DESERT TIME -- A JOURNEY THROUGH THE AMERICAN SOUTHWEST
Chapter 32: tree line
We are ten thousand feet up on the Utah-Nevada border, at tree line, and here they are.
After we've stood awhile breathing, watching them, it occurs to me that we are waiting for them to move. To continue to move. They look caught in mid-gyre; reaching, clasping, flowing, splitting, leaping. They whirl, they clench, they point to the sky in liquid attenuations.
They are very big. Their colors are as vivid as costumes: ochre and russet, and brushed silver, and a green so bright it looks false. They are bristlecone pines. Some of them have not moved in thousands of years, since the seeds that carried their embryos rattled down between the stones.
Unless you count growth and death as movement. This one is more than three thousand years old and still growing, still reproducing, still dying. It is in motion in place, one frame of a time-lapse.
The bristlecones live in a desert of quartzite stones that have the glistening sterility of freshly dynamited marble. It is the moraine of a mountain glacier. Some of the stones are the size of automobiles, others the size of chairs. They look bulldozed and dumped, which is more or less the truth.
Even the small trees are old. A bristlecone the size of a Christmas tree (the firs that take a dozen years maybe to grow to harvest for the trade) will be older than the American Constitution. It has passed its bicentennial, and is young.
The mountain glacier is old, and is the godparent of the bristlecones, the founding father. It's still here; the only glacier left of the old swarm. It has shrunk to a lens of dirty white against the more than eighteen-hundred-foot headwall, in a quartzite amphitheater that was quarried again and again in colder, wetter times by larger, more unsettled rumps of ice. Glacial cirque: humongous sag in an armchair of stone. The bristlecones live on the lip of this chair.
We move on, up, into the amphitheater in the mountain peak. We climb over naked talus and drifts of old snow. A few limber pine and Englemann spruce grow here, pruned and broomsticked, with skirts of wind timber. The sun is hot and clean.
Alpine desert. Water here is snow or ice most of the time: in other words, not water at all. The sun has no mercy in the white stones. The wind shears leaves, branches, bark, blows what would make soil away. dries our snow-wet boots in minutes.
Here in the rock rubble there are patches of arctic-alpine tundra. A currant bush twines between stones where the wind can't go; it has long coppery thorns and furry leaves, defense against the light. There are swatches of mosslike foliage with full-sized flowers, true dwarfs: a purple milk vetch, a white phlox, a daisylike composite. Farther on there are more snowdrifts and a steep lip of stones, and we are on the glacier.
The ice here is under the stones, the stones are a kind of carapace. From the air this looks like a tongue of rubble; it's called a rock glacier. We hear melt-water underneath, running through holes. We've left the tundra behind. Here there are only lichens.
We lie down for a rest, pillowing our heads on packs, and around us the cirque is like a citadel of stacked metamorphic layers. The sun is like a blanket on our legs. Around us there are battlements, towers, ruined buttresses. Wheeler Peak is Cambrian quartzite, five hundred and fifty million years old, brittle, fractured by the uplift of the Snake Range, crazed with northeast-southwest-trending joints. It made easy meat for ice.
There are streaks of snow all down the cirque's flanks and dust-wrinkled drifts, and under the headwall -- facing northeast where it gets most shelter from midsummer sun -- a bigger drift. In summer a crack appears between big drift and wall, a bergschrund, all of seventy-five feet deep. Looking down, we see the light in this crevasse is the jewel-like blue of years-compacted snow. Snowline -- orographic snowline -- is the size of a room, where more snow falls each year than melts. Unmelted snow stacks up there and the weight of it settles the whole a little, every year, like a person leaning back in a chair. All glacial movement is a species of settling, grinding rock forward under the rump.
Sixty-five million years ago during what's called the "Tahoe Glaciation" (mountain glaciers being a species different from that of continental ice-sheets, their seasons have different names) the Wheeler ice went down as low as eighty-three hundred feet, along Baker Creek, down to eighty-six hundred on Lehman Creek. That's as far as it ever went. Then it retreated. Between thirty-five and thirteen thousand years ago it went to the valleys again, out of its cirque and down the creekbeds, fattened by heavier snows and defended by deeper cold. It retreated again, leaving rubble and scars. Ten thousand years ago and again within the last five thousand, glitches in weather fattened the ice and sent the rock tongues moving down. Within the last century there's been a half-degree centigrade rise in mean annual temperature, and that's enough, the "glacieret" is dying from lack of food, the rock tongues are stilled, pitted with melt pools. Stilled long enough, a few centuries, a few thousand years, the alpine desert dwarfs will colonize the cracks between these stones, too.
Between this alpine desert above and the Great Basin desert below, there is forest. Mule deer live in the forest, and coyotes, squirrels, raccoons, the Clark's nutcrackers that gather bristlecone pine seed and bury it in clutches. Pinyon and juniper trees grow lowest of all, then ponderosas, then white fir and Douglas fir, drier slopes of mountain mahogany, cool patches of aspen, then Englemann spruce and limber pine, and highest and loneliest of all, at timberline, the Great Basin bristlecones.
They are some of the oldest living things in the world. They have been known to live for more than four thousand years. Below and out of sight where even the junipers fade down into coppery haze, the Great Basin desert lies between its ranges like a sea. Scattered brittle shrubs: sagebrush, winterfat, shadscale, horsebush, a few grasses, gravel and dust. We are glad to be out of that and into this. We've come to an island world, ice desert in desert air, filled with light and stone and the clean breath of snow, the kind of place where bristlecones can live.
Nevada Fleabane and Wheeler Peak: The tiny and the immense are what one sees; there is not much in between. Notice how distinct the tree line of Wheeler Peak is from this distance, and how the dark zone of evergreen forest lies between tundra above and desert below. Foothills wear a scattered forest of junipers and pinyons and sage. There are no rivers. On the summit where we stand there is only broken gravel and these little purple flowers.