340 
PRE-CAMBRIAN    ROCKS    OF    NORTH    AMERICA. 
[bull.  86. 
finds  litliological  representatives  in  the  pre-Cambrian  rocks  of  the  east- 
ern provinces  of  the  Dominion  and  in  the  Appalachian  axis. 
Dawson,  (G.  M.)101,  inl891?  describes  a  section  in  the  Selkirk  range 
and  compares  it  with  a  section  of  the  interior  plateau  region  at  Kootanh 
and  Adams  lakes  and  on  the  west  side  of  the  Eocky  mountains.  Th( 
sections  are  given  and  correlated  as  follows: 
Provisional  comparative  table  of  formations  met  with  (1)  in  the  eastern  border  of  the  in 
terior  plateau  of  British  Columbia,  {2)  in  the  Selkirk  range,  and  (3)  on  the  western  si<f 
of  the  adjacent  portion  of  the  Eocky  mountain  ranges. 
Section  on  Kootanie  and 
Adams  lakes. 
2.  Section  in  the  Selkirk  range 
on  line  of  Canadian  Pacific 
Railway. 
3.  Section  in  tlie  Rocky  moun- 
tains (west  side  of  range, 
McConuell). 
Feet. 
6.  Greenish  and 
gray  schists, 
with  lime- 
stone    2, 000 
5.  Limestone  o  r 
marble  with 
black,  glossy 
argillites  and 
some  gray 
schists  2,500 
Quartzites,  with  gray 
schists    and   some 
limestone 
Black  shaly  argillites, 
limestone,  and    gray 
schists. 
Feet. 
Feet. 
Halysites  beds,    dolo- 
mites, and  quartzites    1, 300 
or  more. 
Graptolite-  bearing 
shales.    Black  fissile 
argillites,  with  some 
limestone 1, 500 
Chiefly  green- 
ish, with  some 
gray  schists.  4,050 
Chiefly  gray, 
with  some 
greenis  h 
schists 8,550 
Gray  schists  and 
gray  quartzites, 
with  somequartz- 
ose  conglomerate 
and  interbedded 
blackish  argil- 
lites, the  last 
chiefly  toward  the 
base 25,000 
Greenish  and  gray 
calc-schists  and 
greenish  and 
reddish  shales 
and  slates,  with 
some   dolomitic 
limestone 10,000 
(probably). 
2.  Black,  shaly  or 
schistose  ar- 
gillite,  with 
some  lime- 
stone   1,000 
or  more. 
Blackish  argillite- 
schists  and  phyl- 
1  i  t  e  s,  generally 
calcareous,  with 
some  beds  of  lime- 
stone and  quartz- 
ite 15,000 
Dark  argillites, 
with  some  quarfo- 
ites  and  conglom- 
erates, the  latter 
particularly 
toward  the  sum- 
mit.      Base     not 
seen 10, 000 
or  more. 
&  • 
Mica  -schists, 
gneisses,  and 
marbles 
...  5,000 
or  more. 
ea'aj  Gray  gneissic 
£  ©  rocks  and  coarse 
2'fc       mica-schists  ... 
. .     5,  000 
or  more. 
Associated  with  the  Archean  schists  are  certain  granitoid  rocks  whk  I 
may  represent  either  portions  of  the  schists  in  which  the  bedding  hjil 
been  obliterated  or  very  ancient  intrusives.     Besides  these  there  is  j  f 
least  one  later  series  of  intrusive  granites  which  are  probably  later  ths,  j 
most  of  the  Paleozoic  rocks.     The  Shuswap  series  of  the  Adams  lal  ( 
section  appears  to  be  traceable  on  their  line  of  strike  into  diabases  ai 
diabase  rocks,  which  are  often  agglomerates  and  pass  into  volcanic  a** 
rocks.    In  the  Shuswap  series  of  the  Selkirk  nearly  half  of  the  enti 
mass  of  the  rocks  exposed  consist  of  intrusive  or  vein  granite  wii 
pegmatitic  tendencies.     In  the  Mseonlith  series  the  lamination  isoft* 
true  bedding,  but  in  some  cases  a  slaty  cleavage  is  developed.    In  tl 
