Friday, October 31, 2014

On the Road: Final Geo-challenge

Where am I?  what's all that weird orange rock?!  maybe I was out too long.
Plants and Rocks is back from vacation, with one more geo-challenge to share.  But I had to wait until today to post it (hint).
It was a land of strange and eerie rock creatures – hundreds of them!
Those in the prime of life were spooky ...
... but the old and dying evoked sympathy.  Though made of rock, their lives are short.
Where on Google Earth? Click on image to see hordes of rock creatures southeast of parking lot.

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(music – Ghosts in the Kitchen, © Poorpersons Enterprises 2003)

Monday, October 27, 2014

On the Road: Geo-challenge 2

Where are we now?  View is from behind, as the sun sets.
Plants & Rocks is still on on the road and finding it hard to blog, so here’s another quick geo-challenge.  The first was the geologically very cool Uinta uplift; more on that later.  Then I visited another Laramide range.  This one has an unmistakable east flank – too easy for a geo-challenge.  Instead, here are views “from behind”.
Sandstone cliffs in evening light with a laccolith in the distance.
Another laccolith on the right horizon – in fact the type locality.
Morning view.  The large mesa to the southwest is capped with volcanic rocks.
In the “high country”.  No Precambrian rock is exposed, and the vegetation is piñon-juniper woodland.

Wednesday, October 22, 2014

On the Road: Geo-challenge 1

Where are we?

Plants & Rocks is on vacation.  First destination was an east-west mountain range often described as an anomaly because contemporaneous ranges mostly trend southeast-northwest.  Actually there are several others like it, though not as large.  This one may have been influenced on the north by the Cheyenne Belt -- an east-west suture zone where crust was accreted to ancient North America roughly 1.5 billion years ago.
Red sedimentary beds on left are Precambrian.  They fooled all three early geological explorers.
The Precambrian core of the range is sedimentary – conglomerate, sandstone, siltstone and shale.  Sediments were deposited in a rift valley when the continent was coming apart, close to where it had been sutured.  It didn’t tear all the way, but was deep enough to accumulate 20,000+ feet of material.
Something like seven hundred million years later, the east-west mountains rose during a great regional mountain-building event (below).
Sedimentary strata on the flanks of the uplift were steeply folded, making for great scenery.  Some roads follow strike valleys between spectacular hogbacks.
The sedimentary rocks are just as wonderful on the south side of the mountains – like the ones below.
Josie Bassett ranched here at the mouth of the box canyon until she was 89.  “Independent in both action and thought, she lived life on her own terms.”

Sunday, October 12, 2014

Walking the Devil’s Backbone

Driving home from Rocky Mountain National Park we stopped just a few miles west of Loveland, Colorado, to examine the Devil’s Backbone.  How could we not?!  It’s an eye-catching landform and there’s a trailhead at the south end, right off Highway 34.

Demonic geologic features are common in Colorado -- there are at least twenty-one (Colorado Geological Society 2009).  Curiously, all are composed of either igneous rock or Mesozoic sandstone (Mesozoic means 252-66 million years old).  Some early geologists assumed the Devil's Backbone was igneous, a dike.  It has that look -- long, linear and narrow.  But then someone investigated and found it’s Mesozoic sandstone, specifically the Dakota sandstone -- sediments deposited by rivers flowing into an interior seaway to the east roughly 100 million years ago.
Here the Dakota is a mix of fine and coarse river deposits.  Note nearly vertical orientation of beds.
Along the Front Range of the Rocky Mountains, the Dakota forms hogbacks -- ridges of steeply-tilted sedimentary strata.  In the Devil’s Backbone the sandstone is really steep, basically vertical.  It's part of the west flank of a small anticline (uplift) east of the main Rocky Mountain uplift.  The more gentle east flank of the anticline is visible from the trail.  In the next photo, it's marked by rimrock with trees on the horizon, above boulder-strewn slopes.  The Triassic red Chugwater Formation is exposed in the valley below.  The valley also contains the “crest” of the breached anticline (cut through by erosion.)
Looking from the Backbone toward the hogback on the east flank of the anticline. 
The Wild Loop trail along the Devil’s Backbone is about two miles roundtrip, and is an easy stroll.  A short spur leads to the “Keyhole” where you can stand among the Devil’s vertebrae!
A demonic vertebra.
The Keyhole.
Long's Peak (Rocky Mt NP) from inside the Keyhole; Dave's finger rests on summit (click on image to view).
For more information, download the trail brochure provided by Larimer County’s Parks and Open Spaces.  This is the southern end of a network of trails extending north along the Front Range to Fort Collins.  Consider a weekday visit.  It’s popular, and the parking lot often fills on weekends.

NOTE:  The Devil has multiple backbones -- at least eight in the USA.

