from America From the Air
Mt. Rainier rises to 14,411 feet of elevation. On four different sides, its slopes drop more than two vertical miles to valleys nestling at its feet ten miles away. (Sea level, for that matter, is just 42 miles away.) It’s the most impressive mountain in the lower 48 states. Definitely. If our word for it or your own eyes don’t convince you, it’s the runaway winner according to two mathematical measures—”prominence” and “spire measure“—for rating impressive mountains. Mt. Shasta is more massive and about as high, but Rainier’s beetling, crevassed glaciers make it appear higher, and over time they’ve made it steeper in reality, as well. It is the most heavily glaciered mountain in the lower 48. Its lodge, Paradise, received over a thousand inches of snow in a single winter. (A U.S. record at the time, it was subsequently bested by Mt Baker, the second volcano northward in the Cascade chain.)
In an average year, around ten thousand people set out to climb Rainier—several hundred on a favorable day. A little more than half reach the top. On some routes, all it will take you is a professional guide, excellent fitness, and good luck with the weather. The “easy route” takes two days, gaining about 5,000 feet the first day, then gaining 4,000′ and descending 9,000′ on the second; a handful of übermensch types have sweated it out in one day. Most years, a few climbers die, and many are rescued.
Another superlative often heard is “most dangerous mountain in the U.S.” That’s not about climbing accidents, it’s about a volcano. The Cascades, a subduction-related arc running from northern California to southwestern British Columbia, include a dozen volcanoes bearing evidence of activity within the last 10,000 years. What makes Rainier more dangerous than the rest is the sheer mass of ice on its slopes, and the number of people living on what might be called its floodplain.
In the past 10,000 years, Mt. Rainier generated at least sixty lahars (la-HARs, an Indonesian word for mudflows). These consist of rock—mainly as fine particles such as volcanic ash—mixed with water to a consistency and color resembling wet concrete. They flow down river valleys at speeds in the range of 15 to 100 miles per hour, picking up boulders, cars, and anything else along the way. When lahars stop flowing, they set up like concrete, making rescue of buried victims impossible.
Entire ridges and slopes high on the mountain consist of lahar ready-mix just a little too dry or too frozen to have slid down the mountain . . . yet. Many kinds of events can trigger lahars. Rising magma within the mountain can melt ice and cause a lahar. Eruptions of ash, mixing with melting glaciers can form a lahar. Rising magma can bulge the mountain’s flank outward until it collapses, sending rock into the valleys to mix with rivers and form a lahar.
Those triggers involve volcanic activity, which offers advance warning via the network of seismographs and GPS sensors set up for this purpose. Alternatively, lahars can start without any volcanic activity. This happens because the mountain’s lava flows are locally subjected to acidic hot watery fluids percolating out from its interior, turning rock very gradually into clay. At some point, perhaps after a lot of rain or a hot afternoon, it gives way without warning.
Hotter, flashier kinds of eruptions will also come sooner or later; potential hazards include lava flows or pyroclastic clouds. Even in the event that hot lava, ash, or gases trigger them, lahars pose the greater danger to the Seattle and Tacoma metro areas, where more than 150,000 people live on top of old Mt. Rainier lahars—the best available indicators of where future lahars may go.
Mt. Rainier is a composite volcano, built by eruptions of lava flows and pyroclastic debris over a period of about half a million years. The current summit, a crater about a quarter-mile across, is likely less than two thousand years old. It erupted small volumes of pumice several times between 1820 and 1894.
Dangers notwithstanding, Washingtonians experience Mt. Rainier first and foremost as a glorious talismanic Northwest presence. Flights in and out of SEA are usually well below cruising altitude when they pass the mountain, enhancing your view. North-south flights in good weather display a whole sequence of snow-laden volcanoes, a line of celestial guardians.
My Friend the Hover Fly
from Roughing It In the Twenty-first Century (unpublished MS)
Hold that swat!
You just felt an insect alight on your arm or leg. You look, you see a yellowjacket . . .
Hold that swat, it’s time to make friends.
