GRATON.] 
THE    CAROLINA   TIN    BELT. 
189 
The  position  of  this  belt  is  very  largely  dependent  upon  the  dis- 
tribution and  structure  of  the  formations.  It  has  long  been  recog- 
nized that  many  of  the  rocks  are  ancient  and  highly  metamorphosed 
sediments,  and  as  early  a-s  1856  Doctor  Lieber,  State  geologist  of 
South  Carolina,  had  worked  out  much  of  the  structure  of  the  area 
in  which  the  tin  belt  lies.  The  present  idea  of  the  geology  of  the 
region  may  be  summarized  as  follows: 
Sedimentary  rocks — shales,  limestones,  and  sandstones — have  been 
intensely  metamorphosed  and  contorted.  Their  age  has  not  been 
definitely    determined,    but    it    is    doubtless    great.     The    resulting: 
Fig.  12. — Sketch  map  showing  location  of  Carolina  tin  belt. 
products  now  appear  as  schists  or  slates,  partly  marmorized  lime- 
stones, and  impure  quartzites,  and  have  been  bent  up  into  a  sharp 
anticlinal  fold.  The  axis  of  this  fold  conforms  with  the  general 
direction  of  the  greater  uplifts  to  the  west,  and  hence  the  rocks 
strike  northeastward.  A  noticeable  turn  or  bend  in  the  axis  of  the 
fold  takes  place  near  the  boundary  between  North  Carolina  and 
South  Carolina,  and  corresponds  to  the  similar  bend  in  the  main 
Appalachians. 
The  anticlinal  fold  is  shown  particularly  well  near  Blacksburg, 
