VAN   HISK. 
EASTERN    UNITED    STATES.  423 
The  Ocoee  or  basal  division  of  the  Potsdam  is  semimetamorphic, 
Eozoic,  mountain-making,  and  has  a  thickness  of  10,000  feet.  Equiv- 
alent with  this  are  the  slates  and  conglomerates  of  Monroe  county,  the 
Little  Tennessee  river,  the  west  fork  of  Little  Pigeon,  of  Sevier  county,  of 
the  French  Broad  in  Cocke  county,  of  Big  Butt,  and  of  Laurel  gap  of 
Iron  mountain.  The  metamorphic  rocks  occur  in  stratified  beds,  are 
mostly  of  the  variety  called  gneiss  or  stratified  granite,  and  all  are  met- 
amorphic. The  line  of  separation  between  the  metamorphic  rocks  and 
those  to  the  west  is  sometimes  well  defined,  but  often  poorly,  the  rocks 
gradually  losing  their  crystalline  characters  and  running  insensibly 
into  the  adjacent  conglomerates  and  slates.  The  general  line  of  sepa- 
ration conforms  to  the  Appalachian  ridges.  The  metamorphic  beds  and 
the  other  groups  all  appear  to  follow  the  same  law  of  dip  and  strike. 
The  dip  is  in  the  main  at  a  high  angle  to  the  southeast.  The  author 
has  not  been  able  to  satisfy  himself  as  to  want  of  conformableness  in 
thQ  beds,  although  in  Johnson  county  the  metamorphic  gneiss  comes  ab- 
ruptly against  the  limestone  j  and  other  similar  cases  occur,  but  these 
unconformable  junctions  are  naturally  referable  to  local  fractures  and 
displacements,  and  this  unconformableness  is  local  and  not  the  rule. 
There  is  no  reason  for  believing  that  the  metamorphosed  beds  include 
formations  of  any  more  recent  date  than  the  Ocoee  conglomerates  and 
slates,  and  a  portion  of  them  are  certainly  referable  to  this  group.  The 
remainder,  although  conformable,  may  be  and  most  likely  are  older. 
The  transitions  froin  the  slates  and  conglomerates  to  the  gneiss  and 
mica-schists  are  well  seen  at  Ducktown  and  at  the  Ocoee.  There  is  no 
sufficient  reason  for  referring  any  of  these  rocks  to  the  Huronian  or 
Laurentian. 
Bradley,198  in  1875,  describes  sections  in  east  Tennessee  from  Athens 
to  Murphy,  and  from  Knoxville  to  Murphy.  The  rocks  include  semi- 
metamorphosed  slates,  like  those  of  Ocoee,  quartzites,  crystalline  lime- 
stones, and  gneisses,  all  being  regarded  as  probably  of  Silurian  age, 
with  the  possible  exception  of  the  massive  granite  at  Marietta,  Oobb 
county,  Georgia.  The  Silurian  rocks  thus  include  the  Taconic  and 
pyroclastic  rocks  of  Emmons. 
Elliott,199  in  1883,  states  that  the  mica-schist  and  gneiss  at  Jasper 
dips  beneath  the  marble  and  is  therefore  metamorphosed  Knox  sand- 
stone. The  porphyritic  gneiss  of  the  West  Atlantic  railway  is  identi- 
cal with  that  at  Talking  rock,  and  is  a  metamorphosed  form  of  the 
Ocoee  sandstone. 
LITERATURE    <>F    SOUTH    CAROLINA. 
Euffin,200  in  1843,  describes  as  primitive  the  limestones  which  enter 
South  Carolina  at  York,  west  of  Kings  mountain,  and  run  to  Spartan- 
burg. Embracing  nearly  all  the  country  above  the  lower  falls  of  the 
river  is  a  granitic  region. 
Tuomey,201  in  1818,  gives  a  report  on  the  geology  of  South  Carolina. 
