Wadsworth. ] A474 [March 17, 
ing and can find nothing in it that proves sedimentation or is incon- 
sistent with that repeatedly seen by us in known eruptive rocks. 
3°. The folding and contortion of the banding would take place 
in any rock whatever its origin, after it was in position, if subjected 
to proper conditions. A lava flow buried and subjected to the same 
compression and up-tilting, shows foldings and contortions as would 
a sedimentary rock in like position and subject to the same agencies. 
This we find to be the case in the older lava flows. Hence folding 
and contortion of banding in rocks, like the banding, iscommon to” 
both sedimentary and eruptive rocks, and like the latter (banding) 
is no proof of either origin. 
4°. Joints and cleavage planes are well known to be common to 
both sedimentary and eruptive rocks, hence their presence cannot be 
taken as proof of either origin. 
5°. Whoever advanced the view that since the associated rocks 
were sedimentary, therefore the jaspilite and ore must be, prob- 
ably intended it for a bit of facetiousness, since he must have been 
aware that this principle would prove the great majority of dikes and 
veins to be sedimentary. A dike passing through slate must be sedi- 
mentary because the slate is sedimentary! Do we not find rocks in- 
truded through sedimentary ones in every position, both parallel with 
the stratification and oblique or perpendicular to it? Can any geolo- 
gist ever have been so ignorant of the mutual association of eruptive 
and sedimentary rocks as to have soberly advanced the above idea? 
How then can the alternation of one rock with another be taken as 
proof that they both originated in the same manner? 
It is generally accepted that the old copper-bearing basalts of Ke- 
weenaw Point are lava flows. Now they are interlaminated with sand- 
stones and conglomerates. Does this prove that the sandstones and 
conglomerates are lava flows, or again does it prove that the lava 
flows are detrital just as the sandstones and conglomerates are? 
However absurd this line of argument may seem now, it has been 
applied in the past to the above-mentioned beds on Keweenaw 
~ Point. How quickly would the fallacy be seen, if we should claim 
that the Calumet conglomerate was a lava flow because it was inter- 
laminated between two lava flows? Would such a supposition be any 
more erroneous than the one advocated for the iron ore, which would 
make a lava flow on a sea beach, afterwards buried in detritus, to be 
of the same origin as the detritus above and below it? 
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