How does Marge Piercy use imagery in Woman on the Edge of Time?

Imagery:

"Into that asylum that offered none, the broken-springed bus roughly galloped ... as she was beckoned out with rough speed, she was surprised to see gulls wheeling above, far inland, as over other refuse grounds. Little was recycled here. She was human garbage carried to the dump."

"Captivity stretched before her, a hall with no doors and no windows, yawning under dim bulbs."