Thursday, July 23, 2015

Stuck – in a Land of Flat Plants

Plant specimens waiting to be shelved for posterity.
Lucy Corrander says it’s time for the next stuck-foot gathering already!  I was caught by surprise, but I knew I would be “stuck” in the Rocky Mountain Herbarium, with my camera, so I made it a dual-purpose visit.  I wasn’t “stuck” as in “be or remain in a specified place or location, typically one perceived as tedious or unpleasant” (New Oxford American Dictionary).  I like being in the herbarium.  Rather I was “stuck” as directed (but not randomly ... sorry, Lucy)
“plant your foot firmly in a roughly random place and see what you can see without moving.  Best is when you plant both feet.”
Aven Nelson's vasculum and field books.
I planted both feet on a table in the prep room – yes, on top of it – so I could point the camera straight down on memorabilia of Aven Nelson, Father of Wyoming Botany.  Nelson came to Laramie, Wyoming Territory, as one of five faculty hired for the brand new university in 1887.  He was to teach English, but the Board of Trustees mistakenly hired two English professors; the better-qualified Mr. Smith got the job.  Nelson was asked to teach biology, botany, horticulture, agriculture and calisthenics, and to oversee the library.  He accepted.  After several years, his responsibilities narrowed to botany and horticulture, and finally just botany.  Largely self-taught, he had a long and illustrious career.  The Rocky Mountain Herbarium is generally considered to be his greatest contribution.
In the old days a botanist put collected plants in a vasculum while in the field.  Now we mostly use plastic bags.
Some readers may ask “What’s an herbarium?”  It’s a collection of preserved plants – specifically plants or plant parts that have been dug up or cut off, pressed, dried, and mounted on 11.5” x 16.5” archival paper, usually with water-based glue.  In the old days, plants were attached with thin strips of tape, or even sewn to the sheet.  A label contains information about where the plant was collected, habitat, collector and date, and anything else noteworthy.  People sometimes think there must be a protective cover, but not.  Yet when properly processed and stored, herbarium specimens last centuries.

The sheets are stored in folders in air-tight cabinets – organized by family, genus, species, and subspecies and variety if applicable.  There are 825,000 mounted specimens in the Rocky Mountain Herbarium.  Another 350,000 are still in newspapers, waiting to be processed.
Gray alder collected by Aven Nelson and Elias Nelson (not related) in Yellowstone Park in 1899.
Label from the gray alder specimen.  Elias was Aven Nelson's first graduate student.
Nelson's Yellowstone field book; gray alder entry is on the right.

This being summer, Wyoming field botanists are at work right now processing the day’s harvest (it’s 8 PM as I write).  Plant specimens are removed from plastic field bags, cleaned of dirt, and placed between sheets of newspaper – carefully arranged to show everything a future researcher might want to examine.  Collection data are recorded in a field book or digital device.  The specimen is added to a growing stack, alternating with corrugated cardboard.  This continues until all plants are in the press, then it's bound tightly with cord or straps, and set somewhere to dry.  Botanists in base camps with electricity can use a plant drier, where the heat of 100 watt light bulbs circulates through the cardboard, drying plants in several days or less.  The more transient may use the dashboard of their field vehicle parked into the sun, or tie the press to the vehicle roof if the weather is hot.
Tools of the trade (I didn't take this photo from the prep room table).
In the old days, plants were dried using felt blotters between specimens in the press.  Every day they had to be replaced with dry ones.  Keeping a supply of dry blotters on hand was a miserable job in wet weather:
"We sit for hours before a hot camp fire, with the sweat pouring down our face, to completely dry our papers and plants.  How I wish the plants dried at once, but often it takes several days and sometimes a week." (unknown collector, in A Wild Flower by any other Name by Karen Nilsson)
Leslie Goodding, Aven Nelson's 19-year old student assistant, pressing plants in Yellowstone Park in 1899.  It must be the end of the field season judging by his shoes (click on image to view).

Large batches of dried plants periodically arrive at the Rocky Mountain Herbarium to be added to the collection.  First they’re put in a deep freeze to kill any pests, then they’re added to the backlog of specimens waiting to be mounted.  When it’s their turn, collection data are entered into a database, and herbarium labels are printed.  Everything then goes to the prep room – where my feet were stuck.  It’s here that dried pressed plants and their labels are glued to sheets of paper.
Plant mounting station.
Newly-mounted plants are stacked with wax paper and felt sheets between specimens, and left to dry overnight.  Sand-filled sections of inner tubes are used as weights.
Though my feet were stuck, I could twist around far enough to see the clean-up area.

