By examining pots from prehistory to modern times, geologist John Shaw of the University of Liverpool in England has discovered just how dramatically the field has changed.
“When we plot the results from the ceramics,” he notes, "we see a rapid fall as we come toward the present day.
Geological evidence suggests that this bridge is a former land connection between India and Sri Lanka.
The rate of change is higher over the last 300 years than it has been for any time in the past 5,000 years.
It’s going from a strong field down to a weak field, and it’s doing so very quickly." At the present rate, Earth’s magnetic field could be gone within a few centuries, exposing the planet to the relentless blast of charged particles from space with unpredictable consequences for the atmosphere and life.
It was reportedly passable on foot up to the 15th century until storms deepened the channel: temple records seem to say that Adam's Bridge was completely above sea level until it broke in a cyclone in 1480.
The sea separating India and Sri Lanka is called Sethusamudram meaning "Sea of the Bridge".