616 A. W. GRABAU LOWER ORDOVICIC FORMATIONS 



The best exposures arc in the south bank of the river, from 500 to 600 

 meters below the mouth of the Fogelsang. Here the lowest /one of the 

 region with Glossograptus Jiinchsi Hopk. is seen, but not in contact with 

 any lower formation. A hundred meters or more upstream, however, 

 occurs an outcrop of the Geminus bed of the Upper Didymograptus 

 shales. Since no other formations falling between these two are known 

 in this region, the hiatus (St. Peter hiatus of American nomenclature) 

 occurs in this interval. The lowest zone of the next higher series — that 

 is, that of Climacograptus rugosus Tull. (= zone of Dicranograptus 

 clingani Carr.) or the Lower Hartfell — is shown in the river bed only a 

 short distance below this. 



In the Eostanga district, on the north border of the Ordovicic-Siluric 

 zone of West Scania (38 kilometers north from Lund), we meet with 

 other exposures of these strata, though the lower beds of the Ordovicic 

 are not seen. We did not visit the sections, but they have been fully de- 

 scribed both by Tullberg (1883) and by Moberg. There seems to be 

 some confusion regarding the interpretation of the lower beds, but the 

 Orthoceras limestone of this section probably lies above the horizon of 

 the Upper Didyinograptus shales instead of below it. The two are not 

 found in the same section, and this interpretation is based purely on 

 paleontologic evidence, the stratigraphic evidence at first sight being 

 against this. 



The Orthoceras limestone is seen only in the Kvarnbacken (Mill Brook) , 

 where it forms an isolated outcrop of black, hard, often crystalline lime- 

 stones, alternating with lighter gray beds, exposed in the bed of the 

 stream and dipping about 45° south. It has yielded a number of fossils: 

 those reported by Tullberg and Moberg being: 1, Asaphus acuminatus 

 Ang. ; 2, JEglina umbonata (Ang.) ; 3, Illcenus esma/rki Schloth; 4, 

 Ampyx carinatus (Ang.) Linss. ; 5 r Niobe emarginula Aug., and species 

 of Ptychopyge, Trinucleus, and Orthis, as well as a Cystid. As Moberg 

 remarks: "The limestone belongs with certainty to the upper part of the 

 Scanian Ortlwcera.s limestone (Asaphus beds)" (Guide, page 80). Com- 

 pared with the Esthonian development, we find that number 3 of the 

 above list characterizes all three divisions of B III, while number 5 is 

 characteristic of B III a and B III ft. In Dalarne and Westergotland 

 Illcenus esma/rki occurs in the Asaphus limestone above the Limbata beds 

 and, as I have shown, above the hiatus. By these standards, then, the 

 Orthoceras limestone of Eostanga belongs to the upper part of the Middle 

 Ordovicic, representing probably a part of the Lower Dicellograptus hori- 

 zon. In the Mill Brook it is followed, after an interval of 400 meters, 

 by hard Orthis shales with Calymene clilatata Tull., Ampyx rostratus 



