396  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,  1905. 
used  and  drawn  into  bags  or  barrels  for  the  market."  This  process  of  manufacture  has* 
several  decided  advantages  over  the  ordinary  process:  (1 )  Crushed  and  crumbled  lime  car 
be  used  in  this  way  which  can  not  be  barreled  for  shipment  as  "lump''  lime,  although  its 
quality  may  be  equally  good;  (2)  coarse-grained  limestone  which  does  not  retain  the  luurr. 
well  on  burning  can  be  utilized  in  this  process;  (3)  the  hydrated  lime  "will  not  absorb  mois- 
ture, in  other  words  it  will  not  air  slake,  hence  will  keep  in  good  condition  until  used;' 
this  fact  much  decreases  the  risk  in  shipment  by  water  and  leads  to  a  proportional  reduc- 
tion in  insurance  rates:  lime  thus  prepared  may  be  shipped  in  bulk  and  for  long  distances 
the  Rockland-Rockport  Lime  Company  having  recently  made  shipments  to  Panama  foi 
disinfecting  purposes;  (4)  "as  the  lime  has  been  reduced  to  a  powder,  there  is  absolutely 
no  liability  of  its  pitting  on  the  walls."  Finally,  it  is  believed  that  this  process  of  manufac- 
ture is  not  greatly  more  expensive  than  the  manufacture  of  common  lime;  the  machinery 
needed  is  not  complex;  savings  in  the  matter  of  materials  utilized  and  of  insurance  have 
already  been  mentioned;  and  then1  is  an  additional  saving  when  shipments  are  made  in 
cloth  bags.  These  are  much  cheaper  than  casks,  which  cost  1(>  to  17  cents  each,  and  being 
light  can  be  shipped  back  after  emptying  and  used  again  and  again. 
GENERAL  CHARACTER  AND  MODE  OF  OCCURRENCE. 
The  limestones  of  Knox  County  have  all  been  completely  recrystallized  since  their  origi- 
nal deposition.  They  are  now  virtually  marbles,  although  either  too  coarse,  too  dark 
colored,  or  too  much  fractured  to  ba  used  for  ornamental  or  building  purposes.  In  color  the 
rock  used  varies  from  dark  purplish-gray  to  pure  white,  the  commonest  colors  being  light 
gray  and  dark  blue-gray.  In  the  Rockland  quarries  a  variety  showing  alternate  bands 
of  grayish  white  and  dark  blue-gray  is  very  common.  In  the  bulk  of  the  rock  quarried 
the  grains  are  under  one-sixteenth  inch  in  diameter,  and  in  some  occurrences  they  are  m 
small  as  to  be  unrecognizable  with  the  naked  eye,  but  in  other  cases  may  reach  a  diameter 
of  one-fourth  of  an  inch. 
The  general  form  of  the  limestone  bells  has  already  been  described,  and  is  shown  on  figs. 
13  and  II:  it  remains  now  to  discuss  briefly  th<  structural  relations  of  which  this  distri- 
bution is  an  expression.  All  the  sedimentary  rocks  of  this  region  were  deposited  in  a 
nearly  horizontal  position,  as  muds.,  sands,  and  marls,  upon  the  ocean  bottom,  where  they 
gradually  consolidated  to  form,  resp<  ctively,  shal<  s,  sandston<  s,  and  linn  stones.  At  a  later 
period  these  sediments  were  thrown  into  a  series  of  long,  narrow  folds  commonly  trending 
20°  to  30°  east  of  north,  or  about  parallel  to  the  general  trend  of  (his  part  of  the  coast. 
As  in  most  regions  where  folding  of  this  kind  has  taken  place,  the  larger  folds  were  them- 
selves thrown  into  a  serii  s  of  smaller  folds,  which  trend  parallel  to  the  larger  ones — a 
relation  which  may  be  illustrated  by  the  curved  surface  of  a  crimping  hon,  which  is  itself 
fluted  with  minor  folds. 
Tli.  minor  folds  in  this  region  are  closely  compressed,  SO  much  so  that  when  seen  in 
cross  section  opposite  sides  of  a  fold  are  often  nearly  parallel.  As  a  result  of  this,  the  beds 
are  now  for  the  most  pari  steeply  inclined,  as  may  be  observed  in  the  easternmost  series 
of  quarries  of  the  Rockland-Rockport  Lime  Company,  west  of  Rockland.  Here  the  bed- 
ding is  indicated  by  a  very  distinct  banding,  which  is  almost  vertical.  The  relations  are 
complicated  by  the  presence  of  cross  folds,  which  trend  about  at  right  angles  to  the  main 
folds.  They  influence  the  form  of  the  limestone  belts  in  various  ways;  for  example,  the 
narrowing  of  the  Rockport  belt  about  one-half  mile  south  of  Lily  Pond  is  due  to  a  cross 
fold,  which  in  this  case  is  an  up  fold  or  anticline,  while  in  the  region  southwest  of  Rockland 
the  interrupted  character  of  the  narrow  limestone  belts  is  also  due  to  the  presence  of  cross 
folds.  Within  the  main  limestone  belt  the  crookedness  observed  in  the  trend  of  some  of 
the  limestone  "veins"  is  due  to  folds  which  cross  the  main  folds  diagonally. 
During  this  process  of  severe  folding,  the  various  types  of  sediments  wi  re  intensely 
altered,  the  shales  being  changed  to  schists,  the  sandstones  to  quartzite,  and  the  linn  stones 
to  marble.  The  schists  are  well  exposed  at  Bear  Hill,  Ingrahams  Hill,  and  many  other 
places,  and  are  commonly  known  as  "land  ledge."     The  muds  from  which  they  were  derived 
