388  PRE-CAMBRIAN    GEOLOGY   OF    NORTH   AMERICA. 
26  Age  of  the  sandstone,  by  William  B.  Rogers.     Idem,  pp.  394,  395. 
27  First  biennial  report  of  the  progress  of  the  geological  survey  of  Michigan, 
by  Alexander  Winchell.     Lansing,  1861,  pp.  339. 
28  Some  contributions  to  a  knowledge  of  the  constitution  of  the  copper  ranges 
of  Lake  Superior,  by  C.  P.  Williams  and  J.  F.  Blandy.  Am.  Jour.  Sci.,  2d  ser., 
vol.  34,  1862,  pp.  112-120. 
29  On  the  iron  ores  of  Marquette,  Michigan,  by  J.  P.  Kimball.  Idem,  vol.  39, 
1865,  pp.  290-303. 
30  On  the  position  of  the  sandstone  of  the  southern  slope  of  a  portion  of  Ke- 
weenaw Point,  Lake  Superior,  by  Alexander  Agassiz.  Proc.  Boston  Soc.  Nat. 
Hist.,  vol.  11,  1S6T,  pp.  244-246. 
31  Die  vorsilurischen  Gebilde  der  "  Obern  Halbinsel  von  Michigan  "  in  Nord- 
Amerika,  by  Hermann  Credner.  Zeitschr.  Deutsch.  geol.  Gesell.,  vol.  21,  1869, 
pp.  516-554.  See  also  Die  Gliederung  der  eozoischen  (vorsilurischen)  Forma- 
tionsgruppe  Xord-Amerikas,  by  Hermann  Credner.  Zeitschr.  gesammten  Natur- 
wissenschaften,  vol.  32,  Giebel,  1868,  pp.  353-J05. 
32  On  the  age  of  the  copper-bearing  rocks  of  Lake  Superior,  by  T.  B.  Brooks 
and  R.  Pumpelly.     Am.  Jour.  Sci.,  3d  ser.,  vol.  3,  1872,  pp.  428^32. 
33  Iron-bearing  rocks,  by  T.  B.  Brooks.  Geol.  Survey  Michigan,  vol.  1,  pt.  1, 
1869-1873,  pp.  319,  with  maps. 
34  Copper-bearing  rocks,  by  R.  Pumpelly.  Idem,  pt.  2,  pp.  1-46,  62-94,  with 
maps. 
35  Copper-bearing  rocks,  by  A.  R.  Marvine.     Idem,  pt.  2,  pp.  47-61,  95-140. 
36  Paleozoic  rocks,  by  Charles  Rominger.     Idem,  pt.  3,  p.  105. 
37  Observations  on  the  Ontonagon  silver-mining  district  and  the  slate  quarries 
of  Huron  Bay,  by  Charles  Rominger.  Geol.  Survey  Michigan,  vol.  3,  pt.  1,  1876, 
pp.   151-166. 
3S  On  the  youngest  Huronian  rocks  south  of  Lake  Superior,  and  the  age  of  the 
copper-bearing  series,  by  T.  B.  Brooks.  Am.  Jour.  Sci.,  3d  ser.,  vol.  11,  1876,  pp. 
206-211. 
39  Classified  list  of  rocks  observed  in  the  Huronian  series  south  of  Lake  Su- 
perior, by  T.  B.  Brooks.     Idem,  vol.  12,  pp.  194-204. 
"'  Metasomatic  development  of  the  copper-bearing  rocks  of  Lake  Superior,  by 
Raphael  Pumpelly.     Proc.  Am.  Acad.  Arts  Sci.,  vol.  13,  1878,  pp.  253-309. 
41  First  annual  report  of  the  Commissioner  of  mineral  statistics  of  the  State  of 
Michigan  for  1877-1878,  by  Charles  E.  Wright.     Marquette,  1879,  229  pp. 
42  Notes  on  the  iron  and  copper  districts  of  Lake  Superior,  by  M.  E.  Wads- 
worth.  Bull.  Mus.  Comp.  Zool.  Harvard  Coll.,  whole  ser.,  vol.  7 ;  geol.  ser., 
vol.  1,  No.  1,  pp.  157.  See  also  On  the  origin  of  the  iron  ores  of  the  Marquette 
district,  Lake  Superior.  Proc.  Boston  Soc.  Nat.  Hist.,  vol.  20,  1878-1880,  pp. 
470-479.  On  the  age  of  the  copper-bearing  rocks  of  Lake  Superior  (abstract). 
Proc.  Am.  Assoc.  Adv.  Sci.,  29th  meeting,  pp.  429-430.  On  the  relation  of  the 
"  Keweenawan  series  "  to  the  Eastern  sandstone  in  the  vicinity  of  Torch  Lake, 
Michigan.  Proc.  Boston  Soc.  Nat.  Hist.,  vol.  23,  1884-1888,  pp.  172-180;  Sci- 
ence, vol.  1,  1883,  pp.  248,  249,  307. 
43  Upper  Peninsula,  by  C.  Rominger.  Geol.  Survey  Michigan,  vol.  4,  1881, 
pp.  1-248,  with  a   geological  map. 
44  Geological  report  on  the  Upper  Peninsula  of  Michigan,  exhibiting  the  prog- 
ress of  work  from  1881  to  1884,  by  C.  Rominger.  Geol.  Survey  Michigan,  vol. 
5,  pt.  1,  1895,  pp.  179. 
45  On  a  supposed  fossil  from  the  copper-bearing  rocks  of  Lake  Superior,  by 
M.  E.  Wadsworth.     Proc.  Boston  Soc.  Nat.  Hist.,  vol.  23,  1884-1888,  pp.  208-212. 
46  Observations  on  the  junction  between  the  Eastern  sandstone  and  the  Ke-< 
weenaw  series  on  Keweenaw  Point,  Lake  Superior,  by  R.  D.  Irving  and  T.  C. 
Chamberlin.     Bull.  U.  S.  Geol.  Survey  No.  23,  1885,  124  pp.,  17  pi. 
