﻿652 
  Forty-seventh 
  Report 
  on 
  tee 
  State 
  Museum. 
  

  

  Series 
  IV. 
  The 
  Potsdam 
  sandstone 
  is 
  traceable 
  some 
  miles 
  up 
  

   the 
  stream 
  valleys, 
  as 
  is 
  graphically 
  shown 
  by 
  the 
  map. 
  The 
  

   small 
  patches 
  that 
  rest 
  on 
  the 
  gneiss 
  northwest 
  of 
  Crown 
  Point 
  

   Centre 
  are 
  curious 
  and 
  interesting 
  little 
  remnants, 
  over 
  which 
  

   the 
  creek 
  now 
  tumbles 
  in 
  cascades. 
  The 
  Calciferous 
  sandstone 
  

   forms 
  a 
  small 
  patch 
  on 
  the 
  southeastern 
  lake 
  shore, 
  and 
  then 
  

   north 
  of 
  the 
  steamboat 
  dock 
  it 
  appears 
  in 
  great 
  force, 
  until 
  

   it 
  dips 
  under 
  the 
  Chazy 
  limestone, 
  which, 
  at 
  the 
  end 
  of 
  the 
  point, 
  

   in 
  turn 
  passes 
  below 
  the 
  Trenton 
  limestone. 
  Brain 
  erd 
  and 
  Seely 
  

   estimate 
  the 
  Chazy 
  as 
  305 
  feet 
  thick. 
  (Bull. 
  Geol. 
  Soc. 
  Amer., 
  II, 
  

   300, 
  1891.) 
  In 
  the 
  deep 
  railway 
  cut 
  at 
  2 
  on 
  the 
  map, 
  by 
  pacing 
  

   and 
  calculating 
  on 
  the 
  dip, 
  I 
  estimated 
  that 
  350 
  feet 
  of 
  cherty 
  blue 
  

   limestone 
  of 
  the 
  Calciferous 
  were 
  exposed, 
  with 
  five 
  feet 
  of 
  slate 
  

   about 
  100 
  feet 
  above 
  the 
  base 
  of 
  the 
  exposure 
  This 
  is 
  division 
  A 
  

   of 
  Brainerd 
  and 
  Seely, 
  and 
  its 
  general 
  thickness 
  for 
  the 
  region, 
  they 
  

   estimate 
  at 
  310 
  feet. 
  These 
  cherty 
  limestones 
  are 
  devoid 
  of 
  

   fossils. 
  Under 
  the 
  microscope 
  the 
  chert 
  is 
  seen 
  to 
  be 
  perfectly 
  

   amorphous 
  (colloid) 
  silica, 
  set 
  with 
  innumerable 
  rhombs 
  of 
  calcite, 
  

   but 
  with 
  no 
  sponge 
  spicules 
  or 
  any 
  trace 
  of 
  organic 
  life. 
  

  

  This 
  section 
  is 
  one 
  of 
  the 
  best 
  in 
  the 
  Champlain 
  valley, 
  for 
  the 
  

   Siluro-Cambrian 
  rocks, 
  as 
  the 
  faults 
  are 
  practically 
  absent 
  and 
  

   the 
  series 
  is 
  conformable 
  from 
  the 
  Potsdam 
  into 
  the 
  Trenton. 
  

   No 
  TJtica 
  slate 
  is, 
  however, 
  met 
  on 
  the 
  east 
  shore 
  above 
  Ticon- 
  

   deroga 
  until 
  we 
  reach 
  Essex. 
  

  

  Series 
  V. 
  The 
  dikes 
  are 
  represented 
  by 
  diabase. 
  Three 
  are 
  

   found 
  in 
  JNo. 
  7 
  slope 
  at 
  Hammond 
  ville. 
  One 
  crosses 
  the 
  highway 
  

   east 
  of 
  Breed's 
  pond 
  in 
  the 
  western 
  part 
  of 
  town 
  (179), 
  another 
  

   appears 
  near 
  the 
  railway, 
  northwest 
  of 
  Penfield's 
  pond 
  (80, 
  81), 
  

   another 
  is 
  due 
  north 
  of 
  this 
  (at 
  68) 
  and 
  three 
  cut 
  Koe's 
  spar 
  bed 
  

   (101) 
  due 
  north 
  of 
  the 
  last, 
  near 
  Moriah. 
  Undoubtedly 
  there 
  are 
  

   many 
  more 
  not 
  exposed. 
  

  

  Series 
  VI 
  The 
  quaternary 
  deposits 
  are 
  mostly 
  clays 
  along 
  the 
  

   lake 
  and 
  these 
  have 
  a 
  great 
  development. 
  They 
  rest 
  on 
  wonder- 
  

   fully 
  glaciated 
  limestone. 
  The 
  principal 
  scratches 
  run 
  north 
  

   twenty-eight 
  to 
  thirty 
  degrees 
  east 
  but 
  another 
  set 
  is 
  north 
  twelve 
  

   degrees 
  east. 
  Westward 
  from 
  Crown 
  Point 
  village, 
  terraces 
  and 
  

   deltas 
  of 
  post-glacial 
  sands 
  and 
  gravels 
  are 
  widely 
  developed 
  and 
  

   would 
  well 
  repay 
  study. 
  The 
  contour 
  maps 
  are 
  needed 
  for 
  this. 
  

  

  Mines. 
  — 
  The 
  iron 
  mines 
  at 
  Hammondville 
  have 
  ranked 
  with 
  

   those 
  at 
  Lyon 
  mountain 
  and 
  yield 
  only 
  to 
  the 
  Mineville 
  deposits 
  

  

  