A sediment core obtained from the anoxic Great Ghost Lake at an elevation of 2150 m reveals interlaminated dark and light colored sediments. The brightest sediment has the smallest mean grain size (9.9µm; the mode is 10.5µm), and contains the least vanadium (5 ppm), carbon (3.5%) and sulfur (0.026%). On the other hand, the darkest sediment has the largest mean grain size (52µm; the mode is 80.7µm), and contains the most vanadium (13 ppm), carbon (16.3%) and sulfur (0.15%). Non-distinctive sediments are bimodal in size distribution and the chemical properties fall between the two extremes.
The relative brightne of the sediments seems to correlate with the paleoclimate in China. The darkest sediment corresponds to the warmest temperature and wettest period while the brightest sediment corresponds to the lowest temperature and driest period.
Another sediment core collected at the 1670 m high Yuen-Yang Lake shows similar signals but has lower frequency interlamination with a 450 year periodicity which is close to the 420-year solar oscillation cycle. Preliminary studies show that several other lakes may show similar low frequency interlamination.