Two boreholes, one to a depth of 300 m, and the other to a depth of 100 m below sediment surface were drilled at 53°41´48´´N-108°21´06´´E. The core was collected down to 200m in the first borehole, and totally in the second one. Yield of the cores was more than 95%. Sediments consist of terrigenic and biogenic silts. All along the section, clay layers alternate with layers of diatomaceous silt. Studies of the section revealed that sediments accumulated under deep water during all the period of their deposition; no hiatuses or unconformities were found. Studies done in Russia, USA, Japan and Germany gave results that are consistent with each other. Correlation of magnetic properties with the palaeomagnetic scale revealed that the age of sediment at 200 m is 5 My. Mean sediment accumulation rate was constant and equaled 4 cm per 1 ky, Rhythmic structure of the sediments consisting of layers of diatom-barren clays and diatomaceous silts is due to cyclic changes of cold and warm climates.