Analysis of Heaping

What came to me
this early spring morning
is the way the mountains
are sliding sideways
along the horizon,
their tan-gold shapes
having come unstuck,
their time
no longer standing
still, the serrated edge
of distance
they had been before
now blurred, and blurred
too the eyes now
peeping at them, unblinking
at--what?--their
geomorphic essence,
but, suddenly
rocked by a pair of birds
seamlessly tracing each
other's zigs and zags:
life's instincts all
but unknowable
to rock
heaping upon rock.