52 Editorial Comment. 
more rounded, and more likely to be destitute of detritus from 
eruptive rocks. 
The division of the eruptives into two classes they think is 
not w^arranted. The so-called massive trap of the Bohemian 
range is itself bedded, and even contains interstratified conglom- 
erates. 
The dip of the eastern sandstones toward the southeast is not 
due, in the opinion of the authors, to the extrusion of the Bohe- 
mian range; for this dip is found not only at the contact but at 
points beyond the possible reach of such extrusion. 
The so-called jaspers are of the same nature as the quartz 
porphyries and felsytes of the Keweenaw rocks, and these are 
regarded as acid eruptives within the rocks of that series. 
They could not hence have been caused by any metamorphism 
of the sedimentary beds produced by the eruptive rocks of the 
Bohemian range. They were, further, the source of the peb- 
bles of the Keweenaw conglomerates, and must, therefore, on 
the hypothesis of Messrs. Foster and Whitney, have antedated 
the Bohemian disturbance. 
The series of fissures which gave vent to the trap of the 
Keweenaw rocks are supposed not to have been along the course 
of Kewenaw point, but quite to the southward, and they are 
now probably buried by the newer sandstones. 
They accept, however, number 6 of the propositions of the 
Foster and Whitney view, but they qualify it by two exceptions; 
(a), that the fissure was not formed subsequent to the produc- 
tion of the eastern sandstone, and (b), when formed it did not 
give vent to any eruptive material. These exceptions are neces- 
sary because the sandstones on the opposite sides of the Bohe- 
mian range do not seem to have been faulted away from each 
other and if they had been the enormous downthrow of 35,000 
feet would be required to explain their present relative positions; 
also because at points cast of lake Gogebic the low^ermost 
members of the Keweenaw series, dipping northward, are found 
to be overlapped in unconformable position by the eastern sand- 
stone. 
The Agasslz viav regards the south face of thethe trap range 
of Keweenaw point as an ancient shore cliff, having been pro- 
duced entirely by the erosion of the waves of that sea in which the 
