Tuesday, October 11, 2016

Plant on a Pedestal


This month I’m making an oblique and tenuous segue from Tree-Following, for I have no news to report of my serviceberry. After a long vacation, all kinds of things have to be done right away! (of course ;-) Instead, this post is about one of its brethren growing nearby under challenging circumstances. Though it’s only a meter tall and technically a shrub, it’s as impressive and inspiring as a tree.

The serviceberry doesn’t sit directly on the ground but rather on a pedestal—which sounds lovely, but it was created by “erosion of soil from around the base of a plant such that it appears to be on a pedestal” (source). [Pedestaling usually refers to erosion, but frost heaving and accumulated soil or litter can create pedestals too. And I stumbled across a webpage that mentioned plants with pedestals of lateral roots—news to me.]
Plant on a pedestal created by erosion. Arrow points to exposed roots (source).
Range managers consider pedestaled plants indicators of over-grazing. A healthy allotment (pasture) has no pedestaling. If mature plants are on pedestals, the allotment is said to be at risk, and the stocking rate should be reduced. In worst cases, erosion has pedestaled all plants and exposed roots. These allotments are classified as unhealthy. Complete removal of livestock may be necessary for the range to recover.
The pedestal has all but disappeared, leaving the serviceberry standing on its roots.
But this serviceberry grows where no cow would ever think of going—on a steep slope where there's little to eat. However, slope and rock type make erosion inevitable. At the same time, the tilted beds of sandstone and siltstone offer benefits. Soil develops from softer siltstone. Seeds germinate, grow into seedlings, and send roots down to the water that falls as rain, and accumulates in underground fractures in the sandstone.
Serviceberry on Boulder Ridge (center of photo); Hutton Lake behind. Photos taken in August.
A wild currant grows here too, just visible behind the serviceberry.
In spite of the tough situation, these shrubs have enough vigor to produce fruit!
A wild currant (red) lies next to where the root enters the ground (click on image to view).
Boulder Ridge on the south side of Hutton Lake, Laramie Valley, Wyoming.

Our monthly gathering of tree-followers is kindly hosted by The Squirrelbasket. Check out tree news from around the world ... and consider joining us!

Wednesday, October 5, 2016

Glacial Beauty in the High Uintas

Glacial-sculpted quartzite in the high Uinta Mountains (answer to recent Geo-challenge).

Fifty years ago this fall, I chose a topic for my first science paper. I assumed that my parents saved all my early scholastic efforts, but when I had to empty their closets, cabinets and drawers, I found that was not the case. Yet I can still clearly see the report—in a durable black cover with a hand-cut white label hand-printed in large blue font: Glaciers and Ice Ages. That was a formative time, and it’s rare that I look at glacial landscapes without thinking of Mr. Brunello and my first venture into earth science.

Four years later I discovered John Muir—adventurer, scientist, and imaginative nature writer. He considered glaciers beauty-makers. His memorable descriptions of their power and artistry strengthened my determination to get into the high country.
“glaciers work apart from men, exerting their tremendous energies in silence and darkness, outspread, spirit-like, brooding above predestined rocks unknown to light, unborn, working on unwearied through unmeasured times, unhalting as the stars, until at length, their creations complete, their mountains brought forth, homes made for the meadows and the lakes, and fields for waiting forests, earnest, calm as when they came as crystals from the sky, they depart.” (from Yosemite Glaciers, 1877)
Mr. Brunello and John Muir were with me again last month, in the high country of the Uinta Mountains (northeast Utah). It was just 10,000 years ago that glaciers finally departed, melting away when there no longer was enough snow and cold to grow. They left behind high broad basins with “homes made for the meadows and the lakes, and fields waiting for forests” … and lots of rock.
En route to the Notch (center skyline), past one of many lakes, ponds and meadows.
From the Crystal Lake trailhead, I hiked north to the Notch—a low point between two peaks and a divide between two drainages. It's 10,600 feet above sea level, close to the surface of the old ice cap. Above, piles of fallen rock had been spared; below, the basins were largely free of debris—swept clean by glaciers.
East of the Notch is a pile of fallen rock at about 10,800 feet—above the height of the ice cap.
Felsenmeer (rock field) in foreground, at 11,400 feet on Bald Mountain a few miles east of the Notch. Bald Mountain, Reid's Peak (mid-photo), and Notch Mountain were nunataks that stood above the ice cap.
In the Notch, I wandered around on scratched and polished rock littered with blocks. Glacier bottoms are often likened to sandpaper because they’re covered in grit—embedded boulders, pebbles, sand and dirt that grind away at rock surfaces. Larger fragments carve grooves and etch long parallel striations; finer material polishes the rock.
Glacial polish at the Notch. Note regular fractures and blocky rocks (more below).
Many striations were black. Is this algae or lichen? or weathering?
Glaciers carry rocks on their surfaces as well as below—those that fell or slid down onto the ice. They're left behind when a glacier melts, randomly scattered about, often far from their source—hence the term erratic.
Blocky erratics scattered about, in this case not far from their source.

