﻿Stratigraphy 
  of 
  Eastern 
  New 
  Mexico. 
  105 
  

  

  5. 
  Covered 
  40' 
  

  

  6. 
  Fine-grained 
  light 
  gray 
  siliceous 
  limestone 
  with 
  much 
  

  

  chert. 
  Much 
  fractured 
  and 
  cemented 
  with 
  calcite 
  

  

  veins 
  75' 
  

  

  s- 
  

  

  Total 
  thickness 
  285' 
  

  

  The 
  Mississippian 
  strata 
  were 
  found 
  by 
  the 
  writer 
  only 
  

   in 
  the 
  southern 
  Sacramento 
  and 
  southern 
  San 
  Andreas 
  

   Mountains. 
  

  

  The 
  Pre-Pennsylvanian 
  Unconformity.— 
  The 
  long 
  ero- 
  

   sion 
  interval 
  prior 
  to 
  the 
  deposition 
  of 
  thick 
  Pennsyl- 
  

   vanian 
  sediments, 
  occurring, 
  so 
  far 
  as 
  known, 
  throughout 
  

   the 
  southwest, 
  denotes 
  a 
  very 
  important 
  time 
  break 
  in 
  

   Paleozoic 
  sedimentation 
  in 
  the 
  mountain 
  areas 
  of 
  eastern 
  

   New 
  Mexico. 
  Later 
  Mississippian 
  and 
  earliest 
  Pennsyl- 
  

   vanian 
  strata 
  are 
  probably 
  everywhere 
  lacking. 
  Earlier 
  

   Paleozoic 
  is 
  also 
  lacking 
  except 
  in 
  south-central 
  New 
  

   Mexico. 
  Subsequent 
  to 
  the 
  marked 
  deformation 
  of 
  the 
  

   Basement 
  Complex, 
  there 
  is 
  no 
  evidence 
  of 
  orogenic 
  de- 
  

   formation 
  until 
  late 
  in 
  the 
  Pennsylvanian. 
  In 
  eastern 
  

   New 
  Mexico, 
  as 
  in 
  the 
  Rockies 
  farther 
  north, 
  Paleozoic 
  

   strata 
  of 
  widely 
  varying 
  ages 
  lie 
  directly 
  on 
  each 
  other 
  

   without 
  evidence 
  of 
  angular 
  unconformity 
  and, 
  indeed, 
  

   often 
  without 
  clear 
  stratigraphic 
  evidence 
  of 
  the 
  great 
  

   time 
  breaks 
  indicated 
  by 
  the 
  fossils. 
  From 
  the 
  northern 
  

   San 
  Andreas 
  Range 
  to 
  the 
  northern 
  limits 
  of 
  our 
  region, 
  

   the 
  Magdalena 
  strata 
  rest 
  on 
  a 
  remarkably 
  even 
  surface 
  

   of 
  the 
  Basement 
  Complex. 
  Farther 
  to 
  the 
  north, 
  how- 
  

   ever, 
  the 
  surface 
  of 
  the 
  Basement 
  Complex 
  must 
  have 
  

   been 
  one 
  of 
  marked 
  relief, 
  for 
  the 
  Magdalena 
  sediments 
  

   in 
  the 
  Sangre 
  de 
  Cristo 
  Range 
  contain 
  much 
  arkose. 
  

  

  Magdalena 
  Group. 
  — 
  The 
  greatest 
  thickness 
  yet 
  meas- 
  

   ured 
  of 
  Magdalena, 
  in 
  the 
  Pecos 
  Canon 
  near 
  the 
  sources 
  

   of 
  that 
  river 
  in 
  the 
  Sangre 
  de 
  Cristo 
  Range, 
  is 
  2450 
  feet. 
  

   The 
  thickness 
  may 
  be 
  greater 
  along 
  the 
  Front 
  Range 
  

   farther 
  northeast. 
  Magdalena 
  rocks 
  are 
  entirely 
  lacking 
  

   at 
  some 
  localities 
  in 
  the 
  Sangre 
  de 
  Cristo 
  Range 
  and 
  

   around 
  the 
  small 
  crystalline 
  areas 
  of 
  central 
  New 
  Mex- 
  

   ico. 
  It 
  is 
  probable, 
  as 
  will 
  be 
  explained 
  farther 
  on, 
  that 
  

   the 
  Magdalena 
  is 
  lacking 
  in 
  a 
  large 
  area 
  in 
  central 
  New 
  

   Mexico. 
  The 
  Magdalena 
  covers 
  a 
  large 
  area 
  on 
  the 
  sum- 
  

   mits 
  and 
  the 
  flanks 
  of 
  the 
  Sangre 
  de 
  Cristo 
  Range, 
  and 
  

   forms 
  the 
  eastern 
  dip 
  slopes 
  of 
  the 
  Sandia 
  Mountains 
  and 
  

   the 
  southern 
  Manzano 
  Mountains 
  east 
  of 
  Albuquerque; 
  

  

  