466  PBE-CAMBRIAN    GEOLOGY   OF    NORTH   AMERICA. 
ments  may  have  been  mingled  with  the  igneous  rocks  by  actual 
fusion. 
Ells  and  Barlow,88  in  1895,  describe  the  physical  features  and 
geology  of  the  proposed  Ottawa  Canal  between  St.  Lawrence  River 
and  Lake  Huron.  The  proposed  canal  for  several  hundred  miles  trav- 
erses for  the  most  part  Archean  rocks  nearly  at  right  angles  to  the 
strike  of  their  schistosity  or  banding.  The  work  of  Logan,  Murray, 
Lawson,  Adams,  and  others  of  the  important  workers  on  the  Cana- 
dian crystallines  is  briefly  summarized. 
The  Grenville  series  of  the  Original  Laurentian  area  probably  illus- 
trates the  most  perfect  section  of  Laurentian  rocks  which  we  can 
yet  recognize.  This  section  shows  various  kinds  of  gneisses,  foliated 
and  stratified,  with  foliated  and  massive  granites  and  syenites,  pyrox- 
enic,  dioritic,  hornblendic,  and  quartzose  rocks,  and  quartzite  and 
limestone.  In  the  basal  beds  of  the  limestone  and  quartzite,  supposed 
to  constitute  the  upper  member  of  the  series,  are  interstratified  bands 
of  rusty  quartzose  gneiss,  which  from  the  available  evidence  is  be- 
lieved to  form  an  integral  part  of  the  limestone  series.  This  portion 
presents,  in  its  banded  arrangement  of  quartzose  and  calcareous  rocks, 
the  usual  aspect  of  true  altered  sedimentary  strata.  The  same  well- 
banded  arrangement  is  also  visible  in  some  of  the  directly  underlying 
gneiss ;  but  microscopic  examination  shows  that  in  the  great  mass  of 
this  gneiss  evidence  of  aqueous  origin  is  wanting.  Some  portions  of 
the  igneous  rocks  are  undoubtedly  older  than  the  limestones,  and 
probably  represent  the  lowest  known  portions  of  the  earth's  crust. 
Other  portions  are  clearly  established  to  be  of  more  recent  age  than 
the  crystalline  limestone.  The  oldest  gneisses  are  foliated  rather 
than  stratified,  but  in  their  foliation  they  underlie  the  regular  series 
of  stratified  hornblende  and  other  gneisses  which  occur  frequently 
between  the  Fundamental  gneiss  and  the  crystalline  limestone  and 
quartzite  series  at  the  summit  of  the  section.  To  this  fundamental 
series  may  be  assigned  the  rocks  of  Trembling  Mountain,  those  form- 
ing the  anticlines  north  of  Lachute,  rocks  from  various  places 
throughout  the  Grenville  district,  and  large  areas  at  different  places 
along  the  upper  Ottawa  River  section.  Concerning  many  of  the  in- 
termediate gneisses,  it  may  be  said  that,  while  in  their  general  aspect 
they  resemble  stratified  sedimentary  rocks,  their  study  under  the 
microscope  shows  them  to  have  presumably  a  different  origin,  so  that 
it  is  possible  that  the  true  altered  aqueous  portion  may  be  confined  to 
the  areas  of  crystalline  limestone  with  the  associated  bands  of  quartz- 
ite and  grayish  quartzose  and  hornblende  gneiss.  The  crystalline 
limestones  are  particularly  developed  along  the  Ottawa  River  sec- 
tion, from  the  vicinity  of  Deschenes  Lake,  west  of  Ottawa  city,  to  the 
village  of  Bryson,  in  which  section  they  are  frequently  cut  by  large 
areas  of  granitic  and  dioritic  rocks.     At  one  place,  near  the  Chats, 