Tuesday, October 7, 2014

Tree-following: that first question

Do you remember that first question ... back in February when the cottonwoods were leafless, the ground in snow, and the river under ice?
“Is this a single individual, connected underground?”
Time passed, more questions arose:  What kind of cottonwood? (lanceleaf)  How tall? (58.4 feet)  Male or female? (female).  But the first question was never answered.
Cottonwood at dawn.  Is this a single tree, or six?
Most cottonwoods send up suckers -- shoots from buds on the roots.  Old stumps and even fallen branches sometimes produce shoots that grow to maturity.  So it’s reasonable to suspect that this clump is a single individual.  Most cottonwoods along the Laramie River are clumped like this.
Lanceleaf cottonwoods along the Laramie River in early morning light.  Note bird on wire (more later).
Then a clue appeared.  The east half of the cottonwood tree I'm following is now yellow, the west half still green.  Perhaps this isn’t a single tree after all.  We investigated.
My cottonwood tree(s) -- now green and yellow.
Its canopy.
Glen at base of tree(s).
We crept into the little glen among the trunks.  The sound of pitter-patter footsteps and buzz-like whispers swelled and then quickly subsided -- probably river elves fleeing their sanctuary.  To the east towered three stems (maybe-trees) with yellow leaves.  Two to the south still had green leaves as did the younger one to the northwest, which split just above the ground.
Three stems with yellow leaves (green ones belong to stems on right out-of-sight).
Two stems to the south still sport green leaves, though they're fading.
This younger stem became two at some point.
So how many trees?  Might we say at least two -- the yellow and the green?  Then a vague distant memory from botany-student days surfaced.  Being immobile, plants may resort to phenotypic plasticity and produce different forms from the same inherited DNA.  Besides, I like the whole clump and want to follow it.  Are you wondering how one follows an immobile organism?  Apparently you don’t know of the tree-following frenzy hosted by Lucy Corrander.  Visit this month’s gathering to learn more.
A bird with a distinctive silhouette.
Back to the bird on the wire.  A belted kingfisher has been fishing from this wire across the river just upstream from the footbridge for at least 20 years.  As the EPA says, “No information was found in the literature on life expectancy for this species.”  So every year I wonder:  Is this a single bird, or many?
Sometimes our “intrusions” benefit wildlife -- belted kingfishers love telephone wires near streams and ponds.


Tuesday, September 30, 2014

Urban Tumbleweeds -- free & hardly lonely

Tumbleweeds are integral to our beloved American West -- a land of wide open spaces where tumbleweeds, cowboys and other free spirits can go wherever the wind takes them.  They symbolize the revered rugged individualist -- loyal only to his own personal code.
Lonely but free I'll be found ... drifting along with the tumbling tumbleweeds.
The Drifting Cowboy (Tumbleweed Series), 1925.  Source.
But truth be known -- tumbleweeds are foreigners.  They snuck in from Eurasia, probably in the 1800s in “contaminated” feed.  And contrary to Western myth, they do just fine within the confines of town.  So when Lucy Corrander offered to host a virtual Street Plants gathering, urban tumbleweeds came to mind.
Tumbleweeds grow as the situation allows -- small in small spots, bigger where there's more space.
The “tumble” in their name comes from what they do.  These are traveling plants.  After they die and dry out each fall (being annuals), they break loose and tumble along, blown by the wind.  Seeds fall out along the way, or wherever the tumbleweeds land -- lodged against fences, under cars, or in trees.
The “weed” part of their name means they’re unwelcome.  That's due largely to their fecundity, which is astonishing (more below).  The results can be overwhelming ... as when unwelcome tumbleweeds invaded Clovis, New Mexico.  Neither man nor machine could handle the unruly plants.

Based on yearly inventories of my hedge, trees and fences, three species of tumbleweed inhabit our neighborhood.  Most common by far is kochia or summer cypress (Kochia scoparia).  Mature plants range from a single short stem to robust branching individuals up to six feet tall.  In a good year, a large plant may produce 50,000 seeds; the average is 14,600 (source).  And that’s a relatively small tumbleweed family! (more below).
Tiny kochia waif takes back the street.
Robust summer cypress, all decked out in fall colors.
Kochia hedge, drying in preparation for travel.
Kochia showing broken-off stem.  There’s a separation or abscission zone near the base of each plant.

Russian thistle (Salsola kali, S. tragus or Kali tragus) is the “tumbleweed” of Western legend, though in our neighborhood it’s not even half as common as kochia.  Mature plants may be up to five feet in diameter, and are oval to round -- made to roll.
Photo by Forest & Kim Starr, via Wikipedia.
Like kochia, Russian thistle scatters seeds as it tumbles along.  But the winged seeds can travel with the wind too, independent of their parents.  The reproductive output of this tumbleweed is massive -- a "typical" plant sows 250,000 seeds (source).
See them tumbling down ... pledging their love to the ground
Green Russian thistle, with drying summer cypress to right and behind.
Maturing Russian thistle has a beauty to it  -- pink and green and a bit fleshy.
The small leaves of Russian thistle are sharp-tipped when young, get even sharper with age (above), and become hard and penetrating when dry.  Lambs get mouth sores if they eat dried tumbleweeds, and cowboys wear leather gloves to clean them from fences.
Young Russian thistle with flowers in leaf axils.  Photo by 

Tumble mustard (Erysimum altissimum) is the least common and least familiar of our tumbleweeds, but look around and you’ll always find some.  In fact, my yard inventories show it to be almost as common as Russian thistle.  Plants are similar to Russian thistle in size but are even more fecund -- a single plant is said to produce up to 1.5 million seeds -- unbelievable!  Tumble mustard has several adaptations not found in the other tumbleweeds. Their pods shatter slowly, so seeds are scattered farther afield as the plant tumbles.  Kochia and Russian thistle seeds don’t survive more than a year, but tumble mustard can generate sizable seedbanks lasting 40 years or more (source).
Last year a tumble mustard dropped seeds by these PVC pipes.  Now an offspring is ready to take off.
There’s a nice geometry to tumble mustards, with their wide branching.  Thin green structures are seedpods.

In the photo below, all three tumbleweeds line up side-by-side, with many more behind. Soon they'll break loose and roam ... drifting east with the wind.
Left to right:  tumble mustard, kochia and Russian thistle.
I'm a roaming cowboy riding all day long ... tumbleweeds around me sing their lonely song.  Nights underneath the prairie moon ... I ride along and sing this tune:
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 Tumbling Tumbleweeds, written by Bob Nolan, 1930s.