Long-term climato-limnological cycles found in a 3.5-million-year continental record

Analysis of physical properties in long sediment cores (BDP96) from Academi cian Ridge in Lake Baikal indicates that major climato-limnological changes during the past 3.5 Myr occurred at about 2.5-2.8, 1.7-1.9, and 0.9-1.2 Ma , which were close to times of major geomagnetic polarity reversals (Matuya ma/Gauss, Olduvai, Jaramillo + Matuyama/Brunhes). The principal climato-lim nological oscillation has a long-term period of nearly 1,000 kyr, which cor responds to the periodicity of fluctuation in solar insolation. It also see ms to be related to geomagnetic field intensity. Other long-term period of 400 kyr corresponds to Milankovitch parameters of eccentricity. These resul ts suggest that changes in solar insolation were closely related to long-te rm environmental variations in the deep continental interior.