Rifting in the central segment, however, coincided with the Cretaceous Normal Superchron ( also known as the Cretaceous quiet period ), a 40 Ma period without magnetic reversals, which makes it difficult to date sea-floor spreading in this segment.
22.
:: I think there is persuasive modeling of magnetic reversals with a simple liquid outer core model-though the disruption I'm asking about, if plausible, could cause all sorts of weird phenomena . talk ) 01 : 01, 17 April 2011 ( UTC)
23.
In 1991, Rio " et al . " proposed placing the Sicilian as a sub-stage below ( before ) the Brunhes Matuyama magnetic reversal, as part of a newly defined Selinuntian Stage which would be divided into the Santernian, Emilian, and Sicilian sub-stages, completely replacing the Calabrian.
24.
In 1971, Dr . James D . Hays of the Lamont-Doherty Earth Observatory of Columbia University noted a strong correlation between recent flips and species extinctions of tiny marine creatures known as radiolarians . " The evidence, " he wrote in The Bulletin of the Geological Society of America, " is strongly suggestive that magnetic reversals either directly or indirectly exert a selective force ."
