PHOSPHATE    DEPOSITS    IN    WESTERN    UNTTED    STATES.  453 
the  upper  Carboniferous  series,  and  in  the  Montpelier  region  I  here 
are  siliceous  limestones  and  red  sandstones  containing  ammonites 
and  other  fossils  of  lower  Triassic  age. 
GEOLOGIC  STRUCTURE. 
The  geologic  structure  of  the  region  under  discussion  is  very  com- 
plex. The  strata  have  been  uplifted,  sharply  folded  and  ('nulled, 
and  partially  buried  beneath  the  overlap  of  later  sediments.  It  has 
been  noted,  however,  that  the  phosphate  series  has  been  very  little 
disturbed  or  displaced  by  the  movements  which  have  affected  the 
sedimentary  section  as  a  whole. 
WASATCH    RANGE. 
In  Weber  Canyon,  where  the  phosphate  series  occurs,  there  is  in 
the  underlying  Weber  quartzite  a  sharp  anticlinal  fold  that  develops 
into  a  thrust  fault.  This  structure  is  not  readily  detected  on  account 
of  the  heavy  wash  and  the  overlap  of  later  sediments. 
BEAR    LAKE    PLATEAU. 
The  Bear  Lake  Plateau  comprises  the  region  ea^  t  of  Bear  Lake 
and  the  area  to  the  south  represented  on  the  maps  of  the  Fortieth 
Parallel  Survey  as  Bear  River  Plateau.  It  also  represents  the  east- 
ern side  of  the  Wasatch  uplift.  The  sharply  compressed  fold  of  the 
Weber  Canyon  section  appears  to  extend  through  this  area,  as  the 
Carboniferous  beds  where  exposed  are  in  general  characterized  by 
steep  dips  and  local  variations  in  strike.  A  similiar  structure  is 
reported  east  of  the  north  end  of  Bear  Lake. 
CRAWFORD    MOUNTAINS. 
The  Crawford  Range  extends  from  Bridger  Creek  in  a  southwest- 
erly direction,  with  outliers  to  the  north,  including  the  Beckwith 
Hills  north  of  Twin  Creek.  Veatch  a  considers  the  structure  as  a 
broken  anticline  with  a  syncline  developed  on  the  eastern  slope.  A 
fault  of  considerable  displacement  follows  the  eastern  side  of  the 
range  and  probably  extends  to  the  north  in  the  Sublette  Range  east 
of  Cokeville. 
SUBLETTE    RANGE. 
The  Sublette  Range  is  formed  of  a  sharply  compressed  series  of 
Weber  quart zites  and  upper  Carboniferous  beds.  On  the  eastern 
side  of  the  range  a  fault  of  considerable  throw  occurs,  bringing  the 
Bear  River  Cretaceous  beds  against  the  upper  Carboniferous.  In  the 
northern  part  of  the  range  the  dip  flattens  and  the  topography  is 
much  less  rugged  in  character. 
a  Veatch,  A.  C,  Prof.  Paper  U.  S.  Geol.  Survey  No.  56,  1907. 
