HAYES.] 
INTRODUCTION. 
V6 
exhaustive  treatises  on  economic  or  other  geologic  subjects.    Volumes 
of  this  series  are  sold  at  cost  of  publication. 
5.  Geologic  folios  of  the  United  States  Geological  Surrey. — Under 
the  plan  adopted  for  the  preparation  of  a  geologic  map  of  the  United 
States  the  entire  area  is  divided  into  small  quadrangles,  bounded  by 
certain  meridians  and  parallels,  and  these  quadrangles,  which  number 
several  thousand,  are  separately  surveyed  and  mapped.  The  unit  of 
survey  is  also  the  unit  of  publication,  and  the  maps  and  descriptions 
of  each  quadrangle  are  issued  in  the  form  of  a  folio.  When  all  the 
folios  are  completed  they  will  constitute  a  Geologic  Atlas  of  the  United 
States. 
A  folio  is  designated  by  the  name  of  the  principal  town  or  of  a 
prominent  natural  feature  within  the  quadrangle.  It  contains  top- 
ographic, geologic,  economic,  and  structural  maps  of  the  quadran- 
gle, and  occasionally  other  illustrations,  together  with  a  general 
description. 
Under  the  law,  copies  of  each  folio  are  sent  to  certain  public  libra- 
ries and  educational  institutions.  The  remainder  are  sold  at  25  cents 
each,  except  such  as  contain  an  unusual  amount  of  matter,  which  are 
priced  accordingly. 
Circulars  containing  lists  of  these  folios,  showing  the  locations  of 
the  quadrangular  areas  they  describe,  their  prices,  etc.,  are  issued 
from  time  to  time,  and  may  be  obtained  on  application  to  the 
Director  of  the  United  States  Geological  Survey.  The  following  list 
shows  the  folios  issued  to  date,  with  the  economic  products  discussed 
in  the  text  of  each,  the  products  of  greatest  importance  being  printed 
in  italics. 
List  of  geologic  folios,  showing  mineral  resources  described. 
No. 
Name  of  folio. 
State. 
Area 
in 
sq.  m. 
Author. 
Mineral  products  described 
as  occurring   in   area  of 
folio. 
1 
Mont 
3, 354 
980 
932 
969 
932 
975 
932 
975 
465 
925 
938 
Iddings,  J.  P.;  Weed, 
W.H. 
Hayes,  C.W 
Liudgren,    W.;    Tur- 
ner, H.W. 
Hayes,  C.W 
Gold,    copper,   clays,   lime, 
? 
Ringgold 
Ga.-Tenn 
Cal 
stone,  coal. 
Coal,  iron,  manganese,  lime, 
3 
clays,  stone,  road  metal. 
Gold,    copper,    quicksilver, 
chromite,  stone. 
Coal,  iron,  lime,  stone,  road 
4 
Kingston 
Tenn 
<s 
Sacramento 
Chattanooga 
Pikes  Peak-Cripple 
Creek. 
Cal 
Tenn 
metal,  clay. 
Gold,  copper,  chromite,  iron, 
coal,  stone,  lime,  clay. 
6 
Hayes,  C.W 
7 
Colo 
metal,  clay. 
Gold. 
8 
Tenn 
Hayes,  C.W 
Eldridge.G.H 
Keith,  A 
q 
Anthracite-Crested 
Butte. 
Harpers  Ferry 
Colo 
metal,  clay. 
Coal,  silver,  stone,  lime,  clay. 
Iron,  ocher,    copper,  stone, 
road  metal,  lime,  cement. 
Gold,  copper,  chromite,  iron, 
manganese,    ocher,    coal, 
stone,  lime,  clay. 
10 
Va.-W.  Va.- 
Md. 
Cal 
11 
Turner,  H.  VV 
