132 
CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY.   L906,   PART    1. 
member  of  which  is  more  or  less  dependent  on  the  others,  but  which 
taken  together  form  such  a  matchless  combination  of  raw  mate- 
rials. The  simple,  regular  topographic  features  of  the  valley  havl 
made  accessible  the  ores  and  stone  at  vwvy  point  where  they  are  ol 
workable  character,  and  enterprising  railroad  companies  have  rap- 
idly  improved  the  opportunities  for  developing  the  region.  The 
only  serious  problem  involved  by  the  valley  topography  is  that  oi 
obtaining  a  water  supply  adequate  for  manufacturing  purposes. 
The  relatively  high  altitude  of  the  valley,  as  before  stated,  haf 
diverted  the  streams  that  rise  within  its  borders  The  supply  from 
large  springs  is  now  nearly  all  utilized  as  soon  as  it  emerges  from 
the  ground,   hut    this   is   not    sufficient    to   meet    the  demands.     The 
a  ha  ha 
Birmingham  city  supply  is  piped  from  the  distant  C 
and  some  of  this  water  is  used  by  manufactories,  although  its  cost 
in  large  quantities  is  necessarily  almost  prohibitive.  Two  courses 
are  open  to  the  manufacturers  first,  that  of  forming  an  association 
and  building  another  large  aqueduct  from  Cahaba  River  and,  sec- 
ond, that  of  sinking  deep  wells  at  the  Several  plants.  The  first  plan 
involves  cooperation  and  its  results  are  assured.  The  second  plan 
can  be  carried  out  by  individual  firms,  hut  it  would  he  an  expensive 
experiment . 
GEOLOGY. 
STB  VTIGR  VPHY. 
The  rocks  underlying  Birmingham  Valley  and  constituting  its  bor- 
der- may  be  grouped  in  the  following  section: 
Section  "/  Paleozoic  rocks  m  Birmingham  Valley. 
System. 
Format  ion. 
M  issive  very  hard  s,m<M  one,  somewhal  pebbly. . . 
Interbedded  shale  and  sandstone 
Carboniferous Bangor  limestone 
•  '<  > x ith >« >r " '  sandstone  and  shale 
I  Fori  Payne  cherl 
mian Chattano*   -  
Silurian Rockwood  (Clinton    shale,  sandstone  and  iron  ore 
ician Chickamauga  ("Trenton"    limestone 
Cambro-Ordovician...  [£™*  magnesian  limestone  and  cherl 
I  Knox  dolomite 
Cambrian Conasauga  shale  and  limestone 
I'hickiK 
ss. 
Feet. 
100 
m 
100-2 
201 
0- 
■in 
50 
;  in 
■J!  II 1 
.  0, 
(1 
21 
180 
."()( 
200 
*<)( 
2,000  '_' 
:<>( 
:,i  ii  i 
r.ni 
a  1 
a  ii 
a  Base  ii"!  expose  I. 
Tlie  base  of  the  Cambrian  system  is  not  exposed  in  this  area,  and 
t he  rocks  above  the  massive  sandstone  may  be  considered  as  belong- 
ing to  the  coal  measures  and  consequently  outside  of  the  iron-on 
district. 
