304 The American Geolociisf. May, 1895 
the ordinavy products of sedimentation, and by the formation 
of surface hivas. These basic rocks, coming from the deeper 
portions of the earth, are now closely associated with acid 
eruptives, such as red felsytes and red granites, which may 
have been generally the products of fusion of the sedimenta- 
ries, as recently demonstrated by Bayley in Minnesota.* The 
metamorphism of the clastic materials of this second series 
was widespread. It is common to all of the areas represented 
in the table, but the actual appearance of molten rock among 
the fragmentals has only been found in the Cortlandt and Ad- 
irondack areas. However, in the northern extension of the 
Adirondack area into Canada this character is well described 
by Selwyn and Ells.f 
1. The last historical event which we can use as a datum for 
comparison in this connection, is the subsidence of the turbu- 
lence and the non-conformable deposition of the Potsdam 
sandstone (Dicellocephalus zone) in places upon all of the 
earlier strata, this being accompanied by a progressive sub- 
sidence of the region. 
It is therefore legitimate, and in accordance with the ten- 
dency of the evidence, to infer that the succession of geologic 
events in the Adirondack region was substantially concordant 
with that in the Taconic and the Cortlandt areas. The steps 
were emphasized by the eruptive epochs, and these ph^'^sical 
disturbances were probably the main causes of the changes of 
the Taconic subfaunas. We cannot yet differentiate the erup- 
tives in either of these areas into two or more parts as to 
dates. We are certain only of one. But in the Lake Supe- 
rior region, as will be shown, there were at least three sepa- 
rate eruptive epochs. 
THE NIPISSING BEACH ON THE NORTH 
SUPERIOR SHORE. 
By F. B. Taylor, Fort Wayne, Ind. 
When the writer's article on the abandoned shore lines of 
the south coast of lake Superior;J; was written the position and 
*Eruptive and sedimentary rocks on Pij^oon point, Minnesota, and 
their contact phenomena. Bull. No. 109, TJ . S. Geol. Survey. 
fGeolo<rical Survey of Canada, Rep. of progress for 1877-78, pp. .5A to 
7A; Ditto, 1887-88, Reports on tlie geology of the eastern townships. 
|Am. Geologist, vol. xiii, June, 1894. 
