boutwell.]  PARK    CITY    MINING    DISTRICT,   UTAH.  145 
axis,  which  pitches  northerly.  The  economic  significance  of  this  fact 
is  that  the  two  limestone  formations  which,  in  certain  portions  of  this 
camp  include  valuable  ore  bodies,  are  thus  preserved  for  some  distance 
from  burial  beneath  igneous  intrusives  to  the  north,  and  are  brought 
into  accessible  positions  immediately  north  and  northeast  of  the  city. 
This  arch  appears  to  have  been  faulted  along  a  general  NNE.  zone  of 
fracture  at  the  east  side  of  Deer  Valley  Meadow,  with  the  net  result 
that  the  eastern  side  has  moved  relatively  a  considerable  distance  to 
the  south.  To  the  south  and  within  this  general  zone  of  deformation 
several  hundred  feet  of  sediments  have  been  overridden  and  buried  by 
strong  overthrust  faulting.  McHenry  Canyon,  the  scene  of  some  of 
the  earliest  mining  of  this  region,  follows  for  a  considerable  portion 
of  its  extent  a  great  fault  along  which  the  displacement  was  not  less 
than  2  miles. 
The  principal  mineralized  fissure  zone,  passing  in  a  northeast- 
southwest  direction  through  the  center  of  the  district,  has  been  the  seat 
of  much  faulting.  On  one  of  the  fissures  in  this  zone  the  northern  side 
has  dropped  several  hundred  feet,  and  on  another  the  south  side  has 
dropped  considerably. 
Pronounced  faulting  of  direct  importance  to  mining  has  occurred 
in  the  western  portion  of  the  district.  In  Empire  Canyon  a  fault 
truncates  the  "  Permo-Carbonif erous "  limestones  and  throws  their 
northern  continuation  westward  for  approximately  a  mile.  A  few 
hundred  feet  to  the  north  of  this  fault  in  Empire  Canyon  a  northwest- 
southeast  fault  displaces  the  contact  between  the  upper  Carboniferous 
limestones  and  the  Ontario  quartzite,  so  that  the  north  side  is  offset 
westward  for  several  hundred  feet. 
Evidence,  mainly  of  paleontological  character,  tends  to  show  that 
the  strata  which  form  the  ridges  inclosing  Thaynes  Canyon  and  White 
Pine  Canyon  all  belong  to  the  uPermo-Carboniferous,"and  that  these 
ridges  are  duplications  due  to  faulting  along  northeast-southwest 
planes.  Other  significant  instances  similar  to  those  above  described 
have  been  worked  out,  and  many  cases  of  folding  and  faulting  have 
!  been  observed. 
In  general  there  was  Assuring  in  a  northeast-southwest  direction 
before  the  deposition  of  ore,  and  in  northeast-southwest  and  north- 
west-southeast directions  subsequent  to  both  igneous  intrusion  and 
ore  deposition. 
Glacial  feature*. — Evidences  of  local  glaciation  abound  in  the  upper 
portions  of  the  canyons  which  head  on  the  higher  divides  and  peaks. 
Although  the  exact  succession  of  events  during  the  period  of  ice 
invasion  in  this  region  can  not  be  stated  here,  the  occurrence  of  typical 
features  may  be  cited.  These  include  characteristically  polished  and 
striated  bed-rock  surfaces,  rounded  profiles  of  canyons,  irregular 
kame-like  deposits  of  mixed  debris,  erratics  perched  high  on  the  sides 
Bull.  225—04 10 
