He crunched over the hoarfrost on the main flagged trail across the river of ice, and then wound downstream on the western bank, passing the little millefleur fellfields, coated with frost that was already beginning to melt in the light. He came to a place where the glacier dropped down a small escarpment, in a short crazed icefall; it also took a few degrees’ turn to the left, following its bordering ribs. Suddenly a loud creak filled the air, followed by a low-frequency boom that vibrated in his stomach. The ice was moving. He stopped, listening. He heard the distant bell-sound of an under-ice stream. He hiked on, feeling lighter and happier with every step. The morning light was very clear, the steam on the ice like white smoke.

And then, in the shelter of some huge boulders, he came upon an amphitheater of fellfield, dotted with flowers like flecks of paint; and at the bottom of the field was a little alpine meadow, south-facing and shockingly green, the mats of grass and sedge all cut with ice-coated watercourses. And around the edges of the amphitheater, sheltered in cracks and under rocks, hunched a number of dwarf trees.

It was krummholz, then, which in the evolution of mountain landscapes was the next stage after alpine meadows. The dwarf trees he had spotted were actually members of ordinary species, mostly white spruce, Picea glauca, which in these harsh conditions miniaturized on their own, contouring into the protected spaces they sprouted in. Or had been planted in, more likely. Sax saw some lodgepole pine, Pinus contorta, joining the more numerous white spruce. These were the most cold-tolerant trees on Earth, and apparently the Biotique team had added salt tolerance from trees like the tamarisks. All kinds of engineering had been done to aid them, and yet still the extreme conditions stunted their growth, until trees that might have grown thirty meters high crouched in little knee-high pockets of protection, sheered off by winds and winter snowpacks as if by hedge clippers. Thus the name krummholz, German for “crooked wood” or perhaps “elfin wood”— the zone where trees first managed to take advantage of the soil-building work of fellfields and alpine meadows. Treelimit.

Sax wandered slowly around the amphitheater, stepping on rocks, inspecting the mosses, the sedges, the grasses, and every single individual tree. The gnarly little things were twisted as if cultivated by deranged bonsai gardeners. “Oh how nice,” he said out loud more than once, inspecting a branch or a trunk, or a pattern of laminate bark, peeling away like phyllo dough. “Oh how nice. Oh for some moles. Some moles and voles, and marmots and minxes and foxes.”