Sunday, June 25, 2017

Our Lady of the Roadside

In a disturbed land cleared of life and showered with trash, sacred datura stands in regal glory. She thrives next to heat-radiating asphalt, fully illuminated by the sun and soaking up the rare runoff. At dusk, when the searing heat of daytime subsides, she opens great white trumpet-shaped flowers to welcome night visitors. The large fragrant patches of white, conspicuous even in the dim light, are produced for one reason—sex. Datura may be sacred but she’s hardly celibate.

Her lure is irresistible. Hawkmoths flit from flower to flower, feeding on copious nectar deep in the throat, bumping anthers, picking up pollen. Then at the next flower (1), a moth brushes against the receptive stigma waiting at the opening, leaving behind a few grains. Within minutes pollen tubes grow down the style, and male gametes make the long journey to fertilize ovules. With seed development, the ovary matures into a large plump spine-covered seed pod—a “thorn apple.”
Datura wrightii can grow to 3 feet in height, with flowers up to 8 inches long.
Bud and flower (beginning to wilt at 9 AM, 75º F).
Flower in bud. When the time is right, it will unroll and turn white.
Exserted stigma waits for pollen, at the tip of a very long style; anthers visible at top of throat.
With age, sacred datura becomes the thorn apple (source).
In winter, if temperatures fall well below freezing, sacred datura disappears—or so it seems. But she’s only dormant, resting underground as large fleshy tuberous roots until spring. Then she rises again.
Sacred datura’s mighty root (source).

Sacred datura’s beautiful fragrant flowers, though clearly worthy, do not explain the widespread reverence she commands. Something much more exotic attracts worshippers—her powers of prophecy, divination and healing. Indigenous peoples throughout northwest Mexico and the southwest US have taken advantage of datura’s psychoactivity. In her early study of the California flora, Mary Elizabeth Parsons noted that “they [California Indians] administer it to their young dancing women as a powerful stimulant, and before going into battle the warriors take it to produce a martial frenzy in themselves” (Parsons 1907). In several cultures, boys were given datura as part of initiation into manhood (Fuller 2000). They fell into unconsciousness, which destroyed all memories of childhood (and sometimes the initiates as well), and then were taught the stories, traditions and rituals of their tribe.

Shamans, mystics and seekers continue to worship datura (2), even though it’s among the most dangerous of vision-inducing plants. All parts contain deadly tropane alkaloids—atropine, hyoscyamine, and hyoscine. Safe dosage is difficult to determine because individual plants vary in potency, humans differ in tolerance, and the onset of noticeable effects is slow. Cases of datura poisoning, including death, are usually due to deliberate consumption (source). Survivors can be temporarily or permanently scarred—with damaged lungs, stomach, intestines, kidneys and/or heart, and perhaps blindness and mental impairment.

Yet there will always be people willing to risk datura’s dangers for her promises—sufferers and seekers, lost souls and spiritual adventurers, thrill-seekers and those hoping to see beyond what we’ve been programmed to perceive. I suspect that as long as humans exist, sacred datura will be a “plant of the gods.”
Original source unknown.


(1) Datura wrightii is self-compatible—fertilization does not require pollen from a separate plant. But pollinators are helpful. Visiting hawkmoths have been shown to increase rates of self-pollination as well as outcrossing (Bronstein 2009).

(2) Datura wrightii is native to southwest North America, not just on roadsides but also in other open sandy habitat, e.g. desert washes. Its close relative, Datura stramonium, is the similarly-revered jimsonweed. Datura belongs to the nightshade family (Solanaceae), as do many other plants that offer us pleasure, poison, or both—chilis, petunias, potatoes, tomatoes, tobacco, belladonna, deadly nightshade and more.


Bronstein, JL, et al. 2009. Reproductive biology of Datura wrightii: the benefits of a herbivorous pollinator. Annals of Botany 103: 1435–1443. doi:10.1093/aob/mcp053

Fuller, RC. 2000. Stairways To Heaven: Drugs In American Religious History. Basic Books.

Parsons, ME. 1907. The wild flowers of California. Dover Books (1966).

Schalau, J. 2015. Backyard Gardener: Sacred Datura. Arizona Cooperative Extension, Yavapai County.

Monday, June 19, 2017

Lace Curtain in the Desert

Why would there be a lace curtain out in Utah’s West Desert, and why would anyone want to see it? Maybe it's in a ghost town (they're popular)—a faded old curtain hung by some hopeful soul long ago, now blowing in the wind. But no … it's something much more intriguing. The road led to a tattered rock curtain, hanging on an extinct volcano. And not just any volcano but a hydrovolcano, born in a lake. Water explains the curtain … and more.
Utah’s West Desert today.
After driving several hundred dry sparsely-vegetated miles through western Utah, it was hard to envision this place being deep underwater just 15,000 years ago. But it was; the evidence is clear. During the cooler wetter times of the last glacial advance, much of Utah’s West Desert was covered by giant Lake Bonneville; the “Great” Salt Lake is a pond in comparison.