Why do we do this?  … because we can’t just say that a particular plant species grows in particular place, even if we are “experts.”  If we document our report with a specimen – deposited in a reputable accessible repository – all kinds of potential problems are avoided.  Everyone makes identification errors, even experts.  Plant names may revised with additional study – and our specimen can be used for such studies.  And on and on, as Vicky Funk of the US National Herbarium convincingly explains in 100 Uses for an Herbarium (Well at Least 72).
To my right I had a view of herbarium cabinets (above).  At the Rocky Mountain Herbarium, cabinets are on tracks that can be shifted to open up aisles, a system called … but wait!  Who is that man at the very end of the row, staring at me?!
His gaze was stern.
It was Aven Nelson, Father of Wyoming Botany, watching over his herbarium.

While I was staring back at Dr. Nelson, another botanist showed up.  Laurie asked why I was standing on the table.  When I explained, she chuckled and kindly posed for a photo.

Thursday, July 16, 2015

Beautiful Stones & Battered Relics

"what rolled pebbles are to the Geologist—Battered relics of past ages often containing within them indelible records capable of intelligible interpretation" (John Herschel to Charles Lyell, 18361) 
Three years ago, I walked up a desert wash in Utah that was littered with beautiful multicolored stones – hard igneous and metamorphic rocks worn smooth.  They seemed out-of-place in a land of soft red sandstone, and in a sense they were.  For their birthplace had disappeared long ago – a mountain range now gone.  Their enchanting ghost-like presence was irresistible.

Those stones have been in the back of my mind ever since.  I’ve wanted to visit their vanished source, the ghostly range.  Last May I finally did.  It was gone of course, but I stood on the remains of its slopes, and marveled at how we can conjure up the distant past from battered stones.
Standing on an ancient alluvial fan.

The hard smooth stones I found in the wash and the surrounding soft red rocks all belong to the Cutler Formation.  Pinnacles, balanced rocks, sculpted ridges, and the like are often called “rock formations,” but geologists use the term more formally.
“A formation is a rock unit that is distinctive enough in appearance that a geologic mapper can tell it apart from the surrounding rock layers.  It must also be thick enough and extensive enough to plot on a map.” (Utah Geological Survey)
Geologist is on right.
Rocks of the Cutler Formation are sedimentary – made of debris deposited roughly 300 million years ago, during the early Permian Period.  When I traveled from the southeastern corner of Utah to western Colorado last spring, I watched the Cutler change – from mudstones to sandstones to conglomerates. This diversity is revealing.  It’s how we discern a mountain range that’s been gone for at least 150 million years.

These rocks are Herschel’s “battered relics” with “indelible records capable of intelligible interpretation.”  But to interpret them intelligently, geologists must determine the grain size of their sediments:
Classification of grains by size (source of values).
Measuring and classifying grains is tedious but informative.  Grain size speaks to the environment of deposition and the proximity of the source.  Even the laziest stream can carry fine sediments, often far from their origins.  Larger grains need more energetic transport – faster streams on steeper gradients.  The largest – boulders – are carried only by raging torrents, and dropped close to the source.
Click on image for larger view (unlabeled diagram from Fillmore 2011).

In the southeastern corner of Utah, Cutler rocks include a lot of mudstone – fine sediment carried all the way to what was then the coast of North America.  Wind-blown sand formed dunes, now sandstone.  Sometimes the sea advanced, adding limey mud which became thin beds of limestone.
Cutler slopes below cliffs of Cedar Mesa sandstone, viewed from the Moki Dugway.
Cutler outcrops capped with Cedar Mesa sandstone in the Valley of the Gods.

About a hundred miles to the northeast, in Fisher Valley near Moab, the Cutler Formation is noticeably coarser – mostly sandstone with beds of gravel and cobbles.  Cross-bedding is common, both eolian (wind) and fluvial (streams).  It’s thought that braided networks of streams crossed this area, sometimes passing through isolated dune fields.  Braided drainages mean the gradient had dropped significantly and streams lost energy.  This happens today below mountain slopes – below their alluvial fans (Fillmore 2011; see diagram above).
Fisher Valley is where I found beautiful stones in a wash three years ago.
One of the Fisher Towers, with fluvial (stream-deposited) sandstone and layers of gravel (click on image to view).

Last May I went to Gateway, Colorado – 15 miles northeast of Fisher Valley – to see “the only exposures of the very coarse, most proximal [closest to source] Cutler Formation” (Fillmore 2011, italics added).  It took only a bit of searching to find some, below the Palisade.  Here was the Cutler very near its ghostly source!
Lower red slopes are the Cutler Formation; northwest of Gateway, east of Dolores River.
Next photos are from the outcrop on the bottom half of this slope.
This is only 15 miles from Fisher Valley, but the sediments are much coarser.
Cobbles and boulders carried by energetic streams; the source wasn’t far away.
A Cutler road is a rocky road!
Conglomerates alternated with sandstones and mudstones.  These deposits have been attributed to swollen mountain streams that overflowed their channels, dropping rocks and mud on alluvial fans (Fillmore 2011).
The stones were as beautiful as the ones I found in the wash in Fisher Valley three years ago – polished multicolored igneous and metamorphic rocks.
Conglomerates are sedimentary rocks even if the clasts (fragments) are igneous and metamorphic.

