[Russell Towle's journal]
“3/8/87 Early morning; about 2:00 A.M. […]
I traded skis and boots with the young man on yesterday's tour, N____, who was having trouble with floppy shoes and heels rolling off the skis, so I ended up plunging into the onion creek canyon with his equipment, and now, the next day, find a dull pain in my ankles. Well, I learned a lot about guiding large groups yesterday. I learned that the first-aid kit must be part of the picture, and that as leader I must rely on someone else to be sweep, bringing up the rear, for, despite my injunction that no one go off by themselves, D____ got out ahead of the group and proved to have a non-existent sense of direction. When I finally found him he was miles away from the meadow we had had in view and set as our lunch spot. Poor guy.
Eric says that a lot of interest has been expressed about the upcoming Lover's Leap hike I am to lead. It may be split into two consecutive hikes. Great. While I do not have my own copy yet, I saw one yesterday—of what, you ask? Well, dear diary, I made the front page of the Roseville paper on March 4, including a large picture with me standing beside the Lovers' Leap oak, captioned and everything…”
[Russell Towle's journal]
Birds and Storms
[North Fork Trails blogpost, March 8, 2006:A series of storms has swept across the Sierra, some warm, some cold, and here at 4000', there has been the most annoying alternation between rain and snow.
Currently, I have six to eighteen inches of very wet snow on the ground. For a day the temperature has been thirty-five degrees, an inch of rain has dropped, and the snow pack is a sopping, soggy mass.
It is interesting to observe the birds coping with this. I was building a five-foot-high snow tetrahedron up in the Meadow the other day, and heard that strange warbling chorus of the flocking Sandhill Crane*. Clouds swirled over most all the sky, with tiny patches of deep blue here and there. Suddenly the noisy cranes came into view, between tall pines, as I saw them, but a few hundred feet above, actually; they formed ragged V's and I estimated the flock at two hundred birds.
To fly northeast on this day! With violent snow showers assaulting the crest! What brave and noble birds! Where is the Plutarch, to record their extraordinary lives!
Then, this morning, under a sullen blanket of fog spewing rain and sleet and rain and sleet, a sudden heavy shower drove some perky-crested Stellar Jays into the shelter of a Canyon Live Oak, a gnarled mass of twisted branches and dense evergreen foliage, clinging to a cliff; several jays made the same abrupt move, into the live oak, and while the sleet pounded down and bounced off the soggy snow, the jays moved stealthily lower into the volume of the foliage. More and more and more leaves acted as tiny shingles above them, and they could pick and choose the dry zones.
In June, when the young of the Stellar Jay emerge from the nest in adult plumage, they exhibit a behavior I have seen in other bird species, and which is likely some deeply-rooted and primeval mechanism. The juveniles will wait, on some pine branch, say, for their parents to bring them food, tasty morsels of many kinds, I think; and as the parents wing into view, the juveniles slightly spread their wings, and beat them rapidly, and squawk excitedly, saying "Here I am—feed me! feed me! feed me!"
I took some corn chip crumbs out to the cement steps, and scattered them over steps and snow alike, and waited inside. Soon a crowd of jays discovered the treasure. I was intrigued to see one jay holding its wings a little akimbo and beating them rapidly. It was the juvenile "feed me" behavior, yet this bird was an adult, a near-yearling at the least.
There did not seem to be much aggression or competition between the half-dozen jays on the steps. But crumbs were plenty.
I saw that the jays preferred the steps to the snow; I suspect they fear exposing their deep blue bodies against white snow to the sharp eyes of some hawk. The darker background of wet cement would guard them from the hawk's keen eyes.
Paleovalleys and Ignimbrites
[North Fork Trails blogpost, March 8, 2006:English is an Indo-European language, as are two “dead” languages, Latin, and the still older Sanskrit. From the Sanskrit “Agni,” (god of the hearth, and mediator between gods and men) we move to the Latin “ignis,” fire, from which we get our English “ignite,” and also that vastly rarer word, “ignimbrite,” meaning “fire rock” or welded tuff; and “tuff” (not tufa) is volcanic ash.
Rhyolitic volcanoes tend to have explosive eruptions in which a “glowing avalanche” of incandescently hot lava particles will spread out, perhaps flowing down a valley, and just so soon as that glowing avalanche stops, it freezes into solid rock. It is a cataclysmic event and will kill everything in its path.
