Usually the aim is correlation, demonstrating that a particular horizon in one geological section represents the same period of time as another horizon at some other section.

Images of the Beijing skyline seemingly bathed in a soup of smog and haze have been a common sight on the world s TV screens in recent days and weeks.

As Iran scanned the strategic horizon, it seemed obvious that the US had invaded Iraq because Saddam did not have any weapons of mass destruction. This made Ahmadinejad s insistence on Iran s nuclear rights popular with the Iranian masses and the middle class alike.