112 G. F. Sarris — Journey through Russia. 



" leptite." It may be describee! as a foliated arkose, containing, 

 however, mucb minute quartz. The rock is salmon-pink in tint 

 A conglomerate of the same material runs through the quarry 

 This has been severely dealt with ; the raetamorphic action which 

 rendered the sandstone foliated has drawn out the original pebbles 

 into long lens-shaped patches, the major diameters of which, in all 

 cases, are parallel to the folia. Macroscopically there does not 

 appear to be much mica ; but micro-examination proves that that 

 mineral is fairly abundant in exceedingly minute flakes. To the 

 naked eye all the mica appears white, or bronze-coloured, though 

 thin sections of the rock demonstrate the existence of a little biotite. 

 Evidently the colourless mica has been produced at the expense of 

 alkali-felspars, and the felspathic constituents as seen in the rock, 

 as it stands at present, have largely become saussuritic. The larger 

 fragments of quartz are very interesting. If I dared use the term 

 in reference to a foliated rock I should say that they act as 

 phenocrysts, for that is exactly what they resemble when one 

 first glances at them under the microscope. They are scattered 

 amongst the exceedingly minute fragments of quartz, altered 

 felspar, and mica, which form a kind of groundmass, out of which 

 they stand conspicuously ; and they have been broken up into 

 small fragments by the crushing and shearing to which the rock 

 has been subjected, whilst they present the usual phenomena of 

 cataclastic structure. 



The evidence in the field is clearly borne out by micro- 

 examination. I wish we had had more time at this spot, for 

 I feel convinced that much light on an interesting phase of dynamo- 

 metamorphism would be shed by a careful examination of the 

 district. This leptite is foliated enough to place it beyond the 

 pale of an ordinary arkose, and yet not sufficiently to cause it to 

 be regarded as a true schist. 



In respect to the relative age of this rock — unfortunately, its 

 junction with the schists near Kulovesi railway station is a fault, 

 and along that line of junction was the only hope of determining 

 its position with reference to the older rocks of the district. At 

 the same time, it is believed that it is younger than the granites of 

 the area, as these latter are brought up against, but do not cut 

 through it. Following the classification detailed in the last 

 article, this leptite and conglomerate are distinctly Pre-Cambrian. 

 But they are, no doubt, much younger than the Pre-Bothnian gneiss. 



The next day was devoted to an examination of some rocks 

 on the shores of Lake Nasi (Nasijarvi). We set out in two 

 enormous barges which had been decked over for the occasion, 

 and these were drawn by two very fussy little steam-tugs. It 

 is almost needless to say that nearly all Tammerfors came out 

 to see us off. After a boisterous passage to the other side of the 

 lake, our first point d'appui was the locality where " archsean 

 fossils " are found. The landing, and then slipping over many 

 hundred yards of well-polished rock with beautiful glacial strise, 

 proved rather exciting, which excitement was considerably 



