604 



A. W. GRABAU LOWER ORDOVICIC FORMATIONS 



LOWER ORDOVICIC OF DALARNE 



This province shows several interesting developments of the earliest 

 Ordovicic rocks, a part of which I was enabled to study under the guid- 

 ance of Dr. Elsa Warburg and Prof. Carl Wiman, both of Upsala. Im- 

 portant sections have been worked out by G. Holm, 30 S. L. Tornquist 

 (1883-1884), H. Heclstrom (1894), F. v. Huene (1904), 37 and Carl 

 Wiman (1906). Marr 38 has also added some interesting facts regarding 

 this district. 



In the environs of Nittsjo, on the eastern end of Siljan See, some of 

 the most complete sections are seen. These are best approached from the 

 village of Rattvick, which lies on the shore of the lake, which is here 



Figure 6. — Section of the Lower Ordovicic Formations shown in the Railroad Cut near 

 iSjurherg, in Dalarnc, Sweden 



From a sketch by the author. Paleozoics are faulted into the granite mass, the fault 

 block showing at the base fresh granite, which passes upward into decomposed granite. 

 This is succeeded by the Obolus conglomerate (0), the Glauconitic sand (G-), and the 

 limestone comprising the Ceratopyge bed (C), the Planilimbata limestone (P), and the 

 Limbata limestone (L). 



skirted by the railroad. About 4.5 kilometers northwest of Rattvick sta- 

 tion, by the road which parallels the railroad, and less than a kilometer 

 beyond the little settlement of Sjurberg, there is found in the railroad 

 cut an interesting section which is here reproduced. 39 



The top of the granite basement of the series consists of from 0.1 to 

 0.4 meters of weathered granitic material, which passes upward into an 

 irregular bed of fine conglomerate, mostly with quartz pebbles and granite 



80 Ueber einige Trilobiten aus dem Phyllograptus Schiefe Dalekaliens. Bit. K. v. Akad. 

 Handl., Stockholm, 1882, Bd. 6. No. 9. 



37 Centralblatt f. Min., etc., 1904, No. 15. 



38 J. B. Marr: On the Cambrian (Sedgw. ) and Silurian rocks of Scandinavia. Quar- 

 terly Journal Geol. Soc, London, 1S82, p. 315. 



39 H. Hedstrom : Geologiska notiser fran Dalarne I. Stockholm, Geol. For. Forh., Bd. 

 16, 1894, pp. 585-593. Ibid., Till frag an om fosforitlagrans uppfcradlandi och forekomst. 

 ide geologiska formations. Ibid.. Bd. 18, 1S96, pp. 05-70. 



Wiman : Om ceratopygeregionen inom Siljansiluren. Ibid.. Bd. 2S, p. 453. 



And Warburg's Guide to Excursions, C.CL, 10th Intern. Geol. Cong. (No. 21), p. 3. 



