﻿350 
  A. 
  W. 
  Giles 
  — 
  Niagara 
  Limestone 
  at 
  Rochester. 
  

  

  along 
  the 
  course 
  of 
  the 
  new 
  Barge 
  canal 
  just 
  south 
  of 
  its 
  

   junction 
  with 
  the 
  Erie 
  canal 
  in 
  Greece 
  northwest 
  of 
  the 
  

   city. 
  They 
  are 
  firm, 
  compact, 
  free 
  from 
  cavities 
  and 
  

   exhibit 
  no 
  brecciation. 
  2 
  

  

  The 
  central 
  portion 
  of 
  the 
  formation, 
  above 
  the 
  basal 
  

   beds 
  just 
  noted, 
  is 
  well 
  displayed 
  in 
  various 
  places 
  in 
  and 
  

   about 
  the 
  city. 
  The 
  Allen 
  creek 
  section 
  east 
  of 
  Rochester 
  

   has 
  long 
  been 
  known, 
  and 
  along 
  the 
  course 
  of 
  the 
  Gen- 
  

   essee 
  river 
  exposures 
  may 
  be 
  seen 
  at 
  the 
  Court 
  street 
  

   bridge 
  on 
  the 
  south 
  side 
  of 
  the 
  city, 
  and 
  again 
  at 
  the 
  

   "rapids" 
  one 
  mile 
  south 
  of 
  the 
  bridge. 
  In 
  the 
  present 
  

   deepening 
  of 
  the 
  river 
  at 
  the 
  i 
  i 
  rapids 
  ' 
  ' 
  to 
  afford 
  a 
  harbor 
  

   extending 
  from 
  the 
  Barge 
  canal 
  at 
  South 
  Park, 
  located 
  

   beyond 
  the 
  southern 
  limit 
  of 
  the 
  city, 
  to 
  Court 
  street 
  

   great 
  quantities 
  of 
  fresh 
  rock 
  have 
  been 
  excavated 
  

   and 
  thrown 
  out 
  onto 
  the 
  river 
  banks 
  on 
  either 
  side. 
  A 
  

   definite 
  and 
  comprehensive 
  conception 
  of 
  the 
  lithologic, 
  

   mineralogic 
  and 
  faunistic 
  characters 
  of 
  a 
  considerable 
  

   vertical 
  section 
  in 
  the 
  central 
  part 
  of 
  the 
  Lockport 
  lime- 
  

   stone 
  may 
  be 
  obtained 
  in 
  a 
  few 
  hours 
  study 
  here. 
  The 
  

   finest 
  section 
  is 
  found 
  along 
  the 
  course 
  of 
  the 
  Barge 
  canal 
  

   from 
  Greece 
  to 
  its 
  junction 
  with 
  the 
  river 
  at 
  South 
  Park. 
  

   This 
  section 
  affords 
  a 
  complete 
  sequence 
  from 
  the 
  basal 
  

   beds 
  nearly 
  to 
  the 
  upper 
  limit 
  of 
  the 
  formation. 
  

  

  This 
  central 
  portion 
  of 
  the 
  limestone 
  is 
  full 
  of 
  cavities 
  

   and 
  exhibits 
  brecciation 
  on 
  a 
  large 
  scale. 
  The 
  number 
  of 
  

   cavities 
  and 
  the 
  degree 
  of 
  brecciation 
  increase 
  upward 
  in 
  

   the 
  formation. 
  

  

  At 
  the 
  top 
  of 
  the 
  formation 
  the 
  beds 
  show 
  a 
  complete 
  

   gradation 
  into 
  the 
  Salina 
  shales 
  above. 
  These 
  upper- 
  

   most 
  layers, 
  but 
  a 
  few 
  feet 
  in 
  total 
  thickness, 
  are 
  nearly 
  

   everywhere 
  thin-bedded, 
  compact, 
  being 
  almost 
  entirely 
  

   free 
  from 
  cavities 
  and 
  exhibit 
  little 
  or 
  no 
  brecciation. 
  

  

  The 
  restriction 
  of 
  the 
  brecciation 
  to 
  the 
  same 
  portion 
  

   of 
  the 
  formation 
  to 
  which 
  the 
  cavities 
  are 
  confined 
  sug- 
  

   gests 
  a 
  relationship 
  between 
  the 
  two. 
  This 
  connection 
  is 
  

   reinforced 
  by 
  the 
  fact 
  that 
  the 
  rock 
  most 
  affected 
  by 
  brec- 
  

   ciation 
  is 
  adjacent 
  to 
  the 
  cavities, 
  commonly 
  being 
  the 
  

   walls 
  of 
  the 
  cavities 
  themselves, 
  and 
  especially 
  the 
  larger 
  

   cavities. 
  Inasmuch 
  as 
  the 
  cavities 
  are 
  irregular 
  in 
  dis- 
  

   tribution 
  through 
  the 
  strata 
  the 
  brecciation 
  shows 
  no 
  defi- 
  

  

  2 
  All 
  or 
  nearly 
  all 
  of 
  the 
  beds 
  which 
  are 
  considered 
  here 
  as 
  basal 
  Lock- 
  

   porl 
  will 
  probably 
  be 
  classified 
  in 
  the 
  future 
  as 
  Gates 
  limestone, 
  a 
  formation 
  

   recently 
  established 
  by 
  Chadwick 
  lying 
  above 
  the 
  Rochester 
  shale 
  and 
  below 
  

   the 
  basal 
  member 
  of 
  the 
  Lockport, 
  the 
  Decew 
  limestone. 
  

  

  