G. F. Harris — Journey through Russia. 113 



accentuated as two or three members fell into pools of water 

 conveniently arranged by Nature in big and deep boles in the 

 immediate vicinity of the " Pre-Cambrian oi'ganic remains." 



Tlie "archaaan fossils" gave rise to an animated discussion. 

 There, on the smooth surface of the phyllades, we saw some 

 circular and ovoid markings outlined by black carbonaceous- 

 looking rings. Nobody seemed to know what they were, and it 

 is to be observed that no one even ventured to give them a generic 

 and specific name " in order that they may hereafter be identified." 

 Vague remarks about " fossil wood " and " impure phyllades " 

 closed the visit to this spot. 



Ke-embarking, we went to an island in the lake, where 

 a remarkable phenomenon awaited investigation. I have said 

 (p. 15, ante) that the Bothnian schists in the neighbourhood of 

 Tammerfors are characterized by the presence of conglomerates 

 on several horizons. As we landed on this island the large pebbles 

 in one of these conglomerates, many of them 3 and 4 inches in 

 diameter, were very conspicuous, and the bed here cropping out must 

 be many yards in thickness. Although indurated, and to a certain 

 extent otherwise metamorphosed, this conglomerate is fresh enough 

 to enable each pebble to be clearly made out, or defined from 

 amongst its neighbours. On the beach the rock is much weathered, 

 and decomposition has set in on the surface of the majority of 

 the pebbles, which are pitted with small holes. Beautiful little 

 faults, having a throw of a foot or so, are seen in several places ; 

 they go right through the pebbles, and slickensides is not an 

 uncommon phenomenon. 



The structure of this archeean conglomerate exhibits a few 

 points of interest. In addition to the larger stones mentioned there 

 is much grit and fine quartzose sand, the grains of the latter being 

 angulate. The larger pebbles are for the most part fragments of 

 volcanic rocks presenting large phenocrysts of a triclinic felspar. 

 It is difiicult to determine the precise nature of these volcanic rocks, 

 but in one of my micro-preparations there is certainly a small 

 pebble of '• labrador porphyry." The extinction angles of four large 

 phenocrysts of the felspar in this are -f- 34, -J- 36, + 36, -|- 38, 

 indicating labradorite. These phenocrysts, however, are much 

 altered and have many inclusions. The augite is not very 

 satisfactory and cannot be distinctly identified ; I infer its former 

 existence by green decomposition products in small phenocrysts 

 having the approximate appearance of augite. 



In addition to these pebbles of volcanic rocks the conglomerate 

 is made up of pieces of rolled phyllade. Mr. Sederholm remarks ^ 

 that all the rocks represented by these pebbles crop out to the south 

 of the conglomerate, and there is, therefore, no reason to suppose 

 they have travelled very far. But he mentions some strangers 

 to the district as occurring therein, viz., " deux varietes de granite 

 ou syenite quartzifere, et une diorite quartzifere." 



1 Guide xiii, " Les Excursions en Finlande," p. 4. 



DECADE IV. VOL. V. NO. III. 8 



