The Bamboo Iron Ore. iriiieliell. 243 
tion of the rock, and are features well known in the red 
quartz porphyries of the Kewcenawan. The rock also Shov/s 
fluxion, poikilitic and spherulitic structures. Certain gray 
sericitic schists that occur between this rhyolyte and the overly- 
ing quartzyte or conglomerate are supposed to be a part of the 
rhyolyte rendered schistose and sericitic by dynamic pressure 
and crushing, although the zone occupied by these schists is 
sometimes 150 or 200 feet wide, and "may in places contain 
some sedimentary rock." In the same manner an arkose-like 
schistose zone lies between tiic granite and the quartzyte that 
overlies, and is thought to be due to alteration of the granite by 
dynamic pressure. A question might arise, whether, in the 
light of the author's descriptions, the dioryte should be consid- 
red a different rock from the granite. These igneous rocks 
are considered the basement floor on which, with a structural 
non-conformity, the quartzyte and its basal conglomerate were 
deposited. 
The Baraboo scries comprises three parts : ( 1 ) the Baraboo 
quartzyte formation, consisting mainly of quartzyte but con- 
taining also a small amount of conglomerate at its base, (2) 
the Seeley slate formation, consisting of a quite uniform gray 
clay slate, and (3) the Freedom formation, consisting of two 
members, a lower, of iron ore, ferruginous slates, ferruginous 
dolomyte and ferruginous chert, and an upper, of dolomyte. 
The first mentioned of these (Baraboo quartzyte) is well 
known, having been described several times by different geolo- 
gists. It is unquestionably a very widespread formation, ex- 
tending into northern Wisconsin, into Minnesota and to 
northwestern Iowa. It has been styled Barron County quartz- 
yte. New Ulm quartzyte and Sioux quartzyte. It is in several 
places accompanied by red slate, hardened and semi-metamor- 
phosed, making the well-known catlinyte in Pipestone county, 
^Minnesota. It was first named by Dr. C. A. White, Sioux 
qitartayte, from its outcrops in northwestern Iowa. Tlie 
catlinyte beds of Pipestone county in INIinnesota and of Bar- 
ron county. Wis., are perhaps represented at Baraboo by the 
more clayey and schistose beds enclosed in the quartzyte, now 
converted to a schist, as described by Dr. Weitlman, bv siiear 
and differential movement incident to the uplifting of the 
quartzyte ranges. Near Ablemain's such uplifting so fractured 
