This was gold-mining country. As they followed the trail upwards, past sloping fields of dried grass, they came at last through groves of widespreading oaks, under which the sunlight winked in heliographic spangles, and out into a raw landscape of canyons and ridges that had been laid bare by hydraulic mining. There was nothing but wind, glare, and silence. All around, the ochre soil had been sluiced away from the foothills by thousands of gallons of high-pressure water, until the rocks were exposed like the jagged teeth of an old-time pioneer, and the bones of the Sierras showed through.

Alongside the trail, for mile after mile, wooden flumes carried fast water down out of the mountains to the mines below, leaving the silted bed of the American River, which appeared and reappeared below them at turn after turn in the trail, as a winding yellow ribbon of mud. It was this mud that was seeping westwards into the Sacramento River, and down into San Francisco Bay, staining the water and polluting the oyster beds. ‘There used to be trout in that river,’ Theodore remarked. ‘These days, I wouldn’t give a catfish any chances.’

Collis squinted out over whole fields that were nothing but picked-over boulders, shimmering with winter sunlight. He saw abandoned arroyos, with derelict mining huts and collapsed flumes that still spouted cascades of white water. And for hour after hour, there was nothing but hollows and spines of rock that had been scratched at and scraped at until every fragment of loose topsoil had been worried free. There were hillsides that had been blasted with huge charges of powder, twelve or fifteen hundred kegs, until they collapsed and could be washed over with nozzles for the tiniest specks of gold.

Collis felt as if he were travelling across the surface of some desolate prehistoric world, with only the grating of the buckboard’s wheels and the hot low whistle of the wind to disturb the silence. Up above them, red-tailed hawks turned and turned in the blatant sky.

But they were making their way up into the mountain now, and the mining valleys were more deeply clefted. The steep sides of the road were bristling with Shasta firs, mountain hemlock, and pines. It grew cooler, and more fragrant, and through the dark trunks of the trees they could make out the peaks of the High Sierras, as white as sugared almonds.

The mining communities through which they drove were generally no more than a cluster of makeshift cabins, a general store, and a cookhouse-cum-saloon. Bearded men in dusty hats watched them pass. Sometimes they called ‘How d’you do?’ but more often they stayed silent.