﻿GEOLOGY 
  OF 
  THE 
  PORT 
  LEYDEN 
  QUADRANGLE 
  21 
  

  

  ite) 
  ; 
  4ofo 
  of 
  green 
  hornblende 
  and 
  green 
  augite 
  and 
  5;^ 
  of 
  hyper- 
  

   sthene, 
  magnetite, 
  biotite, 
  zircon 
  and 
  apatite. 
  This 
  type 
  is 
  in 
  

   contact 
  witli 
  another 
  gabbroic 
  rock 
  which 
  has 
  a 
  considerable 
  

   percentage 
  of 
  quartz 
  and 
  hypersthene 
  and 
  some 
  microperthite. 
  

  

  7 
  Very 
  dark, 
  long, 
  narrow 
  patches 
  which 
  are 
  probably 
  inclu- 
  

   sions 
  are 
  common. 
  They 
  usually 
  consist 
  mostly 
  of 
  decomposed 
  

   hornblende 
  and 
  basic 
  plagioclase 
  together 
  with 
  some 
  quartz, 
  

   magnetite 
  and 
  biotite. 
  

  

  Undetermined 
  Precambric 
  areas 
  

  

  Unfortunately 
  several 
  large 
  Precambric 
  areas 
  are 
  so 
  deeply 
  

   buried 
  under 
  Pleistocene 
  deposits 
  that 
  the 
  character 
  of 
  the 
  un- 
  

   derlying 
  rocks 
  is 
  entirely 
  unknown. 
  These 
  areas 
  have 
  been 
  so 
  

   indicated 
  upon 
  the 
  geologic 
  map. 
  

  

  PALEOZOIC 
  ROCKS 
  

   The 
  Paleozoic 
  rocks 
  occupy 
  a 
  little 
  over 
  one 
  half 
  the 
  area 
  of 
  

   the 
  quadrangle 
  on 
  the 
  west 
  side. 
  Except 
  at 
  the 
  extreme 
  south 
  

   they 
  always 
  lie 
  to 
  the 
  west 
  of 
  Black 
  river. 
  The 
  maximum 
  thick- 
  

   ness 
  of 
  the 
  Paleozoic 
  formations 
  is 
  approximately 
  1500 
  feet. 
  

  

  Potsdam 
  sandstone 
  

  

  The 
  Potsdam 
  sandstone 
  is 
  of 
  upper 
  Cambric 
  age 
  and 
  is 
  the 
  

   most 
  ancient 
  sedimentary 
  formation 
  bordering 
  the 
  Adirondacks. 
  

   It 
  is 
  not 
  present 
  in 
  outcrop 
  in 
  the 
  Port 
  Leyden 
  quadrangle 
  nor 
  

   in 
  fact 
  along 
  the 
  whole 
  southwestern 
  border 
  of 
  the 
  Adirondacks, 
  

   although 
  it 
  is 
  most 
  likely 
  present 
  beneath 
  the 
  later 
  formations. 
  

   South 
  of 
  Port 
  Leyden 
  the 
  deep 
  wells 
  at 
  Utica 
  and 
  at 
  Rome 
  show 
  

   a 
  basal 
  sandstone 
  which 
  is 
  more 
  than 
  likely 
  the 
  Potsdam. 
  West 
  

   of 
  Port 
  Leyden 
  the 
  Potsdam, 
  according 
  to 
  Orton,^ 
  is 
  most 
  cer- 
  

   tainly 
  present 
  in 
  the 
  deep 
  wells 
  of 
  Oswego 
  county 
  at 
  Central 
  

   Square, 
  Parish, 
  Pulaski 
  and 
  Stillwater. 
  The 
  nearest 
  outcrops 
  

   of 
  the 
  sandstone 
  are 
  something 
  like 
  20 
  miles 
  north-northwest 
  

   of 
  the 
  Port 
  Leyden 
  quadrangle 
  and 
  from 
  there 
  northward 
  to 
  the 
  

   St 
  Lawrence 
  it 
  is 
  a 
  common 
  surface 
  rock. 
  

  

  Pamelia 
  limestone 
  

  

  The 
  Pamelia 
  limestone 
  was 
  named 
  by 
  Professor 
  Cushing 
  from 
  

   a 
  town 
  in 
  Jefferson 
  county 
  where 
  he 
  recently 
  recognized 
  it 
  as 
  

   a 
  distinct 
  formation, 
  ^ 
  Between 
  the 
  Potsdam 
  and 
  the 
  Pamelia, 
  

  

  ^ 
  Petroleum 
  and 
  Natural 
  Gas 
  in 
  New 
  York. 
  N. 
  Y. 
  State 
  Mus. 
  Bui. 
  30. 
  

   1899. 
  

  

  Geol. 
  Soc. 
  Am. 
  Bui. 
  1908. 
  19:155-76. 
  

  

  