CONTENTS. 
Page. 
Introduction 11 
Chapter  I.  General  account  of  the  pre-Cambrian  rocks  of  North  America-  16 
Definition  of  pre-Cambrian 16 
Major  distribution  and  structure  of  pre-Cambrian  rocks 16 
State  of  knowledge 17 
Distinguishing  features  of  pre-Cambrian  rocks 18 
Subdivision  of  the  pre-Cambrian 19 
The  dual   classification 1 19 
Difficulties  in  local  use  of  classification 24 
Archean  system : 26 
Subdivision  of  Archean  system 26 
Origin  of  the  Archean 29 
Rocks  in  accord  with  Hutton's  law  that  the  present  is  the 
key  to  the  past 29 
Departure  from  uniformitarianism 30 
Cleavage    and    gneissose    structure    in    the    Archean    and 
crustal   shortening '. 31 
Conclusion  concerning  origin  of  Archean 32 
Algonkian  system 32 
Extent  and  subdivision  of  the  Algonkian 32 
Fossils  in  the  Algonkian 33 
Length  of  Algonkian  time 35 
Deformation  and  metamorphism  of  the  Algonkian 35 
Unconformity  beneath  the  Cambrian 36 
Unconformities  within  the  Algonkian 37 
Unconformity  between  Algonkian  and  Archean 38 
Correlation  of  pre-Cambrian  series : 40 
Pre-Cambrian  rocks  of  other  countries 47 
British  Isles 47 
Scandinavia 50 
Finland 51 
Russia  and  central  Europe 53 
South  Africa l_  54 
India 54 
Australasia. 54 
China 54 
Japan 57 
General 58 
History  of  names  applied  to  pre-Cambrian  rocks 58 
Chapter  II.  Summary  of  literature  for  North  America  (general) 64 
3 
