PIEDMONT  PLATEAU  AND  PORTIONS  OF  THE  APPALACHIANS.      689 
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  parallel  to  the  bedding,  and  they  also  par- 
take of  the  schistose  structure  of  the  matrix  in  which  they  are  con- 
tained. Every  stage  in  the  passage  from  the  fine-grained  rock  to  the 
conglomerate  with  pebbles  is  seen,  and  there  is  no  question  that  the 
itaeolumite  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,90  in  1859,  gives  a  general  account  of  the  rocks  of  South 
Carolina.  The  peculiar  structure  of  the  schisfbse  aphanites  is  re- 
garded as  due  to  weathering.  In  the  Greenville  and  Pickens  districts 
the  succession  includes  gneisses,  limestones,  and  mica  schists,  the 
ruling  dips  being  southeasterly.  Tuomey 's  representation  of  these 
rocks  as  GO  to  70  miles  thick  is  believed  on  theoretical  grounds  to  be 
incorrect.  The  ruling  southeasterly  dip  of  the  slates  is  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  parallel  ridges.  It  can  not  be  asserted  that  any  of 
the  mica  slate  beds  exceed  100  feet  in  thickness  and  the  horizontal 
slates  25  feet.  The  talcose  slate  below  the  itaeolumite  is  frequently 
highly  graphitic.  Above  the  talcose  slate  is  limestone,  and  above 
this  the  itaeolumite,  the  outlines  of  the  latter  being  extremely  tor- 
tuous. The  dike  rocks  are  aphanite,  porphyritic  hornblende  rock, 
eurite,  and  garnet.     A  detailed  account  of  itaeolumite  is  given. 
Lieber,91  in  1859,  definitely  states  that  itaeolumite  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 
Allegh  anies. 
See  also  North  Carolina,  section  5  of  this  chapter. 
SECTION  8.     GEORGIA. 
SUMMARY  OF  LITERATURE. 
Peck,92  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. 
Cotting,93  in  IS:}*'),  divides  the  Primary  formation  into  granite, 
syenite,  porphyritic  granite,  gneiss,  mica  slate,  talcose  slate,  granular 
limestone  or  marble,  serpentine,  greenstone,  epidotic  gneiss,  quartz 
55721— Bull,  ".GO— 00 44 
