  Astronomical observations were used as a marker for time and the Calendar
from ancient times. A more subtle calibration of epochs is thrown up by an
observation of the position of the solstices and equinoxes, because these
points shift in the sky with the years resulting in the gradual shift of
celestial longitudes $\lambda$. Chronology based on such observations however
needs to be backed up by hard evidence. We match both to take us back to
$10,000$ B.C., the epi-paleolithic period, and the beginning of civilization
itself.
