A strange phenomenon of the colourful sandstone at Redend Point in Studland Bay is the natural occurrence of hollow pipes or tubes running through the rocks. No-one seems certain about the way they have formed geologically but it is something to do with the way that water-borne iron minerals have settled out in the sandstone.
You can see the open ends of these intriguing features underfoot in the wave cut platform around the base of the cliffs – half concealed sometimes by seaweed and flint pebbles; on the floors of shallow caves where they can resemble small volcanoes; on the ceilings of the undercut rock where you can sometimes see daylight shining through the tubes from higher up in the cliff; broken open in fallen beach boulders and on the cliff face itself; and as strange pedestals at the base of the cliff where the sea has eroded away the softer surrounding rock to isolate the naturally occurring iron-lined hollow pipes.
Jessica's Nature Blog 
Fascinating!
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Dalinian!
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..I’ve seen similar structures in Apsley Guise, Bedfordshire, and Harpenden, Herts. I would find intricate pieces of rusty sandstone that you would swear were cast iron.
A picture of Ironstone from Apsley Heath, http://www.nquire.org.uk/journal/contribution/1406#
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Thank you, CentralOhioNature.
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Yes, a bit surreal.
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Thanks, Pete. Yes, I guess these structures are commonly found in sandstones. Maybe the sandstone in your area is of the same type and date as that at Studland Bay.
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..no longer live in the South. Now in the NW Highlands! We have some good geology up here!!..
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Bizarre Jessica – never seen anything like that befoe.
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Wow, how amazing! They look like little Martian volcanoes.
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They are strange things, aren’t they?
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I wonder how many people notice them. Perhaps you have to know they are there.
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