Shear Beauty along the Highway

Crenulated beds (chevron folds) with alpine phlox.

Wyoming Highway 130 crosses the Medicine Bow Mountains west of Laramie.  North of the highway immediately beyond the turnoff to Brooklyn Lake are low dull-brown slopes that I’ve ignored for 30+ years.  Foolish me.

On the "dull" brown slopes are glacially-polished slate outcrops with fine multi-colored folds. The outcrops aren't extensive, but the patterns and colors are so intriguing that I stayed almost an hour looking at rocks and plants.

This is the French slate, exposed in the Mullen Creek - Nash Fork shear zone -- part of the Cheyenne Belt, a dramatic geologic structure that crosses southern Wyoming.  Rocks south of the Belt are Proterozoic (really old, 1.72 to 1.75 billion years); those to the north are Archean (really really old, two billion years or more).  Roughly 1.7 billion years ago, oceanic arc terranes collided with Wyoming along what was then the southern coast of North America, creating “the best agreed upon suture zone in the Precambrian of the western United States” (Whitmeyer and Karlstrom 2011).  The French slate was caught up in the mayhem and beautifully folded.

The green Yavapai province, a collection of oceanic arc terranes, was sutured to the south coast of North America along the Cheyenne Belt in what is now southern Wyoming (click on image to view; arrow added).  Modified from Whitmeyer and Karlstrom (2011).

The deformed slate seemed quite durable.  I couldn’t find any small fragments to take home, and cracks and soil pockets for plants were few.

Requisite ruler for scale (6 in, 12 cm).

Fernleaf daisy in a narrow shallow fracture.

Mountain candytuff in a small soil pocket.

Lichen grow on the rock surface, over fine-scale folds.

Grouse whortleberry and common juniper (lower right) surround a small outcrop of deformed slate.

The French slate is thought to have started as fine sediments deposited in deep ocean waters off the southern coast of North America (Lanthier 1979).  Then along came the colliding oceanic arc terranes, and the ocean was squeezed out of existence.  We say "collision" but it was hardly a single dramatic event.  Whitmeyer and Karlstrom estimate it took place 1.76 to 1.72 billion years ago -- a period of 40 million years.

It's so hard to grasp geologic time at these scales!  The quartzite boulder below is much easier.  It's an erratic left by a glacier 12-16 thousand years ago -- just recently.  The glacier also polished the folded French slate, a nice touch.

Glacial erratic made of Medicine Peak quartzite; it was carried down from the high Snowy Range to the west.

How to get there

From Wyoming Highway 130 roughly 7.5 miles northwest of Centennial, turn north (right) on the road to Brooklyn Lake.  Almost immediately turn left into the Nash Fork Campground if it’s open (recently it hasn't been) or park nearby.  From the bulletin board/restroom area near the entrance, walk 20 to 30 yards west to the brown outcrops just above the highway.  The folds are obvious.

From Google Maps.  Arrow shows location of outcrops.

Sources

Hausel, WD.  1993.  Guide to the geology, mining districts and ghost towns of the Medicine Bow Mountains and Snowy Range Scenic Byway.  Geol Surv WY Public Info Circ 32.

Lanthier, R.  1979.  Stratigraphy and structure of the lower part of the Precambrian Libby Creek Group, central Medicine Bow Mountains, Wyoming.  Contrib to Geology, Univ Wyoming 17:135-147.

Whitmeyer, SJ and Karlstrom, KE.  2011.  Tectonic model for the Proterozoic growth of North America.  Geosphere 3:220-259.

Fall Flower Selfies

Sunflower selfie (Helianthus annuus).

“Selfie” was the Oxford Dictionaries Word of the Year in 2013:

selfie noun, informal (also selfy; plural selfies):  a photograph that one has taken of oneself, typically one taken with a smartphone or webcam and uploaded to a social media website 

Courtesy of randomtruth; used with permission.

Did you know that animals other than humans take selfies?  They trigger cam traps and then a human uploads them to social media.  My current favorites feature pygmy rabbits (above) and their neighbors (like the young coyote below), posted by randomtruth at nature of a man.  It’s wonderful to see these guys going about their daily business unperturbed by us.

Courtesy of randomtruth; used with permission.

