606 [April 30. 



of deposit ; until finally in parts still nearer the eruptive rocks the 

 whole is a dense, compact, subcrystalline mass. 



It was, therefore, evident that the " Harte Schiefer " of M.i 

 Keilhau, marked by that author by a distinct colour in hisj 

 geological map, was nothing more than a portion of the lower' 

 Silurian shale with its overlying bands of Pentamerus limestone, 

 which we had followed from Solvsberg by Velo to the tract be- 

 tween the falls of the Drammen and Steens fjord, and which, 

 unaltered in the plain and considerably modified in the undulating 

 grounds, had become metamorphic on the side of the granitic and 

 porphyritic mountains. 



Having passed over a considerable tract of ancient gneiss, which 

 occupies all the region to the west of the Drammen river, we found, 

 on traversing that river in a boat at Vigersund, a repetition of 

 similar phenomena; for there the lower Silurian sandstone be- 

 neath the fucoid shale (which is rarely seen in this region of 

 Norway) is thrown up into vertical masses and converted into 

 quartz rock in contact with a dyke of greenstone, whilst the alum 

 schist which succeeds is traversed by a white porphyry, and is 

 highly brittle and anthracitic. 



The same relations are, indeed, seen all along the frontier of the 

 gneiss between Vigersund and the port of Drammen, quartz rock or 

 altered lower Silurian sandstone, of which I shall speak at greater 

 length when describing Sweden, there forming the lowest Silu- 

 rian course, and being surmounted by black schists and flagstone 

 with calcareous nodules, from some of which we obtained speci- 

 mens of Asaphus expansus and Orthoceratites, 8fc. 



To the north of the Drammen the Silurian escarpment is strik- 

 ingly affected by the eruption of granite and greenstone, the latter 

 apparently forming the lower boss near the town, the former rising 

 into a little eminence at the foot of the hill side. We could, how- 

 ever, draw no sort of geological separation between the greenstone 

 and the granite, as to their age or effects. The granite is indeed 

 most distinctly seen to protrude through the sandstone, which 

 in many parts folds over it as a cap or dome, and is of a red 

 colour, and indented like quartz rock. Still higher up, the sides of 

 the escarpment are composed of amygdaloidal trap, in which are 

 included separate angular fragments of flags and sandstone, one of 

 which 50 feet long, and 12 to 15 feet high, appears as a highly 

 altered, reddish, micaceous flagstone. 



In the next example which we visited, or that which occurs at 

 the hamlet of Dielebeck, a few miles north of Drammen, the meta- 

 morphism of the strata has been carried to a greater extent than 

 in any case previously cited. Rose-coloured, large-grained granite 

 there occupies the hill called Paradis Backen, on the northern 

 slope of which the limestone and shale repose in slightly inclined 

 strata. 



At this spot the limestone, in the beds of which at a certain 

 distance from the granite the Pentamerus oblongus has been occa- 

 sionally found, is in the state of marble ; and the fact of its having 



