Bwlch y Groes (meaning 'pass of the cross') is depicted on modern and historic (1901) Ordnance Survey mapping. It is located at a natural pass between the hill country of Merioneth and that of north-west Montgomeryshire, between the county boundary (immediately east) and a district boundary (immediately west). Historic Ordnance survey mapping shows the county boundary dilineated by stones and the district boundary dilineated by mounds, at 100-200m intervals. The pass is likely to have always formed a line of communication between the seperate areas, and the name suggests the existence of a cross or calvary. The ridge to the east of the pass is depicted as Foel y Groes (meaning ridge of the cross) on modern and historic ordnance Survey mapping.

Sources include:
Ordnance Survey, 1901, second edition 6inch

N Vousden, RCAHMW, 9 July 2012