Hi Selchie (new name or new member? if the latter then welcome!)

A Logan stone is a piece of a tor (exposed rocky outcrop) that has become detatched and now balances on a small area that forms a pivot point. This means that they can be rocked. Hopefully someone will tell us all why they are called 'Logan Stones'. I do remember reading the reason once, but I've forgotten :-)

Some do have folklore attached and it is a fairly appealling idea that they were held special by the Ancients, just as the the Pony-y-Pridd rocking stone is said to have been. Being a bit of a landscape freak I want to check one or two out.