Thus, the meltwaters from the ice sheet would be rich in oxygen-16. From the isotope data they have collected thus far, Moore, Rea, and their research team, have drawn a few conclusions. Although it might make sense that huge amounts of meltwater would raise lake levels, Moore says it was during low stands, not the high stands, that the lakes were dominated by meltwater which flowed quickly through the system. During times of high lake levels there was a cooler climate, but not because of meltwater. The isotopic compositions of lake waters became richer in oxygen-18 with each successive highstand, indicating less rather than more meltwater.
Meltwaters appear to have been present in the system much later than previously thought.
The picture is quite complex, since each lake and each major basin has its own history. Now the researchers are trying to obtain more oxygen isotope data to relate to fossil pollen found in lake sediments. The paradox is the evidence in the geological record showing that liquid water existed on the Earth billions of years ago, yet calculations based on our knowledge of the Sun and other similar stars indicates that the sun radiated so little warmth back then that the Earth's surface water should have been frozen. The early Earth was widely different from today. Four differences that would have affected climate are a cooler sun, an atmosphere much higher in carbon dioxide with little oxygen, a faster Earth rotation rate, and much less land area.