Other pieces from Portmahomack have been recognised as grave markers, incised with simple crosses. These are comparable to examples known from Iona and other early Christian sites in Argyll and western Scotland. Much of the Portmahomack sculpture has been assigned by radiocarbon dating of the layer in which it was found to the 8th century.
Portmahomack's grave markers, featuring simple crosses, are similar to those found at Iona and other early Christian sites in Argyll and western Scotland.  Radiocarbon dating has determined that much of the Portmahomack sculpture dates back to the 8th century.