Two sections through once articulated valves of L. gibbosa, now leached away. By chance, the mason has cut through along the long axes of the shells giving the effect of ‘angel wings’. The ribs and costae can be seen on the upper example of the two. Once again, this is from the Roach used on the new wing of BBC Broadcasting House.
One photograph illustrates that this is indeed Urban Geology - the scale is indicated by a fag end!
I have just started reading this huge archive and it is a cornucopia of geological insights and delights! A pity it is mostly in London.