Yellowjacket wasps are interested in your food or your sweet drink, but rarely in your skin unless they are stinging you. If this one hasn’t stung yet, it probably is not a wasp at all but a hover fly, a friendly stingless insect which mimics the appearance of a bee or a wasp in order to ward off predators.
Take a close look: are the two dark antennae stubby and short, much smaller than the eyes (hover fly) or are they long, slender, and turned down (bee or wasp)? Is there a short, foot-like dark proboscis stepping around on your skin? That’s the hover fly’s tongue lapping up salty sweat. Eee-eww, gross! Well, think of it as washing you. Your tasty salts are what attracted it to you in the first place.
When Gabriel first made friends with a hover fly, he named it Fred. Every time a similar fly came around lapping at his skin, it was his friend Fred back for another visit. Miles away, or a year later, Fred! I’ve been missing you!
As for those long, down-turned yellowjacket antennae, look to see if this insect’s front legs are darker than the other four. If you’re lucky, you may see the fly flap its wings, raise its two front legs and wave them around. It’s making them look like wasp antennae—using behavior to strengthen anatomical mimicry.
Hover flies are a large family of flies comprising some 6,000 species. A majority of the species have black-and-yellow-banded abdomens to mimic this or that well-armed member of the bee-and-wasp order. The bands may be white rather than yellow, and they range from simple (in half-inch-long Syrphus ribesii) to ornate enough to adorn a lyre (on quarter-inch Toxomerus geminatus). Many species have a thorax that shines like polished brass or gold; many have enormous maroon or red eyes. On males the two eyes are plastered to each other on the top of the head; on females, a narrow but distinct forehead separates them. Either way, these bug eyes cover most of the head.
So, do they do more to earn our friendship than just look pretty, slurp on us, and refuse to pack heat?
Absolutely. They rank high among our allies that benefit plants. Most hover fly adults feed on pollen and nectar, making their family second only to the bees as pollinators. Many hover fly larvae feed primarily on aphids, insects that commonly erupt into life-sapping infestations on plants.
Seeking sweat and replicating bees, hover flies are often called “sweat bees”—but there is a family of actual bees that warrant that name. Ironically, those real sweat bees resemble honeybees less than hover flies do, typically being black or green without conspicuous color bands. (They may sting if partially crushed, but their sting is weak unless you are severely allergic.) In length, sweat bees are typically 1/4 to 3/8 inch, hover flies 1/4 to 5/8 inch, and yellowjackets 1/2 to 3/4 inch; other wasps and bees range widely in size.
A good alternate name for hover flies is “flower flies.” Some entomologists campaign for “flower” to prevail over “hover.” I think they want to to raise the family’s “favorables” in the public eye—a noble effort, but needless. Many kinds of insects pollinate flowers, but very few can match a hover fly’s hovering skills. Bumble bees hover a bit, sashaying from side to side as they descend upon a blossom, but male hover flies spend minutes at a time hovering perfectly. They are the insects you often see maintaining a fixed position in a beam of light along a forest trail.
Watch for the fly to zoom abruptly off to the side, then immediately resume the same spot it held before. This is a male hover fly defending aerial territory where a female may show up, ready to mate. When he darted off, he was chasing a rival away. (Or was that the rival male that won the confrontation and took over the mid-air post? If you can tell which one of them came back, your eyeball muscles must twitch faster than mine.)
A position in a beam of light can be maintained longer than one in the shade because the fly absorbs heat from the sunbeam, supplanting calories he would otherwise burn to maintain an optimum body temperature for efficient hovering; this allows him more minutes before he has to leave in search of the next nectar snack. Scientists have calculated the precise caloric benefit of the sunbeam and judged it sufficient to explain the fly’s preference for sunbeams. They have not, as far as I know, determined whether sweat-slurping hover flies are males shopping for nuptial gifts, as is the case with butterflies sipping from mud, or “puddling.”
Recycling For Bird Brains
from Rocky Mountain Natural History
To the long list of amazing weight-saving adaptations in birds, studies of chickadees add the ability to grow new brain cells. You may have heard that you lose brain cells throughout adulthood (especially when you overindulge) and never grow new ones. Not true. The discovery of newly formed neurons in chickadees foreshadowed a similar find in humans. In both species, the new cells are in the hippocampus, a part of the brain involved with learning and memory.
