In December time tumbles downhill, like a rushing creek, towards Christmas, whereupon it slows and spreads wide like a meandering river flowing towards the silt-depositing delta of January. That’s when the detritus of the hectic preceding year finally settles, where a new year starts to be built on rich alluvial sediments. This brief and tumultuous annual cycle is a speck in geological time. Walking with a geologist changed my view of time, my sense of place. Learning to recognise signs of the slow processes of geology brought unexpected surprises.
My friend, Heather, is a geologist from Seattle, in the northwest corner of the USA. She teaches geology to night classes, after her day job as a hydro-geologist. On a recent visit to Castlemaine, Victoria, Heather taught me some basic geology, taught me to see where I live more deeply.
A stroll through the streets and surrounding forests of Castlemaine in Central Victoria, and a ramble along the Lerderderg River, near Bacchus Marsh, opened my eyes to how we can observe the earth’s crust from anywhere, anytime, and see its effects on human existence. We are standing on it. These were slow walks back into deep time, glimpsing the subtle changes to the environment at the whim of geological forces. We were talking about something very old, things happening at an imperceptibly slow pace. Heather called it geological time. Thinking in these terms, everything in the present moment seems to slow down.
Some may remember school geology lessons, sadly made boring by dusty rock samples with no context and tired science teachers. Heather found simple logical ways to explain things. She brought in human interaction with geology. For example when she spoke about sedimentary rocks, particularly coquina which is a rock made of sea shells cemented together, she mentioned the Spaniards who found and quarried it in Florida, the only stone available, and built the fort, Castillo de San Marcos, in St. Augustine in the 1600s which still stands today. I looked at the worn slate and sandstone blocks that form the steps to the Castlemaine Market Building and imagined their underwater origins, the millennia of sedimentation and pressure that formed them and the extraordinary uplifts and folding that brought the stone to the surface, then much later to be chipped into shape by masons’ tiny tools.
The anticlinal fold exposed on Lyttleton Street in Castlemaine attracts viewers from around the world. This tight fold of sandstone forms an arch, the now eroded top of a rainbow shape bulging from a core. The pressures that bend rocks into such beautiful shapes are humbling. Heather also pointed out the elongated hills and uplifted rocky ridges in the bush around Castlemaine, running predominantly north south, which are the tops and bottoms of the eroded folds. The bedrock was deposited about 450 million years ago, the igneous intrusions through the folded rocks occurred less than a million years later. These north-south ridges guided canny gold diggers to places where illusive gold-bearing, quartz saddle reefs emerged. The bush remains pock marked with mine-shafts and mullock heaps, reminders of the exploitation of the Victorian goldfields. Mapped onto paper, the patterns of the north-south ridges in the box ironbark forests of Central Victoria are like delicate scratchings, an artistic expression from the hand of geology.
Geologists use the same language world wide to describe different types of minerals, rocks and stone and the myriad of things that happen to them. Geological words are beautiful, said aloud. Try ‘minerals’, ‘igneous’, ‘metamorphic’ and ‘sedimentary’. Slowly try ‘anticlinal’, ‘uplift’. Heather used these words with affectionate familiarity; it was catchy. Then try the sharpness of quartz, a crystal harder than steel; then softer sounds of ‘schist’ and ‘shale’. The blub, splutter and power of the word ‘volcano’ evoke calamitous eruptions.
‘Uniformitarianism’ is an ungainly word with big impact. It means that the same processes we see preserved in rocks today, processes from millenniums past, are still going on in the same way this very moment. It ushered in the classical concept that ‘the present is the key to the past’. A quicksilver tingle in the back of my neck sharpened my view of the sandstone folds hugging the Lerderderg River. As we walked, the same processes were occurring as formed this rocky ledge eons ago. Ripples on a vertical wall of rock showed that water had once flowed over a horizontal sand bed here. These tidal ripples remained, pressured into a sandstone pattern of exhilarating beauty. Invisible things were happening in this stunning place. Water continued to lay down sediment in rippling patterns in slower moving sections of the creek, wind continued to erode, geothermal heat and pressure continued to act deep underground.
Reading rocks is about knowing minerals, their source, their story, how they came to be where they are. Heather sees the minerals and their surrounding events, actions, interactions, their friends and enemies. She gave attention to the tiniest detail of hand-held rock samples, peering at their composition through a small magnifying glass. Next she was scouring roadside cuttings for folding and vulcanizing, then reading distant horizons to see the larger designs of geological forces. She pointed out patterns that put the story together, made sense of time.
Mineral is such a lovely word. To a geologist a mineral will be naturally occurring, inorganic, solid, have its own chemical compositions and be internally consistent in its crystal form. Their worldly possibilities are all around me; the salt on my sandwich, the talc which beads on a shopkeeper’s nose, my Dad’s gold wedding ring, the iron in the neighbour’s corrugated fence.
My sense of place is deepened as I learn how it formed, why it exists in its current shapes. Knowing these things is a kind of intimacy with the land. Since Heather’s visit, I often keep a small pebble in my pocket and know that it is inscribed with the history of the universe. It may tell a story of coming from molten magma or perhaps a meteorite from outer space. The pebble may come from rocks that have been pressurized and heated for millions of years below the surface, and in their turn, under the forces of wind and water, eroded into sands or silts and perhaps eventually soils. These are carried by streams and winds on long journeys and may eventually sink to the bottom of lakes or the sea as sediment, where they settle and harden to again form rocks. When oceans recede and that rock is exposed once more to erosion, it crumbles into stones. Every stone will have its cyclical story. I become a part of the history of that pebble in my pocket. How I look at stones has now become part of who I am.
Walking with Heather meant understanding the environment at a deeper level, its past, present and future. It created a different way of thinking about time.
I breathe in deeply, savouring this infinitesimal short blink of a moment. If you don’t know a geologist, try simply to observe your landscape closely, let its secrets speak to you. In the rush towards Christmas I cradle the stone in my pocket, contemplating the story behind it, the geological story behind life. The rewards of a geological view of time and place are abundant and profound.