160  CONTRIBUTIONS    TO    ECONOMIC    GEOLOGY,   1905. 
sand  on  the  river  beach  near  Fort  Stevens;  a  third  represented  the  material  directly  east  of 
the  sand  dunes  and  characteristic  of  the  interior  plain  between  the  sand  dunes  and  the  clay 
ridge;  a  fourth  was  taken  at  Warrenton,  also  in  the  Clatsop  Plains  region  toward  the  north- 
east ;  and  the  fifth  was  taken  from  the  dredge  William  II.  Ladd,  which  is  excavating  the 
river  channel  in  Columbia  River  at  Pillar  Rock,  about  12  miles  from  the  mouth.  In  addition 
to  these,  many  small  samples  were  taken  over  this  entire  area  wherever  variations  promised 
to  give  interesting  results.  Finally,  by  means  of  driving  pipes  to  a  depth  of  100  feet,  it  was 
found  that  the  surface  conditions  extended  certainly  that  far,  and  well  records  at  Hammond 
station  show  varying  layers  of  sands  and  clay  to  a  distance  of  400  feet.  The  specimens  were  I 
separated  at  the  concentrating  pavilion  in  Portland. 
Examination  was  also  made  of  the  sands  in  the  large  sand  bar  of  Columbia  River  opposite 
Hood  River,  Oregon.  Twenty  tons  collected  at  this  point  were  separated  at  the  concen- 
trating pavilion  in  Portland. 
Field  work  in  southern  Oregon  and  in  California. — After  the  investigation  of  the  sands  at 
the  month  of  Columbia  River,  Mr  dale  joined  Prof.  J.  F.  Kemp  at  Grants  Pass  and  aided 
him  in  the  examination  of  the  heavy  sands  found  in  the  placer  mines  at  Leland,  Wolf  Creek, 
Grants  Pass,  at  the  Champlin  dredge  south  of  Grants  Pass,  at  Kirby,  and  at  Waldo;  proceed- 
ing southward  they  crossed  the  Oregon  line  at  Crescent  City,  Cal.,  and  turned  north  along  the 
beach,  collecting  samples  at  Smith  River,  the  mouth  of  Pistol  River,  the  mouth  of  Rogue 
River,  Gold  Beach,  Bandon.  Marshfield,  and  Ophir,  Oreg.  Professor  Kemp  then  examined 
similar  placer  deposits  on  Snake  River  in  Idaho,  while  Mr.  Gale  turned  to  the  south  and 
examined  the  ocean  beach  from  Crescent  City  to  Eureka,  Cal.,  and  then  went  eastward  to 
Weitchpec,  on  Trinity  and  Klamath  rivers,  California,  and  finally  secured  many  valuable 
samples  of  black  sands  from  Siskiyou,  Sierra,  and  Butte  counties,  Cal. 
Other  beach  sands  were  examined  by  Mr.  W.  T.  Schaller  at  San  Diego,  Lompoc,  Aptos, 
San  Luis  Obispo,  and  in  the  neighborhood  of  San  Francisco,  Cal. 
Mr.  H.  E.  Crain,  of  Cheyenne,  Wyo.,  collected  several  tons  of  ore  from  the  Rambler  copper 
mine,  Wyoming,  for  examination  for  platinum.  He  also  visited  the  Bighorn  Mountains  of 
Wyoming  and  collected  samples  of  black  sands  in  that  region. 
Dr.  Joseph  Hyde  Pratt  investigated  the  placers  of  Yellowstone  River  near  Miles  City  and 
Helena,  Mont. 
Mr.  Walter  Harvey  Weed  collected  samples  of  chrome  iron  ore  sand  in  the  neighborhood 
of  Soldiers  Delight,  Baltimore  County,  Md.,  and  Mr.  D.  B.  Sterrett  collected  a  number  of 
black-sand  samples  from  the  Balsam  Forest  region  of  North  Carolina.  Mr.  F.  C.  Hess 
collected  and  shipped  to  Portland  several  tons  of  black  sands  from  the  beach  at  Cape  Nome, 
Alaska.  Mr.  II.  C.  Landes,  State  geologist  of  Washington,  and  Mr.  Karl  W.  Bachert  col- 
lected several  tons  of  black  sands  from  the  Pacific  beach  from  Cape  Flat  tery  south  to  Ozette. 
One  of  the  writers  collected  a  ton  of  black  sand  from  Grays  Harbor  at  Hoquiam,  Wash.; 
another  ton  of  sand,  unusually  rich  in  magnetite,  from  Damons  Point,  Grays  Harbor;  and 
several  sacks  of  sand  representing  the  Pacific  beach  at  Moclips,  Wash.,  as  well  as  two  car- 
loads of  tailings  from  the  dredges  at  Oroville  and  Marysville,  Cal. 
CONCENTRATION  EXPERIMENTS. 
By  the  courtesy  of  the  Lewis  &  Clarke  Exposition  Company,  a,  pavilion,  100  feet  long  by  50 
feet  wide,  adjoining  the  Mines  Building  on  the  exposition  grounds  was  provided  for  the 
installation  of  concentrating  machinery,  thus  enabling  the  Survey  to  carry  on  large-scale 
experiments  to  find  the  best  methods  of  separating  the  useful  minerals  in  the  black  sands 
collected.  This  concentrating  plant  was  under  the  supervision  of  Prof.  Robert  II.  Richards, 
of  the  Massachusetts  Institute  of  Technology.  The  invitation  to  various  manufacturers  of 
concentrating  machinery  to  cooperate  in  this  work  by  sending  full-sized  machines  resulted 
in  the  following  equipment: 
Wilfley  concentrator,  erected  by  the  Mine  and  Smelter  Supply  Company,  of  Denver,  Colo.,  and  oper- 
ated by  Mr.  A.  W.  Park. 
Laboratory  Wilfley  concentrator,  built  for  the  United  States  Geological  Survey. 
