Figure 4. Stratigraphic variation in the ratio of the red (650 nm) to blue (450 nm) wavelengths at Holes 1077A and 1077B, displaying a pronounced periodicity that may correspond to the 23-k.y. precession cycle. A five-point smoothing procedure was applied to the data set.

Figure 4. Stratigraphic variation in the ratio of the red (650 nm) to blue (450 nm) wavelengths at Holes 1077A and 1077B, displaying a pronounced periodicity that may correspond to the 23-k.y. precession cycle. A five-point smoothing procedure was applied to the data set.