﻿XXII 
  ANNUAL 
  REPORT 
  OF 
  THE 
  DIRECTOR 
  

  

  Valley 
  Range. 
  To 
  the 
  east 
  of 
  these 
  peaks, 
  stretching 
  far 
  be- 
  

   yond 
  the 
  present 
  channel 
  of 
  the 
  Rio 
  Grande, 
  there 
  was 
  once 
  

   a 
  great 
  Tertiary 
  lake, 
  which 
  was 
  gradually 
  filled 
  with 
  the 
  sands 
  

   washed 
  into 
  it 
  on 
  every 
  hand 
  and 
  by 
  the 
  ashes 
  blown 
  out 
  of 
  

   the 
  adjacent 
  volcanoes. 
  This 
  great 
  lake 
  formation 
  is 
  in 
  sonic 
  

   places 
  a 
  thousand 
  feet 
  in 
  thickness. 
  When 
  the 
  lake 
  was 
  tilled 
  

   the 
  Rio 
  Grande 
  cut 
  its 
  channel 
  through 
  the 
  midst 
  to 
  a 
  depth 
  of 
  

   many 
  hundreds 
  of 
  feet. 
  The 
  volcanic 
  mountains 
  to 
  the 
  west- 
  

   ward 
  send 
  to 
  the 
  Rio 
  Grande 
  a 
  number 
  of 
  minor 
  streams, 
  which 
  

   in 
  a 
  general 
  way 
  are 
  parallel 
  with 
  one 
  another. 
  The 
  Rio 
  Grande 
  

   itself, 
  and 
  all 
  of 
  these 
  lateral 
  streams, 
  have 
  cut 
  deep 
  gorges 
  and 
  

   canyons, 
  so 
  that 
  there 
  are 
  long, 
  irregular 
  table-lands, 
  or 
  mesas, 
  

   extending 
  from 
  the 
  Rio 
  Grande 
  back 
  to 
  the 
  Valley 
  Mountains, 
  

   each 
  mesa 
  being 
  severed 
  from 
  the 
  adjacent 
  one 
  by 
  a 
  canyon 
  

   or 
  canyon 
  valley; 
  and 
  each 
  of 
  these 
  long 
  mesas 
  rises 
  witli 
  a 
  

   precipitous 
  cliff 
  from 
  the 
  valley 
  below. 
  The 
  cliffs 
  themselves 
  

   are 
  built 
  of 
  volcanic 
  sands 
  and 
  ashes, 
  and 
  many 
  of 
  the 
  strata 
  

   are 
  exceedingly 
  light 
  and 
  friable. 
  The 
  specific 
  gravity 
  of 
  some 
  

   of 
  these 
  rocks 
  is 
  so 
  low 
  that 
  they 
  will 
  float 
  on 
  water. 
  Into 
  

   the 
  faces 
  of 
  these 
  cliffs, 
  in 
  the 
  friable 
  and 
  easily 
  worked 
  rock, 
  

   many 
  chambers 
  have 
  been 
  excavated; 
  for 
  mile 
  after 
  mile 
  the 
  

   cliffs 
  are 
  studded 
  with 
  them, 
  so 
  that 
  altogether 
  there 
  are 
  many 
  

   thousands. 
  Sometimes 
  a 
  chamber 
  or 
  series 
  of 
  chambers 
  is 
  en- 
  

   tered 
  from 
  a 
  terrace, 
  but 
  usually 
  they 
  were 
  excavated 
  many 
  

   feet 
  above 
  any 
  landing 
  or 
  terrace 
  below, 
  so 
  that 
  they 
  could 
  

   be 
  reached 
  only 
  by 
  ladders. 
  In 
  other 
  places 
  artificial 
  terraces 
  

   were 
  built 
  by 
  constructing 
  retaining 
  walls 
  and 
  filling 
  the 
  inte- 
  

   rior 
  next 
  to 
  the 
  cliff 
  with 
  loose 
  rock 
  and 
  sand. 
  Very 
  often 
  

   steps 
  were 
  cut 
  into 
  the 
  face 
  of 
  a 
  cliff 
  and 
  a 
  rude 
  stairway 
  

   formed 
  by 
  which 
  chambers 
  could 
  be 
  reached. 
  The 
  chambers 
  

   were 
  very 
  irregularly 
  arranged 
  and 
  very 
  irregular 
  in 
  size 
  and 
  

   structure. 
  In 
  many 
  cases 
  there 
  is 
  a 
  central 
  chamber, 
  which 
  

   seems 
  to 
  have 
  been 
  a 
  general 
  living 
  room 
  for 
  the 
  people, 
  

   hack 
  of 
  which 
  two, 
  three, 
  or 
  more 
  chambers 
  somewhat 
  smaller 
  

   are 
  found, 
  due 
  chambers 
  occupied 
  by 
  one 
  family 
  are 
  some- 
  

   times 
  connected 
  with 
  those 
  occupied 
  by 
  another 
  family, 
  so 
  that 
  

   two 
  or 
  three 
  or 
  four 
  sets 
  of 
  chambers 
  have 
  interior 
  communica- 
  

   tion. 
  Usually, 
  however, 
  the 
  communication 
  from 
  one 
  system 
  of 
  

  

  