260  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   1903.  [bull. 225. 
has  an  elevation  of  about  980  feet  above  tide,  while  the  highest  points 
in  the  area  reach  an  elevation  of  3,400  feet.  The  mountains  rise  1,000 
to  2,000  feet  above  adjacent  drainage.  The  lower  valleys  have  com- 
monly broad  bottoms  with  abruptly  rising  side  slopes;  the  higher 
valleys  are  narrow  and  V-shaped.  At  Middlesboro  there  is  a  broad  flat. 
Structure. — This  basin  is  structurally  a  flat-bottomed  syncline  or 
trough  with  sharply  flexed  sides.  The  axis  of  the  syncline  lies  near 
but  a  little  southeast  of  Cumberland  River,  running  between  Poor  and 
Clover  forks  on  the  east  and  between  Stony  Fork  of  Yellow  Creek 
and  Clear  Creek  west  of  Middlesboro.  From  this  axis  there  is  a 
gradual,  though  not  always  uniform,  rise  in  either  direction,  averag- 
ing possibly  100  feet  to  the  mile,  to  Pine  and  Cumberland  mountains, 
where  the  rocks  are  flexed  sharply-  upward  at  angles  varying  up  to 
perpendicular,  though  usuallj7  less  than  70°.  A  notable  transverse 
fault  belt  crosses  the  area  from  north  to  south  in  the  neighborhood  of 
Middlesboro.  In  this  belt  were  noted  several  minor  faults  in  the  gap 
at  Pineville  and  in  the  territory  adjacent  on  the  east;  a  fault  with 
downthrow  to  the  west  of  over  1,200  feet  along  the  west  face  of  Rocky 
Face  Mountain;  a  fault  with  apparent^  considerable  horizontal  move- 
ment at  Cumberland  Gap;  while  all  the  small  hills  in  or  immediately 
around  the  plain  at  Middlesboro  give  evidence  of  highly  confused 
structure,  as  though  the  shales,  which  make  up  a  large  part  of  the 
exposed  strata  at  that  point,  had  given  way  with  folding  and  probably 
faulting  under  the  stresses  which  produced  the  faults  just  mentioned. 
Other  faults  were  noted  at  Shillaly  Creek,  on  Ewings  Creek,  and  else- 
where. The  upturning  of  the  rocks  in  Pine  Mountain  is  in  connection 
with  the  great  Pine  Mountain  fault,  previously  mentioned.  The 
structure  in  Cumberland  Mountain  is  monoclinal,  being  part  of  the 
western  limb  of  the  Powell  River  anticline.  Along  some  of  the  dis- 
tance this  monocline  is  distinguished  by  the  strata  being  sharply 
bent  at  the  bottom  from  an  almost  horizontal  to  an  almost  vertical 
position,  then  at  the  top  being  bent  again  into  a  nearly  horizontal  posi- 
tion, probably  with  considerable  fracturing  at  the  upper  bend. 
STRATIGRAPHY  AND  COALS. 
The  outcropping  rocks  of  this  basin  consist  of  sandstones  and  shales 
with  coal  beds.  So  far  as  found,  the  fossils  show  that  all  of  the  coal- 
bearing  rocks  belong  to  the  Potts ville  group  of  the  Pennsylvanian 
series.  The  lower  part  of  the  section  is  predominantly  sandy  and 
often  conglomeratic.  The  name  Lee  conglomerate  has  already  been 
applied  to  that  part  of  the  section  in  adjacent  areas.  It  should  be 
noted,  however,  that  when  first  applied  it  was  with  the  impression 
that  these  basal  sandstones  represent  all  of  the  Pottsville  of  Pennsyl- 
vania, so  that,  while  the  name  here  is  applied  to  what  is  believed  to 
be  the  same  series  of  rocks,  a  recent  study  of  its  fossil  plants  shows 
