MURCHISON SILURIAN ROCKS OF SCANDINAVIA. 



39 



Thickness in feet. 

 12. 



280 {} J; 

 370 9. 



{ 



700- 



160 



30 to 40 



50 



150 to 160 



Total 1930 



Local Subdivisions. 



Upper Malmo limestone . 



Graptolite-schists . . . 



Orthoceratite-limestone . 



Upper encrinal schists 



Coralline and encrinal lime 



stone 



b. Pentamerus-limestone 

 a. Argillaceous schists . 



Calcareous sandstone . . . 



} Calcareous and argillaceous 

 flags (Orthoceratites and 

 Encrinal schists) . 

 Graptolite-schists . . 

 Orthoceratite-limeston e 

 Graptolite-schists . . 

 Alum-schists . . . 

 Quartzite and unfossiliferous 



Local Groups. British equivalents. 



f Upper Silurian. 

 * Upper Malmo ■{ (Woolhope, 

 Wenlock, & 

 [ Ludlow Rocks.) 



)- Lower Malmo . Llandovery 

 Rocks. 



Oscarskal 



Lower Silurian. 

 Caradoc. 



> Upper Oslo . Llaudeilo. 



* Lower Oslo . . Stiper Stones, 

 rocks. 



In referring to the section, fig. 1, we see, that the alum-schists (2) 

 with bituminous limestone rest upon unfossiliferous and siliceous grau- 

 wacke (1), evidently the equivalents of a part of the Longmynd 

 (Cambrian) of Britain. In No. 2, the lowest zone in which intel- 

 ligible fossils have been detected in Scandinavia, or the " Regiones 

 A, B," of Angelin, there are found small Graptolites, Graptopora 

 flabelliforrnis, several species of Lingula, including one like L. Da- 

 visii, a horny shell nearly allied to Obolus Apollinis, Agnostus 

 pisiformis, Olenus scarabceoides, Boeck, Olenus (Trilobites) latus, 

 Boeck (Eurycare latum, Angelin), (Trilobites alatus, Boeck), Sphcer- 

 ophthalmus alatus, Angelin, Trilobites pusillus, Sars, Olenus (Dalm.) 

 gibbosus, Wahl., and Asaphus grandis, Sars. 



This zone (2), being unquestionably the same as the Regiones A, B, 

 of Angelin in Sweden*, is manifestly the northern equivalent of the 

 " primordial zone " of Barrande in the Silurian Basin of Bohemia, and 

 of the Stiper Stones and Lingula-schists of Britain ; and, though only 

 150 feet thick, contains Graptopora^ flabelliforrnis (Gorgonia of 

 Eichwald), mixed with Lingula as in our country, and with them the 

 Agnostus pisiformis and the Graptolite Didymograpsus geminus, as 

 well as the Silurian Brachiopod Orthis calligramma, the last three 

 of which occur also in the true Llandeilo zone of the Silurian region 

 of Britain. In other words, we thus see clearly how, in extending our 

 survey, it is impracticable in general classification to separate the 

 Lingula-flags, or "Zone Primordiale," from the Lower Silurian rocks. 



The next mass of schists (3, 4, 5), with an intermediate limestone, 

 bears a close analogy to its congener in Britain, by ushering in with 

 it a profusion of brachiopods, and clearly represents the Llandeilo 

 formation. Thus, amongst its fossils are the Graptolites, Diplograp- 

 sus pristis, D. folium, D. teretiusculus, Graptolithus Sagittarius, and 

 the shells, Orthis calligramma, O. elegantula (O.parva, de Vera.), 



* See M. Barrande's lucid memoir, " Parallele entre les Depots de Boheme et 

 de Scandinavie," 1856. 



f The generic name proposed by Mr. Salter in 1857 for this curious form, 

 which is evidently one of the Fenestellidae, and connects that group with the 

 Graptolites. Report American Assoc, for 1857, Montreal. 



