GR translation: human harvests rippling out of sight

[Mike Jing]

V372.33-41, P378.32-40   Where’s the city Slothrop used to see back in
those newsreels and that National Geographic? Parabolas weren’t all
that New German Architecture went in for—there were the spaces—the
necropolism of blank alabaster in the staring sun, meant to be filled
with human harvests rippling out of sight, making no sense without
them. If there is such a thing as the City Sacramental, the city as
outward and visible sign of inward and spiritual illness or health,
then there may have been, even here, some continuity of sacrament,
through the terrible surface of May.

What does "human harvests" refer to here?
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