Linda Grashoff's Photography Adventures

Posts tagged “iridescence

Walking Downriver in September—1


November 17, 2019

This post might have included 34 photographs, but my better judgement intervened. I still want to show you a lot of what I saw on the annual fall downriver walk that my husband and I take. But I’ll break up the photos into three separate posts, one today, one tomorrow, and one Tuesday. This batch is all about the iridescent evidence I saw of the benign bacterium Leptothrix discophora. As you know if you’ve followed this blog for very long, the iron bacteria, of which L. discophora is one, are obsessions of mine (and the subject of my book They Breath Iron: Artistic and Scientific Encounters with an Ancient Life Form). So here we go again: 19 images of L. discophora films, preceded by an overall photograph of the river as it flows downstream.

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12 The orange material you see on the ground beneath the water in this photograph and others is iron oxide, which L.discophora precipitates out of the water.

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14 This photograph and the one following show L. discophora‘s film on top of a pudding-like substance that is probably the product of another iron bacterium called Leptothrix ochracea.

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16 Notice the iridescence on the leaf- and algae-covered shale in the middle of the photograph. It indicates that the film-covered water recently receded from this area. Click on the photograph to see it larger.

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19 This is a crop of the previous photo.

20 And this is a tighter crop. Click on the photograph to see even more detail.


August on the Vermilion River, 2019 Version


September 16, 2019

Leptothrix discophora was in splender when I drove out to the Schoepfle Garden August 11. I didn’t see huge patches of it, but enough medium-size patches to satisfy me. The handiwork of L. discophora and other iron bacteria was also in evidence as great gushy trails down to the water. Along my walk I dallied over some rocks I considered first among equals. Number 9 is mudstone that held some kind of salts that left pits as they washed out in the river.

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Not Leptothrix discophora—Vintage or Otherwise


November 13, 2018

A week ago Friday I was in the parking lot of our nearby drug store, waiting for my passenger to finish her shopping. It’s boring just to wait for someone. Enter my iPhone! It had just finished raining. What lucky timing. These are not Leptothrix discophora films but thin films of oil or gasoline on the puddles, which is what L. discophora films are often taken for. You can see why. Both exhibit color interference, also called thin-film interference. These films—unlike films of L. discophora—have no fracturing. (Compare with images in the previous post.)

Fabian Oefner is an artist who uses thin films of oil in his work.

 

 

 

  

 


Vintage Leptothrix discophora


November 3, 2018

This summer and fall have seen far too much rain to produce much in the way of colorful Leptothrix discophora films. But I miss them, so this post delves into photographs I took of this evidence of iron bacteria along Ohio’s Vermilion River between 2008 and 2010, before I’d started the blog. Some of these photos may be repeats of other dives into the archives. I hope that since I can’t remember if I’ve shown them, you can’t either.

 

 

 

 

 

 

 


Iridescence along the River 9


August 8, 2018

The second photograph is a long view of the area that featured the Leptothrix discophora films July 14.

 


Iridescence along the River 8


August 7, 2018


Iridescence along the River 7


August 6, 2018

When the water level recedes, it leaves traces of the Leptothrix discophora film on the rocks and mud. The close crop shows the iridescence best. Click on it to see the image even bigger. (The paw prints are from a raccoon.)

 


Iridescence along the River 6


August 5, 2018


Iridescence along the River 5


August 4, 2018


Iridescence along the River 4


August 3, 2018

The detail crops show more of what drew my eye. The puckering indicates loss of water from the film.