Freycinet Experiences 2: Rambling Along the Rift

Geology isn’t sexy, or so we’ve been told. Yet show anyone a pure sand beach and a sapphire sea, and you’ve got them, whether or not they recognise the geology behind the appeal.

[Great Oyster Bay from Hazards Beach] 

Our second day on the Freycinet Peninsula doesn’t start like a geology excursion. But as we journey south by boat, I admit to pondering the origins of the great misshapen rectangle that is Great Oyster Bay. And I wonder too why we’re occasionally seeing dolerite. I think of this peninsula as dominated by granite. Why are two rocks of such different origins rubbing up against one another here?

There are more immediate questions first. Today we have a choice: to take the high road or the low road. The former climbs from the northern end of Cooks Beach over 579m Mt Graham, then winds back to Wineglass Bay. The latter starts south of Cooks Beach, and follows the western coastline of the peninsula to Hazards Beach. From there it’s over the low-level Isthmus Track to Wineglass Bay. Jodi and four others take the high road; Eric, Lynne and I take the low road. And yes, we’ll be in Wineglass ‘afore them!

[On the low road, with the high road in the background] 

The swell is rising as we drop the “high roaders” at the beach. There are some sand-churningly anxious moments before “Shep” extricates the boat from the beach. Minutes later he deposits us in a sea-weedy bay a bit further south, and we start our foot journey north.

Above us to the east are the wooded hills that rise to the granite peaks of Mts Freycinet and Graham. To our west are the dancing blue waters of Great Oyster Bay, and at our feet there’s dolerite – as well as questions that require a geological answer.

It turns out that today we’re walking the eastern rim of a graben. This is a kind of mini rift valley which has dropped relative to the higher blocks (horst) on either side. In the case of Great Oyster Bay, the graben has been inundated by the sea, which now separates one higher block (the Freycinet Peninsula) from another (the hills above Swansea). The rift was a late consequence of the long, complicated pulling apart of the super-continent of Gondwana. This began around 200 million years ago, and precipitated the injection of huge quantities of dolerite beneath what is now Tasmania. The graben probably formed closer to the period in which Tasmania finally tore away from Antarctica, around 65 million years ago.

[She-oak woodland, Freycinet Peninsula] 

As well as pulling blocks apart, these earth movements rotated and twisted the pre-existing rocks. Older granites, which had formed a huge sub-surface bubble around 400 million years ago, were brought to the surface here. The tearing apart also caught up some younger dolerite on the Freycinet side of the rift.

What remains today is a predominantly granite peninsula – albeit with dolerite and sedimentary remnants – separated from a predominantly dolerite eastern Tasmania.

If I seem to have strayed a little too far from white sands and blue seas, let me return to them. The beaches and the sea we’re walking beside simply wouldn’t be that colour without the slowly eroding pure quartz that’s derived from the granite. Other rock types usually contain fine-grained (ie muddy) elements. This granite has very few impurities to cloud the water, resulting in a rare, translucent clarity. And of course the beaches couldn’t be here without a graben deep enough to allow ocean inundation.

[Approaching Hazards Beach] 

Knowledge of these geological coincidences may not add to every walker’s enjoyment of this place, but it does enlarge my appreciation of a superb day in a rare landscape. So too does the fact that we can amble, knowing we have ample time to make our Wineglass Bay rendezvous with the other group. We pause for coffee, take way too many photographs, enjoy a swim (in my case a very brief one) and take the time to exchange bits of our life story. We also ponder millennia of Aboriginal presence along this coast as we come across some of the many shell middens that dot the area.

[An Aboriginal shell midden, Freycinet Peninsula] 

Despite our leisurely pace, we reach Wineglass in time for a long and restful lunch. After the almost deserted western side, the bay is very busy. Groups, couples, individuals spread out and take up their own little bit of this paradise.

