﻿64 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  to 
  curve 
  from 
  the 
  north 
  to 
  the 
  northeast 
  and 
  from 
  the 
  northeast 
  

   back 
  to 
  the 
  north. 
  It 
  has 
  been 
  shown 
  that 
  there 
  are 
  principal 
  joint 
  

   sets 
  in 
  both 
  these 
  directions 
  in 
  the 
  region 
  and 
  the 
  fault 
  slips 
  are 
  

   thought 
  to 
  be 
  determined 
  in 
  position 
  by 
  these 
  joints. 
  The 
  average 
  

   trend 
  of 
  the 
  faults 
  is 
  to 
  the 
  north-northeast. 
  In 
  this 
  direction 
  there 
  

   are 
  no 
  main 
  joints. 
  The 
  faults 
  maintain 
  this 
  general 
  direction 
  by 
  

   alternately 
  following 
  the 
  north 
  and 
  the 
  northeast 
  joints, 
  this 
  appar- 
  

   ently 
  being 
  a 
  more 
  easy 
  method 
  of 
  accomplishing 
  the 
  deformation 
  

   with 
  north-northeast 
  trend 
  than 
  the 
  method 
  of 
  creating 
  new 
  frac- 
  

   tures 
  in 
  that 
  direction 
  along 
  which 
  the 
  slipping 
  might 
  take 
  place. 
  

   Both 
  the 
  Hoffmans 
  and 
  the 
  McGregor 
  faults 
  illustrate 
  this 
  curving 
  

   tendency. 
  

  

  The 
  faults 
  send 
  off 
  frequent 
  branches, 
  which 
  are 
  more 
  likely 
  to 
  

   appear 
  at 
  a 
  curve. 
  In 
  many 
  cases 
  one 
  branch 
  will 
  be 
  found 
  in 
  a 
  

   north-south 
  and 
  the 
  other 
  in 
  a 
  northeast-southwest 
  direction. 
  By 
  the 
  

   branching, 
  the 
  throw 
  of 
  the 
  fault 
  is 
  divided 
  among 
  the 
  branches. 
  

   It 
  often 
  happens 
  that 
  the 
  throw 
  of 
  the 
  branches 
  steadily 
  diminishes 
  

   until 
  they 
  fade 
  out 
  while 
  at 
  the 
  same 
  time 
  that 
  of 
  the 
  main 
  fault 
  in- 
  

   creases 
  until 
  it 
  attains 
  the 
  amount 
  it 
  had 
  prior 
  to 
  the 
  branching. 
  

   This 
  process 
  seems 
  frequently 
  repeated. 
  

  

  During 
  the 
  successive 
  stages 
  of 
  the 
  faulting 
  in 
  the 
  region, 
  as 
  

   the 
  long 
  rock 
  slices 
  slipped 
  past 
  one 
  another, 
  it 
  is 
  but 
  natural 
  that 
  

   irregularities 
  in 
  the 
  slipping 
  would 
  develop, 
  producing 
  cross 
  strains 
  

   in 
  the 
  slices 
  and 
  tending 
  to 
  promote 
  cross 
  breaks. 
  That 
  such 
  cross 
  

   breaks 
  are 
  of 
  frequent 
  occurrence 
  in 
  the 
  general 
  region 
  is 
  quite 
  

   certain, 
  though 
  exposures 
  are 
  not 
  sufficiently 
  good 
  to 
  permit 
  their 
  

   certain 
  location 
  within 
  the 
  Saratoga 
  quadrangle. 
  The 
  obvious 
  

   tendency 
  would 
  be 
  for 
  such 
  cross 
  breaks 
  to 
  occur 
  along 
  planes 
  of 
  

   weakness, 
  such 
  as 
  the 
  contacts 
  between 
  two 
  formations 
  of 
  very 
  

   different 
  strength. 
  There 
  seem 
  to 
  be 
  two 
  zones 
  in 
  which 
  such 
  

   breaks 
  would 
  be 
  most 
  apt 
  to 
  occur, 
  one 
  at 
  the 
  contact 
  between 
  the 
  

   Precambric 
  crystallines 
  and 
  the 
  Potsdam 
  sandstone, 
  and 
  the 
  other 
  

   at 
  the 
  contact 
  between 
  the 
  limestones 
  and 
  the 
  overlying 
  shales. 
  

  

  There 
  is 
  some 
  suggestion 
  of 
  frequent 
  cross 
  breaks 
  in 
  the 
  faulted 
  

   slices 
  at 
  the 
  Precambric-Potsdam 
  contacts, 
  but 
  in 
  no 
  case 
  known 
  

   to 
  us 
  has 
  the 
  evidence 
  been 
  worked 
  out 
  in 
  detail. 
  A 
  prominent 
  

   topographic 
  feature 
  of 
  the 
  southeast 
  border 
  of 
  the 
  Adirondacks 
  

   is 
  the 
  way 
  in 
  which 
  the 
  Precambric 
  portions 
  of 
  the 
  fault 
  slices 
  

   sharply 
  break 
  down 
  on 
  the 
  south 
  to 
  the 
  level 
  of 
  the 
  Paleozoic 
  plain. 
  

   In 
  every 
  one 
  of 
  the 
  faulted 
  slices 
  the 
  Precambric 
  rocks 
  are 
  fol- 
  

   lowed 
  by 
  Paleozoic 
  rocks 
  on 
  the 
  south. 
  The 
  Precambric 
  territory 
  

  

  