3ampbell.]  THE    DEER    CREEK    COAL    FIELD,    ARIZONA.  245 
7011.  These  fossils  have  been  examined  by  Dr.  G.  H.  Girty,  who 
pronounces  them  to  be  of  Pennsylvania!!  age. 
Cretaceous  sandstone  and  shale. — Resting  on  the  Pennsylvanian  lime- 
stone at  every  point  at  which  it  is  exposed  in  this  field  is  a  series  of 
greenish-gray  sandstone  and  shale  beds  which  contain  the  coal  that 
gives  this  basin  its  economic  importance.  At  most  points  these  beds 
appear  to  rest  conformably  upon  the  Paleozoic  limestone,  but  in  the 
Middle  field  there  is  a  visible  unconformity  between  the  limestone  and 
the  overlying  sandstone  and  shale. 
Different  opinions  have  been  held  regarding  the  age  of  the  coal- 
bearing  beds.  Devereux,a  who  reported  the  field  m  1881,  noted  the 
occurrence  of  fossil  leaves  with  the  coal,  and  on  the  strength  of  their 
resemblance  to  forms  with  which  he  was  familiar  he  doubtfully  referred 
the  beds  to  the  Tertiary  system. 
On  the  basis  of  their  apparent  conformity  to  the  limestone  below, 
Blake h  regarded  them  as  Carboniferous,  but  probably  this  conclusion 
was  based  upon  report  and  was  not  the  result  of  an  examination  in  the 
field. 
During  the  examination  made  by  Walcottc  in  1885  some  fossil  plants 
were  collected  from  the  shale  associated  with  the  coal  beds  of  the 
Upper  field.  These  were  submitted  to  Prof.  L.  F.  Ward,  who  was 
able  to  determine  the  presence  of  the  genera  Sequoia,  Sabal,  Phr<i</- 
niites,  Myrica,  and  Viburnum.  Owing  to  the  fragmentary  nature  of 
the  material  no  specific  determinations  were  made,  but  the  formation 
was  doubtfully  referred  to  the  Cretaceous.  During  the  present 
examination  similar  material  was  collected  from  the  sandstone  over- 
lving  the  coal  in  the  Lower  field  and  also  along  the  contact  between 
the  sandstone  and  the  underlying  Carboniferous  limestone  southwest 
of  Saddle  Mountain.  This  material  is  so  poorly  preserved  that  no 
specific  determinations  could  be  made,  but,  according  to  Dr.  F.  H. 
Knowlton,  one  fragment  suggested  Sequoia  reiclienbachi.  The  other 
forms  are  too  indefinite  for  classification,  but  they  may  belong  to  Pla- 
tanus,  Cinnamomum  affine,  or  Asimina  eocenica.  The  material  is  so 
indistinctly  preserved  that  Doctor  Knowlton  would  not  venture  an 
opinion  as  to  its  age,  but  the  forms  given  are  those  which  generally 
are  characteristic  of  the  upper  Cretaceous.  In  the  Middle  field  frag- 
ments of  invertebrates  are  abundant  in  a  conglomerate  bed  which  is 
in  contact  with  the  Carboniferous  limestone.  Some  were  collected 
and  submitted  to  Dr.  T.  W.  Stanton,  who  states  that  they  are  imper- 
fect specimens  of  Ostrea  and  Exogyra.     He  states  "the  latter  genus 
aDevereux,  W.  B.,  The  Deer  Creek  coal  fields,  Arizona:  Eng.  and  Min.  Jour.,  vol.  32, 1881,  pp.  404-405. 
b Blake,  W.  P.,  Reports  on  Mines  and  Mining:  Reports  of  the  governor  of  Arizona  to  the  Secretary 
of  the  Interior  for  1896,  p.  42;  1898,  p.  67;  and  1901,  p.  108. 
cWalcott,  C  D.,  and  Bannon,  M.,  Deer  Creek  Coal  Field,  White  Mountain  Indian  Reservation, 
Arizona:  Senate  Ex.  Doc,  No.  20,  48th  Cong.,  2  sess.,  p.  7. 