[The "high roaders" return along Wineglass Bay] 

Lynne and I find a driftwood log in the sun, and settle down to wait for the “high roaders”. When they get back we gather ‘round each other like a happy pack of dogs, keen to share news of the day. But there’s rain forecast, and Gil and his bus are waiting for us back at the carpark, so Jodi gently urges us to talk while we walk. After a day like this, try to stop us!

 

[Just beating the rain back to the carpark] 

Kissing Granite

Green Pools near Denmark, Western Australia 

Wild spring winds are a regular part of living on Australia’s south island. Tasmania lies fair in the path of the roaring forties, that belt of constant winds which sailing vessels depended on for rapid movement around the globe from the 16^th to early 20^th centuries. In spring these winds grow in intensity, pinched between the still-cold southern waters and the warming continent.

But we are visiting Western Australia. It is much drier, older and lower in latitude than our island. Its southernmost point barely reaches 35 degrees south. We are not expecting wild winds.

Tell that to the wind! The day we walk in the Porongurup Range it is gusting to gale force. The range, a smoothed over jumble of granite, is only twelve kilometres long, two kilometres wide, and less than 700m high. As we crest the rise that leads towards Castle Rock, a prominent knuckle of bare granite, the wind tears through the trees, buffetting us constantly.

There’s one moment when it rips straight off the bald rock ahead of us, bringing an unmistakably familiar smell. I am slightly surprised to realise it’s the whiff of granite. I’d never considered that rocks might have their own scent, but this reminds me of wind off Mt Amos, or off any of the granitic rocks or mountains of Tasmania’s east coast.

Balancing Rock (I hope!), Porongurups, W.A. (photo Lynne Grant) 

The similarity between the granites of the west and those of Tasmania is geochemical rather than chronological. In this part of Western Australia the granites are derived from the ancient Yalgarn craton, a plateau formed from a vast molten bubble nearly three billion years old. It comfortably pre-dates the Australian continent. Tasmania’s Devonian granites, in contrast, are a measly 400 million years old.

But granite is granite, with quartz, feldspar and mica its main ingredients. And I suppose it’s that blend of earth materials, being micro-shorn by the gale, that I am smelling. Given that this part of the world has probably not been glaciated for millions of years – as opposed to Tasmania’s most recent glaciation just 10-12 000 years ago – it is wind, rain and wave action that have been the main agents of rock weathering.

They have done a spectacular job. The low range has no peaks to speak of, just rounded domes with the odd egg-shaped tor. And throughout much of the south-west of Western Australia the beaches, the soil, the predominence of sand, are in large part down to the erosion of granite. Even the “sand groper” moniker given to Western Australians is an outflow.

The next day we go to where the granite meets the sea, in Torndirrup National Park near Albany. If anything, the wind has intensified. It’s a “good” day to visit the Blow Holes, if good means being blown off your feet and covered in sea spray.

Wild weather at The Gap, Torndirrup NP, W.A. 

We arrive first at the Gap and the Natural Bridge, two granite formations resulting from the wild interactions of rock and Southern Ocean. As we reach the carpark, the wind rocks the car fiercely. Sea spray rises in great spumes, lashing the carpark in a salty deluge. We park as far from the spray as we can, eschew the short but inundated track to the Gap itself, and try to climb some boulders for a side-on view out of the spray. I want to film and photograph, but am literally knocked off my feet.

I’m forced to crawl to the top of a loaf-like knoll. I lie there waiting for a let-up, periodically poking my head into the firing line. As I hug close to the rough-skinned granite, the wind and spray are deafening. I could see it as a fine chance to converse with the rock. I might, for instance, ask why its pink and clear crystals are so large. It might tell me that they result from slow sub-surface cooling while it was forming. And why, I might continue, are you so flecked with black mica, and coated with rust and dust-coloured lichen? But then our conversation would probably be cut short by a lull, and I’d have to “go over the top” to start filming.

The Blowholes in action, Torndirrup National Park, W.A. 

