The iridescent film on a small beach stream issuing from iron-rich volcanic rocks at Yachats in Oregon produced some lovely natural abstract patterns thanks to the colonies of iron-oxidising bacteria.
Following yesterday’s posting about a pond with a strange orange substance beneath shallow cloudy water, I received a most interesting comment suggesting that the orange colouring might not be decomposing algae as I had initially thought but the result of bacterial activity. Linda Grashoff has a special interest in iron-oxidising bacteria and has written many posts on the subject in her WordPress blog Romancing Reality, and she has written a beautiful and lavishly illustrated book about this fascinating topic. It is called “They Breathe Iron – Artistic and Scientific Encounters with an Ancient Life Form“. She said:
Your “something russet and mysterious” is indeed iron that has been oxidized and precipitated out of the water by the iron bacteria. The patches of pale blue film on top of the water—shown in the first and last photograph—are created by Leptothrix discophora, one of the iron-oxidizing bacteria. Other iron bacteria also oxidize iron in the water and are probably present along with the L. discophora on the edges of this pond. The L. discophora bacteria live at the air/water interface, with one end of their rod-shaped bodies in the air and the other end in the water. My guess is that the film keeps the tiny bodies oriented. As the microbes reproduce, they shove parts of the film over and under other parts, so that the film becomes thicker. Various film thicknesses produce various colors by light-wave interference, often resulting in the appearance of an oil slick.
This made me think about another occasion when I had encountered a strange little stream issuing from rocks at Yachats in Oregon on the west coast of America. It possessed a distinct iridescent film, and flowed across green photosynthesising organic matter that in places was coated orange. Bubbles of oxygen were trapped within the ?algae and beneath the film on the surface of the water. The rocks on the beach were rich in iron. The small stream must have been a good example of the activity of iron-oxidising bacteria in action.
This post shows a few photographs from that site – and more will follow tomorrow.
Patches of sunlight, green leaves, and blue sky were reflected on the shallow milky water of the pond. Bare branches and twigs draped over and into the pool. A few pine needles and autumn leaves lay motionless on the meniscus. A delicate matrix of dying Mud Water Starwort stems could be seen making abstract patterns just below the shaded surfaces while swathes of something russet and mysterious cloaked the mud.
Shallow Water Tidal Ripple Patterns 4-7 Photographs of natural patterns created by reflected sunlight on the crests of minor ripples in clear shallow seawater lapping with the incoming tide around the island of Burry Holms at the tip of the Gower Peninsula in South Wales. Here shown in negative format to highlight the intricacies of the natural designs.
Shallow Water Tidal Ripple Patterns 1-3 Photographs of natural patterns created by reflected sunlight on the crests of minor ripples in clear shallow seawater lapping with the incoming tide around the island of Burry Holms at the tip of the Gower Peninsula in South Wales. Here shown in negative format to highlight the intricacies of the natural designs.
The wind was blowing really hard across the navy blue water surface of slacks trapped behind the shingle banks at Rochefort Point. Rochefort Point is a short walk from the Louisbourg Fortress in Cape Breton, Nova Scotia. The ripples were tight packed and narrow, travelling at speed. The water was actually a brackish brown but reflected the clear blue of the sky resulting mostly in dark blue hues. From some angles and in certain lights the sun shone through the ripples revealing the reddish colour of the water. The low standing crests of the waves were so distinct that it seemed as if the water was viscous.