The third cyclical variation is related to the changes in the tilt ( obliquity ) of the Earth's axis of rotation over a 41,000 year period.
(The third cyclical variation; is related; to the changes in the tilt ( obliquity ) of the Earth's axis of rotation over a 41,000 year period)
The third cyclical variation
is related
to the changes in the tilt ( obliquity ) of the Earth's axis of rotation over a 41,000 year period