688  PRE-CAMBRIAN    GEOLOGY    OF    NORTH   AMERICA. 
from  the  contact  of  the  underlying  intensely  heated  granite.  These 
formations  have  no  invariable  order  of  superposition,  although  they 
generally  overlie  one  another  in  the  following  manner:  Clay  slate, 
talcose  slate,  mica  slate,  hornblende  slate,  gneiss;  and  associated  with 
these  are  also  beds  of  limestone,  quartz,  chlorite,  slate,  and  soapstone. 
A  very  massive  gneiss,  known  as  "  table  rock,"  on  the  west  side  of 
Saluda,  rests  unconformably  upon  the  slates,  and  is  regarded  as  evi- 
dence of  the  prior  deposition  of  the  slates,  and  also  as  evidence  of  a 
time  break  between  the  two.  The  mica  slates  pass  by  insensible  gra- 
dations into  the  talcose  slates.  The  lime  rock  is  interlaminated  both 
with  gneiss  and  with  mica  slates,  the  latter  occurring  at  Kings  Moun- 
tain. The  quartz  rocks  are  regarded  as  residual  material  left  by  the 
disappearance  of  the  micaceous  and  talcose  portion  of  the  rock.  It 
sometimes  passes  into  a  conglomerate-like  phase,  but  this  is  a  step  on 
the  way  toward  complete  crystallization.  The  quartz  rock  at  times 
passes  into  itacolumite.  The  magnetic  and  hematitic  ores  are  asso- 
ciated mostly  with  the  slates  and  limestones,  and  appear  as  beds  inter- 
laminated with  and  grading  into  them. 
LiEiiER,88  iii  L858,  describes  the  rocks  of  the  Chester  and  York  dis- 
tricts. They  are  divided  into  clay  slate,  which  includes  limestone, 
itacolumite,  and  specular  schist;  and  hornblende  slate,  which  includes 
talcose  slate  and  mica  slate.  The  first  class,  which  may  possibly  be 
Paleozoic,  appears  wherever  the  Tertiary  deposits  have  been  removed 
by  erosion.  It  has  a  dip  unconformable  to  the  talcose  slate.  Itacolu- 
mite is  described,  and  below  it  at  times  is  found  specular  schist  and 
above  it  limestone.  The  igneous  rocks  are  divided  into  trachytic, 
trappean,  and  granitic  rocks.  The  trachytic  rocks  include  eurite, 
quartz  porphyry,  coarse  trachyte,  domite,  and  phonolith ;  the  trap- 
pean rocks  include  diorite,  diorite  slate,  soapstone  (?),  talcose 
trap  (?),  melaphyre,  and  aphanitic  porphyry;  the  granites  include 
coarse-grained  granite,  syenite,  and  other  granite  and  gneiss. 
Lieber,89  in  1858,  divides  the  rocks  of  Union  and  Spartanburg  into 
Super-itacolumite,  Itacolumite,  and  Sub-itacolumite  groups.  The 
first  includes  limestone.  The  second  includes  itacolumite  with  talcose 
slate,  limestone,  specular  schists,  and  itacolumite  conglomerate.  The 
third  includes  clay  slate,  talcose  slate,  mica  slate,  and  gneiss.  There 
is  no  definite  proof  that  the  gneiss  occupying  the  lowest  position  is  of 
sedimentary  origin.  Indeed,  there  is  greater  probability  that  it  is, 
strictly  speaking,  a  granite  having  a  parallel  distribution  of  the  scales 
of  mica.  It  passes  into  the  ordinary  granite,  with  no  distinct  bound- 
ar}T  between  the  two.  The  mica  slate  overlying  the  gneiss  is  of  in- 
significant thickness,  as  shown  by  the  fact  that  mining  shafts  and 
streams  frequently  cut  through  it  to  the  gneiss.  The  dip  of  the  slate  is 
almost  ahvays  constant  to  the  southwest.  It  is  the  predominant  posi- 
tion in  the  country  for  the  metalliferous  veins.     The  itacolumite  is 
