boutwell,]       IRON    ORES    IN    THE    UINTA    MOUNTAINS,    UTAH.  223 
corresponding  amphitheater  of  Soapstone  Basin.  From  Soapstone 
Basin  the  fall  to  the  main  canyon  of  Provo  River  is  abrupt,  but  from 
near  its  head  to  its  outlet  from  the  range  the  Provo  flows  in  a  terraced, 
graded,  alluvial  bottom,  which  merges  on  the  west  with  Kamas  Prairie. 
GEOLOGIC   FEATURES. 
Stratigraphy  and  structure. — The  stratigraphy  and  structure  of  the 
Uinta  uplift  have  been  described  by  S.  F.  Emmons  as  follows: 
The  geological  structure  of  the  Uinta  Range,  like  its  physical  structure,  is  in  its 
main  outlines  remarkably  simple  and  regular.  Its  main  mass  was  formed  by  the  up- 
lifting of  an  immense  thickness  of  practically  conformable  strata  at  the  close  of  the 
Cretaceous  period  in  a  broad,  anticlinal  fold,  having  the  form  of  a  flat  arch  or  inverted 
U .  The  movement  which  produced  this  fold  was  accompanied  by  comparatively 
little  fracturing  and  dislocation  of  strata  and  by  no  intrusion  of  igneous  rocks. 
*     -x-     -x- 
The  conformable  series  of  beds  involved  in  the  Uinta  fold  extend  in  geological 
horizon,  as  far  as  their  age  has  been  satisfactorily  determined,  from  the  Carboniferous 
up  to  the  top  of  the  Cretaceous.  The  Carboniferous  formation,  whose  beds  form  the 
main  'mass  of  the  range,  is  represented  by  the  groups  of  the  Weber  Quartzite,  Upper 
Coal-Measures,  and  Permo-Carboniferous.  The  beds  of  the  first  of  these  form  the 
crest  throughout  the  greater  part  of  its  extent,  lying  nearly  horizontal  or  inclined  at 
very  low  angles.  They  consist  of  a  lower  series  of  white  and  reddish  compact  quartz- 
ites,  a  middle  series  of  purple,  coarse  quartzites,  and  an  upper  of  red  and  striped 
sandstones,  in  all  of  which  no  unconformity  was  observed;  they  are  in  general  barren 
of  all  fossil  remains,  only  two  species  of  Spirifer  obtained  from  quartzite  debris  hav- 
ing been  found  by  us;  but  as  they  are,  quite  conformable  with  the  limestones  of  the 
Upper  Coal-Measure  group,  which  abound  in  well-defined  fossil  remains,  they  have 
been  referred  to  the  Weber  quartzite  group. 
Their  thickness,  as  observed  in  different  parts  of  the  range,  is  from  10,000  to  12,000 
feet,  while,  as  their  base  is  never  reached,  the  actual  thickness  of  the  formation  may 
be  indefinitely  greater.  This  fact  might  seem  to  throw  some  doubt  on  the  correct- 
ness of  the  assumption  that  they  all  belong  to  the  Carboniferous  formation,  since  the 
Weber  quartzite  in  the  Wasatch  Range,  at  a  comparatively  short  distance  to  the 
west,  attains  a  development  of  only  5,000  to  7,000  feet,  and  the  general  tendency  of 
all  the  formations  is  to  thin  out  to  the  eastward.  Lithologica  Jy,  also,  the  lower  beds 
of  this  group  resemble,  perhaps,  the  Cambrian  rather  than  the  Weber  quartzite  of 
the  Wasatch,  and  it  might  be  supposed  that  the  upper  portion  of  this  group  had  been 
deposited  over  a  shallow,  rounding  uplift  of  Cambrian  rocks  in  such  a  manner  as  to 
show  no  appreciable  unconformity  of  angle. 
*  *         •  *  *  *  *  * 
Since  the  above  was  written,  there  has  been  published  in  the  report  of  Prof.  J.  W.  Powell  on  the 
Geology  of  the  Eastern  Uinta  Mountains,  sections  made  in  the  canyons  of  the  Green  River,  showing 
an  unconformity  of  deposition  in  these  beds,  which,  if  correct,  would  seem  to  prove  the  latter  sup- 
position to  be  more  correct.     [Footnote  by  S.  F.  Emmons.] 
While  throughout  the  greater  portion  of  the  range  the  folding  *  *  *  has  been 
mainly  produced  by  forces  *  *  *  at  right  angles  to  its  longer  axis,  there  has 
also  been  some,  though  considerably  less,  longitudinal  compression  *  *  *  pro- 
ducing minor,  transverse  corrugations    *.   *    *. 
In  the  eastern  portion  of  the  range  the  longitudinal  compression  has  been  propor- 
tionately greater  *  *  *  The  crest  of  the  main  fold  is  much  widened,  and  bent 
somewhat  to  the  southward     *     *     *.     To  the  south  of  the  main  fold  the  region  of 
