bassler.]         CEMENT    MATERIALS    OF    VALLEY    OF    VIRGINIA.  543 
the  belt  of  argillaceous  limestone  brought  up  on  the  western  flank 
of  the  Massanutten  Mountain  syncline.  The  same  rocks  reappear 
on  the  eastern  flank,  3  to  4  miles  distant.  The  intervening  country 
is  occupied  by  Martinsburg  shales,  all  of  the  younger  rocks  found  on 
Massanutten  Mountain  having  been  removed  by  erosion.  The  favor- 
able composition  of  the  rock  and  the  proximity  of  these  two  belts  to 
railroads — the  western  to  the  Baltimore  and  Ohio  and  the  eastern  to 
the  Shenandoah  Valley — cause  them  to  be  worthy  of  attention.  The 
following  analysis  of  specimens  from  the  eastern  belt  in  the  vicinity 
of  Weyers  Cave  shows  more  magnesia  than  the  average : 
Analysis  of  Trenton  limestone,  near  Weyers  Cave,  Va. 
Silica  (Si02) 14.  G2 
Alumina  (ALA)  and  iron  oxide  (Fe£Oa) G.  90 
Lime  carbonate  (CaC03) 07.92 
Magnesium  carbonate  (MgC03) 4.09 
Water  fH20) 3.94 
Staunton. — East  and  northeast  of  this  place  the  Trenton  limestones 
are  well  developed,  and,  together  with  the  shales  and  pure  limestones 
near  by,  offer  abundant  raw  material  for  the  manufacture  of  cement. 
The  railroad  facilities  at  Staunton  are  exceptionally  good,  for  here 
a  plant  could  obtain  coal  and  ship  its  products  over  several  lines. 
Ordinarily  coal  could  be  had  on  the  most  favorable  terms  over  the 
Chesapeake  and  Ohio,  but  in  times  of  labor  disturbances  in  the  New 
River  field  the  fuel  supply  could  still  be  obtained  from  the  Fairmont 
region.  The  Trenton  limestones  in  the  vicinity  of  Staunton,  as  a  rule, 
run  unusually  high  in  lime,  so  that  shales  or  clays  for  mixture  with 
them  will  be  necessary.  Unlimited  quantities  of  shales  may  be  found 
in  connection  with  the  limestone,  but  deposits  of  good  clays  are  not 
so  common.  In  this  region  the  lower  part  of  the  shales  are  unusually 
calcareous,  as  the  following  analyses  show,  but  higher  up  in  the  series 
the  percentage  of  lime  is  very  small : 
Analyses  of  Martinsburg  shales  and  Trenton  limestone,  vicinity  of  Staunton,  Va. 
[Charles  Catlett.  analyst.  1 
Silica  (Si02) 
Oxides  (A1,Oh,  Fe2Os) 
Lime  (CaO)  . . 
Magnesia  (MgO) 
Carbon  dioxide  (C02) 
1. 
2. 
3. 
4. 
19.28 
19.92 
23.08 
10.28 
9.86 
10. 70 
10.  08 
4.36 
36.42 
37.05 
35. 89 
45. 79 
1.08 
1.72 
.94 
.79 
31.70 
32. 80 
1—3.  Calcareous  shales  showing  variation  in  composition. 
4.  Trenton  limestone. 
