Discovery of the Hadrynian Polar Track and further study of the Grenville problem

Palaeomagnetic poles from North America for the period 1,150–650 Myr fall on a simple single great circle polar track—the Hadrynian Track, and the Grenville Loop. This Loop is consistent with Laurentia and Grenvillia having been an integral single plate unit from the onset of remanence blocking (metamorphic cooling) in the Grenville Province.