There must be a million million just like it that you have ignored. Yet you examine more closely. Soon you see the variations in colour, remnants of its glorious sovereign existence before being lost in the morass. You inspect the variation in form, the undulations in its structure. Fraction by fraction, this cubic millimetre of Earth reveals itself to you, and begins to tell you a story.
It is a very long story. It is an account no campfire could contain. Where it begins is only part of the tale; a part shrouded in the error bars of science, clumsily approximated by crude machines. To start at the finish is the only option on hand. How did it arrive at you feet? You look at the sea, the surf lapping at your feet; the sand in constant flux; insight creeps in, the dawn of new understanding. There are many grains twirling around. Some of those scratches and striations are now explained – it has been a rough ride for this crystal of quartz, knocked around by a thousand waves.
Looking further afield, you notice the froth of a longshore current, battered by the surf, interrupted by rips. There is movement there, and it comes along the beach. You and your grain of sand walk against the flow, constantly aware of the opposing flow only meters offshore. Suspended sand swirls in the breaking waves and the turbulent water heaves. As the surf gets choppier, you find yourself at an entrance where muddy water surges out into the deep. It is a river, and it is flowing. The water is not clear, clays and silts cloud the current and obscure the ripples of sand beneath. You look upstream; it stretches out into a vast estuary, the hills and the headwaters in the distance. You cannot follow this grain’s prior journey any further; already you are far from your car, far from the comfort of civilization. Whence did this miniature grain originate?
Having walked the length of the coast to the river, you have reversed perhaps the most recent decades of the grain’s history. The span of time reaches back far, far further than that. You have merely glimpsed a small episode on a diminutive stage. Were you to travel upstream, you would begin to grasp the forces at work. Look again at that grain. It is translucent in the light, a shimmering signal of its illustrious past. Underneath the craggy exterior lies a former glory.
Travelling upstream, you would find larger grains with the telltale reflectance of partially worn crystal faces. These are your grain’s younger cousins. Quartz is very tough; a great deal of abuse is required to wear down a noble crystal face. There would be other grains too, of different parentage. Feldspars, birefringent, coloured with earthen hues; flakes of mica, sparkling in the sunlight, flittering away in the flow. You have travelled back in time, seeing your grain in younger days, perhaps a thousand years ago.
Climbing the shores, boarding an all-terrain vehicle, you traverse the steep slopes of an increasingly incised valley. Returning to the bank, you see not sand, but pebbles, and boulders, huge, lumbering hunks of rock. Immovable for man, toys to the forces of nature. Focusing closely at a rounded stone, you are struck with the diversity. All the cast is there, but in varying states of disrepair. The feldspars are softening, the micas peeling off. But there, there like glass, is your quartz. Steadfast in adversity. Rubbing your finger over the specimen, crystals of quartz fall into your hand, splendid crystal faces twinkle in the rays. You are close to the source. Ten thousand years.
Gazing further up, you can see the granite dressed hills of the headwaters. You are drawn inexorably towards the majestic vista. Hiking boots on, you tramp up the slopes. Here, in the furthest reaches of this guiding stream, you find a large rock face. It shows its age, the skin peeling like an old onion. The crumbling face reveals beautiful perfection beneath. A batholith, older than the very hills it supports. Drilling in, you retrieve a core of sparkling granite. There, there in that smooth exposed surface, you see the players in their heyday, ready to act out the next scene, anticipating an audience. Yet there has been a pause. Time frozen in the act of crystallization. The quartz crystals are perfect, the feldspars lustrous pink, dark mafic minerals teasing for identification. You are at the chrono-crossroads, where time has stood still. This rock has been like this for six hundred million years, waiting unwearyingly for the next act. Pushed and heaved through the Earth, your grain’s distant cousins have remained firm, with only the slow decay of atoms for company.
Before even that ancient crystallizing moment, those grains had another story to tell. Granite to migmatite, migmatite to metamorphosis; metamorphosis to diagenesis, and then on to sedimentation before one day, on a beach, near a river … it is a story for another day. We have reached back some half a billion years, and yet there is another four billion to go. Cycle upon cycle, these minerals have seen it all. They will see it again. How privileged we are to comprehend the journey for but an imperceptible stretch of time.