Ch. XXXV.] METAMORPHIC ROCKS. 737 



stratified, as applied to these rocks, sufficiently attests their division 

 into beds very analogous, at least in form, to ordinary fossiliferous 

 strata. This resemblance is by no means confined to the existence in 

 both occasionally of a laminated structure, but extends to every kind 

 of arrangement which is compatible with the absence of fossils, and 

 of sand, pebbles, ripple-mark, and other characters which the meta- 

 morphic theory supposes to have been obliterated by plutonic action. 

 Thus, for example, we behold alike in the crystalline and fossiliferous 

 formations an alteration of beds varying greatly in composition, color, 

 and thickness. We observe, for instance, gneiss alternating with lay- 

 ers of black hornblende-schist, or of green chlorite-schist, or with 

 granular quartz, or limestone ; and the interchange of these different 

 strata may be repeated for an indefinite number of times. In the 

 like manner, mica-schist alternates with chlorite-schist, and with beds 

 of pure quartz or of granular limestone. 



We have already seen that, near the immediate contact of granitic 

 veins and volcanic dikes, very extraordinary alterations in rocks have 

 taken place, more especially in the neighborhood of granite. It will 

 be useful here to add other illustrations, showing that a texture un- 

 distinguishable from that which characterizes the more crystalline 

 metamorphic formations has actually been superinduced in strata once 

 fossiliferous. 



In the southern extremity of Norway there is a large district, on 

 the west side of the fiord of Christiania, in which granite or syenite 

 protrudes in mountain masses through fossiliferous strata, and usually 

 sends veins into them at the point of contact. The stratified rocks, 

 replete with shells and zoophytes, consist chiefly of shale, limestone, 

 and some sandstone, and all these are invariably altered near the 

 granite for a distance of from 50 to 400 yards. The aluminous shales 

 are hardened and have become flinty. Sometimes they resemble jas- 

 per. Ribboned jasper is produced by the hardening of alternate 

 layers of green and chocolate-colored schist, each stripe faithfully 

 representing the original lines of stratification. Nearer the granite 

 the schist often contains crystals of hornblende, which are even met 

 with in some places for a distance of several hundred yards from the 

 junction ; and this black hornblende is so abundant that eminent 

 geologists, when passing through the country, have confounded it 

 with the ancient hornblende-schist, subordinate to the great gneiss 

 formation of Norway. Frequently, between the granite and the 

 hornblende slate above-mentioned, grains of mica and crystalline fel- 

 spar appear in the schist, so that rocks resembling gneiss and mica- 

 schist are produced. Fossils can rarely be detected in these schists, 

 and they are more completely effaced in proportion to the more crys- 

 talline texture of the beds, and their vicinity to the granite. In some 

 places the siliceous matter of the schist becomes a granular quartz ; 

 and when hornblende and mica are added, the altered rock loses its 

 stratification, and passes into a kind of granite. The limestone, 

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