Mount Lofty summit

Go up to the railed platform on top of Mount Lofty, a little over seven hundred metres above the sea and some fifteen kilometres east of the city, and you are not so much admiring a view as reading a diagram.

Most of the roughly 350,000 people a year who make the climb come for the skyline — the grey-green quilt of the suburbs running out to the bright thread of Gulf St Vincent, with Yorke Peninsula and, if the day is generous, Kangaroo Island lying low on the horizon beyond.

Look at it as a naturalist instead and the same view turns into a cross-section, the whole gulf-to-range transect laid out below you at a glance: salt water, plain, range front, summit forest, all stacked in the order they occur on the ground.

It helps that Mount Lofty has been a reference point for exactly this reading since the country was first charted from outside.

Matthew Flinders picked out the summit from the deck of the Investigator in 1802, fixing it as the landmark peak of “the ridge of mountains” running north behind the gulf, and the name has anchored the map ever since (Flinders 1814).

It is, despite its name, a modest peak — the high point of only the southern Mount Lofty Ranges, not the whole chain, an honour that belongs to Mount Bryan, well to the north and considerably taller.

What earns Mount Lofty the climb is its position, not its height: a single platform from which almost the entire argument of this book can be taken in at once.

Everything below has arranged itself according to one changing ration of rain.

The dry plains at the mountain’s foot make do with a few hundred millimetres a year; force the same sea winds up the range front and they cool, wring themselves out, and hand the high ranges something like twice that total, one of the widest rainfall swings you can drive across in twenty minutes anywhere in the country (Gill 2014).

That is also why the forest around the lookout — stringybark and messmate, with tree ferns crowding the damp gullies below — counts among the plants and birds of one of Australia’s fifteen national biodiversity hotspots: a cool, wet island held up against a drying continent by nothing more than altitude (Gill 2014).

There is a twist worth carrying back down the hill.

The ranges do not just catch the rain, they steal it, so the country over the crest, in the immediate lee of this summit, is thrown into a rain shadow and tips straight back down into mallee — meaning the wettest ground on the whole transect is this high middle, not the far end of it, and the gradient is less a ramp than a lopsided arch.

None of it would exist to be read at all without the slow violence underneath it: this block of ranges has been shoved up along active faults for millions of years, rising faster than even the toughest summit rock can be worn back down, which is the patient, ongoing reason there is a mountain here to climb in the first place (Quigley 2010).