52  PRE-CAMBKIAN    GEOLOGY    OP    NORTH    AMERICA. 
Succession  of  pre-Cambrian   rocks  in  "  Fenno-Scandia  " — Continued. 
Names  of  the  subdivisions. 
Supercrustal  rocks. 
Infracrustal  rocks. 
Jatulian. 
Upper  Jatulian. 
(Onegian). 
Augite  porphyries  and  their  tuffs, 
"  metabasites,  "anthracite,  dolo- 
mites, slates,  sandstones. 
Lower  Jatulian. 
"Metabasites,"  dolomites,  quartz- 
ites  and  quartzitic  sandstones, 
conglomerates. 
Unconformity. 
Upper  Kalevian. 
"Metabasites,"    quartzites,   con- 
glomerates. 
Kalevian. 
Unconformity. 
Post-Kalevian  granites,  inject- 
ing the  Kalevian  and  older 
rocks,  thus  forming  "veined 
gneisses." 
Lower  Kalevian. 
"Metabasites,"  talc  and  chlorite 
schists,     dolomites,     phyllites, 
quartzites  and  quartzitic  schists 
(often  glassy),  conglomerates. 
Unconformity. 
Post-Bottnian  granites,  inject- 
ing the  Bottnian  and  older 
rocks,  thus  forming  "veined 
gneisses." 
Bottnian. 
Uralite  porphyries  and  their  tuffs, 
plagioclase    porphyrites,     con- 
glomerates,  phyllites,   leptites, 
etc. 
Unconformity. 
Post-Ladogian    granites,     dio- 
Ladogian. 
Phyllites  and  mica  schists,  glassy 
quartzites,    conglomerates    (?), 
"metabasites,"  dolomitic  lime- 
stones, halleflintas,  etc. 
rites,  amphibolites,  etc.,  in- 
jecting the  Ladogian  and 
older  rocks,  thus  forming 
"veined  gneisses." 
Katarchcan. 
Granitic  gneisses,  "metabasites,"  etc. 
From  this  succession  it  appears  that  in  Finland  there  are  at  least 
four  pre-Cainbrian  sedimentary  series.  For  the  Jotnian,  Jatulian, 
Kalevian,  and  Bottnian,  Sederholm  makes  exactly  the  same  point  as 
has  been  made  with  reference  to  the  Algonkian.    He  says : 
At  least  as  far  back  as  during  Bottnian  time  the  climatic  conditions  were 
not  sensibly  different  from  those  of  later  geological  periods,  as  shown  by  the 
existence  of  rocks  which,  in  spite  of  their  metamorphic  character,  show  them- 
selves to  be  sediments  with  the  same  regular  alternation  of  clayey  and  sandy 
material  ("annual  stratification")  as  the  glacial  clays  of  that  same  region, 
explainable  only  by  assuming  a  regular  change  of  seasons.0 
a  Op.  cit.,  p.  95. 
