Tuesday, 14 July 2009

An Ascent of Mt La Perouse

Through a quirk in geology, the long ascent of Mt La Perouse begins atop one of Australia’s longest descents. Exit Cave worms its way 23km into the Ordovician limestone beneath these Southern Ranges. Lesser holes pepper the forest and unwary walkers in this wild area have disappeared without trace. But such chilling thoughts are soon distracted by the steepness of the uphill walk. It is all climb, through still, damp and overwhelmingly green forest. The hue is not just on the mossy forest floor or in the leaves but at every level, from roots to trunks to branches to fungi. There are fluorescent greens, sombre olives, glaucous blue-greens, lively gold-tinged greens and deep sea greens. The very air has a greenish tinge.

But thoughts of colour are unlikely to distract you for long from the relentless climb. There is nothing to do but hoist and haul yourself between, through, around and sometimes over the trees. After an hour, perhaps two, of sweat-raising effort you may sense a change in the air, and notice a change in the scale and type of trees. As you break out of forest and into a more open tea-tree and paperbark scrub, there are glimpses of the distant coast. The scent of decay-tinged damp is replaced by a sharper, cleaner air that somehow smells blue. After the shy light of the forest the sun here can be blindingly bright. If the day is calm – and sunny, calm conditions are not the norm here – you may find yourself sharing the air with a myriad flying insects: beetles, dragon flies, butterflies and a host of diptera. Most won’t trouble the walker, though march flies may show an interest in any exposed skin. As will leeches.

Although the scenery has changed, the incline of the track has not. And the more open going is countered by sections of deep mud that stand between here and the blandly named Hill 1. By the time you have trudged up to this bald, wind-battered eminence, you will have gained nearly 800m in altitude as well as a good thirst. While you take your break, the other bare hills of Moonlight Ridge are still ahead. By blunt logic these are named Hills 2, 3 and 4. But they are dwarfed by the majestic mountains that start to dominate the scene above: the Hippo, La Perouse, the Cockscomb.

Geological dramas from many eras have helped create the landscape around you. Even in (geologically) recent times – the last couple of million years – glaciers calving off Mt La Perouse and nearby peaks have dozed out deep valleys, gouged cirques, deposited morraines and left resistant rock standing above the fray. In the last several millennia, although the glaciers have gone, wind, water and ice have continued to chip away at the landscape. As you traverse Moonlight Ridge and close on Mt La Perouse itself, you climb through sedimentary rocks scraped almost clean by glaciers. First are the often softer Permian siltstones, then the more recent Triassic sandstones. Downvalley to your left Arndell Falls plunges from a cliff at the edge of a later dolerite intrusion. Although it’s tempting to leave the track here and head straight for the growing bulk of Mt La Perouse, the more oblique approach via the Pigsty Ponds is far easier. Just as you start to climb from these morraine-dammed lakes onto Maxwell Ridge, a cairned route to the left leads you up the long humped slope to the remarkably bare and flat-topped “peak” of Mt La Perouse.

The sandstone here was laid flat on a sandy plain, and despite all the ructions of the last 200 million years, remains remarkably flat to this day. If you were inclined to celebrate your ascent with a football game, the top of La Perouse would not look out of the question. But the winds that blast here most of the time, and prompted walkers to build a massive (and sheltering) summit cairn, would rule out most forms of football most days of the year. A quick and grateful look towards the indented coast; a peek over the edge towards the classic cirque lakes called Swallows Nest Lakes; an admiring photograph over the striking doleritic Cockscomb; a quick celebratory drink; these would be the best you could ask of La Perouse, even on a good day.
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