In 1876, geologist Grove Karl Gilbert published an exquisite map of Lake Bonneville (click on image below). It was indicated with light blue crayon; today’s lakes were colored dark blue. [In spite of the great care that went into the map, the scale was incorrect. A corrected version, on the map below, was pasted on later.]
Restored Outline Of Lake Bonneville, Gilbert, 1876; David Rumsey Map Collection.
Gilbert and EE Howell worked on several geographical surveys with the US Army Corps of Engineers, led by Lt. GM Wheeler. Among other things, they documented location and elevation of many relic Bonneville shorelines, visible as terraces above valley bottoms. They determined the maximum height of the lake, and based on known topography, mapped it in detail. Their map even shows smaller islands—the tops of today’s hills and buttes.

In the Sevier arm of Lake Bonneville (home of today’s Sevier Lake/Playa), there were at least 15 islands, many of which were volcanic. The highest was today’s Pahvant Butte (arrow below). “It is the tallest of all the volcanic hills, and, standing alone upon the plain, is a conspicuous landmark. Its general form is that of a cratered cone, but the crater is open at the south, and the circling crest has an acute culmination at the north” (Gilbert 1890).
Pahvant Butte—an extinct hydrovolcano and former island in Lake Bonneville.
Pavant Butte, from the south. Gilbert 1890.
Pahvant Butte, from the south. May 2017.

At the recommendation of a friend, I visited Pahvant Butte in late May. It’s hard to miss, being clearly visible from a distance. The state of Utah provides directions and roadsigns to the butte and other volcanic features in the Black Rock Desert.

From the Clear Lake Bird Refuge Road, the road to Pahvant Butte heads north, with fine views of the south side of the cone with its crater, and the Bonneville and younger Provo shorelines below. Not long after Pahvant’s last eruption, Lake Bonneville rose and breached the divide into the Snake River drainage in southern Idaho. It dropped to what’s called the Provo level. “The Bonneville shore-line is trenchantly drawn about the sides of the butte at mid-height. The Provo shore-line appears at its base” (Gilbert 1890).
Lava flows in the area predate not just the cone but also Lake Bonneville.
When I reached the butte, I turned north and drove around it on a 2-track signed with a jeep-like symbol suggesting 4WD high-clearance. But it wasn't, at least not as far as the Curtain. My first stop was “underwater” at the base of the steep slope leading up to the old Bonneville beach. I like to ponder such things!
The next stop was for great views of the palagonitized tuff that forms the upper half of the butte. It was deposited after the volcano had grown above the lake surface. It’s thought that erupted material contained very hot water (1), which altered and consolidated the dark basaltic tephra (volcanic fragments) into yellow-brown palagonite. In contrast, material in the lower half of the butte was deposited underwater, cooled quickly, and was not altered (similar phenomena have been observed in Iceland; Oviatt and Nash 1989).
Unaltered black tuff deposited underwater; yellow-brown palagonitized tuff deposited above the lake surface.

On the north side of the butte, I spotted the Lace Curtain. The 2-track to the base of the wall was rough but passable.
Lace Curtain; yellow-brown palagonite above.
The Curtain is steep, suggesting the rock is hard and resistant to erosion. And yet it's quite eroded, in its own bizarre way. It's thought that in this area, mineral-rich groundwater (2) cemented volcanic deposits, though inconsistently. Then violent storm waves on Lake Bonneville beat against and eroded the north side of the butte, exposing the cemented rock. Waves continued to batter the rock, breaking it down. Inconsistent cementation explains the “lacy” pattern.
Whose abode is this?
My photographic reverie was interrupted by shrill kik-kik-kiksfrom two prairie falcons circling and diving overhead. One landed high on the Curtain and stayed for twenty minutes watching me, until I left. I had planned to camp on the old beach below the Curtain, and “watch” the sun set over Lake Bonneville. But I let the falcons have the place to themselves.
Concerned prairie falcon.

Back at home, I searched the scientific literature for information specific to the Lace Curtain. White (1996) studied only the underwater part of the Pahvant volcano; he makes no mention of the Curtain. Nor do papers about above-water deposits. Most online sources reference Case (2002):
“… intense storm waves cut a vertical cliff into the cone. The cut exposes an intricate lacy pattern caused by the partial cementing of the tuff by minerals in ground water. The cliff is known as the ‘Lace Curtain’ because of its white color and mysterious lacy pattern.” (italics added)
If you know of more information about the geology of the Lace Curtain, please add a Comment below.

Sunset over Lake Bonneville, from just south of Pahvant Butte.


(1) Experts disagree on the source of water for palagonitization. Some suggest groundwater (e.g. Case 2002), others lake water (e.g. Oviatt and Nash 1989).

(2) Cementing is sometimes attributed to Lake Bonneville water rather than groundwater. But it seems too localized to be due to lake water.

Sources (in addition to links in post)

Case, WF. 2002. Geosights: Pahvant Butte in the Black Rock Desert, Millard County, Utah. (accessed 18 June 2017).

Farrand, WH, and Singer, RB. 1991. Spectral analaysis and mapping of palagonite tuffs of Pavant Butte, Millard County, Utah. Geophysical Research Letters 18: 2237-2240.

Gilbert GK. 1890. Lake Bonneville. US Geol. Surv. Monogr. 1: 1– 438.

Oviatt, CG, and Nash, WP. 1989. Late Pleistocene basaltic ash and volcanic eruptions in the Bonneville basin, Utah. Geo. Soc. Amer. Bull. 101: 292-303.

White, JDL. 1996. Pre-emergent construction of a lacustrine basaltic volcano, Pahvant Butte, Utah (USA). Bull. Volcanol. 58: 249–262.