From the Notch, I hiked back down into the waste-swept basin and on to Clyde Lake, one of at least 70 lakes in the area covered by the ice cap. On the east, the lake was bounded by a long roche moutonnée glowing in the sun. Glaciers create these asymmetric ridges by grinding a gentle slope on the upstream side and plucking rocks to form a steep step downstream.
“Roche moutonnée” may mean sheeplike rock, or it may refer to wigs once fashionable among French gentry, which were smoothed over with mutton fat (source; discussed here).
“Showing a rock-basin lake [Clyde Lake] and portions of the waste-swept floor of the catchment area.” (Atwood 1909). On skyline: Notch Mountain split by the Notch, Reid's Peak, Bald Mountain. Roche moutonnée on right.
Clyde Lake with east half of Notch Mountain, Reid's Peak and Bald Mountain behind; 2016.
The roche moutonnée at Clyde Lake has a beautifully polished slope with a regular system of fractures, I suspect due to the sedimentary heritage of the rock.
Graininess of the quartzite made rock identification difficult in the geo-challenge. 

Glacial landscapes are shaped by the bedrock as well as by ice. In the Uinta Mountains, glaciers mostly worked with quartzite—but barely. Metamorphism was low-grade, so these rocks are softer than typical quartzite. The bedding and graininess of the progenitor sandstones (technically quartz arenite) are often visible, and in places the rock is sandstone. This was my first exposure to glaciated metasedimentary rock, and the novel patterns and forms were irresistibly photogenic.

Orientation of rock beds also contributed to glacial artistry. On the broad crest of the Uintas, strata are nearly horizontal, which is conducive to large areas of polish and striations, and shallow depressions for lakes, ponds and meadows. Flat areas are separated by steep steps where glaciers plucked out rocks.
Nearly horizontal quartzite beds on Mount Watson, behind small plucked step.
Blocky step below the Notch.
Another view of horizontal fractured beds below the Notch.

The Notch and Clyde Lake are on one of the most popular day-hikes in the Uinta Mountains. The trailhead at Crystal Lake is easily accessible from Mirror Lake Scenic Byway (Highway 150; fee for recreational use; closed in winter), and the Forest Service provides a small map free-of-charge. The section of trail between Clyde Lake and the turn-off to the Notch is fairly new; it's not on older maps and websites, which can be a source of confusion (I heard two hikers acrimoniously debating the correct route). Also, there are two trails at the trailhead, with no indication that they’re part of the same loop. A month ago, one was marked closed due to fire even though the Clyde Lake fork wasn’t. I mention all this because perhaps—like me—you assume that popular “tourist trails” don’t require close attention. (Yes, I had to backtrack … but only once.)

Sources (in addition to links in post)

Atwood, WW. 1909. Glaciation of the Uinta and Wasatch Mountains. USGS Prof. Paper 61.

Hansen, W. 1969. The geologic story of the Uinta Mountains. US Geological Survey Bulletin 1291. PDF

Kelly, M. 2012. Influence of structural variability on glacially-eroded steps, Uinta Mountains, Utah. MS Thesis, Geology, University of Illinois at Urbana-Champaign.

Tuesday, September 27, 2016

Geo-challenge: range? rock? process?

Where is this immense gallery of scratched and polished carvings? Who was the sculptor? What was the clay?

Ideas, answers? Please add a Comment below. A post will follow, after I’ve recovered from Post Vacation Trauma.  ANSWERS HERE

Sunday, September 18, 2016

Of Quartzite and Lily Pads

Hayden Peak, constructed of sandstone and quartzite masonry on a Cyclopean scale.
“… the view of one of these mountain lakes, with its deep-green water and fringe of meadowland, set in a sombre frame of pine forests, the whole enclosed by high walls of reddish-purple rock, whose horizontal bedding gives almost the appearance of a pile of Cyclopean masonry, forms a picture of rare beauty.” —pioneering geologist Frank Emmons, after working in the Uinta Mountains in 1869 and 1871

One cool evening high in the Uinta Mountains of northeast Utah, I strolled along Butterfly Lake below Hayden Peak, hoping to catch its Cyclopean masonry illuminated by alpenglow—or at least the golden light of early evening. But the brilliant reds and purples I imagined never appeared. Instead, the mountain simply turned dull and then dark.
Yet at the same time, the lily pads at the west end of Butterfly Lake glowed in the low light, joined by tree reflections floating on the water.
In Utah, Rocky Mountain pond-lilies (Nuphar lutea ssp. polysepala) grow only at higher elevations in the northeast part of the state. They stay some distance from shore, not liking shallow water. “Thus, the plants are seldom available to collectors, except by wading into icy water by the most determined of botanists.” (Stan Welsh in A Utah Flora)

Other common names include yellow pond-lily, for obvious reasons; spatterdock, because the capsules burst and spatter seeds about; and brandy-bottle, for the shape of the capsule.
Yellow sepals surround the pistil and stamens; petals are inconspicuous (source).
See the half-submerged brandy bottle?
Leaf stalks grow directly from large thick rhizomes firmly buried in mud. Blades can be a foot across.
Lily pads (leaf blades) usually lie flat on the water surface, providing hideouts for fish, frogs and other aquatic critters. But the season at Butterfly Lake is winding down. The water level has dropped, and leaves are starting to dry, fold up, turn color.

