608 A. W. GRABAU LOWER ORDOVICIC FORMATIONS 



The graptolites are evidently the equivalent of the Lower Arenig of 

 Britain and of the Lower Deepkill of America. As already noted, M-ega- 

 laspides delecarlica is a close relative of, if not identical with, M. schmidti, 

 from the upper part of B 1 (3 of the East Baltic region. Niobe Iceviceps 

 also occurs in East Baltica in B I /? and B II a. The basal limestone 

 of Skattungbyn is regarded by Wiman as the Ceratopyge limestone. 



ORDOVICIC OF JAMTLAND 



Strangely enough, Phyllograptus shale is present in Jamtland, though 

 unrepresented in the more southerly regions. This seems to be an expan- 

 sion from the Christiania region passing to the west of the Mttsjo region 

 in Dalarne (eastern end of Siljan See), but including the northern end 

 of the Dalarne Paleozoic province (Skattungbyn) . The shale has already 

 been referred to as carrying intercalated limestone bands with the Mega- 

 laspides fauna, and thus serving to bring the two facies from east and 

 west together. Moberg has found a representative of the Ceratopyge 

 limestone as a thin bed overlying the Upper Cambric in some sections. 

 In this he found Eorthis christianice Kjerulf, Niobe Iceviceps Aug., and 

 Cyrtometopus cf. foveolatus Ang. In another bed he found Niobe in- 

 signis Linrs. and Megalaspis stenorhachis Ang. ? 



The Orthoceras limestone of Jamtland is particularly well developed 

 in the country north of Brunflo, and between that place and Ostersund. 

 It has much the character which it possesses in Westergotland, that is 

 to say, it represents both the lower Megalaspis limbata division, which 

 belongs to the Lower Ordovicic, and the Asaphus-Gigas-Platyurns divi- 

 sion, which belongs to the Upper Ordovicic. Here, then, as in Dalarne 

 and in Westergotland, the Orthoceras limestone includes within itself the 

 hiatus which represents practically the whole of the Middle Ordovicic 

 (Chazyan of the American scale) and a part of the Lower Ordovicic as 

 well. In thickness the limestone varies from 37 cm. in the Brunflo region 

 to 90 meters in Kloi'stjo and Skalangen. 42 



A peculiar development of the basal part of the Ordovicic is found in 

 the Locknesjo Lake region of Jamtland and has been described in detail 

 by Wiman. 43 Besting directly on the granitic basement is a breccia and 

 residual arkose derived from the decomposition of the underlying rock. 

 This is locally known as "Loftar stone," and it is succeeded by the Ortho- 

 ceras limestone, a part of which it may actually replace. The following 

 section (figure 7), given by Wiman, shows the relation of these beds. 



42 Moberg : "Silurian of Sweden," p. 146. 



43 Carl Wiman : Ueber die Silurforniation in Jamtland. Bull. Geol. Institute, Univer- 

 sity Upsala, vol. iv, pt. 2, 1899. 