I found another photogenic Cutler outcrop, with everything from boulders to mudstone. Cross-bedding was obvious.  Looking at these "battered relics" it was easy to imagine engorged streams rushing down mountain slopes, dropping debris as they slowed. 
Are the thin white layers caliche?

During the early Permian, southeastern Utah and western Colorado were dominated by Uncompahgria (illustration based on interpretations from Fillmore 2011).
The fine-to-coarse progression of Cutler sediments, from southeastern Utah to western Colorado, points clearly to the source.  It was mighty Uncompahgria – one of the ranges of the Ancestral Rocky Mountains.  We often think of mountains as massive, abiding and immutable, but they too have lifetimes.  Uplift of Uncompahgria began about 300 million years ago, and for a time it stood high.  But after a hundred million years, erosion had reduced it to a low rolling landscape.  Fifty million years later, it was gone.
“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.” (from We too are ephemeral ... just like mountains)
After a 250-million-year layover on the slopes of Uncompahgria, these stones are again on the move, headed down a wash.


Footnote:
1  The quote at the top of the post comes from a letter from astronomer John Herschel to geologist Charles Lyell, an important early proponent of Uniformitarianism (Cannon 1961).  See Suvrat Kher's recent post at Rapid Uplift.


Sources (in addition to links in post)

Cannon, EF.  1961.  The impact of uniformitarianism: two letters from John Herschel to Charles Lyell, 1836-1837.  Proc Am Phil Soc 105:301-314.

Ege, C.  2004.  GEOSIGHTS: Fisher Towers – the towering red rock sculptures of Grand County, Utah.  Utah Geological Survey.

Fillmore, Robert. 2011.  Geological evolution of the Colorado Plateau of eastern Utah and western Colorado.  Salt Lake City: University of Utah Press.


Tuesday, July 7, 2015

Water! (tree following in July)


We’re having a wet summer here in normally-sunny Wyoming.  Field botanists sit in soggy tents, waiting.  Fire lookouts sit in their towers reading book after book in fog, mist and rain.  Impassable dirt roads stay impassible as plants grow, bloom and go to seed, unobserved.  I come home to a yard that's a jungle and too wet to mow except that … 

This no longer applies.  I’m retired.  But I haven’t forgotten.

Those memories were vivid this morning.  I needed to check my tree, as the monthly gathering of tree-followers is upon us.  But it was raining again.  So I rounded up my anorak, inexpensive camera and field assistant, and headed out.

I hoped with all the rain there would be water in the dry canyon where my willow grows.
Willow Canyon is upstream from the notch on the right skyline.
Sure enough – in the normally dry wash about a quarter mile below Willow Canyon, a creek was flowing out toward the prairie (above).  Further upstream it ran over limestone outcrops. The drought-tolerant plants in the cracks had their feet in water.
Limber pine (Pinus flexilis) in shallow water – barely visible as slightly darker limestone.
Gumweed (Grindelia squarrosa) had its head just above water.  The creek must have been higher earlier … there's debris hanging off the flower head.
The field assistant was extra happy with the pools.
I reported the exciting news and soon additional recruits arrived.
We reached Willow Canyon – the creek was flowing there too.  Fortunately it wasn't raining, but I still had to wear my anorak because the mosquitos were so thick.
Willow is on the left – the slightly shorter tree against the cliff, between two junipers.
The willow grows where a side drainage meets the canyon, sending water down off the rim.  In fact, this side drainage was providing all the water for the creek below.  The main canyon upstream was dry.

There was even a sizable pool at the base of the willow.  Today this looks very much like willow habitat!
Willow nook a month ago.
Willow nook today.
The little waterfall was well hidden.  But I climbed around just east of the willow and recorded singing water falling from sky to pool.
video

North of the canyon we followed the creek downstream to the rim.
The creek runs over limestone pavement.
Getting close – bright green patch between two junipers upper left is top of willow.
Looking for kitties in the lush canopy (this is the American pussy willow, Salix discolor).
The creek at the canyon rim.  But it doesn't jump off here.
Instead, it runs into a crevice to become the waterfall below.

How nice that Nature provides such interesting things to ponder!


You should!  Read more about tree following here.