264 W.G. Fearnsides—Lower Ordovician Rocks of Scandinavia. 
following of overlap and unconformity there is little evidence, 
but a close inspection of the phenomena presented by the beds B, 
Glauconite shale and Ceratopygekalk, will convince the most sceptical 
that none of the happenings which we generally associate with 
spasmodic subaqueous erosion are missing. We have noted that 
the upper Dictyonema series is complete only about Kristiania 
and in Skane, and that passing thence north-eastward its thickness 
decreases often to zero, the highest beds being the first to go. 
Further, we have seen that though in North Oland and Oster- 
gotland some part of the series reappears, it is always associated with 
a sandy or conglomeratic phosphate bed containing fragments of all 
manner of older Cambrian and even Pre-Cambrian rocks, and shows 
therefore a passage towards the Odolus conglomerate facies of Dalarne 
and Western Russia. The manner of this change is well brought out 
by the section through the Cambrian and Ceratopyge rocks of Oland 
(Plate VIII) which I have plotted partly from the records contained 
in the new Swedish Geological Survey Memoirs of the Island 
of Oland (O 1-6), and partly from my own observations. This 
section, though fairly true to scale, has a vertical scale about 1250 
times the horizontal, and it will therefore be readily understood 
that in the field all dips are imperceptible, and that quite the most 
remarkable feature of the unconformity is the thinness and extra- 
ordinary regularity of the beds affected. Most unfortunately the 
south end of the island of Oland just fails to contain an area of 
continuous deposition, but from the fact that at Ottenby, as shown by 
Moberg (0 4), shales above and below the surface of discontinuity 
contain identically the same fauna, it must follow that the time value 
of the discontinuity must there be reduced almost to zero. 
B. The Glauconite Shales and Ceratopygekatk. 
Returning now to areas of continuous deposition, we notice first the 
Ceratopyge shale (Brogger's 8a 8) about Kristiania. This, as already 
mentioned, is in its lower part an Alum shale with orstens, but upwards 
becomes greyer and more calcareous. Its thickness is some 16 to 20 
feet. Its lowest beds with their brachiopods, Bryograptus and 
Parabolina have been already considered with the Déctyonema and 
Bryograptus shales. Its middle beds also yield Bryograptus, but 
with it abundant Shumardia, Agnostus Siedenbladhi, Euloma, and 
Ceratopyge, while the higher nodular shales and limestones rich in 
Lriarthrus Angelini seem otherwise quite indistinguishable from the 
overlying Ceratopygekalk. The Ceratopygekalk 3@q consists (K.2) 
of five or six beds of a blue-grey nodular limestone, together about 
4 or 5 feet thick. It is now rather difficult to work, but I was able to 
prove for myself the existence of Wiobe, Symphysurus, and Megalaspis 
in some beds, and of Ceratopyge, Euloma, and Shumardia im others. 
The late Tremadoc genera (British), such as Chetrurus, Dikellocephalus, 
and Holometopus (Ampyz), are also recorded from this horizon, though 
not mentioned in the zone 3848 below. As compared with other 
Scandinavian Ceratopygekalk, 3ay of Kristiania is remarkable for 
its small content of glauconite, which here occurs only in streaks and 
lines with the shale partings between the nodules of the very highest 
