604 [April 30. 



there is an undoubted parallel between the different members of 

 the Silurian rocks of Norway and those of the British Isles, they 

 are in many parts, especially on the sides of the bays of Christiania 

 and Drammen, so perforated by eruptive rocks of posterior age, 

 that, except in such very typical localities as those of Steens fjord 

 and Krokleven, it is difficult to distinguish a clear order of super- 

 position. 



Metamorphosed Silurian Rocks of Norway. — Intending to re- 

 visit Scandinavia in company with my friend M. de Verneuil, and 

 then to work out in greater detail the exact contents of each of the 

 Silurian strata, I shall no longer dwell on that point, but proceed 

 to describe some of the most striking effects produced on those 

 beds by the eruption of the igneous rocks which traverse them. 

 The general section will convey an adequate idea of these 

 intrusions, a small portion of which only, as well as a limited 

 number of the flexures and cracks of the sedimentary strata, are 

 there represented. 



It is sufficient for my present purpose to state, that whether 

 consisting of granites, porphyry, greenstone, or hypersthene rock, 

 these igneous masses all play the same part as the trap rocks, por- 

 phyries, modern granites, and syenites of the British Isles, some- 

 times producing great dislocation with little alteration, at other 

 places very perceptible changes, and in extreme cases a complete 

 metamorphosis of the invaded strata. Of the first of these re- 

 sults of intrusion, it is unnecessary to speak ; nor, indeed, is it 

 essential to dwell at great length upon the second, since the 

 phenomena are completely analogous to thousands of examples in 

 our own Isles, and other parts of the world. In the Silurian tract 



Solvsberg. 



In this diagram the peaks of Syenitic Greenstone ('), Greenstone (o), and Por- 

 phyry ( X ), are represented throwing off and altering the Lower Silurian 

 rock on each side. 



extending north-eastward from the Steens fjord to the insu- 

 lated mountain called the Solvsberg, examples of greenstone, por- 

 phyry, and syenite, intruding upon the Silurian beds, are, indeed, 

 countless. The Solvsberg, which lies to the east of the Lake Kands 

 fjord, is the most prominent and loftiest of these eruptive masses 

 which I visited. Rising to about 1200 feet above the adjacent 

 lake, its summits are seen to consist in parts of a syenitic green- 

 stone, with crystals of labradorite and hornblende, in others of 

 coarse-grained greenstone, and in a third of porphyry ; and its 

 flanks are of black schist and impure limestone, which near the 

 points of contact are in a highly compact and indurated condition, 

 and are thrown up in vertical or dislocated masses, occasionally 

 containing trilobites, orthoceratites, and fragments of other organic 

 remains, all of Lower Silurian age. 



