Geological and paleoceanographic data are now sufficiently good that detailed theories of climatic change can be tested. The data include faunal studies, refined oxygen isotope fractionation studies, and improved analyses of time series in deep-sea cores. In one theory, Weyl (1968) specifies the role of the oceans in modulating climatic change in great detail. The available evidence largely agrees with the major features of equilibrium glacial circulation suggested by Weyl. The North Atlantic was cold, with a low-salinity surface layer and cyclonic subarctic gyres. Atlantic Bottom Water probably was warmer than it is at present, most likely due to disruption of the northern formation of Atlantic Deep Water and the resulting inhibition of Antarctic Bottom Water formation. In addition, glacial Pacific Intermediate Water seems to have expanded at the expense of Pacific Deep Water. However, the data indicate that Weyl's model for the inception or the termination of a Glacial Epoch is inadequate. This test shows that patterns of climatic change can be resolved with increasingly greater detail but that 'first causes' of climatic change remain elusive.