(A) Sketch map identifying the Trégor, Saint-Brieuc and Guinguamp Cadomian tectonometamorphic units to the west of the Saint-Brieuc Bay (modified from Plaine, 2011, unpublished, and from the geological map of France 1/50 000 “vecteur harmonisée”, BRGM, available at http://infoterre.brgm.fr; see also: Chantraine et al., 2001; Ballèvre et al., 2001); note that some of the volcanic and sedimentary rocks from the southern Trégor unit (e.g., Paimpol Formation) may alternatively be associated with the Saint-Brieuc unit (see text; Chantraine et al., 2001); (B) Simplified geological map of the North Trégor volcano-plutonic complex (from Auvray, 1979; Graviou, 1984); dykes are not shown.