REMOVE

1. soil
2. labor
3. trees
4. farming

WHAT

1. Visual Works (hierarchy n … (1)
2. black-and-white film (1)
3. farmers (1)
4. fathers (1)

More 

WHERE

1. Killam, Alberta, Canada (1)

WHO

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

WHEN

1. 1938 (1)
2. 1942 (1)
3. circa 1940 (1)