REMOVE

1. trees
2. landscapes (representations)
3. silver gelatin
4. railroad stations
5. 1920

WHAT

1. exterior views (1)
2. forests (plant communitie … (1)
3. mountains (1)

More 

WHERE

1. Lake Louise, Alberta, Can … (1)

WHO

1. Clyfford Still; Still, Cl … (1)
2. Still, Clyfford (1)

WHEN

1. 1945 (1)
2. between circa 1929 and ci … (1)