Yol.  49.]  ANNIVERSARY  ADDRESS  OF  THE  PRESIDENT.  IO5 
"Beyond  this  point  there  is  no  very  clear  evidence  of  the  sequence 
of  events,  nor  indeed  are  we  to  expect  that  every  chapter  in  this 
geological  record  should  be  complete.  But,  among  the  many  ques¬ 
tions  which  this  interesting  speculation  raises,  there  are  two  which 
seem  to  call  for  special  attention  :  firstly,  whether  the  Authors  are 
right  in  referring  the  origin  of  the  Bed  and  Mottled  Argillaceous 
Earths  to  a  deep-sea  Bed  Clay,  seeing  that  this  theory  requires  a 
second  great  depression  of  the  area.  This  latter  supposition,  unless 
supported  by  corroborative  evidence,  seems  to  be  rather  a  weak  point 
in  the  argument,  though  it  certainly  fits  in  fairly  well  with  the 
present  condition  of  the  adjacent  Atlantic.  Here,  as  we  know,  in 
depths  from  2500  to  3000  fathoms,  Bed  Clay  with  but  few  traces 
of  organisms,  siliceous  or  calcareous,  is  the  predominating  deposit. 
It  is  evident,  however,  from  the  analyses  published  in  the  ‘  Challenger  ’ 
Beport  that  the  term  4  Bed  Clay  ’  is  made  to  cover  a  great  variety  of 
deposits,  so  much  so  indeed  that  it  can  scarcely  be  said  to  possess  any 
definite  meaning  whatever ;  and  it  is  necessary  to  refer  to  the  Synop¬ 
tical  Table  in  each  case,  where  very  interesting  details  as  to  the  per¬ 
centage  composition  of  particular  samples  of  Bed  Clay  are  available 
for  the  student.  The  chemical  analyses  are  somewhat  perplexing, 
owing  to  the  methods  adopted,  but  Dr.  Murray  gives  us  the  average 
composition  of  the  4  Challenger  ’  samples  of  Bed  Clay  as  follows  1 : 
Per  cent. 
Calcareous  organisms  .  6| 
Siliceous  organisms  .  2|  • 
Minerals  .  5^ 
Eine  washings  .  85j 
Messrs.  Jukes-Browne  and  Harrison  are  sanguine  enough  to  con¬ 
sider  that  if  the  4  Challenger  ’  samples  of  Bed  Clay  containing  only 
small  amounts  of  carbonate  of  lime  and  the  samples  of  the  Barbados 
Argillaceous  Earths  had  been  analysed  by  similar  methods,  a  close 
resemblance  in  composition  would  have  been  found  in  them,  and 
that  the  differences  would  have  been  such  only  as  might  arise  from 
the  action  of  organic  acids  percolating  through  the  rock, 
A  more  important  question  is  presented  by  the  undoubted  fact  of 
so  large  a  development  of  Badiolarian  earths,  and  the  inferences  which 
the  Authors  are  disposed  to  draw  respecting  the  great  depths  in  which 
these  deposits  originated.  It  is  a  curious  circumstance  that  no 
Badiolarian  ooze  is  known  to  occur  on  the  floor  of  the  Atlantic 
at  the  present  day.  Haeckel,  as  we  have  seen,  predicated  the 
1  Op.  cit.  p.  197. 
VOL.  XLIX. 
h 
