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RADIOL ARLAN  LOCK  PROM  AUSTRALIA. 
[May  1893, 
above  by  the  white  radiolarian  rock,  which  varies  in  places  from 
10  to  30  feet  in  thickness.  It  is  covered  by  a  layer  of  ironstone 
conglomerate,  of  a  few  feet  in  thickness,  which  caps  the  cliff.  The 
white  rock  appears  to  be  nearly  horizontal ;  it  contains,,  more 
particularly  in  the  upper  portion,  numerous  nodules,  varying  in 
size  from  that  of  a  walnut  to  that  of  a  cocoanut.  In  weathering  it 
becomes  soft  and  shows  a  great  variety  of  tint,  from  pure  white  to 
deep  red.  No  fossils  could  be  found  in  it.  It  is  used  extensively 
for  building  purposes,  and  it  is  eaten  by  the  natives,  probably  on 
account  of  its  purgative  properties.  Mr.  Bassett-Smith  further 
states  that  the  white  radiolarian  rock  is  unaffected  by  heated 
hydrochloric  or  nitric  acid,  and  it  is  the  same  as  that  designated 
4  magnetite  ’  in  Tenison-Woods’s  Report.  It  thus  seems  probable 
that  this  material,  so  widely  distributed  in  the  northern  area  of 
Australia,  and  reaching  in  places  a  thickness  of  130  feet,  may  prove 
to  be,  as  already  suggested,  a  deep-sea  deposit  of  radiolarian  origin.1 
April  3rd,  1893.] 
Discussion. 
The  President  said  that  the  Author  had  been  wise  in  exercising 
caution  as  to  the  age  of  the  rock.  It  probably  came  from  an  area 
where  considerable  oscillations  had  taken  place. 
Mr.  E.  T.  Newton  called  attention  to  the  extremely  unpromising 
nature  of  the  material  whir-h  the  Author  had  to  work  upon,  and  to 
the  very  satisfactory  results  which  he  had  nevertheless  obtained. 
The  Author  briefly  replied. 
1  [Captain  Wharton,  F.R.S.,  has  also  kindly  forwarded  to  me  information  of 
a  similar  character  from  Capt.  W.  W.  Moore  and  from  Mr.  J.  J.  Walker, 
F.L.S.,  both  of  H.M.S.  ‘  Penguin.’] 