There are basaltic tuffs, andesitic tuffs, and rhyolitic tuffs. In this part of the Sierra we have an abundance of rhyolite tuffs. Some are welded tuffs, some were air-borne ashfalls which did not weld, and were either immediately or subsequently remobilized by water; for a long time we have called all these rhyolite tuffs, the Valley Springs Formation, yet they are clearly composed of several to many different tuffs, spanning millions of years of time, beginning, say, in the Oligocene of ~30 m.y.b.p. (million years before the present) to the Miocene of ~20 m.y.b.p.
Hence we ought to split the Valley Springs into smaller, individual formations.
Strangely, although so close to major population centers and hence, to universities with geology departments, the Valley Springs Formation has not been exhaustively studied. Only now are some of its secrets being unlocked; similarly, only now is the much more recent (<3 m.y.b.p.) glacial era coming into focus; and there is so much remaining to discover here in the Sierra, on so many fronts.
It is a good time, a great time, to be a geologist in the Sierra Nevada. When one visits the web pages of these various professors and graduate students, and, sometimes, undergraduates, one sees they must live Indiana-Jones-like lives of high adventure, in lands of danger and mystery; for, hark, there they go, to the wilds of the Tien Shan mountains in northern Tibet, and they study some violent fault zone of critical import, in forming a model of Himalayan geology.
And then, in the summer, say, they come back to the Sierra and examine ignimbrites, in a certain paleovalley which seems to have run from near today's Honey Lake in the north, down past Soda Springs at I-80, and then crossing the upper North Fork to French Meadows reservoir on the Middle North American; thence joining the main Tertiary South Yuba near Michigan Bluff, and on past Yankee Jims and Iowa Hill to Gold Run and points north.
Since it is a paleovalley, predating our modern canyons, its originally continuous course has been broken not only by erosion (i.e., cut by our modern canyons), but by block-faulting: this paleovalley crosses the main Sierra Nevada fault, at a very shallow angle, just north of Castle Peak. To the west of this fault is the upthrown block: the Sierra. To the east is the downthrown block: Lake Tahoe, the Martis Valley, Highway 89 north of Truckee.
The main Sierra Nevada fault is really a stepped series of roughly parallel faults, all along the east side of the Sierra Crest, from south of Mount Whitney, north to about Yuba Pass. A little farther north, and we leave the Sierra for the southernmost of the Cascades volcanoes, Mt. Lassen. The thickness and extent of the “young volcanics” (of which these rhyolite tuffs form a part) is much greater here, in the northernmost part of the Sierra, and the volcanics often obscure bedrock and faults alike.
Back to the paleovalley. Around 1900, the USGS's Waldemar Lindgren mapped it as originating near Castle Peak; the idea that it may originate near Honey Lake (at Diamond Peak) results from field work by accomplished geologists and petrologists including student Dylan Rood, professor Cathy Busby of UC Santa Barbara, and David Wagner, a State geologist.
I should say that the idea of our Sierran paleovalleys having their headwaters east of the Sierra crest, in modern Nevada, is not new at all, but has yet to be widely demonstrated. The ~16 m.y.b.p. Lovejoy Basalt of the Northern Sierra, also presents the case of a paleovalley extending east into Nevada.
But in this particular “Diamond Peak” paleovalley, a little west of Honey Lake, they find five distinct ignimbrites, composed of nine cooling units. They correlate units 1, 4, and 7 of the Soda Springs paleovalley, with units 3, 4, and 5 of the Diamond Peak paleovalley.
Around ten years ago, I accompanied paleontologist Howard Schorn and geologist Dave Lawler to a site in the Soda Springs paleovalley, where we recovered some finely-detailed plant fossils from the river gravels beneath the ignimbrites. But the stratigraphic relations were not exposed there, in fact, we were finding the fossils in an anonymous creeklet threading through glacial till.
These ignimbrites are broadly similar to the famous Bishop Tuff of the Owens Valley, 35 cubic miles of welded rhyolite ash which erupted in an instant from the Long Valley caldera a mere 750,000 years ago; so our local tuffs are much older.
Rood et. al. remark that the lower three ignimbrites were confined to the paleovalley, while the fourth overflowed here and there, and the fifth and uppermost ignimbrite, the youngest, spread more widely still, scarcely at all confined by the paleovalley.
