REMOVE

1. valleys (landforms)
2. sky
3. construction sites
4. ca. 1925

WHAT

1. Visual Works (hierarchy n … (1)
2. banks (landforms) (1)
3. black-and-white film (1)
4. branches (plant component … (1)
5. bridges (built works) (1)

More 

WHERE

1. Spokane, Washington (1)

WHO

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

WHEN

1. 1925 (1)