\i^^ 
Correspondeuce. 
JJBRAR- 
•of Bell's paper liad Jilready been publislied.* Tlit- rocks iiiclucl 
IvUSaii's Upiier Copper-Bearinir series were -svhat an- now known as 
Animikieand tlie Keweenawan, witli possibly liir more n-ei-nt san<l- 
stonesot'Sault Ste. Marie. f Bell says: 
"If it wrre found desirable to iiivi- a shorter nanir to tln' rocks of the 
ii|)per copper-bearinii' series of Lake Siiiicrior, 1 would sugj;est that of 
Nipif/oii. These rocks, as sliewn on Sir W. E. Louan's geological niai) 
of Canada, form a broad band along the noiihwest side of lake Superior, 
running all the way from Thunder liay to Duluth. at the western ex- 
tremity of the lake. AVilhin our territory their north-western limit runs 
inland in a general southwestern course from the north shore of Thun- 
der Bay to Ciun-tlint lake.":}; 
in 1S70 Maj. T. B. Brooks ])roposed tlie name I\eweeiiawian: 
"We are justified, I think, in regarding the co[)i)er-bearing rocks of 
Lake Superior as a distinct and independent series, mitrkini; a definite 
geological perit)d which separates tln^ Silurian from the Huronian ages. 
Should fut ure observations confirm this view it would be advisable to 
have some more conNcnient and geologically acceplalile name for the 
series than that now in use. Since Keweenaw Peninsula forms one of 
the most striking geographical features in Lake Superior and is the lo- 
cality where the C'o])per series are best exposed and were first studied, 1 
suggest, the name Keweenawian for this period. "jj 
Hunt proposed the term Animikie and used the term Keweenaw bt-- 
fore a scientific assembly four days earlier than Bell proposed the term 
Nipigon before a similar assembly. ^loreoscr Hunt used the term Ke- 
weenaw to refer to the copperV)earing rocks of Keweenaw point and 
their e([ui\alents ( i. e.. lo the uppei- di\ision of the I'pper ( 'opper-1 tear- 
ing series of Jjogan). although later his ideas as to the stratigraphic jh)- 
sition of these rocks were erroneous:|| while Bell's term Nipigon was 
])roposed to include both the lower (Animikie) and the upper division 
(Keweenawan) of the l'i)i)er Copper-Bearing series, .\fter the publica- 
tion of the term Nipigon. Hunt suggested that, as there was some «pies- 
tioii as to the ;ii:e of the horizontal sandstones east of Thunder bay, it 
might be used as a local name to designate these horizontal sandstones, 
but he distinctly states that, in his opinion, these sandstones are not lo 
be confounded with those interslralified wit h the Keweenawan." After 
this the mime Nipigon was applied not only as a local designation (ac- 
cording to the suggestion of Hunt), but also by many as a more compre- 
hensive term. In 1 his more comprehensive sense it has not oidy been 
made to include all the post-Animikie rocks in the vicinity of Nipigon 
bay and laki'. but has been used as a general designation for the copper- 
bearing rocks of lake Superior, thus being synonymous with Kewee- 
Jiawan. lieii liim.self uses Nipigon as referring only to the uppe r divis- 
*Geol. Survey of Canada, Report of Progress for iS72-'7.;. pp. S7-111. iS;^. 
tGeology of Canada, pp. 67-S6. 1S63. 
+Geol. Survey of Canada, Keport of Progress for iS72-"7,^ p. lob. 1S7;,. 
S.\nier. Jour. Sci., 3d series, vol. u, p. 210, March. rS76. 
Second Geol. Survey of Pa., E, ".^zoic Rocks, Pt. 1," p. 241, 1S7S. 
* Trans. .\mer. hist. Min. ling., vol. i, p. 342. 
