518  PKE-CAMBRIAN    GEOLOGY   OF    NOKTH    AMERICA. 
Walcott,82  in  1889,  corroborates  the  unconformity  between  the 
series  referred  by  Murray  to  the  Huronian  and  the  overlying  series 
called  Potsdam.  The  latter  is  found  to  contain  the  Olenellus  fauna 
below  the  Paradoxides  and  is  placed  as  lower  Cambrian. 
Walcott,83  in  1899,  states  that  the  Avalon  series  of  Newfoundland 
includes  all  the  pre-Cambrian  sedimentary  rocks  of  that  area.  Over- 
lying them  are  Cambrian  strata  carrying  Olenellus  fauna.  The  As- 
pidella  of  the  Momable  slates  is  probably  of  organic  origin,  but  it 
may  be  questioned.     Other  reported  forms  are  inaccessible  for  study. 
Walcott,84  in  1900,  reports  on  the  results  of  an  examination  of 
Cambrian  and  pre-Cambrian  formations  on  Smiths  Sound,  New- 
foundland, during  the  summer  of  1899.  At  Smith  Point  he  found 
the  Olenellus  fauna  369  feet  below  the  summit  of  the  Etcheminian, 
and  one  of  its  types,  Coleoloides  typicalis,  in  the  basal  bed  of  the 
Cambrian  on  the  south  side  of  Random  Island.  This  retains  the 
Etcheminian  of  Newfoundland  in  the  Lower  Cambrian. 
The  Random  terrane,  so  called  from  a  typical  section  on  Random 
Sound,  is  a  series  of  sandstones,  quartzitic  sandstones,  and  sandy 
shales,  resting  conformably  upon  the  Signal  Hill  conglomerate 
(which  was  formerly  supposed  to  represent  the  top  of  the  Avalon  or 
Algonkian  series)  and  extending  up  to  the  base  of  the  Cambrian. 
The  Random  terrane  is  thus  the  upper  member  of  the  Avalon  series 
and  fills  a  portion,  if  not  all,  of  the  gap  between  the  Signal  Hill  con- 
glomerate and  the  Cambrian.  The  Cambrian  rests  on  the  Random 
terrane  with  a  thin  belt  of  conglomerate.  The  thickness  of  the  ter- 
rane is  probably  1,000  feet.  In  one  horizon  in  the  terrane  were 
found  several  varieties  of  annelid  trails,  including  a  variety  about  5 
mm.  broad,  a  slender  form  J  mm.  broad,  and  an  annulated  trail  2  to  3 
mm.  in  width. 
An  examination  of  the  form  known  as  Aspidella  terranovica 
found  in  the  Momable  terrane  of  the  Avalon  series  proved  the  sup- 
posed fossil  to  be  a  spherulitic  concretion,  and  this  removes  it  from 
among  the  possible  pre-Cambrian  forms  of  life. 
Daly,85  in  1903,  describes  variolitic  pillow  lava  from  Newfound- 
land, and  calls  attention  to  the  widespread  occurrence  of  this  or 
similar  rocks,  frequently  called  ellipsoidal  greenstones,  in  Minne- 
sota, New  Brunswick,  California,  and  Michigan. 
SUMMARY   OF  PRESENT  KNOWLEDGE. 
Granites  and  gneisses,  with  occasional  bands  of  limestone  and 
anorthosite  intrusions,  form  broad  northeast-southwest  bands  which 
seem  to  serve  as  a  skeleton  upon  which  the  island  is  built.  The 
series  has  been  mapped  as  "  Laurentian  "  by  Murray  and  Howley,  but 
may  contain  younger  rocks.  Between  them  and  northwest  of  them 
are  Paleozoic  rocks,  and  to  the  southeast,  forming  a  large  part  of 