Chickadees were found to grow new neurons in the hippocampus in a big burst each fall, when they store seeds in thousands of crevices they will have to find again through winter. An even bigger hippocampal growth spurt hits juveniles when they disperse from their natal territory, and have to learn the ins and outs of the environs they will inhabit for the rest of their lives. But their number of hippocampal cells does not grow through life, as it does in small mammals. One hypothesis is that each hippocampal neuron can store only one memory, and birds resorb and replace neurons whose memories are no longer needed. In a tiny flying animal, a brain big enough for a lifetime of memories might never get off the ground.
Very small birds actually have far more of their body mass in the form of brains, as a percentage, than we do. The fact that natural selection produced big brains here demonstrates that brainpower is critical to survival and reproduction in tiny food-storing birds, as it carries a Neiman Marcus price tag in energetic terms. Brains burn energy far more intensively than other types of tissue. Phenomenal ability to remember exact locations evolved convergently in several unrelated species, all of which lead lives that put those powers to good use—perhaps in caching food, or often in long-distance migration. Some of them have nonmigratory close relatives whose powers of memory don’t amount to diddly squat.
Some kinds of memories are apparently worth holding onto: male warblers recognize the song of each neighbor male. As long as each singer is known to the other, and stays on his own territory, both are spared a fight. They remember each other’s songs from year to year, as they return from Central America and reclaim their old haunts in the Rockies.
[reference: Barnea, A., and F. Nottebohm. 1996. Recruitment and replacement of hippocampal neurons in… chickadees. PNAS 93: 714-718.]
Some Virtues of Silence
One September night I camped on a creekless patch of plateau a little above timberline. I cleaned my dishes as the light dwindled, made tea from melted snow, and sipped. A sliver moon shone somewhere far away, but not here. Ten stars became five hundred, then fifty thousand.
I stood a while longer, not thinking about much, getting cold, listening. The loudest sound was the ringing in my ears, the ringing that’s always there but so quiet that everyday noise buries it. The second loudest sound was a shifting hiss of all the small cascades and waterfalls coming down from peaks ringing the basin, a mile to three miles off. Subtle tides of otherwise imperceptible air movement brought first one cascade’s fricative note to the foreground, and then another’s.
The chill seeped in, demanding a sleeping bag, and first a toothbrush. But oral hygiene was interrupted: silhouetted against the fifty thousand stars, blackness not quite as big as a football flew one quick circle around my head at an arm’s length away, and was gone. It didn’t make a sound.
Did that really just happen?
My disbelief yielded, gradually, as the apparition coalesced, thread by thread, into a plausible narrative:
1. An owl
2. flew over to investigate my scritching toothbrush
3. which may have sounded like a heather vole (the local meadow mouse) gnawing sedges.
4. The owl flew in perfect silence. Owl feathers have soft fringes not found on other birds, and these dampen the whoosh of air across wings. Owls also have large wings for their body weight, enabling slow wing beats. The increased drag from the fringes incurs costs—slow, inefficient flight compared to that of hawks—but the reward is great: with no wind noise covering tiny sounds of prey, owls can hunt in pitch darkness. In laboratory experiments, blindfolded barn owls pinpoint and strike prey by hearing alone.
5. It’s part of evolution’s endless arms race between eaters and eaten. The majority of land mammals are nocturnal because that’s a cost-effective way to gain a step on predators, even though the majority of predatory mammals adapt to nocturnal prey by being nocturnal as well. Few predatory birds can follow suit. Birds generally depend on sight and have much better eyes and poorer ears than mammals, presumably because light travels faster than sound, making it a better medium for navigation while flying. So nighttime remains the right time for many four-legged prey species. If only it weren’t for those owls.
6. Do voles ever survive owl attacks? Do voles even know that owls exist? Or are they formless rumors, suspicions? Your cousins vanishing one by one?
And if the Devil is six, then God is seven.
7. The owl flew in perfect silence and I could hear that.
How often in life did I ever stand outdoors in silence so intense that I could hear an owl’s silence?
