REMOVE

1. soil
2. workers
3. railroads
4. cranes (equipment)

WHAT

1. Visual Works (hierarchy n … (2)
2. athletes (2)
3. barriers (2)
4. black-and-white film (2)
5. buildings (structures) (2)

More 

WHERE

1. Aiken, South Carolina (2)

WHO

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

WHEN

1. 1966 (2)