The sources of these tuff-beds seem all to be to the east, in Nevada, some rhyolitic calderas having been found in the central part of the state, of the same ages. At that time the Sierra had not been uplifted, and the source region of the calderas was higher in elevation than here, so the glowing-hot fiery avalanches of rhyolite ash traveled long distances, down the paleovalleys.
One of these five ignimbrites of the nine discrete cooling units is David S. Harwood's “pink welded tuff,” dated to 22 m.y.b.p., as discussed in his USGS geological map of the Duncan Peak and Cisco Grove quadrangles. Generally speaking, rhyolite tuffs are light in color, white, cream, buff, tan, grey. This “pink welded tuff” is well-exposed in the vicinity of Palisade Lake, just west of Soda Springs. The westward continuation of Pahatsi Road, in the Serene Lakes subdivision, to Cascade Lakes, crosses the glaciated surface of this ignimbrite for about a half-mile, atop the South Yuba-North Fork American divide. Huge granite erratics are scattered everywhere, and one can drive right by thinking that the flat glaciated “bedrock” is granite, too; but it is a welded tuff, and it is Superjacent Series all the way, not Subjacent Series, like our granites.
At Palisade Lake this ignimbrite is seen, in cross-section, to have a massive vertical columnar structure; hence, I think, the name of the lake and of Palisade Creek, a south-flowing tributary of the North Fork. Which of Rood et. al.'s nine cooling units Harwood's “pink welded tuff” is, I cannot say.
These ignimbrites, these welded tuffs, are commonest near the Sierra crest, and are not found much if at all as far west as Dutch Flat. Here, the equivalent tuff-beds are sometimes well-consolidated and seem rather welded, but more typically, they are clearly water-deposited, and have sometimes weathered into a grey clay. The Dutch Flat store is built from the possibly-welded rhyolite tuff of this area. No, here in the lower elevations, so far away from the source calderas, our tuffs tend to be weak, so weak as to almost never be exposed at the surface, as outcrops; near the head of the Green Valley Trail is one small exposure, and there are others around Lake Alta, and west, at Chalk Bluffs.
Well, at any rate, I am delighted that new work is being done on our “young volcanics.” This same team, Rood et. al., look to be involved in studying the next-younger members of the Superjacent Series, the andesitic lahars and all their variants, down in the Carson Pass area. With modern radiometric dating tools, we should gain a much more sophisticated portrait of our late-Tertiary volcanism.
Snow, Storms, and Lions
[North Fork Trails blogpost, March 8, 2007:At last the snow is melting away, the recalcitrant snow, the stubborn snow, the snow which defies day after day of temperatures in the sixties. At 4000' elevation it is all microclimate. Where I live, a few dozen yards separate “The Meadow,” where it has been freezing every night, from “The Cabins,” where it has not dropped below forty degrees for a week or more. The Meadow slopes gently south, but too gently. The Cabins are on a steep south-facing slope.
Hence The Meadow has an unbroken expanse of snow, and in the flat places the snow is still nearly two feet deep.
Yet The Cabins have only small masses of snow here and there, mainly where conifers shed big heaps—these are ring-shaped masses; or on trails, where the flatness of the trail-bed itself is not south-facing, and the snow has been slower to melt; these are linear masses.
They say that Eskimos have fifty different words for snow. We use a couple here in the Sierra, rather imprecisely. One will hear people talk of “powder snow,” or its near-opposite, Sierra Cement. These terms lack precision. To confuse the matter further, the ski areas, knowing people prefer powder to ice, will report a “base” depth of, say, ten feet, and describe conditions on the ski runs as “packed powder,” when a more truthful description would be “groomed ice.”
Anything west of the Sierra Crest can be counted a maritime climate, versus the continental climates found east of the crest. The influence of the ocean moderates the climate west of the crest, keeping it much warmer. Hence Blue Canyon, at 5200', very very rarely ever has temperatures below zero, while Bridgeport, at the same elevation but east of the crest, along Highway 395, drops below zero degrees many times each fall, winter, and spring.
In fact, Bridgeport once held the low temperature record for the entire United States, flat-out 56 degrees below zero. It lies in a large flat valley encircled by mountains. Cold air settles in and intensifies.
