Shedding some light on the colorful limestone overhang

Last week you heard about and saw two pictures of a limestone overhang in a hard-to-reach section of Great Hills Park. I mentioned that direct sunlight never reaches the overhang’s wall and ceiling. That said, the floor of the overhang is a creek bed; with enough water in it, and with the sun low enough in the sky, some rays of light bounce off the water and onto the ceiling of the overhang. Because the water’s surface isn’t perfectly still, the reflected light shimmers overhead, as you see in today’s picture from June 10th.

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And here’s a clever quotation for today: “If somebody thinks I’m cherry-picking, show me the other part of the tree.” — Steven E. Koonin in a televised interview about his book Unsettled on May 25, 2021. Also unsettled is the question of why English speakers have picked cherry-pick rather than the alliterative peach-pick or plum-pick, or else apple-pick, lemon-pick, or some-other-fruit-pick. Maybe cherries got picked because they’re small, and therefore cherry-picking is like nit-picking. One thing’s for sure: cherries make for a much tastier pie than nits. And did you know that cherries was originally the singular of the word? We got it from Anglo-Norman cherise. But that sounded to the folks in merry old England like it was a plural, along the lines of berries and ferries, so they created a new singular, cherry. Linguists call that process back-formation, for which today’s picture of the geological formations at the back of the overhang is therefore appropriate. What fun to lead you from limestone to linguistic information and back again.

© 2021 Steven Schwartzman

A colorful limestone overhang

I live in northwest Austin’s Great Hills neighborhood, which is home to the unsurprisingly named Great Hills Park. An isolated arm of the park, seldom reached because getting there entails walking in a creek and pushing past various obstacles, houses a long limestone overhang. Given the geography and the position of the sun throughout the year, direct light doesn’t fall on the overhang’s ceiling or most of its back. An approaching visitor will initially see the inside of the overhang as very dark, though eyes do get somewhat accustomed after a person has been under the overhang for a bit. Even so, the dimness makes it hard to appreciate the ways in which seeping water over eons has colored the stone. I used flash to light up the formations and reveal the pastel colors that you see in these two images, both from June 10th.

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Did you hear about the family in Edinburgh that has six living generations?

© 2021 Steven Schwartzman

Textures of different kinds

At the Doeskin Ranch in Burnet County on March 24th I focused on textures of different kinds. The photograph above reveals a prickly pear cactus pad from which all the outer covering and inner cells and water had passed away, leaving only the sturdy structure that once supported them. In contrast, the picture below shows a rounded, colorful patch of lichens on a boulder.

For those interested in the art and craft of photography, I’ll add that the first photograph exemplifies point 4, and the second one point 15, in About My Techniques.

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A theme I’ve been pursuing here for a week now is that it’s common to hear politicians and activists bandy about the phrase “common sense,” which is a loaded and misleading term because some or even many things that a majority of people believe to be common sense can be shown not to be true.

Here’s a simple example from the everyday world of buying and selling. Suppose an item in a store goes up 50% in price and later comes down 50% in price. A lot of people would say it’s “common sense” that the rise in price and then the fall in price by the same percent would bring the item back to its original price; in this case the +50% and the –50% would cancel each other out.

Alas, that bit of “common sense” isn’t true. To see that it’s not, let’s give the item in question a specific price, say $40. After that price goes up by half (+50%), it’s $60. After the $60 price gets reduced by half (–50%), it drops to $30. The new price is less than the original $40 price, not equal to it.

Now let’s go a step further. In the real world, switching the order of two actions usually leads to different results. For example, mixing the ingredients for a cake and then baking them will give a very different cake than the one you’d get by baking the ingredients first and then mixing them. Waiting for an empty swimming pool to fill up and then diving head-first into it is recreational; diving head-first into an empty swimming pool and then waiting for it to fill up could well be fatal.

With those examples in mind, it seems “common sense” that if we go back to our example of prices and reverse the order of the two equal-percent changes, we might well get a different result. Specifically, what will happen if this time we first apply a 50% decrease to a price and then a 50% increase? Last time the final price ended up lower than where it started. By reversing the order of the changes, might the price now end up higher than where it started? As I used to say to my students: when in doubt, try it out. Beginning once again with a price of $40, if we reduce it by half (–50%) the new price is $20. If we now increase that $20 price by half (+50%) the final price is $30. The result comes out exactly the same as before: the original $40 price will still end up getting reduced to $30. Unlike many things in the real world, in this situation reversing the order of our actions makes no difference.

