588 A. W, GRABAU LOWER ORDOVICIC FORMATIONS 



entirely composed of Agnostus pisiformis L. and others largely 

 of Olenus gibbosus Wbg. A. pisiformis also occurs in the 



lower shales 15 . 6 ra. 



Middle Cambric Paradoxides beds — 



Not exposed at present 6 . 4 in. 



Lower Cambric, comprising 



Lingula sandstone with Lingula sp 20 . m. 



MicTcwitzia sandstone with 



Mickwitsia monilifera Lns. and Torellella Icevigata Lns., to- 

 gether with impression of Medusites lindstromi Lns., 

 M. favosus N., M. radians Lns., and the raised "trails" 

 which have been referred to Cruziana — and the so-called 

 Eophyton, from which this sandstone originally received 

 its name of "Eophyton sandstone." The base is formed 

 by a conglomerate containing "dreikanter" of quartz, of 

 which several excellent specimens were obtained at 

 Lugnas 10 m. 



Total Cambric 46 m. 



Weathered gneiss, quarried for millstones. 



In a small stream on the west side of the Kinnekulle near Trollinen, 

 where the Lower Didymograptus shale was exposed with the Ceratopyge 

 limestone below it, we found, in the upper beds of the latter, which here 

 is a gray limestone, numerous pygidia of Megalaspis planilimbata, to- 

 gether with a few specimens of other trilobites and EoHMs christianico. 

 This seems to indicate that this exposure is the Planilimbata limestone, 

 which here appears to be continuous with the Ceratopyge limestone. To 

 be sure, the entire mass of the limestone was not exposed, the exposures 

 being rather a series of ledges in the small stream. This makes it pos- 

 sible to overlook any disconformity which might exist between the Cera- 

 topyge and Planilimbata limestone, though certainly none such could be 

 found after careful search. Moreover, these limestone beds evidently lay 

 below the Lower Didymograptus shales, which were exposed farther up 

 the hill, though no actual contact between the two series could be found ; 

 nor could a fault be assumed between the two exposures, for this would 

 place the Ceratopyge limestone with the Planilimbata limestone above the 

 Didymograptus shales. When it is remembered that the Ceratopyge beds 

 are universally found at the base of the Ordovicic — equivalent in part to 

 the Tremacloc of Britain and perhaps the Potsdam of North America — 

 while the Lower Didymograptus shales are the equivalent of our Lower 

 Deepkill zone, it is apparent that the Planilimbata limestone here exposed 

 is of early Ordovicic age, the practical equivalent of our lowest Beekman- 

 town, the Little Palls dolomite, or perhaps the Theresa or Hoyt lime- 



