van  hise]  DISCUSSIONS    OF    PRINCIPLES.  455 
siratn,  originally — in  part,  at  least — of  sedimentary  origin,  which  did 
not  show  by  their  character  that  life  could  not  have  existed  at  the 
time  of  their  deposition,  but  which  proved,  on  examinaion,  to  be  en- 
tirely destitute  of  fossils,  and  which,  moreover,  were  found  everywhere 
to  underlie  unconformably  other  stratified  formations  which  were  re- 
cognized as  containing  the  lowest  known  forms  of  organic  life.  It  is 
denied  that  Eozoon,  beds  of  limestone,  the  presence  of  graphite  in 
crystalline  limestone,  or  any  other  discovered  material  in  the  pre-Pots- 
dam  rocks,  are  sufficient  evidence  for  the  j>resence  of  life. 
It  is  considered  that  we  are  fully  justified  in  saying  that  the  results 
of  geological  investigation  during  the  last  thirty- five  years  have  given 
no  encouragement  to  the  idea  that  below  the  well  known  Primordial 
zone — the  Potsdam  sandstone  of  American  geologists — there  is  another 
series  of  fossiliferous  rocks. 
If  the  Azoic  rocks  are  really  azoic,  as  is  believed,  then  it  follows,  as 
a  matter  of  course,  that  the  series  thus  designated  can  only  be  sep- 
arated into  subsystems  on  purely  lithological  grounds ;  if  they  are  fos- 
siliferous, as  held  by  the  Canada  survey,  then  it  is  equally  clear  that 
any  subdivisions  proposed  for  them  should  have  a  paleontological  basis. 
It  is  denied  that  Aspidella  and  Arenicolites  spiralis  are  of  organic 
origin. 
If  we  examine  the  often  repeated  statement  that  the  Huronian  un- 
conformably reposes  on  the  worn  edges  of  the  Laurentian,  and  contains 
the  debris  of  the  latter,  it  will  be  found  that  in  the  seven  cases  in  which 
the  rocks  referred  to  these  two  formations  were  found  in  contact  in  the 
Canadian  district,  the  Huronian,  with  but  two  exceptions,  is  said  to 
be  conformable  with  and  to  generally  pass  imperceptibly  into  the  Lau- 
rentian. In  one  of  the  these  two  exceptions  the  rocks  show  mutually 
intrusive  relations,  and  in  the  other  the  Huronian  abuts  against  and 
runs  under  the  Laurentian. 
In  all  cases  in  which  pebbles  and  fragments  of  the  Laurentian  have 
been  found  in  the  Huronian,  they  were  seen  occurring  high  up  in  the 
latter  series,  and  not  forming  basement  conglomerates.  All  the  other 
so-called  proof  of  unconformity  has  been  made  out  of  the  fact  that  the 
strike  of  the  foliation  in  the  two  formations,  when  not  in  contact,  has 
been  found  to  be  discordant — worthless  evidence  unless  the  rocks  ob- 
served in  both  formations  be  proved  to  be  sedimentary  and  the  folia- 
tion be  shown  to  be  coincident  with  the  stratification.  Now,  if  the 
Laurentian  was  an  old  metamorphosed  sedimentary  formation  which 
had  been  upheaved  and  contorted,  and  on  whose  worn  edges  the  Hu- 
ronian has  been  laid  down,  the  evidence  of  the  fact  ought  to  be  over- 
whelming in  amount  after  the  country  has  been  studied  for  so  many 
years. 
It  is  well  known  that  any  eruptive  rock  so  soon  as  it  comes  in  contact 
with  erosive  agencies  will  yield  fragmental  material  even  before  it  is 
cold,  and  that  much  eruptive  matter  is  ejected  in  a  fragmental  state? 
