60 Rev. E. Hill — Geological Vidt to Brittany. 



iferous and posterior to the last. The kersantons cut the (Carbon- 

 iferous) Chateaulin schists and are the latest of the eruptive rocks. 



Quimper was our rendezvous. On the afternoon of Aug. 19, after 

 the first meeting, a stroll was taken along the promenade on the 

 left bank of the stream to look at outcrops of ' Petrosilex ' seen there. 

 This is much crushed and a confident opinion on it is not easy to 

 form. Then walking out of the town to the west, we saw, first iu 

 the town a conglomerate of Carboniferous age, then successively 

 along the high road a coarse white gneiss, a mica-schist well exposed 

 in a road cutting, finally a granite. These rocks are said to occur 

 in this alternate fashion over a vast tract of country. Eeturning, we 

 deviated a little to examine a diorite dyke. 



Proceeding by rail to Chateaulin, we commenced the next day by 

 examining the schists of Chateaulin here worked for slates. They 

 closely resemble the slates (also of Carboniferous age) of Vernayaz 

 and Salvan (Switzerland). No fossils occur here; the position of 

 the rocks is established by a few impressions found in some limestone 

 beds towards the base of the series. At Port-Launay below Cha- 

 teaulin a steamer was waiting, placed at our disposal by the Port 

 Admiral of Brest, and embarking, we commenced our descent of the 

 river. After some hours of pleasant transport and jovetty scenery, a 

 landing was made on the right bank near Terenez, where the quart- 

 zites of Plougastel are exposed, and where the grits of Landevennec 

 can be seen to succeed them conformably. We walked along the 

 strand for a mile or two, and found our boats waiting to re-embark 

 the party nearly opposite Landevennec. 



The boats again transferred us from the steamer to the shore in 

 the Eiviere de I'Hopital, at the spot on the right bank marked as 

 Moulin de Mei". There is a tide mill here, whence the name, with 

 large and good machinery ; a breakfast spread in a spacious loft 

 was very welcome. East of the mill and behind it is a fine quarry 

 of kersanton and porphyry. The schists of Nehou are here cut by 

 a mass consisting of kersanton between two bands of porphyry, but 

 the relative age of these two igneous rocks can be determined better 

 by a section described below. From Moulin de Mer, walking west 

 through Logonna and seeing at an estuary the schists of Porsguen, 

 we collected the rare rock quartz-kersanton in a rocky beach at 

 Goulet-quer, and were again put on board the steamer, Kersanton, 

 so frequent in this district, was named after a shallow quarry in this 

 neighbourhood, now, however, disused and overgrown. 



We were landed for the last time this day, about three miles to 

 the N.N.W., at a promontory near Porsguen, to see a most beautiful 

 section. It is in the sea-cliff on the east side of the promontory, and 

 shows the schists of Porsguen, porphyry (raicro-granulite) overlying 

 them, and a dyke of kersanton breaking through both. The black 

 sedimentary rocks are little altered, but tremendously crushed by this 

 double intrusion, and show a rude cleavage set up across the old fissile 

 bedding. Time not allowing a purposed visit to the Isle Longue, 

 our steamer took us through the vast landlocked gulf that is called 

 Brest Eoads (Eade de Brest) direct to the quay at Brest itself. 



