﻿no 
  

  

  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  on 
  the 
  Alexandria 
  sheet, 
  what 
  appears 
  to 
  be 
  a 
  quite 
  similar 
  broad 
  

   belt 
  of 
  limestone 
  borders 
  the 
  west 
  side 
  of 
  Butterfield 
  lake. 
  It 
  is 
  

   however 
  so 
  much 
  concealed 
  by 
  overlying 
  Potsdam 
  sandstone 
  that 
  

   some 
  uncertainty 
  attaches 
  to 
  its 
  extent 
  and 
  purity. 
  But 
  it 
  has 
  a 
  

   breadth 
  of 
  outcrop 
  quite 
  comparable 
  to 
  that 
  of 
  the 
  Indian 
  river 
  

   belt, 
  and 
  seems 
  to 
  consist 
  chiefly 
  of 
  pure 
  limestone. 
  Its 
  dips 
  are 
  

   prevalently 
  to 
  the 
  southeast, 
  and 
  somewhat 
  steeper 
  than 
  in 
  the 
  

   previous 
  case, 
  averaging 
  60°. 
  This 
  means 
  a 
  thickness 
  substantially 
  

   the 
  same 
  as 
  in 
  the 
  other 
  case, 
  and 
  strongly 
  suggests 
  that 
  the 
  two 
  are 
  

   parallel 
  outcrops 
  of 
  the 
  same 
  great 
  limestone 
  belt, 
  and 
  that, 
  since 
  

   they 
  dip 
  toward 
  one 
  another, 
  the 
  structure 
  is 
  synclinal. 
  If 
  this 
  

   be 
  the 
  true 
  interpretation 
  then 
  the 
  schists, 
  amphibolites 
  and 
  quart- 
  

   zites 
  which 
  lie 
  between 
  the 
  two 
  limestone 
  belts, 
  rest 
  on 
  the 
  limestone 
  

   and 
  hence 
  are 
  younger, 
  with 
  the 
  rather 
  massive 
  quartzites 
  about 
  

   Sixberry 
  and 
  Millsite 
  lakes 
  as 
  the 
  youngest 
  of 
  all 
  ; 
  while 
  the 
  schists 
  

   to 
  the 
  northwest 
  on 
  the 
  Alexandria 
  quadrangle, 
  and 
  to 
  the 
  south- 
  

   east 
  on 
  the 
  Theresa 
  quadrangle, 
  underlie 
  the 
  limestone 
  and 
  are 
  

   older. 
  Figure 
  7 
  will 
  illustrate 
  the 
  suggested 
  structure. 
  

  

  \ 
  q 
  

  

  Fig. 
  7 
  Section 
  to 
  illustrate 
  the 
  structure 
  suggested 
  by 
  the 
  Grenville 
  rocks, 
  on 
  a 
  scale 
  of 
  

   4 
  mUes 
  to 
  the 
  inch; 
  s=schists, 
  c=crystalline 
  limestone, 
  q=quartzite 
  

  

  There 
  are, 
  however, 
  two 
  alternative 
  views 
  in 
  regard 
  to 
  this 
  struc- 
  

   ture 
  which 
  may 
  be 
  held. 
  It 
  is 
  possible 
  that 
  these 
  two 
  thick 
  lime- 
  

   stone 
  masses 
  may 
  be 
  separate 
  beds, 
  the 
  one 
  overlying 
  the 
  other 
  and 
  

   separated 
  from 
  it 
  by 
  the 
  thickness 
  of 
  schist 
  and 
  quartzite 
  which 
  

   lies 
  between. 
  This 
  involves 
  the 
  assumption 
  that 
  the 
  series, 
  though 
  

   greatly 
  tipped, 
  is 
  not 
  folded 
  and 
  hence 
  that 
  no 
  bed 
  is 
  cut 
  by 
  the 
  

   present 
  surface 
  along 
  more 
  than 
  one 
  line. 
  Since, 
  however, 
  small 
  

   folds 
  are 
  certainly 
  present 
  in 
  considerable 
  number, 
  the 
  changing 
  dips 
  

   indicate 
  the 
  presence 
  of 
  greater 
  ones, 
  and 
  as 
  we 
  have 
  here 
  two 
  

   great 
  lines 
  of 
  limestone 
  outcrop, 
  the 
  rock 
  showing 
  much 
  the 
  same 
  

  

  