366  roNTIUBUTIONS    TO    ECONOMIC    GEOLOGY,  1906,  PART    I. 
its  superior  durability,  it  has  expressed  itself  strongly  on  the  topog- 
raphy, forming  vertical  cliffs  and  capping  many  limestone  and  shale 
hills.  Its  observed  thickness  ranges  from  a  few  feet  to  more  than 
100  feet,  although  40  to  60  feet  are  the  usual  limits.  In  consequence 
of  its  position  above  ground-water  level  it  is  at  most  places  well 
situated  for  quarrying  and  is  also  well  situated  as  regards  transpor- 
tation facilities,  since  no  less  than  16  railroad  lines  cross  its  area  of 
outcrop  in  Indiana. 
A  Pennsylvanian  sandstone  of  later  age  than  the  Mansfield  is 
worked  extensively  for  glass  sand  at  Coxville,  Parke  County.  The 
geologists  of  the  Indiana  survey  regard  this  rock  as  the  filling  of  a  val- 
ley or  channel  carved  in  the  "  Upper  Coal  Measures."  It  appears  to 
be  younger  than  coal  "VI"  and  older  than  coal  "VII,"  and  may 
correspond  to  the  Merom  sandstone  of  Sullivan  County.  Other  evi- 
dences of  filled  channels  have  been  observed  in  Parke  and  Fountain 
counties,  and  in  Vermilion  County,  111.,  and  these  channels  have  been 
tentatively  referred  to  the  drainage  system  of  the  "  Coxville  Car- 
boniferous River."  a 
Tertiary  (?) . — Deposits  of  sand,  gravel,  and,  in  places,  conglomerat 
occur  on  the  high  points  of  the  upland  bordering  I  he  Ohio  River  flood 
plain  in  Indiana  and  Kentucky.  G.  II.  Ashley6  mentions  their  oc(  ur- 
rence  in  Spencer,  Perry,  Harrison,  Washington,  Floyd,  and  Clark 
counties,  Ind.,  and  the  writer  has  observed  deposits  of  a  similar 
nature  in  Hardin  County,  Ky.  As  these  fragmentary  deposits  are 
associated  with  an  old  peneplain  and  are  evidently  younger  than 
( larboniferous  and  older  t  ban  Quaternary,  t  hey  are  regarded  by  Ashley 
as  of  Tertiary  age.  These  beds,  known  as  the  Ohio  River  formation, 
consisl  of  white,  yellow,  red,  and  brown  sand  and  soft  sandstone, 
which  farther  south  attain  a  thickness  in  places  of  more  than  50  feet. 
The  grain  of  the  material  grows  coarser  from  south  to  north,  and  the 
thickness  of  the  deposits  decreases  notably  toward  the  north.  Beds 
of  various-colored  clays  are  found  at  or  near  the  bottom  of  the  deposits. 
Sands  of  the  ( )hio  River  format  ion  have  been  dug  for  glass  material  at 
De  Panw  and  New  Albany,  Ind.,  and  are  now  being  exploited  at  Tip 
Top,  Ky. 
Maps  and  publications. — The  United  States  Geological  Survey  has 
not  yet  issued  topographic  or  geologic  maps  of  these  areas,  but  the 
Indiana  Geological  Survey  has  thoroughly  covered  the  ground  in  that 
State,  and  much  information  may  be  obtained  concerning  the  sand- 
stones from  the  twentieth,  twenty-first,  twenty-third,  and  twenty- 
eighth  annual  reports  of  the  Indiana  survey,  the  latter  containing  a 
State  geological  map. 
a  Ashley,  G.  H.,  The  coal  deposits  of  Indiana:  Twenty-third  Ann.  Ropt.  Dept.  Geology  and  Natural 
Resources  Indiana,  Indianapolis,  1898,  pp.  80,  300,  345,  378,  385,  386,  and  406. 
b  Ashley,  G.  H.,  and  Kindle,  E.  M.,  The  geology  of  the  Lower  Carboniferous  area  of  southern  Indiana: 
Twenty-seventh  Ann.  Rept.  Dept.  Geology  and  Natural  Resources  Indiana,  Indianapolis,  1903,  pp. 
68-70. 
