(Note that scientists think that the iron found in the ice core came from dust that settled out of the atmosphere, and that the CO2 came from air trapped in bubbles in the ice.
(the CO2; came; from air) (air; trapped; in bubbles in the ice) (the iron; found; L:in the ice core) (dust; settled; out of the atmosphere)
the CO2 air the iron dust
came trapped found settled
from air
in bubbles in the ice
L:in the ice core
out of the atmosphere