Bingi rocks

Tags

aplite, basalt, Bingi Bingi Point, dacite, dykes, geology, wedding anniversary

Forty six years ago, about now, J and I were occupied with our wedding, a low key event with a small guest list and a reception at my parents’ home. He nipped out from work at lunchtime to buy a suit. On Monday when his workmates said “Hey J, what did you do at the weekend?” he said, “Well, as a matter of fact I got married.” 

What began that Friday night led, 46 years later, via four children, four grandchildren, a couple of other partners, and deep unassailable companionship, to a glorious summer day rock-hopping at Bingi Bingi Point, not far from our respective homes, to indulge a shared interest in geology. We’re off to visit younger rocks today, volcanic in origin: aplite, gabbro-diorite, tonalite, dacite and basalt. We’re armed with a couple of mappings of the area’s geology, and we’ve already visited under the guidance of a couple of local geologists so we’re feeling unusually confident.

But before we proceed to rocky analysis, we watch entranced as a couple of whales leap and slap and blow close inshore, just off Bingi Bingi Point, defying photography in the glaring path of the sun. Once they disappear heading south, we focus on rocks. I’m acquiring, at last, a nimbleness that allows me to step over mini-chasms and up and down layers of rock that would usually have me bumming it. Everywhere are rocks I recognise and scapes with wonderful aesthetics.

The place is crawling with dykes: the sombre black shine of basalt, the pinky-apricot of aplite, and the astonishing orange angularites of dacite.

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The dykes provide me with metaphors for our long relationship. It too was born out of molten passion and solidified into interweaving and intrusion. Who could have predicted that this …

… would lead to this?

Tentative postscript: A winding trail through the Penguin dictionary of geology suggests that we may actually have been standing on the earth’s mantle.

Eurobodalla beaches: Meringo and Congo North

Tags

basalt, Bingie Dreaming Track, Congo Beach north, cuttings, Meringo beach, silcrete, William Smith

William Smith, the English father of geology, mapped the underworld of the English landscape. His first interest in geology and the story it tells came as he descended slowly through the eons down a coal mine. His later mapping was made simple by the carving up of the landscape to build railways and canals; cuttings became a rich source of information. Following his example, our Sunday excursion began in a cutting documented in the notes for our November excursion with four geologists. There we found formations similar to the ones in the creek bed and cliffs at the southern end of Congo beach, confirming our diagnosis of basalt.

 

 

After scrutinising the cutting, we headed out to Meringo. Tides were all wrong this weekend, at least from my point of view, so I was keen to walk the length of high tide Meringo beach on a shady section of the Bingie dreaming track, behind overgrown and stabilised dunes. Huge bangalays overarched the sandy path, and we emerged at Meringo lagoon. It's one of a number of ICOLLs (intermittently opened and closed lakes and lagoons) on this part of the coast. It's currently closed by a sand bar, scattered with shallow pools left behind by the sea, and thick with shell-grit. We crossed it to reach the headland, where we again found formations like the ones in the creek on Congo beach.

 

 

We retraced yesterday's steps to the place of silcrete to photograph, and came across a flourish of purple which wasn't there yesterday. While Joe pursued silcrete, I crawled around trying to triumph over bright light, inadequate shadow, and the mysterious resistance of blue and purple to the camera. I collected a shell back tick for my trouble and plucked it off before it really got going in my shoulder. However, the photos were worth it: they've taken up residence in a separate post.

A black slither into the undergrowth beside the track was the first sighting of a snake, something we'd been expecting for the last two days.

 

 

We decided to picnic at Congo north and look at what we were convinced were sandstone cliffs. However, they startled us into incomprehension by having the same stone-wall appearance as the basalt at the south end of the beach.

 

 

We decided we'd been mystified enough for one day, and headed home, stopping three times: twice to indulge a newly-acquired interest in road cuttings and what they reveal, and once to photograph a road sign that unfurrowed our geologically tortured brows and made us smile.

 

 

 

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Eurobodalla beaches: Congo beach south

Tags

basalt, Bingie Dreaming Track, Congo Beach South, Meringo Lagoon, Purple donkey orchid: Diuris punctata

A very different walk this time, not along the beach but along a bush track above the ocean, at least to begin with. Geologically, we were in search of basalt, silcrete and sandstone.

 

 

 

Sometimes the track was close to the water. We dropped over the edge briefly, to what appeared to be our first sighting of sandstone. In this new geological world, we lack all certainty, unless we have a named photograph of that particular rock formation.

 

 

An echidna made its way across in front of us, snout seeking out ants. It decided we were neither ants nor very interesting and pushed itself into the bank, presenting its rear end with neatly arranged gold-tipped quills for our inspection.

 

 

We finally followed, for once, an easy track down to the beach. We began by exploring a dry creek bed. There we found strange formations of rocks arranged almost like a freestone wall. We puzzled over them until we saw one with a chunk out of it, leaving shiny smooth fine grained black: almost certainly basalt. We were far less certain about the crumbly lower levels, with rounded rocks poking out.

 

 

Then we walked along the beach to rocks normally covered but now revealed because the sand has been cut away dramatically by high seas. They were puzzling. Some were obviously basalt, chipped away to a smooth black edge. Others were pocked right through. One presumably rogue piece, an escapee from somewhere else, looked like layered marble – if not rogue, then completely mystifying.

 

 

The rock platform, backed by bush partially hiding similar formations to those in the creek, was black basalt, lava flow in the Middle Oligocene Age, 28 million years ago (if we've read our notes correctly.)

 

 

We left the beach, and came to a headland giving us a spectacular view down the coast beyond Meringo towards Mullimburra and Cathedral Rocks. J found what he was sure were odd pieces of silcrete, some of them possibly shaped by Aboriginal tool makers. At pretty well the same place we saw signs of colonial occupation: an old post and rail fence, meticulous in its rough craftsmanship. We followed it to our end point, Meringo Lagoon, without finding either absolute geological certainty or the silcrete quarry that lies somewhere along the dreaming track.

 

 

As we headed back along the track to the car I spotted the climax of a diverse walk: a tall elegant orchid, with perfect flowers and very long sepals, against the background of the sea: Diuris punctata or the purple donkey orchid.

 

 

 

I'm linking this post to Jo's Monday walks. If you enjoy rambles all over the world, join her and others who combine blogging and an active life here.

 

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