W. G. Fearnsides—Lower Ordovician Rocks of Scandinavia. 265 
beds. The ‘‘ Korrosionsgruppar,”? or Erosion - pocketing, to be 
described later, also is not much in evidence. 3ay gives place 
upward rather abruptly to the nodular grey shales of the Phyllo- 
graptus shale 30. 
In Skane Ceratopygekalk is very indifferently exposed, and is now 
known with certainty only at the mill dam close to Fagelsang 
(S2 and ©). There separated from baked Phyllograptus- -bearing shales 
by a little sill of rotten diabase, some three or four beds of decayed 
and very ferruginous but once crystalline limestone alternating with 
shales containing sheared Bryograptus. Both limestone and “shales 
contain Ceratopyge and Shumardia, and pass down into the Bryograptus 
Fjerulfi shales mentioned as containing the Dictyonema norvegica : a 
A similar limestone mentioned by. Linnarsson & Holst (S10) a 
occurring at Jerrestadt mill in East Skane is no longer visible. 
In all other Swedish districts the failure of the sediment supply has 
left the Ceratopyge beds more or less incomplete, and only in South 
Oland do we find any further certain representatives of Brogger’s 
3a of Kristiania. It is possible that similar beds were really 
deposited over the greater part of Oland and Vestergitland and 
Ostergdtland, but if so must have been caught up again almost 
immediately, and the succeeding glauconitic division can be seen to 
rest variously upon Ceratopyge shale and Dictyonema shale, and 
upon the Acerocare, the Peltura, the Spherophthalmus, and the Orthis 
lenticularis zones of the Alum Shale. In these districts glauconitic 
shales and Ceratopygekalk together are never more than 6 or 7 feet 
thick, yet have a distribution which is almost universal. Despite their 
thinness, their variations in lithological character are multitudinous 
and so complex in their details that they defy further classification. 
As a whole the beds are characterized by the presence of a large 
proportion of glauconite grains and by the strange method of bedding 
which has been termed ‘“ Korrosionsgruppar,” * or Erosion-pocketing 
(see Plate [X). The matrix of the glauconite varies from shale quite 
comparable with the Alum Shales to a limestone of the purest whiteness, 
and the glauconite though sometimes absent may be present in any 
proportion. As arule the lower beds are more muddy and the upper 
more calcareous, but either upper or lower groups may be entirely 
absent. Whenever the glauconite is very abundant it is usually 
associated with knobs or nodules of brown phosphate ranging up from 
the size of a pea to the size of a walnut, whose unworn surface 
contrasts strongly with the lustrous black or green of the grains of 
glauconite. Pyrites i in well-formed cubes or pentagonal dodecahedra 
in single crystals or in shapeless lumps is also rather a feature of the bed. 
With the phosphate nodules, especially at the base of the series, are 
clay galls of older beds and angular fragments of phosphatized orsten, 
which in some cases retain recognizable fossils. In places where the 
glauconite comes to rest upon a discontinuous orsten bed the shales 
between the individual orstens have usually been scoured away, and 
the interspaces filled up with angular fragments of that or any other 
1 J. G. Anderson, ‘‘ Uber cambrische und silurische phosphorit-fithrende Gesteine 
aus Schweden’’: Bull. Geol. Inst. Upsala, ‘vol. ii (1895). 
* J. G. Anderson: Bull. Geol. Inst. Upsala, 1895. 
