A recent report by the Los Alamos National Laboratory states to the effect that terrestrial climatic changes during the past millennium, including the glacial epochs, may be related, even caused, by variations in the sun (Los Alamos Science, Summer 1982). G. Cowan and W. Haxton at Los Alamos theorize that on the basis of sunspot activity and carbon-14 production, such a causal relation exists. Observers of the solar neutrino flux have formed experiments in deep mines to test the hypothesis. The abundances of technetium-97 and -98 related to the flux are determined in a deeply buried molybdenite deposit, thus providing a geochemical record. This record, in conjunction with measurements of the solar neutrino flux (being made underground at the Homestake gold mine in South Dakota by geophysicist R. Davis of the Brookhaven National Laboratory), should provide an unequivocal test of the relationship of variations in the central temperature of the sun, or solar core, with the timing of the Pleistocene period.