1880.] A779 [ Wadsworth. 
We are perfectly willing to leave it to geologists to decide which is 
the simpler hypothesis and which demands least expenditure of time 
and energy. It is, however, not a question of simplicity, but a ques- 
tion of observed facts and evidence. We are perfectly willing to ac- 
cept any theory that will explain the facts observed, but in the pres- 
ent state of knowledge we know of no view except the eruptive one 
that will explain the things seen by us, and we believe that the 
eruptive origin will explain every fact pointed out by those holding 
the view that the ore is sedimentary. We believe that the facts ob- 
served in studying the region under discussion, in a different manner 
from that employed by other observers there, sustain the views of 
Messrs. Foster and Whitney rather than those of more recent inves- 
tigators. 
It is not to be lost sight of, that as it was once fashionable to de- 
cide that rocks were eruptive, without evidence; so now it is likewise 
fashionable to decide that rocks are sedimentary, with like want of 
proof. As once any statement regarding the eruptive origin of any 
rock passed unquestioned, so now the similar wild statements about 
sedimentation pass unchallenged. The reasons for the position taken 
are rarely asked so long as the popular belief runs in the same direc- 
tion. ‘The day seems not so far distant as might be supposed, when 
it will again be as necessary to challenge the statements of those hold- 
ing plutonic views as it is now those holding neptunian ones. The 
popular belief in any subject continually oscillates between different 
opinions like a mighty pendulum, passing and repassing the point of 
truth. But, strange fatality, if it stops at this point, all is stopped, the 
works are dead. When truth is reached or discussion ends, stagna- 
tion ensues. Again, when the pendulum vibrates, woe be to the man 
who swings not with it. In all candor we ask geologists to stop 
and think if the pendulum has not swung decidedly out of the per- 
pendicular on the sedimentary side? ‘ase up a little, brethren, but 
do not swing back too far. 
Besides the eruptive bosses, sheets, dikes, and wedge-shaped 
masses occurring both as overflows and intrusions, in the Marquette 
district, sedimentary deposits exist, as well as others formed from the 
decomposition of the ore and jaspilite 7m szu. For a description of 
these, figures of observed occurrences a fuller. discussion of the 
subjects touched upon here, and many others, an historical account 
and general bibliography of both this and the Keweenaw Point dis- 
trict and a microscopic study of the rocks, the reader is referred to the 
Bulletin of the Museum of Comparative Zoology. 
