Eype Rocks Close Up 5

2 Replies to “Eype Rocks Close Up 5”

1. This whole series of photographs is gorgeous. I wonder if you entertain the possibility of a biogenic origin (in addition to atmospheric oxygen) for the iron oxide shown in this photograph. It’s reminiscent of what I see in northern Ohio in the U.S. (See https://lindagrashoff.wordpress.com/2014/07/13/iron-bacteria-in-northern-ohio-7/.)

   LikeLike

2. Thank you, Linda. It is difficult to be sure. My image does show rusty stains along a series of cracks in the rock, and that is normally associated with seepage of water (not certain whether that would have been rainwater once the rock was exposed to air, or groundwater while still in natural position). The water could have aided the oxidation of the iron minerals in the rock, or the water could itself have contained the iron minerals. The cracks on the surface, to a large degree, follow the grey shadowy lines of a network of fossilised crab burrows in the rock (trace or ichnofossils). The burrows have been infilled with a softer rock than the matrix some time after the hardening of the matrix rock. Within the softer sediment infill of the burrows are numerous small fine spine-like fossils; I am wondering if these might be something like sea-urchin spines (I have some research to do on that).

   So the pattern on the rock is at least partially biogenic but I do not know to what extent, if any, iron bacteria may have been involved. I am increasingly aware of the important role of bacteria in creating biofilms on rocks and the way that this affects the colour of seashore rocks in particular. Your own work in photographing the rainbow-coloured patterns of surface water films created by bacteria is a particularly beautiful example of bacteria at work.

   LikeLike

This site uses Akismet to reduce spam. Learn how your comment data is processed.