Ancient markings
Strange ancient wall markings across Frodsham
These strange markings are found right across Frodsham.
But few people see them or know their true meaning.
These ancient runes mark a level right across Frodsham. Was it to mark a Witches Coven?
No?
Then what are they?
Who made these strange marking in our Sandstone rocks and why?
Many think it is War Office-related, but it is in fact an OS benchmark (BM) and a means of marking a height above sea level.
Surveyors in our history made these marks to record height above Ordnance Datum Newlyn (ODN – mean sea level determined at Newlyn in Cornwall).
If the exact height of one BM was known, the exact height of the next could be found by measuring the difference in heights, through a process of spirit levelling.
They can be found cut into houses, churches, bridges and many other structures. There are hundreds of thousands of them dotted across Great Britain, although they are no longer used today.
This was long before the invention of Global Navigation Satellite Systems (GNSS) which is the method used today for Ordance survey.