van  hise.]  EASTERN    UNITED    STATES.  425 
ness,  as  shown  by  the  fact  that  mining  shafts  and  streams  frequently 
cut  through  it  to  the  gneiss.  The  dip  of  the  slate  is  almost  always  con 
stant  to  the  southeast.  It  is  the  predominant  position  in  the  country 
for  the  metalliferous  veins.  The  itacolumite  is  described  in  detail. 
The  conglomerate- like  itacolumites,  mentioned  by  Tuomey,  are  regarded 
as  real  conglomerates,  with  a  micaceous  and  arenaceous  cement.  The 
pebbles  are  obscured  and  elongated,  the  longest  diameters  being  par- 
allel to  the  bedding,  and  they  also  partake  of  the  schistose  structure  of 
the  matrix  in  which  they  are  contained.  Every  stage  in  the  passage 
from  the  fine  grained  rock  to  the  conglomerate  with  pebbles  is  seen, 
and  there  is  no  question  that  the  itacolumite  is  a  sandstone.  The 
eruptive  rocks  include  granites,  eurite,  and  trappean  rocks,  among 
which  are  schistose  aphanite,  aphanitic  porphyry,  minette,  diorite, 
diorite-slate,  and  saponite.  That  the  schistose  rocks  here  included  are 
really  eruptive  is  shown  by  the  manner  in  which  they  intrude  the 
granitic  rocks. 
Lieber,204  in  1859,  gives  a  general  account  of  the  rocks  of  South 
Carolina.  The  peculiar  structure  of  the  schistose  aphanites  is  regarded 
as  due  to  weathering.  In  the  Greenville  and  Pickens  districts  the  suc- 
cession includes  gneisses,  limestones,  and  mica-schists,  the  ruling  dips 
being  southeasterly.  Tourney's  representation  of  these  rocks  as  60  to 
70  miles  thick  is  believed  on  theoretical  grounds  to  be  incorrect.  The 
ruling  southeasterly  dip  of  the  slates  are  probably  due  to  faults  which 
have  repeated  the  stratified  rocks  many  times.  It  is  concluded  that  the 
isolated  bodies  of  stratified  rocks  overlying  the  gneiss  are  actually 
islands  occupying,  with  much  regularity,  the  apical  lines  of  certain  par- 
allel ridges.  It  can  not  be  asserted  that  any  of  the  mica-slate  beds  ex- 
ceed 100  feet  in  thickness  and  the  horizontal  slates  25.  The  talcose 
slate  below  the  itacolumite  is  frequently  highly  graphitic.  Above  the 
talcose  slate  is  limestone,  and  above  this  the  itacolumite,  the  outlines 
of  the  latter  being  extremely  tortuous.  The  dike  rocks  are  aphanite, 
porphyritic  hornblende  rock,  eurite,  and  garnet.  A  detailed  account 
of  itacolumite  is  given. 
Libber,205  in  1859,  definitely  states  that  itacolumite  is  regarded  as 
occupying  a  constant  position,  and  is  taken  as  a  starting  point  upon 
which  to  determine  the  chronology  of  the  Azoic  rocks  of  the  southern 
Alleghanies. 
LITERATURE   OF   GEORGIA. 
Peck,206  in  1833,  divides  the  mountain-region  rocks  into  Primitive 
and  Transition,  the  first  being  on  the  west,  and  the  boundary  between 
the  two  being  the  Smoky  mountains. 
(Dotting-,  20t  in  1830,  divides  the  primary  formation  into  granite, 
syenite,  porphyritic  granite,  gneiss,  mica-slate,  talcose  slate,  granular 
limestone  or  marble,  serpentine,  greenstone,  epidotic  gneiss,  quartz 
rock,  hornblende,  and  clay-slates.     The  granite  passes  by  imperceptible 