At the Blow Holes the fierce winds and waves produce another wildly spectacular  show. At unpredictable intervals water is punched through holes in the shoreline granite sending fat fountains of spray skyward before the wind whooshes them inland, soaking unwary wave watchers.

Earlier in the week we’d visited altogether calmer waterways, with lichen-daubed granite slabs dipping gently down into shallow, sandy pools. And we’d spent peaceful days in a house built around, against and seemingly at total peace with granite. 

Karri kissing granite xx 

One ancient rock even allowed a karri tree to kiss it. Such are the many humours of granite.

Coasting

[a piece about a trip into the remote south-west of Tasmania]

Parts of Tasmania’s coast are almost grammatical in their punctuations, indents and bracketed views. It makes them hard for even the most literate sailor to read. Southwest Cape is one such place: a remote exclamation mark on a rugged coast, an outpost of granite standing abrupt at the bottom left corner of the state. It is the end of the south coast, and the start of the west coast; the two wildest parts of Tasmania joined at the one point; the alpha and omega of the south-west wilderness.

On foot, reaching it is no simple task. From Melaleuca or Cox Bight - the nearest you will get even by light aircraft - it is still two days of ruggedly beautiful undulations away. All the while you are walking towards Tasmania's weather quarter; preparing to beard the lion in his den. When there's rain nowhere else, the far south-west still has it. "Showers in the far south-west; fine elsewhere."

My first view of the Cape had been from the nearby Ironbound Range some years before. While light clouds scudded over that range, they gathered dark and drear around the Cape. On that occasion I was glad not to be headed there. This time, by some perverse choice, it is my destination. There will be no “elsewhere".

The relatively bare granite of the promontory covers only its last kilometre or so. The rest of the way is barred by scrub. There is only a thin pad to mark the way, and that easily lost in the rain and mist. The arrow-shaped promontory slants south-west towards Antarctica, the narrower the further you go, until it tapers to nothing. The seas pounding this coast have not touched land since South America. They mean to be noticed.

Around our campsite, only salt-tolerant plants will grow because of the insistent salt-laden winds. Though we are at least 100 metres above sea level, a few days without rain has turned the creek water brackish, naturally polluted by the salt winds. The water flavours all our cooking, and is barely drinkable. It is strange to feel such thirst in a place so shaped by water.

There are other thirsts that can be more easily satisfied here, though. Unless you're a sailor, seeing an Australian sunset over the sea is largely the privilege of Western Australians. But the geography of this place allows me to share this wonder.

and every day you gaze upon the sunset
with such love and intensity
it's almost...it's almost as if
if you could only crack the code
then you'd finally understand what this all means. *

We recline on the rough-grained, rounded granite slabs, awaiting that marvellous plunge of sun into sea. The suck and surge of waves speaks the language of patience. The sea has no need for haste - but it will wear down this battlement.

The next day is windy - that at least was predictable, here in the path of the “Roaring Forties”. More surprisingly, it is also fine. We've planned to go to the very end of the cape, but discover that our rope is too short to allow a descent to that last rock. Instead we sit back for a while to watch, listen, feel this special place.

After a time the wind brings odd sounds with it. At first I dismiss it as the sucking sound of waves beneath the rocks. But then I see its source. There on the rocks, about 50 metres diagonally below us, is a haul-out of seals. They are probably New Zealand fur seals - glad to be out of the surging Southern Ocean for a while - lolling about in the lee of the cape.

We watch for an hour or more - far more fascinating to me than climbing. We even begin, with the aid of binoculars, to discern some of the personalities of the group. There's an old and intolerant bull, which bellows at any pups disturbing his sunny reverie. The pups are the embodiment of hyperactivity, chasing and nipping each other, practising with sinuous ease their aquatic skills in and out of the wash and swash of the shore.

All previous human generations would have seen these seals with different eyes. Watching would have been only for the purpose of ensuring greater surprise at the attack. There are different ways of seeing wildlife, but these days it is harder to justify or understand the exploitative ways.

* from Jane Siberry’s song “Calling All Angels”