158 The American Geo/o(/isi. S(M)t«mbcr, I89r> 
far as known. rcpdrtcMl this in the Pcnokcc district, and re- 
ferred it to the l)ase of the Keweenawan.* But a very slight 
exposure was seen near Bessemer in 1885. Mr. W. G. La Rue, 
of Barraboo, Wis., gave nif)re definite information eoneerning 
it. North from the Colby mine near the ])lutls of tlie Kewee- 
nawan range, which there are plainly visible rising as a series 
of hills within a mile or less of the village (Bessemer), he was 
emi)loyed to explore for ore. Under the Keweenawan diabases, 
or gabbro, he found a quartzyte and a sandstone, the two dif- 
fering only in induration, both consisting of crystalline quartz. 
He shafted under the quartzyte in a conglomerate of iron ore, 
and after a tinu^ he found that the conglomerate turned al- 
most at a right angle towartl the north. He did not ascertain 
what was under the conglomerate, but he found the quartzyte 
and sandstone together had a thickness of at least 235 feet. 
This was in the S. W. ^, N. E. ^, sec. 10, 47-16, Michigan. 
Besides the points mentioned in Minnesota two others may 
be referred to. In 1879 the writer noted a red quartzyte, 
wh.ose appearance reminded him of the New Ulm rock, on the 
upper waters of the Temperance river, near the Mesabi divide. 
This is much re-crystallized, however, so far as specimens col- 
lected show, but some of the thin sections consist almost whol- 
ly of (jiuirtz. 'I'his quartzyte range occurs just south of the 
anorthosyte and the red-rock belt, and north of the principal 
Keweenawan ridge. Again, in Bulletin V, of the Minnesota 
geological survey, will be found the record of a deep well 
drilled at Short Line Park, in the St. Louis valley west of Du- 
luth. This well is located about 200 feet above the river, on 
the Hank of the " gabbro" range, which here, however, consists 
of a more or less diabasic, amygdaloidal rock. The drill 
struck at the depth of 468 feet, a quartzose rock, or grit, 
whicli ])roved to develop at a greater dei)th into a siliceous 
conglomerate which was described as pi/riti/croii.s-^ plainly the 
same as that which is at the river side about a mile further 
down the valley, already referred to as probably being ])re- 
Keweenawan. This rock was struck below 230 feet of the so- 
called gal)bro of that region, and developed a thickness of 67 
feet. 
With this it is sutticiently shown that affer the AnimiA-ie 
^Sixteenth Minnesota report, pp. 55-56: Eighteenth report, pp. 42-43. 
