102 STEATIGEAPHICAL GEOLOGY 



In connection with the Cambrian Series of Belgium the recent 

 recognition of similar rocks beneath the eastern counties of England 

 is of much interest, for at Stutton near Ipswich the boring made 

 in 1894-5 entered hard quartzitic rocks at a depth of 994 feet, and 

 traversed them to a total depth of 1525 feet. These rocks are 

 really dark -grey quartzo-phyllades, which M. Mourlon has recognised 

 as resembling those of Villers, near Ath. At Harwich and Weeley 

 in Essex the rocks found below the Gault are dark -grey and purple 

 slates, in which an Orthoceras was found. These must be either of 

 Tremadoc age or a part of the overlying Ordovician Series as 

 developed in Belgium. 



4. Scandinavia 



It is interesting to note that in Norway, Sweden, and Northern 

 Russia the Cambrian strata occur in broad, flat-lying sheets as 

 originally deposited, and are so little altered that they have more 

 the aspect of our Mesozoic clays, shales, and sandstones than of 

 Palaeozoic rocks. Moreover, those of Scandinavia present a complete 

 succession of highly fossiliferous beds, and yet their thickness is 

 only a few hundred feet. 



The Cambrian Series of this region consists everywhere of a lower 

 arenaceous division and an upper argillaceous division, the lower 

 being from 350 to 550 feet thick and the upper from 200 to 400 

 feet. The system is most fully developed in Sweden, and especially 

 in the districts of Scania and Westrogothia, where there is the 

 following succession in descending order (slightly altered from 

 Linnarsson and Tullberg). 29 



IV. Passage Beds (thickness about 50 feet = Tremadoc). 



3. Ceratopyge limestone, with C. forftcula. 



2. Shumardia shales. 



1 . Dictyograptus shales, with Dictyograptus and Obolella Salteri. 

 III. Olenus shales in five zones, with three bands of limestone, thick- 

 ness from 70 to 200 feet ( = Lingula flags). 



5. Zone of Parabolina heres. 



4. Zone of Peltura scarabceoides and Sphcerophthalmus alatus. 



3. Zone of Eurycare and Leptoplastus. 



2. Zone of Parabolina spinulosa. 



1. Zone of Olenus truncatus, 0. gibbosus, and Ag. pisiformis. 

 II. Paradoxides fh&les, divisible into four principal zones, and from 80 



to 160 feet thick ( = Menevian and Solva Beds). 



4. The Andrar.um limestone with 5 feet of shale above ; Agnostus 



laevigatus, \Paradoxides Forchhammeri, and Orthis Hicksi. 



3. Zone of Par. Davidis and Conocoryphe cequalis. 



2. Zone of Par. Tessini with the exsulans limestone at base 



containing Conocoryphe exsulans and Par. palpebrosus. 

 1. Zone of Agnostus atavus, Paradoxides olandicus, and the 

 black Alum shale at the base. 



