Examines an oxygen-isotope record spanning the interval 1.2 to 5.2 million years ago, before the Late Pleistocene ice-age regime. The discovery of 404-kyr and 100 kyr climate cycles which are coherent with the eccentricity cycle of the earth; Analysis of these low-frequency cycles; The support of eccentricity's role in the origin of low-frequency oxygen-isotope cycles before the Late Pleistocene ice age.