Some Points in the Geology of Northern Wisconsin. 113 



The Copper Bearing Series in Ashland county divides nat- 

 urally into three members. 



The lowermost member, designated A, in my report 

 [II. a], covers the broadest surface of country of any of 

 the three divisions. The rocks are always highly crystal- 

 line, generally very coarsely so, and present such a varia- 

 tion in lithological characters that I have not yet attempted to 

 describe all the varieties, or even a small portion of them. The 

 prevailing kinds, which themselves, however, include many 

 varieties, are : 1st, a dark colored, coarsely crystalline rock, 

 breaking with jagged edges, and showing broad, crystalline 

 faces, with often a high lustre, varying in color from a light 

 gray, through green, to dead black, and composed apparently 

 of either hornblende or pyroxene, and a triclinic feldspar, 

 probably in most cases Labradorite, although this last ingre- 

 dient does not seem always to be present; that portion of 

 Ashland county just north of English and Bladder lakes, pre- 

 sents on all outcrops, which are very numerous indeed, rock of 

 this character : 2d, peculiar varieties whose aspect is usually 

 pinkish, from the presence of orthoclase feldspar, and a black 

 mineral probably, hornblenrie, with a varying amount of 

 quartz : 3d, finer grained hornblendic and pyroxenic rocks. 



The indications of stratification in this portion of the group 

 are seldom seen — the whole mass being apparently without it — 

 still, in the few places where they are seen, they are marked, 

 and point towards entire con form ability with the underlying 

 Huronian. 



Next north of and overlying the rocks just described, are 

 the beds of that portion of the group designated B in my re- 

 port [Ill.b.] This division, like the preceding, occupies a 

 belt of country stretching entirely across the county, and 

 having a much greater width on the eastern side. It includes- 

 a series of alternating beds of trap of many different kinds, both 

 amygdaloidal and compact, always cryptocrystalline, and, in the 

 upper portions, beds of a very remarkable conglomerate, (III.c.) 



