Rocks 5-7 SBMBD Close-up rock images from the archives, showing colours, patterns, and textures in some rocks at Middle Beach, Studland Bay, Dorset, taken in March 2014.
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Jessica's Nature Blog 
I am fascinated by the colors in these rocks. I didn’t see a comment box for the previous post, Rocks 1-4 SBMBD, but I had a question. I am curious about the purple band of color. It appears to cut across the strata in the rocks, suggesting that the purple coloration came as a separate event sometime after the sediments were deposited and even folded. Is there an explanation for the purple band?
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Hi, Mic. To be honest I do not totally understand the processes involved in the creation of these colour bands but in an earlier post about the rocks at this location I said “Rock colours, patterns, and textures in the cliff at South Beach, Studland Bay in Dorset, UK. These close-up photographs show details of the natural abstract designs to be found in the rock formerly known as the Redend Sandstone which was part of the Poole Formation and was laid down by river action in the Eocene Period. [Recent geological research has resulted in a re-naming of the rocks in this area so that the Redend Sandstone is now said to be part of the Broadstone Sand Member].
The colours in the sandstone are due to the presence of iron oxides. Different forms of these compounds result in different colours with yellow and brown being fairly typical of limonite and geothite, while the reds are more likely to be hematite. I have noticed in the patterns of rusting iron pier structures and flotsam buoys corroded by saltwater that a great variety of colours, including purple, are commonly found in the decomposition products of iron.” Hope this helps answer your question a bit. Jessica
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Thank you, Jessica. Yes, this is helpful. It is a reminder of the complex processes that gave rise to all the variations we see. I really appreciate your photographs and descriptions, especially relating to your coastal areas.
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