BASSLKR.] 
CEMENT    MATERIALS    OF    VALLEY    OF    VIRGINIA. 
541 
Harrisonburg  and  vicinity. — A  syncline  showing  the  Trenton  argil- 
laceous limestones  and  Martinsburg  shales  occurs  just  west  of  Har- 
risonburg and  extends  northeast-southwest  for  a  distance  of  some 
miles.  The  cement  rock  is  especially  well  shown  along  the  street 
just  west  of  the  Southern  Railroad  depot,  but  exposures  of  the 
shales  and  underlying  argillaceous  rocks  may  be  seen  all  along  the 
country  roads  going  northwest,  west,  and  southwest  from  the  town. 
The  thickness  of  the  argillaceous  limestones  in  this  vicinity  could  not 
be  ascertained  with  certainty  because  of  the  lack  of  continuous 
exposures,  but  it  probably  does  not  fall  short  of  200  feet.  Fos- 
sils indicating  the  Trenton  age  of  the  strata  were  not  uncommon  in 
the  rocks  shown  along  the  western  edge  of  the  town. 
Pure  limestone  deposits  are  found  in  considerable  quantity  east 
and  southeast  of  Harrisonburg.  Exposures  of  this  rock  may  be 
seen  in  a  cut  on  the  Chesapeake  and  Western  Railroad  just  east 
of  the  crossing  with  the  Southern  Railroad.  Here  is  found  a  pure 
gray  limestone  having  the  composition  shown  in  analysis  No.  1  of 
the  table  below. 
From  75  to  100  feet  of  argillaceous  limestones  and  calcareous 
slates  are  exposed  in  a  cut  on  the  Chesapeake  and  Western  Railroad 
southwest  of  Harrisonburg  and  just  west  of  the  Southern  crossing. 
Samples  from  this  cut  were  analyzed  by  Charles  Catlett,*  with  the 
result  shown  in  analysis  No.  2. 
About  1|  miles  north  of  Harrisonburg  the  Southern  Railroad 
passes  through  a  cut  about  20  feet  high  and  400  to  600  feet  in  length, 
exposing  comparatively  horizontal  slaty  limestone.  This  was  found 
to  have  the  composition  shown  in  analysis  No.  4. 
Partial  analyses  of  cement  materials  in  the  vicinity  of  Harrisonburg,  Va. 
[Charles  Catlett,  analyst.] 
Lime  (CaO) 
Magnesia  (MgO)  - 
Alumina  (A1203)  - 
Iron  oxide  (Fe203) 
Insoluble 
1. 
2. 
3. 
54.24 
35.79 
49.00 
.60 
1.42 
2.36 
|   .  00 
3.32 
.70 
2.08 
27.06 
7.00 
38.32 
1.67 
1.58 
25. 24 
1.  Ture  gray  limestone,  cut  on  Chesapeake  and  Western  Railroad  just  east  of  crossing 
with  the  Southern  Railroad. 
1'.  Calcareous  slates,  exposed  in  cut  on  Chesapeake  and  Western  Railroad  just  west  of 
crossing  with  the  Southern  Railroad. 
3.  Dark,  friable  limestones,  exposed  at  crossing  of  railroads  just  south  of  Harrisonburg. 
4.  Calcareous  slates,  cut  along  Southern  Railroad  1£  miles  north  of  Harrisonburg. 
