vanhisb.]  DISCUSSIONS    OF    PRINCIPLES.  527 
Oleuellus  fauna  and  all  doubtful  series  barren  of  fossils  were  regarded 
as  pre-Cambrian,  it  would  still  be  true  that  the  rocks  thus  referred  to 
the  Algonkian  system  would  be  insignificant  in  amount  and  extent  as 
compared  with  the  great  areas  and  volumes  here  included  in  America. 
It  would  also  be  true  that  the  structural  work  upon  such  series  has  not 
progressed  so  far.  This  is  probably  in  large  measure  due  to  the  non- 
occurrence of  such  volumes  of  Algonkian  rocks  in  Europe  as  exist  in 
America  5  but  it  is  also  due  in  part  to  the  fact  that  in  that  portion  of 
Europe  which  has  been  most  closely  studied  there  have  been  since 
Cambrian  time  repeated  powerful  dynamic  movements  and  periods  of 
great  eruptive  activity.  The  conditions  &re  much  the  same  as  in  the 
eastern  United  States,  where  a  study  of  pre-Oambrian  stratigraphy  has 
barely  begun.  In  the  interior  of  the  American  continent  the  conditions 
have  been  far  more  favorable  for  a  structural  study  of  the  pre-Cam- 
brian  rocks. 
NOTES. 
1  Observations  on  the  Geology  of  the  United  States  Explanatory  of  a  Geological 
Map,  Wm.  Maclnre.     Trans.  Am.  Phil.  Soc,  vol.  vi,  pp.  411-428.     With  a  map. 
2  Geological  Text-Book,  for  Aiding  the  Study  of  North  American  Geology,  Amos 
Eaton.     Albany,  New  York,  and  Troy,  1832,  2d  edition,  pp.  134. 
3  American  Geology,  Ebenezer  Emmons.  Albany,  1855,  pp.  194,  251,  with  an  atlas 
and  a  geological  map  of  the  United  States. 
4Esquisse  Ge"ologique  du  Canada,  a  ^Exposition  Universelle  de  Paris,  W.  E.  Logan 
and  T.  Sterry  Hunt.  Paris,  1855,  pp.  100.  With  a  geological  map.  From  transla- 
tion by  Mr.  Robert  Stein. 
P  Manual  of  Geology,  James  D.  Dana,  Philadelphia,  1863, 1st  ed.,  pp.  798.  With 
a  map. 
6  On  the  Occurrence  of ' Organic  Remains  in  the  Laurentian  Rocks  of  Canada,  Sir 
W.  E.  Logan.     Quart.  Jour.  Geol.  Soc,  London,  1865,  vol.  xxi,  pp.  45-50. 
7Esquisse  Geologique  du  Canada,  suivie  d'un  Catalogue  Descriptif  de  la  Collection 
de  Cartes  et  Coupes  G6ologiques,  Livres  Imp  rune's,  Roches,  Fossiles  et  Mineraux 
Econouiiques  envoye"e  a  l'Exposition  Universelle  de  1867,  T.  Sterry  Hunt.  Paris, 
1867, pp.72.     From  translation  by  Mr.  Robert  Stein. 
8  Notice  of  the  address  of  Prof.  T.  Sterry  Hunt  before  the  American  Association  at 
Indianapolis,  James  D.Dana.  Am.  Jour.  Sci.,  3rd  ser.,  vol.  in,  1872,  pp.  86-93;  vol. 
iv,  pp.  97-105. 
9 Manual  of  Geology,  James  D.  Dana.  New  York,  1876,  2d  ed.,  pp.  828.  With  a 
map. 
10  Systematic  Geology,  Clarence  King.  U.  S.  GeoL  Exploration  of  the  Fortieth 
Parallel,  vol.  I,  pp.  803,  12  analytical  geological  maps,  and  accompanied  by  a  geo- 
logical and  topographical  atlas. 
11  Report  of  Observations  on  the  Stratigraphy  of  the  Quebec  Group,  and  the  Older 
Crystalline  Rocks  of  Canada,  A.  R.  C.  Selwyn.  Rept.  of  Prog.  Geol.  Survey  of  Can- 
ada for  1877-78,  pp.  1-15A. 
12  Summary  Report  of  the  Operations  of  the  Geological  Corps  to  December,  1880,  A. 
R.  C.  Selwyn.  Rept.  of  Prog.  Geol.  and  Nat.  Hist.  Survey  of  Canada  for  the  year 
1879-'80,  pp.  1-9. 
13  Notes  on  the  Geology  of  the  Southeastern  Portion  of  the  Province  of  Quebec,  A. 
R.  C.  Selwyn.  Rept.  of  Prog.  Geol.  and  Nat.  Hist.  Survey  of  Canada  for  the  years 
1880-'81-'82,  pp.  1-7 a, 
