Answer to Question 1According to the Milankovitch theory, there is a 100,000-year cycle of eccentricity (departure from a
perfect circle) of Earth's orbit in three areas: the precession of equinoxes, changes in axial tilt, and
orbital eccentricity. This affects the amount of solar radiation coming in at different latitudes,
sometimes resulting in cooling.
Answer to Question 2Varves are laminated silts and clays that are deposited in glacial lakes and marine waters beneath
regions of fluctuating sea ice cover. The darker layers are deposited at the end of the summer season
when the summer's life dies and becomes incorporated in the accumulating sediment. The lighter- and
finer-grained layers are deposited during the winter when the water is still, lacking abundant life, and
receiving little sediment. Thus, each light and dark pair represents one year's accumulation.