13 
TRANSVERSE SECTION ACROSS THE CHRISTIANIA TERRITORY. 
These Lower and Upper Silurian rocks constitute one inse- 
parable and closely connected system. Their highest member, 
composed of calcareous flagstones containing the Leptcena lata, a 
peculiar Spirifer and a shell closely allied to Terebratula Wilsoni, 
is clearly overlaid in the mountainous tracts called Ringerigge, 
to the west of Christiania, by red quartzose sandstone and shale, 
that forms a deposit of great thickness (perhaps 1000 feet) litho- 
logically undistinguishable from the Old Red Sandstone of the 
British Isles, its summit being composed of a conglomerate as in 
the Herefordshire, Salop, &c. In the course of a rapid survey, 
we thus obtained evidence of a succession from Lower through 
Upper Silurian to the Old Red Sandstone inclusive. In a word, 
the latter formation, with great tabular masses of porphyry, is 
thus separated from the ancient gneiss on either side, and occu- 
pies a lofty tract in the centre of the trough, having the Christiania 
fiord on one side, and the Steens fiord and Drammen on the other, 
both of w’hich depressions are filled with the Silurian rocks in 
question (see woodcut and note 1). 
In the Steens fiord, whither we first went in the company of 
Professor Keilhau and afterwards with Professor Forchhainmer, 
we w r ere, indeed, truly delighted to perceive the great symmetry 
with which the Upper Silurian flagstones and tilestones 3 , per- 
Upper Silurian 
Lower Silurian 
1 Explanation of the woodcut : — 
Old Red Sandstone — e. Red sandstone and conglomerate. 
{ d. Calcareous flagstones, &c. 
c. Coralline limestone and shale. 
{ b. Pentamerus limestone. 
a. Schists, flags, and lower sandstone, 
o. Azoic or gneissose rocks, with old granite, greenstone, &c. 
r p. Rhombic porphyry in the Old Red Sandstone. 
1 1. Eruptive and trapprean rocks of various characters. 
2 Mr. Murchison takes this opportunity of acquainting geologists who may not 
have attended to the successive development of his ideas on classification, that 
certain red tilestones at the base of the Old Red Sandstone of England, which from 
mineral aspect were formerly classed with that formation, he has for some years con- 
sidered as forming, together with the bone-bed, the uppermost stage of the Silurian 
rocks. (Anniversary Discourse, Proc. Geol. Soc. vol. iii.) He had, indeed, from the 
first described these beds as being charged with Upper Ludlow fossils (see Silurian 
System, pp. 192, 602). 
SECTION ACROSS THE TERRITORY OF CHRISTIANIA 1 . 
