﻿TEALE.] 
  sindjjad's 
  valley. 
  63 
  

  

  flows 
  to 
  the 
  Dolores. 
  The 
  basin 
  is 
  nine 
  miles 
  in 
  length 
  and 
  from 
  a 
  mile 
  

   and 
  a 
  half 
  to 
  three 
  miles 
  in 
  width. 
  It 
  is 
  widest 
  at 
  the 
  north. 
  On 
  the 
  

   east 
  the 
  dip 
  of 
  the 
  rocks 
  forming 
  the 
  wall 
  is 
  to 
  the 
  eastward. 
  The 
  wall 
  

   is 
  at 
  this 
  side 
  about 
  1,400 
  feet 
  high. 
  On 
  the 
  north 
  it 
  is 
  higher, 
  reaching 
  

   1,600 
  feet 
  on 
  the 
  northwest. 
  The 
  inclination 
  of 
  the 
  beds 
  is 
  to 
  the 
  north- 
  

   ward, 
  changing 
  to 
  the 
  westward 
  as 
  we 
  get 
  around 
  to 
  the 
  west 
  side. 
  

   The 
  western 
  wall 
  decreases 
  in 
  height 
  as 
  we 
  follow 
  it 
  to 
  the 
  southward, 
  

   and 
  on 
  the 
  south 
  side 
  it 
  is 
  only 
  about 
  1 
  ,000 
  feet 
  high. 
  The 
  dip 
  here 
  is 
  to 
  the 
  

   southward. 
  The 
  formation 
  forming 
  the 
  top 
  of 
  the 
  wall 
  is 
  the 
  massive 
  

   sandstone 
  of 
  the 
  Trias. 
  Against 
  these 
  sandstones 
  on 
  the 
  west 
  where 
  the 
  

   trail 
  ascends 
  the 
  bluff. 
  Carboniferous 
  limestones 
  abut, 
  dipping 
  60^* 
  east- 
  

   ward, 
  while 
  the 
  Triassic? 
  sandstones 
  are 
  gently 
  inclined 
  to 
  the 
  westward. 
  

   There 
  is, 
  therefore, 
  a 
  fault. 
  This 
  fault 
  is 
  directly 
  in 
  line 
  with 
  the 
  anti- 
  

   clinal 
  fold 
  noted 
  both 
  south 
  of 
  the 
  Dolores, 
  and 
  north 
  of 
  the 
  valley. 
  This 
  

   fold 
  is 
  at 
  right 
  angles 
  to 
  the 
  course 
  of 
  the 
  Dolores 
  before 
  it 
  is 
  joined 
  by 
  

   the 
  San 
  Miguel, 
  and 
  its 
  axis 
  on 
  both 
  sides 
  of 
  the 
  river 
  is 
  marked 
  by 
  a 
  

   broad 
  valley 
  (Paradox 
  Valley). 
  One 
  the 
  north, 
  also, 
  the 
  Grand 
  cuts 
  

   across 
  the 
  fold 
  at 
  right 
  angles 
  to 
  its 
  axis. 
  It 
  would 
  seem., 
  therefore, 
  

   that 
  the 
  fold 
  must 
  have 
  been 
  formed 
  gradually, 
  the 
  rate 
  of 
  elevation 
  

   not 
  exceeding 
  the 
  cutting 
  power 
  of 
  the 
  streams. 
  This 
  fold 
  may 
  have 
  

   taken 
  the 
  form 
  of 
  a 
  fault 
  on 
  the 
  west 
  side 
  of 
  what 
  is 
  now 
  Siudbad's 
  

   Valley, 
  with 
  the 
  downthrow 
  on 
  the 
  west. 
  This, 
  however, 
  does 
  not 
  ac- 
  

   count 
  for 
  the 
  tipping 
  up 
  of 
  the 
  ends 
  of 
  the 
  Carboniferous 
  strata. 
  It 
  is 
  

   probable 
  that 
  this 
  occurred 
  later. 
  The 
  quaquaversal 
  structure 
  of 
  the 
  

   valley 
  suggests 
  the 
  idea 
  that 
  it 
  marks 
  an 
  eruptive 
  center 
  similar 
  to 
  those 
  

   of 
  the 
  Sierra 
  la 
  Sal, 
  in 
  which, 
  however, 
  the 
  igneous 
  material 
  did 
  not 
  

   reach 
  the 
  surface, 
  causing 
  only 
  a 
  bulging 
  of 
  the 
  strata. 
  Whether 
  the 
  

   fault 
  is 
  the 
  result 
  of 
  this 
  bulging 
  or 
  of 
  the 
  folding, 
  as 
  explained 
  above, 
  

   "we 
  cannot 
  say. 
  That 
  faulting 
  did 
  occur 
  is 
  evident. 
  It 
  left 
  the 
  ends 
  of 
  

   the 
  soft 
  and 
  shaly 
  beds 
  abutting 
  against 
  the 
  hard 
  sandstones, 
  and 
  sub- 
  

   sequently 
  they 
  were 
  bent 
  upward. 
  A 
  force 
  acting 
  from 
  the 
  Sierra 
  lai 
  

   Sal 
  eastward 
  would 
  accomplish 
  this. 
  It 
  remains 
  a 
  question 
  to 
  be 
  deter- 
  

   mined 
  whether 
  the 
  eruption 
  of 
  the 
  mountains 
  had 
  anything 
  to 
  do 
  with 
  

   it. 
  If 
  the 
  fault 
  occurred 
  previous 
  to 
  the 
  upheaval 
  denoted 
  by 
  the 
  dips 
  

   of 
  the 
  strata, 
  there 
  doubtless 
  followed 
  a 
  period 
  in 
  which 
  erosive 
  influ- 
  

   ences 
  were 
  actively 
  at 
  work, 
  and 
  which 
  would 
  assist 
  in 
  rendering 
  the 
  

   site 
  of 
  the 
  valley 
  a 
  point 
  of 
  weak 
  resistance. 
  The 
  breaking 
  of 
  the 
  strata 
  

   attending 
  fhe 
  upheaval 
  would 
  aftord 
  a 
  good 
  beginning 
  for 
  subsequent 
  

   erosive 
  agents, 
  and 
  as 
  they 
  worked 
  deeper 
  and 
  deeper 
  into 
  the 
  soft 
  

   shaly 
  beds 
  the 
  present 
  form 
  of 
  the 
  valley 
  was 
  doubtless 
  gradually 
  at- 
  

   tained. 
  

  

  In 
  the 
  succeeding 
  chapters, 
  I 
  propose 
  to 
  consider 
  the 
  various 
  geolog- 
  

   ical 
  features 
  separately, 
  taking 
  up 
  each 
  formation 
  in 
  order. 
  As 
  already 
  

   mentioned, 
  the 
  greater 
  part 
  of 
  the 
  district 
  is 
  covered 
  with 
  sedimentary 
  

   formations; 
  those 
  represented 
  areCarboniferous,Triassic? 
  and 
  Jurassic"? 
  

   and 
  Cretaceous. 
  There 
  are 
  limited 
  areas 
  of 
  archaean 
  rocks 
  and 
  also 
  of 
  

   volcanic 
  rocks. 
  

  

  