FOR   THE    YEARS    1901-1905,  INCLUSIVE.  207 
Lakes  (Arthur) — Continued. 
41.  The  La  Plata  Mountains.     Observations  on  their  formations  and  the  influence  of 
the  different  igneous  rocks  upon  mineralization. 
Mines  &  Minerals,  vol.  23,  pp.  222-223,  2  figs.,  1903. 
42.  Recent  earth  movements.     An  account  of  some  movements  in  the  Rocky  Moun- 
tains as  shown  by  effects  on  streams  and  mines. 
Mines  &  Minerals,  vol.  23,  p.  228,  1903. 
43.  Summit  County  placers  of  Colorado;  a  description  of  the  great  hydraulic  works 
now  nearing  completion  near  Breckenridge. 
Mines  &  Minerals,  vol.  23,  pp.  241-244,  G  figs.,  1903. 
Describes  the  general  geology  and  the  occurrence  of  placer  gold. 
44.  Redcliff  ore  deposits.     Not  unlike  in  some  respects  to  the  ore  deposits  of  the 
Mancos  contact  and  the  American  Nettie  at  Ouray  [Colorado]. 
Mines  &  Minerals,  vol.  23,  pp.  252-253,  1903. 
Describes  the  occurrence  of  the  gold  ore  deposits. 
45.  The  Bellevue  mining  district  of  Idaho;  the  geological  peculiarities  of  the  veins  as 
shown  in  the  Minnie  Moore  and  the  Queen  of  the  Hills  mines. 
Mines  &  Minerals,  vol.  23,  pp.  271-272,  4  figs.,  1903. 
46.  Secondary  enrichment  of  ore  deposits — its  causes  and  effects — the  conclusions  of 
various  authorities. 
Mines  &  Minerals,  vol.  23,  p.  347,  1903. 
47.  The  Silver  Lake  mine,  near  Silverton,  San  Juan  County,  Colo.     An  instance  of 
successful  operation  of  a  large  mine  at  high  altitude. 
Mines  &  Minerals,  vol.  23,  pp.  389-390,  2  figs.,  1903. 
Includes  notes  on  the  occurrence  and  geologic  relations  of  the  silver-lead  ores. 
48.  The  present  oil  situation  in  Colorado;  a  review  of  the  histories  of  the  several 
regions,  and  the  discoveries  which  have  been  made. 
Mines  &  Minerals,  vol.  23,  pp.  399-401,  2  figs.,  1903. 
Includes  an  account  of  the  geology  of  the  Boulder  oil  field. 
49.  Geology  and  economics  along  the  line  of  the  new  Moffat  railway,  to  be  built 
from  Denver  to  Salt  Lake  City. 
Mines  &  Minerals,  vol.  23,  pp.  418-419,  1  fig.,  1903. 
Gives  observations  on  the  geology  of  the  region. 
50.  Creede  mining  camp.     Valuable  mines  opened  through  the  Nelson  and  Hum- 
phreys tunnels.     A  description  of  the  Humphreys  mill. 
Mines  &  Minerals,  vol.  23,  pp.  433-435,  2  figs.,  1903. 
Describes  briefly  the  general  geology  and  occurrence  of  the  silver-lead  ores. 
51.  A  trip  to  Chihuahua,  old  Mexico.     A  description  of  the  Descubidoro  mine,  with 
some  impressions  of  the  country,  the  people,  and  the  mines. 
Mines  &  Minerals,  vol.  23,  pp.  446-447,  3  figs.,  1903. 
Contains  observations  on  the  geology  and  the  occurrence  of  the  silver  and  gold  ores. 
52.  Zinc  deposits:  their  geology  and  origin  as  shown  in  Wisconsin,  Arkansas,  Mis- 
souri, and  Tennessee. 
Mines  &  Minerals,  vol.  23,  p.  468,  1903. 
53.  Peculiar  mines  and  ore  deposits  of  the  Rosita  and  Silver  Cliff  mining  district  of 
Colorado.     Ore  deposits  in  a  volcanic  throat. 
Mines  &  Minerals,  vol.  23,  pp.  487-489,  4  figs.,  1903. 
54.  Santa  Eulalia  mines.     A  trip  to  the  ancient  and  very  rich  silver-lead  mines  in 
the  Santa  Eulalia  Mountains,  near  Chihuahua,  Mexico. 
Mines  &  Minerals,  vol.  23,  pp.  529-531,  5  figs.,  1903. 
Describes  the  general  geology  and  the  occurrence  of  the  silver-lead  ore  deposits. 
55.  A  remarkable  occurrence  in  the  depths  of  a  fissure  vein. 
Mines  &  Minerals,  vol.  23,  p.  534,  1  fig.,  1903. 
Describes  the  occurrence  of  a  carbonized  tree  in  a  fissure  vein  of  quartz. 
