﻿96 
  PROCEEDINGS 
  OF 
  THE 
  CALIFORNIA 
  

  

  tinent, 
  or 
  a 
  part 
  thereof, 
  and 
  an 
  ice 
  belt 
  contiguous 
  to 
  the 
  continental 
  shores, 
  we 
  

   can 
  readily 
  understand 
  from 
  the 
  manner 
  of 
  the 
  formation 
  of 
  glaciers 
  that 
  it 
  

   moved 
  as 
  a 
  great 
  stream, 
  or, 
  more 
  likely, 
  in 
  currents, 
  from 
  the 
  north 
  ; 
  probably 
  

   with 
  extreme 
  slowness, 
  but 
  with 
  certainty. 
  

  

  Moreover, 
  a 
  body 
  of 
  ice 
  contiguous 
  to 
  the 
  shores 
  of 
  the 
  continent 
  will 
  do 
  its 
  

   work 
  more 
  or 
  less 
  effectually 
  and 
  at 
  greater 
  or 
  less 
  depths, 
  in 
  proportion 
  to 
  its 
  rate 
  

   of 
  progress 
  and 
  its 
  thickness 
  ; 
  so 
  that 
  we 
  can 
  understand 
  how 
  terraces 
  ofdififerent 
  

   elevations 
  may 
  have 
  been 
  formed 
  during 
  that 
  period, 
  without 
  any 
  relative 
  change 
  of 
  

   the 
  level 
  of 
  the 
  sea 
  and 
  bordering 
  land, 
  although 
  the 
  same 
  general 
  effects 
  would 
  

   have 
  been 
  produced 
  if 
  the 
  land 
  had 
  been 
  rising 
  or 
  subsiding. 
  

  

  Moreover, 
  the 
  mass 
  of 
  ice 
  resting 
  on 
  the 
  land 
  may 
  have 
  done 
  similar 
  work 
  

   above 
  the 
  level 
  of 
  the 
  sea, 
  to 
  what 
  may 
  have 
  been 
  beneath 
  it. 
  

  

  Thus 
  these 
  terraces 
  may 
  not 
  indicate 
  the 
  different 
  steps 
  of 
  the 
  elevation 
  of 
  the 
  

   continental 
  shore 
  ; 
  and 
  instead 
  of 
  resorting 
  to 
  the 
  theory 
  of 
  great 
  and 
  violent 
  

   upheaval, 
  per 
  saltum, 
  we 
  see 
  how 
  the 
  elevation 
  may 
  have 
  been 
  gradual, 
  and 
  even 
  

   after 
  the 
  terraces 
  have 
  been 
  formed. 
  This 
  gradual 
  movement 
  of 
  elevation 
  is 
  in- 
  

   dicated 
  by 
  the 
  present 
  level 
  character 
  of 
  the 
  plateaus, 
  or 
  when 
  very 
  broad, 
  by 
  

   their 
  slight 
  inclination. 
  

  

  I 
  do 
  not 
  propose 
  to 
  offer 
  any 
  explanation 
  as 
  to 
  how 
  the 
  ice 
  belt 
  was 
  formed, 
  

   or 
  how 
  it 
  acted 
  ; 
  whether 
  as 
  a 
  great 
  body, 
  disconnected 
  from 
  the 
  continental 
  

   ice 
  sheet, 
  it 
  moved 
  slowly 
  down 
  the 
  coast 
  line 
  by 
  the 
  combined 
  forces 
  of 
  ocean 
  

   currents 
  and 
  the 
  pressure 
  of 
  the 
  greater 
  masses 
  from 
  the 
  northward 
  ; 
  or 
  whether 
  

   it 
  moved 
  as 
  a 
  part 
  of 
  the 
  great 
  ice 
  sheet 
  from 
  the 
  northward. 
  

  

  The 
  evidences 
  of 
  these 
  terraces 
  seem 
  to 
  be 
  found 
  in 
  greater 
  proportion 
  be- 
  

   tween 
  latitudes 
  30 
  and 
  42 
  than 
  further 
  to 
  the 
  north, 
  and 
  this 
  may, 
  in 
  a 
  measure, 
  

   be 
  thus 
  accounted 
  for. 
  

  

  Since 
  the 
  period 
  of 
  upheaval 
  succeeding 
  the 
  terrace 
  formation, 
  r;<^neral 
  and 
  

   local 
  climatic 
  changes 
  have 
  doubtless 
  taken 
  place, 
  tending 
  to 
  the 
  destruction 
  of 
  

   the 
  terraces, 
  and 
  as 
  they 
  were 
  formed 
  in 
  sedimentary 
  rocks, 
  most 
  of 
  their 
  finer 
  

   markings 
  have 
  been 
  obliterated. 
  Throughout 
  the 
  coast 
  line, 
  below 
  latitude 
  40°, 
  

   we 
  find 
  that 
  after 
  the 
  terraces 
  have 
  been 
  elevated, 
  the 
  disintegration 
  of 
  higher 
  

   lands 
  took 
  place 
  with 
  greater 
  activity 
  than 
  at 
  present, 
  and 
  yet 
  the 
  material 
  

   was 
  carried 
  downward 
  without 
  great 
  violence, 
  and 
  formed 
  long, 
  gently 
  inclined 
  

   slopes 
  from 
  the 
  base 
  of 
  the 
  mountains 
  towards 
  the 
  shores 
  or 
  into 
  the 
  valleys. 
  

   One 
  of 
  the 
  finest 
  examples 
  of 
  this 
  is 
  in 
  the 
  Valley 
  of 
  the 
  Santa 
  Clara, 
  east 
  of 
  

   San 
  Buenaventura 
  ; 
  another 
  is 
  the 
  Valley 
  of 
  San 
  Jose, 
  Lower 
  California, 
  whilst 
  

   innumerable 
  examples 
  abound 
  on 
  a 
  smaller 
  scale 
  along 
  the 
  flanks 
  of 
  our 
  moun- 
  

   tains. 
  Such 
  results 
  may 
  have 
  taken 
  place 
  under 
  a 
  climate 
  of 
  great 
  heat 
  and 
  

   excessive 
  moisture, 
  with 
  unceasing 
  precipitation, 
  but 
  without 
  violent 
  rains 
  to 
  

   create 
  torrents, 
  and 
  assisted 
  by 
  the 
  colder 
  weather 
  of 
  winter. 
  Subsequently 
  

   these 
  gently 
  sloping 
  deposits 
  were 
  cut 
  through 
  by 
  torrential 
  forces, 
  which 
  are 
  

   yet 
  at 
  work, 
  but 
  on 
  a 
  decreased 
  scale. 
  

  

  On 
  the 
  coast 
  line 
  many 
  cases 
  can 
  be 
  seen 
  where 
  these 
  long 
  sloping 
  deposits 
  of 
  

   disintegrated 
  material 
  have 
  been 
  cut 
  through 
  by 
  subsequent 
  torrents, 
  and 
  are 
  

   now 
  being 
  undermined 
  and 
  washed 
  away, 
  so 
  as 
  to 
  expose 
  the 
  flanks 
  of 
  the 
  moun- 
  

  

  