As a botanist, I’m envious.  Few plants move enough to justify cam traps.  I thought it would be interesting and fun to help wildflowers take selfies.  But results were mixed.

I started in the backyard, where I could figure out logistics without anybody staring.

It's easy to forget that the camera lens is on the side of the iPad.

Marigolds are still holding on, in spite of the frost.

I put the iPad mini in selfie mode.  Plants can’t use a touch pad as leaves don’t conduct nearly as well as fingers, so I triggered the camera for them.  Rarely were both flowers and photographer in the frame and in focus, so I gave up on that approach.  I just pointed the screen at the plants, pushed the button from the side, and hoped for the best.

It’s been fall here for awhile.  Some days are warm, some are cool, leaves are turning color (there was a frost two weeks ago), and late-season wildflowers are in bloom.  Most are yellow and members of the aster family (Asteraceae) ... but not all.  Let’s have a look.

I walked through the light-industrial/riparian ecotone west of my house, and then along the path by the Laramie River.  Many late-season plants were in bloom and fruit.

Golden aster, Heterotheca villosa.

Curly-cup gumweed, Grindelia squarrosa.  In the close-up below, an arrow points to the “curls” on the “cup” (involucre); click on image to view.

Dandelion (Taraxacum officinale) grows almost everywhere, and all through the growing season.

Families other than Asteraceae were occasionally represented.

Yellow sweetclover (Melilotus officianalis, pea family); it's native to Eurasia.

Tumble mustard (Sisymbrium altissimum, mustard family) is Mediterranean.  This is one of our tumbleweeds -- plants that dry, break off near the ground, and tumble blown by the wind, dropping seeds along the way.

What’s this?!

It’s purple mustard, Chorispora tenella.  This is one of the first plants to bloom in the spring, then it dries up and disappears.  Apparently it occasionally blooms late in the season too.  The things we learn when we look close!

Purple mustard is another introduction from Eurasia.

Me and my tree -- the lanceleaf cottonwood I’m following.  It flowered in May.

“We” took many many photos.  It was very much trial-and-error, mainly because I couldn’t see what was framed.  Eventually my aim improved, so much so that the photos degenerated into simple compositions with none of the charm of selfies.

Wikipedia says selfies “are usually flattering and made to appear casual.”  I’m no expert, but I would add that perspective is somewhat odd.  Also, the composition is often unexpected and, when we’re lucky, whimsical -- like the earlier coyote legs and nose.  I adjusted accordingly.

A casual shot of dandelions casting their seeds to the winds.

One of our purple-flowered wild asters.  Flattering?  I think so.  And nicely out-of-balance.

Firewheels or blanketflowers (Gaillardia aristata), with bumblebees intent on finding food and not the least bit bothered by my intrusion.  (Subjects out-of-focus, background sharp.)

Two sunflowers (Helianthus annuus) with prairie coneflowers (Ratibida columnifera) behind.

Rabbitbrush (Chrysothamnus or Ericameria nauseousa) above and below.

Of course these aren’t true selfies.  But I couldn’t resist poking a little fun at this extremely popular and most curious phenomenon.  What drives our selfie-ing?  All kinds of things it seems to me:  narcissism, whimsy, social nature, hope ... for acceptance or immortality, desire to hang onto good times, or maybe just the need for a good chuckle.

These are Emmie’s first selfies, taken with Photo Booth on a MacBook Pro, and random steps on the keyboard.

Even though Emmie triggered the camera herself, she probably didn’t “make a creative contribution to the work” so she can’t copyright the photos.  But this is a moot point because Emmie isn’t human.  So if you want to use her photos, feel free.  For more explanation, see this article about copyrighting selfies.

Emmie is the newest addition to the Plants and Rocks team.  She loves plants and rocks and everything else.  Black Dog Animal Rescue advertised her as a comedian and entertainer ... and they were right!  She plays with athleticism, enthusiasm and whimsy -- speeds away, leaps in the air, turns so sharply she almost loses her footing, comes flying back, passes me just out of reach, soooo happy.  Then she takes off again ... and again ...  And when I point a camera at her, she poses!  So selfies are understandable ;-)

A real ham (I shot this one).

Geo-dog in-training contemplates 2-billion-year old quartzite tilted to vertical; Snowy Range.