346 The American Geologist. May, isos 
rated by two basal conglomerates. The description would indicate that 
the Cascade formation is the equivalent of the Vermilion of Minnesota, 
or the Coutchiching of Manitoba. It is an old hornblende schist in- 
vaded by irruptive granite. In the same formation is much gneiss 
traversed by basic and acid dikes. 
The Republic formation embraces breccia, conglomeratic schist, 
quartzyte, dolomyte, jaspilyte, granite, felsyte, diabase, porodyte and 
porphyryte. These have a tendency toward chloritic, talcose or hy- 
drous mica schist. The dolomyte is interbedded with quartzyte, and is 
white, flesh-red, light or dark gray and often silicious. The Jaspilyte 
is the iron-ore rock of the formation. It is described from two points 
of view, viz., an eruptive origin and a sedimentary origin. The iron 
ores of this formation are situated, according to the conception pre- 
sented in the report, between two conglomerates, one being supposed to 
be at the base of the Republic and the other at the base of the Holyoke, 
the former being evidently the equivalent of the Keewatin. 
The Holyoke formation which is that which corresponds with the 
iron-bearing formation of the Penokee and the Mesabi ranges (the 
Taconic of the Minnesota reports), embraces a great variety of lithol- 
ogy, viz. : 1. Conglomerate, breccia and conglomerate schist. 2. Quartz- 
yte. 3. Dolomyte. 4. Argillyte, graywacke and schist. 5. Granite 
and felsyte {?). 6. Diabase, dioryte and porodyte. 7. Peridotyte, ser- 
pentine and dolomyte. 8. Melaphyr or picryte. 9. Diabase and 
melaphyr. 
"The conglomeratic schists are often quite chloritic, and pass into chlor- 
ite schists and argillytes without showing any trace of their conglomerate 
structure." The quartzyte is that which is well known as the basal 
member of the Taconic in Vermont, the granular quartz, and partakes 
of the characters of the underlying formation, even shading into and 
alternating with conglomeratic portions and with chloritic debris. 
This quartzyte sometimes fills fissures In the underlying formation, 
causing the appearance of dikes of sandstone, such as those that have 
been described in California and elsewhere. To such dikes Dr. Wads- 
worth gives the name clasoUte, using the term as a generic one, whether 
the fissures were filled by deposition from above, or by earthquake or 
water action from below. "It is an open question whether some of the 
argillytes and schists now found cutting the iron ore beds have not been 
formed as clasolites rather than as true dikes. A similar formation 
might be produced by soft clayey rocks, if, when the associated rocks 
were folded, the clayey material were squeezed into fissures or between 
beds." 
It is not certain yet, according to the report, whether the dolomyte 
supposed to belong in the Holyoke, may not be rather a member of the 
Republic. 
The upper portion of the Holyoke formation develops into "a pecu- 
liar grayish argUlitic sandstone which contains some feldspar," and the 
term graywacke has been provisionally applied to this. It grades into 
an argillyte and as such furnishes roofing slates, though the rock is so 
