THE Earth’s magnetic field was three times its present strength when
dinosaurs roamed the planet, supporting theories that it is generated by an
internal dynamo rather than static magnetic material. Ancient magnetic fields
leave their imprints on volcanic rocks, but field strength is much harder to
measure than direction. John Tarduno of the University of Rochester in New York
state has now used a superconducting device to measure field strength in
crystals that formed 113 million years ago, during a 37-million-year interval
when the magnetic field was exceptionally stable and did not flip direction
(Science, vol 291, p 1779). The…
To continue reading, today with our introductory offers
Advertisement
More from Â鶹´«Ã½
Explore the latest news, articles and features
Popular articles
Trending Â鶹´«Ã½ articles
1
Are Neanderthals descendants of modern humans?
2
Neanderthal infants were enormous compared with modern humans
3
The biggest threat to Chernobyl is no longer radiation
4
From autism to migraines, birth order may have wide-reaching effects
5
How autoimmune conditions can unexpectedly drive mental illness
6
Collapse of key ocean current may release billions of tonnes of carbon
7
The man who crawls into the perilous heart of the Chernobyl reactor
8
Exclusive report: Inside Chernobyl, 40 years after nuclear disaster
9
Largest ever map of universe captures 47 million galaxies and quasars
10
The rise, the fall and the rebound of cyclic cosmology
