jV. H. Winchell on a Great ^r'rmordial Ouartzyie. 177 
southwestern Minnesota, he could read a perfect account of 
the rock he was standing on. I would refer the reader to 
the first annual report of the Minnesota geological survey for a 
somewhat detailed comparison of these widely separate areas 
of this great formation. This similarity was forcibly brought 
to the attention of the writer again in 1S84 when at New Or- 
leans. The State of New York had on exhibition there, with 
other things, a set of rock samples. The Potsdam sandstone 
was represented by a block a foot square and abont eighti nches 
thick. Struck with the great resemblance it bore to the Pipestone 
quartzyte of Minnesota I solicited of Mr. C. E Hall who had 
the specimens in charge, and received from him the donation 
of this block to the muesum of the University of Minnesota. 
On being placed alongside of similar blocks of quartzyte from 
Minnesota, it cannot b^ said to differ in any particular. It is 
red, with some interrupted stripings of light red, but it is a com- 
pact though gramdar quartzyte, and hardly worthy of the name 
sandstone. When subsequently the discovery of a primordial 
fauna was made,in the red quartzyte at Pipestone' there seemed to 
be lacking no important evidence to parallelize these outcrops.'* 
In July, i8S7,the writer visited and examined the rocks of the 
"original Ilin'onian." He was at once convinced of the per- 
fect parallelism of the great quartzyte there displayed with the 
quartzyte of Wisconsin and Minnesota, as claimed Iw the geolo- 
gists of Wisconsin. Some of the details of this similarity will 
be given in a subsequent paper; and in so far as that identity goes 
he was convinced that the Minnesota quartzytes also are Huro- 
nian. But what then is this Huronian quartzyte other than the 
Potsdam sandstone of New York, the red sandrock of Vermont, 
and the granular quartz of the Tacnoic? Things that are equal 
to the same thing an ecjual to each other. The Huronian, so 
far as this quartzyte is concerned, is a part of the Taconic; and 
the Potsdam itself is the same, notwithstanding the contrary 
protestation of Emmons, and in harmony with the conclusions 
of the geologists of the Vermont surve^•. 
' Thirteenth annual report of the geological and natural history survey 
of Minnesota. 
2 Tlie Potsdam sandstone is used in tlic new j)art of Columbiii lollegc 
in Xe\\ ^"ork Citv. 
