64 Rev. E. Hill — Oeohgical Visit to Brittnny. 



some indistinct remains of plants. Beyond Poullaouen are some 

 fine dykes of kersanton, and further on a small one of micro- 

 granulite ; thus intrusions of both these rocks must have been going 

 on as late as in Carboniferous times. For the kersanton, there is 

 some evidence that it did not occur earlier ; no pebbles of it are 

 found in conglomerates which include all the other igneous rocks ; 

 as for instance at about four kilometres before reaching Huelgoat, in 

 a conglomerate belonging to the base of the Carboniferous series. 

 In a quarry about a mile from the road, at Bruguec north of Kerrion, 

 a microgrannlite tuff again proves that the eruptions of this rock 

 towards the end of the Devonian age continued into the Carboniferous. 



The mine of Huelgoat has had a long and interesting history, but now 

 is abandoned. In the walls near it are a few fragments of the Eoclie 

 Verte, a green breccia, which has been the subject of much discussion, 

 but is now considered to be a bed below the Chateaulin schists, and 

 above those of Porsguen (Porphyrite tuffs of the Table). From 

 beyond tlie mine a path leads for some miles through a beautiful 

 wood by the bank of a water channel at a high level on the hill-side 

 to the quaint little town of Huelgoat. 



The porphj'roid granite of Huelgoat resembles that of Eostrenen, 

 and belongs to the same (Carboniferous) age. The great rocking 

 stone called the Eoche roulante, distant about half a mile, is worth 

 a visit, and just below it is a quarry in the granite which there con- 

 tains abundantly pinite. Thence we regained the Carhaix road, and 

 returned along it some two kilometres to the east to see the contact of 

 the granite with Porsguen schists. A dyke of microgranulite cuts the 

 granite a little before reaching the junction. The schists are indu- 

 rated into a rock which has been called Cornien, and the alteration 

 is certainly considerable. We turned north along the main road 

 towards Morlaix to reach, after 3 or 4 kilometres, a long shallow 

 quarry in quartzites of Plougastel, here altered by the granite, and 

 went about a quarter of a mile up a footpath (not marked on the 

 map) to Le Vern for schists of Angers rendered crystalliferous. At 

 An Avallennou on the high road, the Gres a Scolithes is seen little 

 altered. We returned a few hundred yards and took a lane to the 

 south-west, which soon led us over the granite. After some three 

 kilometres it brought us out at Ty le Brennou, where Plougastel 

 schists are seen at their contact with the granite, and where a quarry 

 in a field west of the high road gives a beautiful section of the 

 junction. This completed for the Huelgoat granite what had been 

 done on the previous da^'s for the Eostrenen granite, an examination 

 of the effects produced on all the beds broken through. The parallel 

 bands of strata which cross the country from east to west are in each 

 case interrupted by the great intrusion, and the resulting alteration 

 in each case surrounds the igneous mass as a sort of aureole or halo, 

 intensest at the boundary and dying away at a mile or so from it. 



Our last day was devoted to the neighbourhood of Morlaix. In 

 the morning we drove southwards along the road which leads at first 

 south-west from the centre of the town (past the post-ofiice). About 

 a mile from the town, and a quarter of a mile east of the road (at 