Will my children know such silence? such glittering darkness? Will they know owls, will they see for themselves how the parts fit together and where they themselves stand in the real world?
* * *
A generation later, I climbed onto a ridge to look down at another camp, one set in a cirque cut in contrasting swathes of red-brown mudstone and blindingly white marble. Three small figures made their way past the bleached mountain goat skeleton and around the shore of the glacial-turquoise lake cradled in the cirque. In each of the emerald draws where tiny rills approach the lake, nurturing sodden mosses, yellow monkeyflowers, and succulent saxifrages, they dallied. The three—my daughter and the twins, age 12—were inspecting the verdant draws in search of fairy homes. (Finding several, of course.)
So what’s really changed since the Paleolithic?
This: they were shooting photos of the fairy homes. Pixies into pixels.
(Introduction to a book unwritten)
Humans See Stars
Night after night, last August in the Wind River Range, I had a fantastic sky full of stars, and it set me to thinking. One question that came up was the difference between stars and planets.
Modern astronomy has one answer, and the old astronomy has a completely different one.
Every schoolchild knows the modern answer. Planets—of which the earth is one—orbit the sun, which is a star. Planets emit no light and little or no heat. Stars, in contrast, are insanely bright and hot. Though many times bigger than planets, they (except for our sun) look tiny because they are so far away.
Few schoolchildren know the old answer. Not many highly educated adults do either. One really smart friend with multiple degrees in sciencey fields said it was completely new to her when I explained how the times of moonrise and moonset cycle through the 24-hour day in lockstep with the moon’s phases. Used to be, everyone knew that.
For thousands of years, in nearly all cultures, the following difference between stars and planets was pretty universally known, because anyone can figure it out by diligently observing the night sky with the naked eye and noting its patterns over time.
(They had one big advantage over us moderns. Before 100 or even 40 years ago, the typical naked eye saw a lot more stars than it does now, due to urban light pollution.)
Stars—the overwhelming majority of those dots of light in the night sky—are rigidly, perpetually fixed in relation to each other. That’s kind of amazing: the same pattern, century after century. (It turns out they actually do move, as higher-tech astronomers have learned, but it’s imperceptible at human time scales.) At the same time, this rigid panoply is in perpetual motion as a whole relative to the horizon, on both nightly and yearly cycles. Nightly, it wheels around a center point near the North Star. The panoply we see at any one moment is a hemisphere, but the entire panoply must be much larger, as new portions of it continuously unfurl at one horizon while equal portions sink beneath the opposite horizon.
Planets, in contrast, are the five visible dots of light that differ by slowly moving about across the panoply—“wanderers,” the Greeks called them, planetes. The other celestial bodies in motion are very different: sun and moon are huge discs; shooting stars dart ephemerally; comets turn up in slow motion every once in a very long while.
Comparing the new and old astronomies in terms of quality, I decided that modern astronomy is more interesting; deeper; more satisfying if you’re looking for explanations. I’m in awe of the remarkable intellects who figured it out.
The old astronomy, on the other hand, is more factual and more useful.
Factual, in that its facts (outlined above) survive intact as they have for millenia. In contrast, any given fact of modern astronomy, from basics like the number of planets to esoterica like the abundance of dark matter, stands a serious risk of getting deposed during your lifetime.
Useful, because it provided the basis for measuring time, as well as the basis for navigating around the earth. (Down here on earth, we no longer need stars to navigate by, but our spacecraft still use them.)
For sheer utility, has anything come directly out of post–Copernican astronomy that can bat in the same league as those two things? I couldn’t think of any, but my friend Chris Leger pointed out a foreseeable use that could one-up the old astronomy: predicting and averting an asteroid collision.
So. The old astronomy is truer and (so far) more useful, yet we’ve gone and dropped it from the curriculum of being human. What’s up with that?
To me, it’s one of many ways of being out of touch with the real world.
After stars vs. planets, I moved on to jetliners. Later than approximately midnight, they cross the Wyoming sky only from west to east, and after a while of doing that they cease. I think I can explain that one, too.