Not set in stone

Many thanks to Toomanytribbles. My previous nominations can be found in this post and are all well worth a visit.

While I'm in a mildly gloaty mood I should say a) that scientists who are also photographers or vice versa should join the 'scientist photographer' group on Flickr for a bit of fun and b) My picture was chosen last week in the weekly competition, the topic being 'Memories due to concrete'.