geology of London is well known
The geology of London is well known as a result of all the tunnel which have been excavated through the city over the years. These tunnels are not just related to London's tube (underground railway) but there are many other tunnels for other reasons. One aspect of London's geology is that, even if space wasn't so critical, there is no where one can see classical geological outcrop as one can in many other cities. This is because the bedrock closest to surface, consists of Tertiary clays and sands.