When the sun abandoned the lily patch, I turned back to Hayden Peak. Ferdinand Vandeveer Hayden was another of the pioneering geologists in the Uinta Mountains (1870). In fact, early geologists are extremely popular here:
“… there is one mountain range that commemorates early 19th century geologists and topographers who were influential figures in the geoscience field: the Uinta Mountains. More than 20 major geographic features in this mountain range (lakes, streams, and mountain summits and passes) bear the names of these important geoscientists.” [listed here]
The sandstones and quartzites of Hayden Peak started as sediment in a rift valley back when the continent was being torn apart 750 million years ago (Late Proterozoic). The faults on either side of the peak are much younger—maybe created 65 to 40 million years ago when the range was being uplifted.
The summit of Hayden Peak is 12,479 feet above sea level. Red lines mark faults.

Sources (in addition to links in post)

Dehler, CM, et al. 2005. Uinta Mountain geology. Utah Geological Association Pub. 33.

Emmons, SF. 1877. Descriptive geology: US Geological Exploration 40th Parallel (King). Volume 2.

Hansen, W. 1969. The geologic story of the Uinta Mountains. US Geological Survey Bulletin 1291.  PDF available here.

Welsh, SL, et al. 1987. A Utah flora. Great Basin Naturalist Memoirs No. 9.

Monday, September 12, 2016

A Tree and a Rock

This month I have no news about the serviceberry I’m following. I’m far from home, in a warmer drier land. So instead, here’s a report of a tree I came across on a narrow precipitous ridge crest, holding a boulder in its roots! This was curious enough in itself, but just as interesting were the thoughts it brought to mind. I realized this tree was keeping the boulder from continuing a trip that had started maybe sixty million years ago. Trapped by the tree, it couldn’t make the next leg—a steep 2000-foot descent to the Green River. But the delay would be minor, basically imperceptible. Even five hundred years of imprisonment would be but a fleeting obstacle in this boulder’s journey.
Next leg of the trip—down to the Green River, 2000 feet below the ridge crest.
This is not a local rock—not sandstone, siltstone nor shale. It’s hard tough quartzite, which is why it survived the long punishing journey that started 60 million years ago in the high country of a newly-created mountain range to the north. A fragment of bedrock—perhaps broken by folding, faulting, or frost—was carried many miles by streams, bumped and bashed, worn smooth and round, and left here.
The rock itself is far older than the mountain range. It began as sand in a deep rift valley, 700 million years ago.
For maybe 30 million years, weathering and erosion chipped away at the mountains, reducing them to sand, dirt and pieces of rock. That’s typical—as soon as mountains rise, demolition begins. “Mountains seem massive, abiding and immutable … yet if we look carefully at rocks, if we use them to peer into the past and conjure up the world they came from, we find that mountains too are ephemeral.”
The piles of sand, rock and dirt along the trail used to be part of a mountain range.
The amount of debris carried down and deposited was so immense that the mountain range was largely buried in its own rubble. Probably only the highest peaks stood above extensive gently-sloping surfaces. Then the land rose again—not as mountains, but the entire region. Erosion went back to work, this time exhuming the old buried landscape. It removed much of the debris deposited just a few million years before, but not all. Relic patches remain today on high surfaces—like the narrow precipitous ridge I walked. But unless things change, this too will be gone.

In the meantime, the quartzite boulder will have to wait a bit, because hundreds of years ago a pine seedling managed to get established and now has grown large. Its roots grew down into the pile of debris, circumvented the quartzite boulder, and trapped it. Though trail construction exposed the boulder, it can’t roll down to the Green River just yet. It has to wait until the tree dies and the roots decay. But given the scale of its life, I doubt that it feels the least bit impatient.

Now let’s consider the tree. It’s a pinyon—Pinus edulis (“pine edible”)—one of millions growing in the vast pinyon-juniper woodlands of the American West. Because pinyons live in country that is cold in winter and dry for much of the growing season, they grow slowly, never getting very big. But they are trees of great bounty, producing abundant large seeds beloved of squirrels and jays and little boys.

The sticky green young cones contain maturing seeds, on which wildlife will depend for winter survival (as did people in the old days).
With the right beak or teeth, older cones can be torn from the tree and pulled apart to get at nutritious seeds.
Left alone, cones open on the tree and seeds fall of their own accord.
Big tasty pinyon nuts are worth hunting for—even if you’re only five years old!

Monthly tree-following gatherings are kindly hosted by The Squirrelbasket.