﻿58 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  east 
  side 
  of 
  the 
  fault, 
  at 
  a 
  slightly 
  lower 
  level 
  than 
  the 
  nearby 
  

   Little 
  Falls, 
  is 
  an 
  outcrop 
  of 
  the 
  Theresa 
  passage 
  beds 
  ; 
  at 
  the 
  

   south 
  end, 
  and 
  unquestionably 
  on 
  the 
  west 
  side 
  of 
  the 
  fault, 
  Pots- 
  

   dam 
  sandstone 
  outcrops. 
  Farther 
  west 
  outcrops 
  are 
  plentiful 
  

   on 
  the 
  west 
  side 
  of 
  the 
  fault 
  but 
  there 
  are 
  none 
  on 
  the 
  east 
  side. 
  

   The 
  uncertainty 
  in 
  regard 
  to 
  the 
  matter 
  is 
  whether 
  the 
  Theresa 
  is 
  

   really 
  on 
  the 
  east 
  side 
  of 
  the 
  fault 
  ; 
  a 
  slight 
  swinging 
  of 
  the 
  northern 
  

   apex 
  of 
  the 
  wedge 
  toward 
  the 
  right 
  would 
  put 
  it 
  on 
  the 
  west 
  side. 
  

   The 
  uncertainty 
  is 
  regrettable; 
  we 
  can 
  only 
  say 
  that 
  everything 
  we 
  

   saw 
  in 
  the 
  field 
  led 
  to 
  the 
  confident 
  belief 
  in 
  the 
  relations 
  as 
  illus- 
  

   trated, 
  and 
  had 
  not 
  the 
  Theresa 
  exposure 
  been 
  forthcoming 
  we 
  

   should 
  have 
  been 
  forced 
  to 
  map 
  it 
  at 
  that 
  point 
  owing 
  to 
  the 
  testi- 
  

   mony 
  of 
  exposures 
  a 
  mile 
  to 
  the 
  southwest. 
  Nevertheless 
  the 
  drift 
  

   is 
  very 
  heavy 
  and 
  the 
  mapping 
  of 
  a 
  much 
  faulted 
  district 
  such 
  as 
  this 
  

   must 
  needs 
  be 
  very 
  uncertain 
  under 
  the 
  circumstances. 
  

  

  Rock 
  horses 
  caught 
  in 
  along 
  faults 
  are 
  common 
  enough. 
  But 
  the 
  

   rock 
  concerned 
  is 
  usually 
  intermediate 
  in 
  age 
  between 
  the 
  rock 
  of 
  the 
  

   upthrow 
  and 
  downthrow 
  sides 
  ; 
  it 
  has 
  dropped 
  relatively 
  to 
  the 
  up- 
  

   throw 
  side 
  but 
  has 
  not 
  dropped 
  so 
  far 
  as 
  has 
  the 
  downthrow 
  side. 
  

   Such 
  a 
  wedge 
  occurs 
  in 
  Saratoga 
  along 
  the 
  Saratoga 
  fault. 
  But 
  in 
  

   the 
  case 
  under 
  consideration 
  we 
  have 
  a 
  small 
  block 
  about 
  350 
  yards 
  

   in 
  length, 
  which 
  has 
  dropped 
  down 
  along 
  the 
  fault 
  zone 
  some 
  300 
  

   feet 
  more 
  than 
  the 
  downthrow 
  side 
  has 
  dropped. 
  It 
  is 
  a 
  diminutive 
  

   example 
  of 
  a 
  trough 
  fault. 
  It 
  is 
  difficult 
  to 
  conceive 
  of 
  the 
  me- 
  

   chanical 
  conditions 
  which 
  would 
  permit 
  so 
  small 
  a 
  block 
  to 
  drop 
  so 
  

   deeply 
  into 
  the 
  jaws 
  of 
  a 
  fault. 
  It 
  may 
  be 
  the 
  apex 
  of 
  a 
  large 
  

   dropped 
  block, 
  otherwise 
  entirely 
  eroded 
  away. 
  

  

  What 
  seems 
  to 
  be 
  another 
  and 
  similar 
  case 
  is 
  found 
  along 
  the 
  

   Hoffmans 
  fault 
  a 
  mile 
  west 
  of 
  Porter 
  Corners 
  where 
  a 
  small 
  block 
  

   of 
  Little 
  Falls 
  dolomite 
  lies 
  in 
  the 
  fault 
  zone 
  closely 
  adjacent 
  to 
  the 
  

   Precambric 
  exposures 
  to 
  the 
  west 
  of 
  the 
  fault. 
  To 
  the 
  east 
  the 
  

   drift 
  covers 
  everything, 
  but 
  unless 
  our 
  attempted 
  mapping 
  is 
  totally 
  

   at 
  fault, 
  the 
  rock 
  on 
  the 
  downthrow 
  side 
  should 
  be 
  the 
  Potsdam 
  sand- 
  

   stone. 
  Certainly 
  Precambric 
  rocks 
  come 
  in 
  on 
  the 
  east 
  side 
  of 
  the 
  

   fault 
  2 
  miles 
  away 
  to 
  the 
  northeast. 
  So 
  we 
  infer 
  this 
  to 
  be 
  a 
  small 
  

   dropped 
  block 
  of 
  the 
  same 
  type. 
  

  

  As 
  has 
  been 
  said, 
  the 
  mapping 
  of 
  the 
  West 
  Galway 
  fault 
  across 
  

   the 
  quadrangle 
  is 
  highly 
  conjectural. 
  There 
  should 
  be 
  a 
  fault 
  

   between 
  the 
  Precambric 
  exposures 
  south 
  of 
  South 
  Corinth 
  and 
  

   those 
  of 
  the 
  Theresa 
  at 
  North 
  Greenfield; 
  there 
  should 
  be 
  a 
  fault 
  

   just 
  west 
  of 
  the 
  Potsdam 
  exposures 
  at 
  Corinth, 
  cutting 
  them 
  off. 
  

  

  