On the Forms assumed hy Granite and Gneiss. 317 



conceivable how granite should bo more covered with such 

 blocks than other mountain-rocks. The layers are often smooth 

 on their surfaces, just as if they had been polished. An ob- 

 servation which can bo made in the middle of the town of 

 Stockholm proves that these are produced by rubbing on ono 

 another, that they are true friction surfaces. Proceeding from 

 Sodermalm's sluice, " Stora Glasbruksgata," to the Catharine 

 Church, we find convex strata of gneiss, which are transversed 

 by many small granite veins. These veins, however, regularly 

 exhibit a shift as they pass from one layer to another, so that 

 it is evident how ono layer has advanced over the one imme- 

 diately under it, and undoubtedly not without smoothing and 

 polishing itself on the rubbing surface. The under layers, also, 

 which are covered by others, are just as smooth and as polished 

 as the outer ono at the surface ; and, hence, every external 

 cause of the smoothing, such as the movement of masses of ice 

 or of blocks over the surface, is completely excluded, and must 

 be rejected. 



The whole of Finland, and the greater part of Sweden, are 

 covered by such small granite and gneiss systems, composed of 

 polished layers, and the mode of distribution is very distinctly 

 and beautifully seen in the ideal section which accompanies 

 Engelhardfs Sketches of Finland. This display terminates at 

 the south coast of Finland, and we find on the other side of 

 the gulph, in Esthland and Liefland, indications of extraordi- 

 nary tranquillity in the mountain rocks — a tranquillity and an 

 uniformity which prevail over the greater part of European 

 Russia, and cannot be equalled in the whole of the rest of Eu- 

 rope. The Silurian strata in Esthonia not only lie very regu- 

 larly and quite horizontally on one another, but they are like- 

 wise so little altered, that the organic remains which they con- 

 tain are almost every where easily recognised, and can with 

 facility be removed from the matrix. The newer rocks follow 

 in largo curved masses as far as the Ural and the granite eUip- 

 soid of the Ukraine. 



That the gneiss which covers the ellipsoids of granite in 

 Sweden and Finland, like all gneiss generally, owes its origin 

 to metamorphismy which has formed it from previously existing 

 slates at the time of the elevation of the granite (by the pene- 



VOL. XXXY, NO. LXX. — OCTOBER 1843. Y 



