isplaced by Ptolemy (2.9.1
)in Celtogalatia Belgica.
After the mouths of the Seine,
he mentions the outlet of the river Phrudis [FRUDIS
], Icium (Ἴιξιον ῎ακρον
), and then Gesoriacum (Τησοριακὸν ἐπίνειον
), which is Boulogne.
One of the old Latin versions of Ptolemy has Itium Promontorium, and others may have it too.
He places Gesoriacum and Itium in the same latitude, and Itium due west of Gesoriacum.
This is a great mistake, for, Itium being Cap Grisnez,
the relative position of the two places is north and south, instead of east and west.
There is no promontory on this part of the French coast north or south of Boulogne
at which point the coast changes its direction from south to north, and runs in a general ENE. direction to Calais, Gravelines,
It is therefore certain that there is a great mistake in Ptolemy, both in the direction of the coast and the relative position of Gesoriacum and Itium. Cap Grisnez
is a chalk cliff, the termination on the coast of the chalk hills which cross the department of Pas de Calais.
The chalk cliffs extend a few miles on each side of Cap Grisnez,
and are clearly seen from the English coast on a fine day.
This cape is the nearest point of the French coast to the opposite coast of Kent.