G. F. Harris — Journey through Russia. 



V6 



quartz 26'74. The outermost zone (e) has plagioclase (Ab.2 Anj) 

 44-28, alkali-felspar 6-79, biotite 4-00, quartz 42-82. The mineral 

 composition of the stone between the globular bodies is 

 plagioclase (Abg Anj) 3549, alkali- felspar 16-88, biotite 12-27, 

 quartz 32-53. From this and from the chemical composition 

 of the different zones and the " muttergestein," it is evident that 

 the general tendency of the ordinary separation of the crystals from 

 the original magma was normal — that the zones, on the whole, 

 become more acid as they recede from the nucleus. The proportion 

 of Si O2, for example, in zone h is 61-64, c 72-92, d 74-80, and e 

 75'67, whilst the rock between the globular bodies has 70-46. Not 

 the least interesting feature in these remarkable bodies is the 

 mechanical deformation to which they have occasionally been 

 subjected, and which has had the effect of breaking through the 

 zones and squeezing out some of the substance of the interior. In 

 certain of these Finnish " globular granites " shown at Helsingfors 

 the spheroidal and ovoid bodies have been partially absorbed by the 

 matrix in which they occur. The concentric zoning is clearly 

 marked, and in most cases the minute crystals are so arranged as to 

 produce a radiating effect. 



Fig. 2. — " Globular granite." Diagram showing disposition of zones 

 in one of the typical ovoid bodies (about j nat. size). The dis- 

 tinguishing italics are explained in the text. 



The structure of these bodies differs somewhat from that of the 

 well-known spheroids in the granite of Mullaghderg, County 

 Donegal, described by Dr. Hatch, ^ though the Finnish rock agrees 

 better with the Irish than with certain Continental rocks adverted 

 to by the last-mentioned author. 



At length, after a stay of three days, it was time to leave 

 Helsingfors, and Mr. Sederholm took charge of the party. A long 

 railway ride north, to Taramerfors, and an enthusiastic welcome from 



1 Quart. Journ. Geol. Soc, vol. xliv, 1888, p. 548 et sqq. 