At any rate, genuine powder snow, of the sort they have in the Rockies or in Utah, is a rarity in the Sierra. We do get it from time to time, but usually when the weather people on TV are waxing poetic about powder in the Sierra, it's really the good old Sierra Cement, which is a warm and heavy and sticky snow, somewhat light and fluffy in the first hours after it falls, but let one sunny day go by and, watch out.
The recent sequence of storms laid down the wettest and heaviest of Sierra Cement here at 4000', and as so often happens, periods of real snow were punctuated by periods of what I call “snain,” a mixture of snow and rain, which often looks like snow from the comfort of one's living room, but go outside and you will be getting wet.
This “snain” settles and compacts and wets whatever real snow it falls upon. Freezing temperatures, such as are likely between storms, transform this dense snowpack into a nearly monolithic mass of ice. Let a mixture of snow and snain fall for a week running and one has three feet or so of a material which will stoutly resist melting.
Yesterday afternoon I thought it a good time to burn a pile of brush I had cleared from what we call the High Trail, on a steep slope west of here. The slope is too steep for safe burning in dry conditions. But I expected to find it still partially covered in snow, and it was, so I set to work, and safely burnt the slash, a struggle to be sure, since this brush was itself still partly buried in snow, and I had some wrestling matches merely to pull it free. As the sun lowered in the west, patches of bright sunlight broke through the clouds. I walked back to The Cabins in a meditative mood, my feet sinking deeply into the linear masses of trail-snow. I paused often to admire the scene, and visited some low cliffs which offer a view east. There was sun dappling the North Fork canyon all the way up to Snow Mountain and the Royal Gorge, where the snow-clad cliffs of Wabena Point were almost hidden within light snow showers. The crest itself was lost in clouds.
Now, night-before-last my son Greg reported hearing the sounds of an animal crashing through brush immediately below the Big Cabin, and whatever it was make cat-like "yowling" sounds.
“A bobcat,” I responded at once. For bobcats are common here, and they often vocalize. Once the oak leaves which litter the forest floor dry out, even a small animal sounds like a big animal. A squirrel can sound like a bear.
But then, last night, I myself heard an animal crashing through the brush below the Big Cabin, and no yowling, but one explosive almost bird-like squawk, pitched high. The brush-crashing continued to the west and then quieted.
I related this to Greg and offered a guess, that perhaps a deer made the squawk, as they do make a wide variety of sounds, which few people ever hear. Deer bellow plaintively, for instance, and deer also bark, a dry, coughing, huffing bark. They also bleat like goats, but more softly.
This morning, at dawn, I decided to walk out west and higher to visit my burn pile. As I reached one of the linear masses of trail snow, I saw mountain lion prints from last night. They had not been there yesterday. They could only be from the animal which had been crashing around below the Big Cabin.
|Track of Mountain Lion (Puma concolor)|
It was interesting to note that the lion had stepped in my own tracks of the afternoon whenever it could, and if opportunity offered to get out of the snow altogether, it took it. I photographed a few of the tracks; they are probably the most exact and complete lion tracks I have ever seen. For those who have Storer and Usinger's “Sierra Nevada Natural History,” (U.C. Press, Berkeley), the tracks were exactly as depicted in the Mammals section, Figure 22, on page 328 of the 1973 printing.
So, I warned my family about the lion. Often they arrive home from work and school after dark, and nowadays, with the snow and all, it is a walk of a few hundred yards from car to cabin.
I tracked the lion quite a ways west on the Old Trail. Its tracks were only visible in the linear snow masses, and even then, where it had stepped exactly into one of my own boot-tracks, they were unrecognizable. Only in those few places where it was more or less forced to step in the unbroken snow, had it done so. Two nights in a row it has come near the cabins.
It is fun to observe animal tracks, and I have seen many fox trails, many squirrel paths, and even the tracks of ground-loving quail, written in the snow lately.
*More on Sandhill Cranes(Grus canadensis)
Video and audio of flying, and landing on water ~
Some interesting facts from the Nature Conservancy page on Sandhill Cranes:
“Some evidence points to cranes as the oldest known bird species surviving on Earth. A crane fossil found in Nebraska, estimated to be about 10 million years old, is identical in structure to the modern sandhill crane.
Though cranes and herons share some similarities in appearance, they are actually only distantly related. ... It can be difficult to tell the difference between herons and cranes in flight. One of the easiest ways to distinguish the birds is to remember that herons fly with their necks curved and cranes fly with their necks straight.”