DISCOVERY: City College Plymouth archaeology student Alistair Courtney surveys the cross
It is thought to have once served as a Christian waymarker or boundary stone.
The team, led by Win Scutt and Ross Dean of City College Plymouth, stumbled on the cross when surveying the ruins of a medieval settlement on the slopes of Gutter Tor, Dartmoor. No longer upright, the cross was not identified until the last day of the survey.
"We had assumed it was a gatepost until examining the shape of the stone and the incisions. We were bowled over when we realised what it actually was," said Win Scutt.
Although probably unfinished, the cross has been chiselled from a two metre long block of granite.
The head of the cross has three arms, while the shaft is decorated with a long incised channel.
The cross lies close to the ruins of two medieval long houses that date to the same period.
The survey was being carried out as part of a training exercise for students on the University of Plymouth's Foundation Degree in Archaeological Practice.