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.