igi I. No. 7. A NEW DOWNTONIAN FAUNA OF THE KRISTIANIA AREA. 7 



The Sandstone Series and its Occurrence in the 

 Kristiania Area. 



According to the older maps and the brief accounts of Kkilhau, 

 Kjerulf and T. Dahll. which are still our most important authorities, 

 the sandstone series in the Kristiania area appears as a number of some- 

 what small disconnected areas, the remains of a large, continuous region, 

 the original limits of which cannot now be determined with certaint}-. 

 The existing areas most frequently form comparative!}- narrow marginal 

 zones around the huge beds of Porphyr}-, under which most of the 

 sandstone is hidden. The sandstone appears e\ery\vhere to accompany 

 the Upper Silurian sediments conformably, and to lie evenly above them. 

 In some sections, it is true, KjERULF believed he could show that the 

 upper part of the sandstone was deposited unconformably on the older 

 beds; according to Brogger's subsequent investigations this theor}- is 

 not the true one, since the apparent unconformity is due to later faults. 



The total thickness of the sandstone is estimated by KjERULF as 

 from 1000 to 1200 feet (314 — 376 m.), but this estimate, according to 

 my investigations, appears to be too low, at least as regards Ringerike. 



According to the descriptions given, the most common sediments 

 are red and gray sandstone — frequently in thick beds — slaty sand- 

 stone, and gray or red shale. Both Keilhau and Dahll assert that 

 the richest deposits of shale are found in the lower part of the series- 

 The latter is completed uppermost by a quartz conglomerate, which is 

 then directly covered b\- the beds of dark essexitporphyrite. 



The beds of sandstone often show cross-bedding and ripplemarks. 

 Hitherto fossils had not been found in solid rock. I must however 

 mention that small indeterminate fragments of fish were found by BlOK- 

 LVKKE, near Aas Agricultural High School, in a sandstone boulder which 

 presumably came from the Ringerike district. Further, Til. MÜNSTER 



