GENERAL   ACCOUNT    OF    THE    PRE-CAMBRIAN    ROCKS.  41 
In  the  following  table  the  areas  named  are  not  each  a  separate 
geological  province,  but  may  be  parts  of  the  same  province  which 
have  been  reported  upon  in  different  States  or  by  different  observers. 
Within  these  provinces  certain  correlations  of  series  are  indicated. 
For  instance,  it  will  be  noted  that  fairly  detailed  correlation  of  the 
Algonkian  formations  and  series  is  possible  at  the  present  time 
through  the  Lake  Superior  and  Lake  Huron  regions  and  adjacent 
parts  of  Canada.  In  other  parts  of  Canada  the  lithological  similar- 
ities are  such  as  frequently  to  suggest  correlation  with  series  or  for- 
mations, but  such  correlation  can  not  be  positive  in  advance  of  de- 
tailed work.  In  the  West  the  great  Belt  series  of  Montana  has  been 
found  to  extend  into  Idaho  and  British  Columbia.  Probably  to  be 
correlated  with  it  are  the  quartzites  of  the  Uinta  and  Wasatch  moun- 
tains, and  perhaps  also  of  the  Needle  Mountains  in  southwestern 
Colorado  and  of  the  Grand  Canyon.  The  Belt  series  in  its  now 
known  extent  constitutes  the  greatest  area  of  Algonkian  on  the  con- 
tinent, and  it  may  be  that  this  area  should  be  extended  to  include 
Utah,  Colorado,  and  Arizona  quartzites.  The  part  of  the  Ocoee 
group  of  the  southern  Appalachians  conformably  beneath  the  known 
Cambrian  as  here  defined  may  also  be  provisionally  correlated  with 
the  Belt  series.  The  great -series  of  volcanics  of  the  southern  Appala- 
chians is  correlated  with  volcanics  of  Maryland  and  Pennsylvania, 
and  their  stratigraphic  relations  seem  to  put  them  into  the  Algon- 
kian. For  the  remainder  of  the  country  correlation  of  subdivisions 
of  the  Algonkian  is  not  yet  possible. 
