540  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1904.         L bull.  260. 
commercial  scale.  The  argillaceous  limestones,  in  most  instances, 
have  a  composition  very  similar  to  good  cement  materials  of  other 
regions,  but  this  does  not  necessarily  indicate  that  they  also  will  make 
first-class  cement. 
Woodstock  and  vicinity. — About  350  feet  of  argillaceous  Trenton 
limestones  are  exposed  just  east  of  Woodstock,  the  town  itself  being 
situated  upon  the  cherty  limestones  of  Beekmantown  age.  These 
limestones  and  the  overlying  shales  dip  at  an  angle  of  about  45°  to 
the  southeast,  and  are  the  outcrops  of  the  western  edge  of  the  great 
syncline  forming  Massanutten  Mountain.  Practically  the  same  thick- 
ness of  cement  rock  is  exposed  to  the  northeast  and  the  southwest  of 
Woodstock.  As  this  line  of  outcrops  is  paralleled  by  the  Southern 
Kail  road,  which  is  at  no  place  more  than  3  miles  distant,  numerous 
favorable  sites  for  cement  plants  are  offered.  The  most  promising 
location,  however,  is  in  the  immediate  vicinity  of  Woodstock,  since 
here  the  cement  rocks  outcrop  on  the  western  side  of  the  North  Fork 
of  the  Shenandoah  River.  Farther  south  the  river  flows  between  the 
railroad  and  the  cement-rock  outcrop,  and  would  thus  greatly  increase 
the  cost  of  a  spur  line. 
Pure  limestone  for  mixture  with  the  cement  rock  can  be  found  in 
the  immediate  vicinity,  more  probably  in  greatest  quantity  just  west 
of  the  town.  Limestone  strata  high  in  calcium  carbonate  and  low  in 
magnesia  were  found  interbedded  with  the  dolomites  west  of  Wood- 
stock, and  more  extended  search  will  no  doubt  reveal  an  ample 
supply. 
Good  railroad  facilities,  both  for  obtaining  the  fuel  supply  and  for 
shipping  the  finished  material,  are  to  be  found  at  this  place.  Coal 
could  be  secured  from  the  North  via  the  Baltimore  and  Ohio  and 
Southern  railroads,  and  from  the  South  via  the  Chesapeake  and  Ohio, 
the  Valley  Branch*  of  the  Baltimore  and  Ohio,  and  the  Southern 
railroads.  By  the  same  lines  the  finished  material  could  be  shipped 
to  the  East  and  tidewater. 
Some  miles  east  of  Woodstock  this  same  succession  of  rock  is 
encountered  along  the  eastern  edge  of  Massanutten  Mountain.  The 
cement  rocks  here  occur  along  a  northeast-southwest  line,  paralleling 
the  belt  along  the  western  side  of  the  mountain.  Along  this  eastern 
belt  the  argillaceous  limestones  have  practically  the  same  composition 
as  those  exposed  near  Woodstock. 
Broadway  and  Timber  ville. — Cuts  along  the  Southern  Railroad 
in  the  vicinity  of  these  two  towns  show  the  presence  of  small  syn- 
cline of  shales  and  argillaceous  limestone  very  similar  in  texture 
and  composition  to  the  same  rocks  found  farther  south  about  Har- 
risonburg. 