© 2021 Steven Schwartzman

What do these two have in common?

What the great blue heron (Ardea herodias) has in common with the variegated stone and its shadow is that I photographed them both at Muir Beach in California four years ago today. You might also find that the forms and colors of the heron’s feathers resemble those on the stone.

And here’s a relevant poem for today:

“The Peace of Wild Things”
by Wendell Berry

When despair for the world grows in me
and I wake in the night at the least sound
in fear of what my life and my children’s lives may be,
I go and lie down where the wood drake
rests in his beauty on the water, and the great heron feeds.
I come into the peace of wild things
who do not tax their lives with forethought
of grief. I come into the presence of still water.
And I feel above me the day-blind stars
waiting with their light. For a time
I rest in the grace of the world, and am free.

© 2020 Steven Schwartzman

3-D

 

 

Here’s something different: a stereo* pair I took at a quarry in Cedar Park on September 14, 1980—40 years ago today! To see the image in 3-D, I suggest you get about 15 inches away from the screen and line each eye up with the matching half of the pair. Look straight ahead, then relax your eyes. Once you get used to things, the left half should drift a bit to the left, the right half a bit to the right, and in between them should appear a fused image of the two halves. If you manage to discern that middle image, your brain will interpret it as 3-D and you’ll see the big slab and the boulders behind it as having depth; the cloud was too far away from the foreground to have any depth. People’s vision varies enormously, so to get 3-D you may have to enlarge or shrink the images on your screen, or view the screen from closer or farther away, or put on or take off glasses, or drink a magic potion. Whatever you do, don’t close one eye; it takes two eyes to see 3-D, which is why we have two eyes. (People who have lost the sight of one eye or close one eye retain their sense of how things look in the physical world and may imagine they’re still seeing in 3-D, but they aren’t.)

Here’s a related fact for today: well-known movies filmed in 3-D include “House of Wax” (1953), “Kiss Me Kate” (1953), “It Came from Outer Space (1953), “Creature from the Black Lagoon” (1954), and “Dial M for Murder” (1954).

* We’ve grown up with the word stereo referring to music played through two speakers. More than a century before scientists applied the term to sound, though, they applied it to sight. The Greek original meant ‘solid,’ and solidity, i.e. three-dimensionality, is what a photographic stereo pair conveys.

© 2020 Steven Schwartzman

Inside Carlsbad Caverns

On June 14th last year we visited Carlsbad Caverns National Park in New Mexico.

© 2018 Steven Schwartzman

More of the world below

More visual notes from the underground in New Mexico’s Carlsbad Caverns National Park on June 14th.

It took aeons for an inorganic process, dripping water, to deposit the minerals that built up these intricate formations. Nevertheless, don’t their tops remind you of the branching growth patterns seen in a living organism like broccoli?

© 2017 Steven Schwartzman

The world below

750 feet underground in Carlsbad Caverns National Park lie the caverns. When we visited a couple of decades ago we didn’t think that much of them. On June 14th of this year we took the 1.25-mile self-guided walk through what’s called the Big Room and found its formations quite impressive. The caverns haven’t changed in 20 years. It seems we have.

© 2017 Steven Schwartzman

Some colorful geology on a small scale

Nothing in Austin is going to compare to the Badlands of South Dakota. Sorry, Austin, that’s just how it is. Still, we have some much smaller geological formations here that warrant a look. One is a long limestone slab that arches up and then out over a creek in my Great Hills neighborhood. Historically, of course, aeons of water flowing through the creek eroded the limestone to create the overhang. The back wall, which I don’t think ever gets direct sunlight, stays rather dark even during the brightest part of the day. When I went there on June 29th, I stood facing the wall and used flash to reveal the colors and patterns of the always damp and sometimes wet stone.

No more than a hundred feet to the right of the formations shown here are the mud dauber wasp tubes some of you may remember from five years ago. Two years after that, I showed something that wasn’t a tuft of hair on the underside of the overhang.

© 2017 Steven Schwartzman

Red Rock Canyon Open Space

Just a mile south of Garden of the Gods in Colorado Springs is Red Rock Canyon Open Space. While its formations aren’t nearly as well known nor as extensive or impressive, the rocks do offer up some pleasant colors and intricate patterns. Here are two panels of stone that caught my attention on June 7th. As far as I know, the hole in the center of the second picture is natural.

© 2017 Steven Schwartzman