378 
CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   1905. 
Adjacent  to  the  limestones  there  are  large  deposits  of  glacial  sediments  which  contain 
extensive  beds  of  clays  interstratified  with  sands.  Some  of  the  clay  beds  are  known  to  be  at 
least  40  feet  in  thickness  and  they  have  been  so  thoroughly  washed  as  to  be  unusually  free 
from  gritty  ingredients.  In  case  the  clays  do  not  afford  enough  silica  for  use  in  cement 
manufacture  it  may  be  easily  obtained  from  the  quartzites  and  slates  that  are  near  at  hand 
as  members  of  the  metamorphic  series  of  which  the  limestone  is  a  part. 
A  cement  plant  built  at  Roche  Harbor  could  be  so  arranged  that  the  limestone  at  least- 
might  be  transported  to  the  mills  by  a  gravity  system.  The  final  product  could  also  be 
transported  in  the  same  manner  to  warehouses  on  the  wharf.  The  harbor  here  is  well  pro- 
tected and  the  water  is  sufficiently  deep  for  ocean-going  vessels  to  enter  and  depart  at  any( 
tide. 
Analyses  of  limestone ,  clay,  slate,  and  quartzite  from  Roche  Harbor,  Washington. 
Limestone. 
Clay. 
Slate. 
Quartzite. 
1. 
2. 
3. 
4. 
5. 
6. 
7. 
8. 
0.44 
1.  L3 
98.21 
0.27 
.21 
99.06 
.46 
0.20 
.30 
98.57 
1.02 
55.  81 
26.28 
4.34 
3.  39 
Trace. 
3.98 
6.11 
56.  35 
24.62 
3.66 
2.58 
.31 
3.94 
7.52 
78.0 
6.  98 
6.  45 
1.56 
Trace. 
1.56 
.30 
5.  L5 
72.32 
10.  11 
7.  75 
2.24 
.07 
1.11 
.45 
5.01 
84. 84 
6.78 
3.  03 
.80 
Trace. 
('.ill ionic  acid 
3.  41 
No.  1,  made  in  1888,  by  Moss  Bay  Bematite  and  Eron  Company  <  Limited),  Workington,  England. 
No.  2,  Iliads  in  L893,  by  Pugel  Sound  Reduction  Company,  Everett,  Wash. 
No.  3,  made  in  1902,  by  C.  I'.  McKenna,  New  Fork  City. 
Nos.  5  to  8,  made  by  F.  C.  Newton,  Seattle,  Wash. 
On  the  northwest  shore  of  Orcas  Island  there  are  several  outcrops  of  limest<  ne  very  similar 
in  character  and  occurrence  to  those  described  al  Roche  Harbor,  but  of  smaller  extent.  At 
several  points  quicklime  has  been  made  from  time  to  time  and  the  conditions  for  cement 
making  are  favorable.  The  limestone  ledges  lie  far  enough  above  the  level  of  the  water  to 
make  a  gravity  method  feasible,  and  this  could  be  followed  at  all  stages  of  cement  making 
from  the  quarry  to  the  warehouse  on  the  wharf.  The  water  is  very  deep  and  large  vessel 
may  come  \  ery  close  inshore.  As  at  Roche  I  [arbor  the  limestone  is  entirely  crystalline,  and 
with  its  neighboring  metamorphic  rocks  has  suffered  extreme  folding,  faulting,  and  other 
dislocations.  Along  the  adjacent  shores,  convenient  ly  near  the  outcrops  of  limestone,  there 
arc  shales  and  beds  of  clay  affording  materials  suitable  for  cement  manufacti  re.  Below  are 
some  analyses  of  limestones,  shales,  and  clays  from  this  location  on  Orcas  Island,  made  by 
A.  II.  Cederberg: 
Analysis  of  limestone,  shale,  and  clay  from  Orcas  Island,  Washington. 
Limestone. 
Shale. 
Clay. 
1. 
2. 
3. 
4. 
5. 
6. 
Silica 
l.id 
.04 
97.  45 
1.  11 
97.  23 
.31 
Trace. 
1.21 
62.  8 
19.2 
10.2 
.9 
Undet. 
39.80 
21.62 
29.  10 
2.91 
.41 
2.  15 
57.  3 
21.4 
5.1 
3.1 
.  5 
2.1 
r,3  a 
Iron  and  aluminum  oxides 
"3  9 
Calcium  carbonate 
6  3 
Magnesium  carbonate 
4  1 
Sulhur 
Trace. 
.51 
8 
Alkalies,  etc 
?  9 
