One of the most intense moments in "The Wild Iris" comes when the speaker recalls the horror of being buried alive. Yep, that sounds a lot like death to Shmoop. Luckily, we've got other imagery to compensate for this awfulness, including images of being above ground, and even in the air.
Lines 5-7: So far so good—we're not buried yet. We notice the sunlight flickering over the "surface" of the ground. And we're even looking up toward the sky, observing the pine branches "overhead." Still, this setting is a little ominous. If we were getting on an elevator right now, there's no way we'd press the "down" button. Up, please!
Lines 8-10: But here we are anyway, underground. What a downer.
Lines 13-15: The reference to the earth "bending a little" sounds hopeful, as if we're working our way upward through the "stiff" soil of our underground tomb. Even better, we're able to visualize birds in the shrubs overhead. Though our perspective is shifting upward, it's not too high yet; the birds are darting in and out of "low" shrubs.
Lines 21-23: The concluding image of a "great fountain" conveys a powerful sense of emotional release. The power of the image comes from spatial contrast: the fountain rises high into the air, far from the underground realm of death. And the water is blue as the sky.