BIRI LIMESTONE OF NORWAY 571 



Olenellus shale. 

 Upper Algonkian. 



Sandstone with tracks and trails. 



Quartz sandstone. 



Red and green shale. 



Younger sparagmite. 

 Middle Algonkian. 



Biri limestone. 

 Lower Algonkian 



Biri conglomerate. 



Eed shale and limestone. 



Older sparagmite with dark shales. 

 Crystalline basement. 



Between the Biri limestone and the succeeding beds there was postulated 

 a marked hiatus, the higher beds resting unconformably on the folded 

 and eroded Biri limestone and older beds. 



In 1910 Prof. A. Bothpletz made a detailed study of these beds in the 

 Mjosen region and came to the conclusion that the "Upper Algonkian 

 series" represents merely the overthrust portion of the lower Sparagmite 

 series which grades laterally into sands and quartzites. The series thus 

 resolves itself into a basal sandstone, which merges laterally into Sparag- 

 mite and is followed by the Biri limestone. Such overthrusts from the 

 north or northwest are frequent in the Scandinavian region, bringing 

 sometimes the older sediments as well as the crystallines to rest on the 

 Ordovicic and Siluric. Tornebohm has determined that the entire mass 

 involved in the strata of the Mjosen district has been shoved some 130 

 kilometers or more eastward and southeastward from its original locality. 



The Sparagmite comprises a mixture of arkoses with fresh feldspar 

 crystals, and breccias formed of irregular fragments of crystalline rocks 

 mostly with ill-defined stratification, but interbedcled with well stratified 

 sands and clays. Walther 10 has compared it with the Torridon sandstone 

 of Scotland and considers both of torrential origin formed under the con- 

 trol of a semi-arid climate. The rock is the product of disintegration 

 of the old basement crystallines and of the recomposition of this material 

 into the Sparagmite, with but a small amount of sorting of the fragments. 

 This basal Sparagmite and sandstone Bothpletz regards as, in part at 

 least, early Cambric, though it may go back to pre-Cambric time. The 

 Biri limestone, which succeeds it, is also considered by Bothpletz as of 



ao tiber Algonkische Sedimente, von Johannes Walther. Zeitschrift d. deutschen geo- 

 logischen Gesellschaft, Bd. 61, 1908, pp. 283-305. 



Xlill— Bul^ Gbol. Soc. Am., Vol. 27, 1915 



