jV. H. Winchell on the "Original Hiironian/'' 13 
But the original Huronian embraces, not only these black 
slates and quartzytes, which in their lower portions become the 
"slate conglomerate" of the region, but also, overlying the 
slates and quartzytes, a great quartzyte of a different kind. 
This overlying quartzyte constitutes perhaps the most conspic- 
uous member of the original Huronian. Its thickness is very 
great, reaching perhaps ten thousand feet. It is red in its lower 
half, and nearly white in its upper. Both parts become pebbly, 
and even coarsely conglomeritic in limited and local areas. 
There is probably no stratigraphic or physical break between 
these parts, but while on the gi^ound during the month of Jul}'^, 
1887, it became convenient to distinguish these parts by differ- 
ent names. The lower red portion was named Thessalon 
quartzyte, and the upper white, was named Otter Tail quartzyte. 
These quartzytes are composed almost entirely of silica. The 
original rounded grains are everywhere distinct as individual, 
fragmental ingredients, but the rock is so compacted together, 
and perhaps cemented by "interstitial silica," that no inter- 
granular spaces are empty. 
No one who has seen this quartzyte, and the quartzytes of 
central Wisconsin and Minnesota which have been distinguished 
by local geographic names, — Barraboo quartzyte, Sioux quartz- 
yte, and Barron County quartzyte, — could fail to note at once 
the similarity of lithologic and all outward characters which this 
Huronian quartzyte bears to them. This is so great that the 
observer begins at once to seek for other parallels. He finds 
these in the tilted condition of the strata, in the associated red 
felsytes, in the eruptive intrusions of diabasic rock and the ap- 
parent general parallelism of geological horizon. It is true the 
red quartzytes of central Wisconsin and Minnesota have not 
been proven yet to overlie a series of black slates and quartzytes, 
but in the northern Minnesota the Animike black slates and 
quartzytes are known to underlie a great thickness of reddish 
and gray quartzytes which have been considered the northern 
equivalent of the quartzytes of central and southern Minnesota. 
Indeed the identity of this Huronian quartzyte with these 
more southern quartzytes is so strongly impressed on the ob- 
server that he is compelled at once to assume an identity of age, 
regardless of the late dogma that lithologic characters are of lit- 
