﻿360 
  II. 
  E. 
  Gregory 
  — 
  Andesites 
  from 
  Maine. 
  

  

  so 
  that 
  when 
  the 
  rock 
  is 
  loosened 
  it 
  comes 
  out 
  in 
  flat 
  slaty 
  

   pieces 
  one-quarter 
  inch 
  or 
  so 
  in 
  width 
  and 
  several 
  inches 
  or 
  

   even 
  feet 
  in 
  area. 
  The 
  whole 
  appearance 
  is 
  that 
  of 
  thin- 
  

   bedded 
  sedimentaries 
  which 
  have 
  been 
  folded 
  and 
  faulted. 
  

   The 
  general 
  direction 
  of 
  these 
  cleavage 
  planes 
  is 
  N. 
  30° 
  E. 
  on 
  

   north 
  end 
  and 
  N. 
  35° 
  E. 
  on 
  south 
  end 
  with 
  a 
  dip 
  southeast 
  at 
  

   a 
  high 
  angle. 
  The 
  fault 
  planes 
  strike 
  X. 
  70° 
  E. 
  and 
  besides 
  

   their 
  effect 
  at 
  the 
  ends 
  of 
  the 
  hills 
  in 
  cutting 
  out 
  the 
  thin 
  

   slabs 
  they 
  occur 
  all 
  along 
  the 
  west 
  side, 
  each 
  indicating 
  a 
  slight 
  

   movement. 
  It 
  seems 
  probable 
  that 
  the 
  Edmund's 
  Hill 
  ridge 
  

   owes 
  its 
  origin 
  in 
  part 
  to 
  the 
  formation 
  of 
  a 
  fault 
  block. 
  

  

  The 
  outlying 
  knobs 
  and 
  hills 
  to 
  the 
  east 
  of 
  the 
  main 
  mass 
  

   are 
  also 
  of 
  andesite, 
  usually 
  microcrystalline, 
  but 
  sometimes 
  

   porphyritic. 
  The 
  igneous 
  rock 
  does 
  not 
  extend 
  far 
  to 
  the 
  

   west, 
  but 
  is 
  replaced 
  by 
  arenaceous 
  slates, 
  and 
  while 
  no 
  precise 
  

   boundaries 
  of 
  the 
  formation 
  were 
  determined, 
  the 
  field 
  relations 
  

   suggest 
  that 
  the 
  hill 
  is 
  the 
  remnant 
  of 
  a 
  lava 
  flow 
  over 
  the 
  

   eroded 
  and 
  upturned 
  edges 
  of 
  sandy 
  rocks 
  of 
  Silurian 
  age.^ 
  

  

  Andesites 
  of 
  Holart 
  Hill. 
  — 
  This 
  hill 
  is 
  an 
  isolated 
  mass 
  of 
  

   andesite 
  forming 
  a 
  prominent 
  feature 
  in 
  the 
  landscape 
  as 
  one 
  

   looks 
  west 
  from 
  Presque 
  Isle 
  village. 
  It 
  is 
  situated 
  partly 
  in 
  

   Mapleton 
  and 
  partly 
  in 
  Chapman 
  townships, 
  and 
  is 
  surrounded, 
  

   entirely 
  by 
  low, 
  poorly-drained 
  swamps 
  and 
  forest 
  lands, 
  and 
  

   visited 
  only 
  for 
  lumber 
  and 
  tan-bark, 
  which 
  are 
  secured 
  in 
  lim- 
  

   ited 
  quantities 
  during 
  the 
  winter 
  season. 
  The 
  hill 
  is 
  about 
  IJ 
  

   miles 
  long 
  and 
  f 
  miles 
  wide, 
  and 
  rises 
  quite 
  abruptly 
  above 
  

   the 
  plain 
  to 
  a 
  height 
  of 
  300 
  feet 
  as 
  a 
  single 
  well 
  defined 
  mass 
  

   without 
  branches, 
  or 
  outlyers. 
  The 
  sides 
  are 
  everywhere 
  quite 
  

   steep, 
  and 
  in 
  places 
  present 
  cliffs 
  forty 
  to 
  fifty 
  feet 
  high. 
  The 
  

   top 
  is 
  bare 
  only 
  where 
  fire 
  has 
  recently 
  destroyed 
  the 
  vegeta- 
  

   tion. 
  The 
  talus 
  slopes 
  present 
  a 
  confused 
  mass 
  of 
  large 
  and 
  

   small 
  blocks 
  of 
  andesite 
  which 
  entirely 
  conceal 
  all 
  outcrops 
  

   except 
  where 
  cliffs 
  are 
  exposed. 
  On 
  the 
  west 
  and 
  north 
  sides 
  

   numerous 
  bowlders 
  of 
  red 
  sandstone 
  and 
  conglomerate 
  are 
  

   piled 
  along 
  the 
  slope 
  and 
  mingled 
  with 
  the 
  volcanic 
  material. 
  

   These 
  were 
  traced 
  to 
  their 
  parent 
  ledges 
  scarcely 
  a 
  half 
  mile 
  

   to 
  the 
  north, 
  and 
  the 
  bowlders 
  serve 
  to 
  cover 
  the 
  contact 
  of 
  

   the 
  andesite 
  with 
  the 
  Mapleton 
  sandstone. 
  f 
  Specimens 
  col- 
  

   lected 
  from 
  various 
  places 
  on 
  the 
  hill 
  show 
  but 
  slight 
  dif- 
  

   ferences 
  in 
  composition 
  and 
  texture 
  except 
  the 
  rock 
  from 
  the 
  

   northwest 
  corner, 
  which 
  is 
  a 
  breccia 
  of 
  andesitic 
  fragments 
  and 
  

  

  * 
  The 
  sandstone 
  at 
  Edmund's 
  Hill 
  contains 
  an 
  Eodevonian 
  fauna 
  which 
  corre- 
  

   sponds 
  closely 
  with 
  that 
  of 
  the 
  Gaspe 
  sandstone. 
  I 
  have 
  given 
  it 
  the 
  name 
  

   Chapman 
  sandstone. 
  — 
  H. 
  S. 
  Williams. 
  

  

  f 
  The 
  " 
  Mapleton 
  sandstone 
  " 
  here 
  referred 
  to 
  is 
  a 
  massive, 
  and 
  in 
  places 
  

   coarse, 
  red 
  sandstone, 
  in 
  which 
  plants 
  (Psilophyton, 
  etc.) 
  have 
  been 
  found. 
  It 
  is 
  

   of 
  Devonian 
  age 
  but 
  somewhat 
  younger 
  than 
  the 
  Chapman 
  sandstone— 
  H. 
  S. 
  W. 
  

  

  