Rev. E. Hill — Geological Visit to Brittany. 63 



east of the town, and then a section of the Schistes d'Angers. The 

 road gave some good scenery in its traverse of tlie low ridge called 

 the Montagnes Noires, but whatever else of interest there may be 

 between these and Carhaix was lost in the shades of evening and 

 night. 



Two days were spent at Carhaix, occupied by two long excursions 

 eastwards to Rostrenen and Goarec respectively, to study the pheno- 

 mena of metamorphism on each side of the great intrusion of the 

 Eostrenen granite. Deviating from the direct road to pass through 

 Paule, we were there shown the first signs of alteration in (Carboni- 

 ferous) Chateaulin schists. Near Glomel the change had gone 

 further, and small but perfect crystals of andalusite had been formed. 

 We walked about two miles west of Glomel on a road, and then 

 turning north down a lane about half a mile collected in a quarry 

 near Bressillion andalusite in altered (Devonian) schists of Plou- 

 gastel, thence returning south-west and south, saw near Kervennan 

 the same mineral developed in the (Silurian) schists of Angers, 

 while at Rostrenen itself, just outside the village, we collected the 

 beautiful porphyritic granite that is the agent of all this change. 

 The porphyritic crystals of felspar reach a large size, and in decom- 

 posed rock they lie as pebbles in a sand. To the south of the village, 

 in a large rock on the side of the road, near Kerbescont, the schists 

 of Plougastel reappear altered into leptinolite. 



Beyond Eostrenen (this was on the second day), about the kilo- 

 metre stone marked 17, a fragment of schist is seen actually included 

 in granite ; further on, sandstones belonging to the Chateaulin 

 schists occur little altered, and about one mile before reaching 

 Plouguernevel, a small excavation on the road-side shows an actual 

 contact ; a mass reposing in a trough of the granite, with an isolated 

 piece completely surrounded. Further on, they are seen again in a 

 pit with a pond, less altered as being further from the granite. 



At Goarec, at the east end of the village, on the north side of the 

 road, is a quarry in a rock unlike anything we saw elsewhere, and 

 said to resemble the Porphyroides of the Ardennes. It is supposed 

 to pass into the schists, but its relations are not seen here. South- 

 east from Goarec along the high road the Schistes d'Angers are seen 

 in fine crags. Quitting the route at Bon Eepos, and denying ourselves 

 more than a distant glance at the picturesque abbey, we crossed the 

 •canal and entered on an extensive wood. After following the canal 

 bank a mile or more, we turned south to reach the abandoned Forges 

 des Salles, just beyond which in the wood is a quarry in some highly 

 ■cleft ' schistes a chloritoid.' On the roadside three or four miles 

 further (east side, just before the group of houses called St. Brigitte), 

 is a shallow quarry in a kind of slate, which while showing only 

 traces of cleavage, and containing fairly abundant and quite recog- 

 nizable fossil impressions (Trilobites, Ortliis, etc.), is also full of fine 

 crystals of andalusite, which lie in the closest proximity to the 

 fossils. 



Quitting Carhaix on the 27th August, and driving to the N.W., 

 cuttings made for the road show sections of Chateaulin shales with. 



