Rev. E. mil — Geological Visit to Brittany. 59 



IT. — In Brittany with the Geological Society of France. 



By the Eev. E. Hill, M.A., F.G.S., 

 Tutor of St. Jolin's College, Cambridge. 



THE French Geological Society last yeai* made Finistere the 

 object of their annual excursion, and hy their kindness I had 

 the great pleasure of joining the party. As Brittany is so interest- 

 ing a region, already very accessible by railways, and soon to become 

 even more so, it has occurred to me that a brief account of the 

 excursion may be acceptable to our English geologists, and at any 

 rate afford them an index to some localities which will well repay 

 a visit. 



It will be convenient to preface with a table of the strata, 

 according to the nomenclature and classification of Dr. Barrois.^ He 

 arranges the beds of this region as follows : 



Carboniferous. 



Coal-measure Schists and Conglomerates. 

 Schists and Sandstones of Chateaulin. 

 Porphyrite Tuffs. 

 Porphyry Conglomerates and TufEs. 



Devonian. 

 Nodular Schists of Porsguen. 

 Schists and Limestones of Nehou. 

 "White Grit of Landevenuec. 

 Schists and Quartzites of I'lougastel. 

 Limestone of Eozan (with Strophomena Looiensis). 



Silurian. 



Nodular Schists (with Cardiola inierrtipta). 



j^mpelite Schists (with Graptolites) . 



"White Sandstones. 



Slaty Schists of Angers. 



Armorican Grits (Gres a scolithes). 



Eed Conglomerates and Schists of La Cheyre. 



Cambrian. 

 Schists and Conglomerates of Gouriu. 

 Phyllades of Douarnenez (or of St. Lo). 



Primitive. 

 Schists of Grois. 

 Mica- Schists of Audierne. 

 Granitic Gneisses of Pont-Scorff. 



Dr. Barrois regards the Cambrian Schists of Gourin as correspond- 

 ing to Barrande's Etage C ; any identification of the beds below 

 must at present be conjectural. 



Among the eruptive rocks the granite of Pontaven is Cambrian or 

 Pre-Cambrian ; the porphyi'oid granites of Rostrenen and Huelgoat 

 are of Carboniferous age ; the granites with two species of mica 

 (granulites) of Quimper, Le Faouet, and Morlaix, are also Carbon- 



^ See " Aper^u sur le constitution geologique de Finistere " in the Jime number of 

 " Le Guide Scientifique " (Paris, J. Michelet, 25, Quai des Grands Augustins ; 

 London, J. A. Berly, 3, Deronda Eoad, Heme Hill, S.E.). 



