404 Scientific Intelligence. 
would remark that the Act has ~ ably and fully discussed 
before in the works of previous observers, Furthermore, while 
veins on a small scale are occasio ally: seen, we were unable to 
find upon either the jasper or its associated ore a single character 
belonging either to a vein or an infiltration deposit. It ther etore 
g n this country, it is necessary that the question should 
be answered by the facts, and not by any preconceived. theory or 
idea. The question now is what are the facts, and their most 
probable explanation. The first and_most important thing to be 
observed in dec pie this is the relation of the jaspery formation 
to its countr 
This relation is well shown in and about the a i rae 
mine at Ishpeming. On the north side of one of the ned 
pits just east of the main workings, the junction of the jaaper and 
ore with the chlorite schist was observed and figured. Specimens 
were also taken that show the contact. e junction of the two 
is very irregular, the banding of the jasper and ore following the 
and becomes 3 sanbariee an indurated argillite. The contact and 
iaitions of the two rocks are not such as are seen when one sedi- 
meutary rock is laid down tipon another, but rather that observed 
when one rock is intrusive through another ; and in this case the 
intrusive one is the jasper and its associated ore. On the south 
side of the same pit the jasper bows in and out in the schist, 
contour. Lying agaiust it is a long arm jasper, similarly 
ded, which ends i unded k In the southwest corner 
the jasper and ore with the schist could be observed, se do lg spr 
is seen to be an eruptive one, on the part of the form he 
School-house mine east of the Lake Superior mine, the jasper 
forms a dike with a knob-like ending, the lamination aaiee) 
following the curvature of the sides. The contacts between the 
ore and schist were well-marked i nes, Overlying the 
ore was found on one side a ferruginous and quartzose breccia and 
conglomerate composed principally of the ruins of the underlying 
fl 
rate the underlying ore and a Mr. Brooks’s ——_ 
g the “quartzite” of the Marquette district is undou 
ay sen true rol this rock, that when he finds the “ quartzite,” adja. 
