perched block

perched block

[′pərcht ′bläk]
(geology)
A large, detached rock fragment presumed to have been transported and deposited by a glacier, and perched in a conspicuous and precarious position on the side of a hill. Also known as balanced rock; perched boulder; perched rock.
References in periodicals archive ?
The decision to demolish the flats - the second block to be knocked down after the precariously perched Block E in October 2012 - was taken as engineers and insurers did not feel it was worth the risk to save them.
FLATS TO BE DEMOLISHED NEXT WEEK HOUSING developers have set a date to demolish a precariously perched block of flats in Newburn.