Re: Rift zones, anyone?
'Isn't there a 180 million year continuous record of the Earth's magnetic field in the North Atlantic? And a similar record in NZ's volcanic record? What's the point of this research? I smell graft ...'
The recent magnetic history of the Northern Hemisphere is well measured because there are huge numbers of industrial sites and pottery kilns going back thousands of years. The Southern Hemisphere is much less well understood because those technologies didn't develop nearly so much.
As for magnetic records, the North Atlantic is only about 50My, the oldest ocean floor is located in the Western Pacific off of Japan and the Philippines and is as you say about 180My.