130210 Ecce Superchron

I always thought Trevor’s Suzuki was a DR Big or somesuch. I suppose Superchron Chaser would do just as well if not better.

In T’s own words then –

Behold the Mighty Superchron

As I’m sure we all know, over millions of years the Earth’s magnetic field has alternated between periods of normal polarity and reverse polarity when magnetic north and magnetic south have interchanged. This could be why sometimes we don’t know if we’re coming or going. These periods, or intervals, of geomagnetic reversal are called chrons. A superchron is a polarity interval lasting longer than 10 million years.
 
In the early 20th century geologists first noticed that some volcanic rocks were magnetized opposite to the direction of the Earth’s field. These reversals have been recorded in the ‘frozen’ ferrimagnetic minerals of consolidated sedimentary deposits or cooled volcanic flows on land. Kiama, on the coast a couple of hours south of Sydney, was the site of two strong volcanic flows which came out of Saddleback Mountain, now a collapsed volcanic vent. The cooled volcanic flow (basalt, or blue metal) became valuable for countless construction needs.
 
The now long disused blue metal quarry on Bombo Headland in Kiama, is of scientific importance as the site of the discovery of the longest known geomagnetic polarity interval called the Kiaman Reverse Superchron. The Kiaman Reverse Superchron lasted for more than 50 million years, starting around 312 million years ago.
 
I was there just the other week. Damn! Missed it.
 
Thanks to wikiwhatsit for filling some gaps in my schoolboy recollections.
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