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.












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.


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.


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.



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.














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.



Iridescence along the River 3

August 2, 2018

Iridescence along the River 2

August 1, 2018

Iridescence along the River 1

July 30, 2018

As promised, here come the photos of the Leptothrix discophora biofilms I saw along the Vermilion River July 14. Those of you new to this blog may find a brief introduction to what you see in this photograph useful. Those wanting to know more may care to explore some links.

Can of Curls

July 23, 2018

Beats Me 2

May 7, 2018

Scroll down to see what I think the purpose of these things might be. And if you are curious about the iridescence, look at my reply to Bluebrightly’s comment on yesterday’s post.



The long story about the possible purpose of these things starts with the following two photographs.


I took the photograph of the centaur and its home on the dumpster before walking from the parking lot into the Oberlin Dollar General store. While I was paying for my purchase, one of the store employees came up to me all grins and asked if I was with “the remodel team.” When I conveyed total puzzlement, she went on: “We saw you taking photographs of the dumpster and wondered if you were with the remodel team; this store is about to be remodeled.” And that’s why a dumpster was parked in the parking lot. Try saying with a straight face that you just like to photograph dumpsters. I had to add that I photograph other things, too.

So, back to what beats me. I wonder if these things are used to move everything out of the store while it is being remodeled. I can’t figure out how they would work, but they are another new addition to the parking area of the store. I could have gone back into the store for clarification, starting with, “I just took some pictures of those . . .” Nah, I didn’t think so. Why push my luck.

Beats Me 1

May 6, 2018

Back to the Garden 4

November 8, 2017

I saw some Leptothrix discophora films at Schoepfle Garden last month. Here is one patch, with details of the overall photograph beneath.




New in Town

October 16, 2016

This dumpster wasn’t around the last time I photographed dumpsters in Oberlin. How nice to meet it.


Downriver Walk 2015—Still More Leptothrix discophora

November 9, 2015

Sometimes a Leptothrix discophora film can look colorful but very shear, very translucent. Why? I don’t know. (For that matter, I don’t know why some of the L. discophora films look opaque.) The first photo shows what I mean. The other four photographs show a film where much or all of the water has run out from underneath it as the river recedes from the bank so that the film rests on rocks or soil.

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Downriver Walk 2015—More Leptothrix discophora

November 1, 2015

I saw more manifestations of Leptothrix discophora September 18 than I showed last week. Here are five more views of it. The sixth photograph shows the iron-oxide precipitate of another oxidizing iron bacterium or bacteria and a lighter precipitate of a different mineral, perhaps aluminite, which has made its appearance in the Vermilion River riverbed on other occasions. To quote from my book, “Aluminite hasn’t been studied in the Vermilion River, but elsewhere it is known to form around fungal and bacterial masses.”

The talk I gave about my book to the Friends of the Oberlin College Library October 27 was recorded, and the video is now online.

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Downriver Walk 2015—Leptothrix discophora

October 26, 2015

No walk downriver would be completely rewarding without finding some stunning biofilms and precipitates of the iron bacteria. This year, as usual, the reward was there.

I’ll be speaking about my book, They Breathe Iron: Artistic and Scientific Encounters with an Ancient Life Form, at the Friends of the Oberlin College Library tomorrow at 4:30 in the Moffett Auditorium of the Mudd Center. If you’ll be in Oberlin then, please come and say hello.

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July Iridescence 7

September 21, 2015

You can see how much Leptothrix discophora favors still river water by how it often insinuates itself in rocks that block the current.07312015 Schoepfle Garden-219

July Iridescence 6

September 14, 2015

You can see enough iridescence here for me to include this photo in the series, but what really got me was how clearly you can see the reflections of individual leaves in the water and Leptothrix discophora film.

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July Iridescence 4

August 31, 2015

The jewel in its setting: Here is a photograph of another patch of Leptothrix discophora that shows the context, also taken the last day of July.

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