Abstract:
It had been previously found that sampled rocks from Beacon sandstones at Mt Bastion, Beacon Heights and Table Mountain were very weakly magnetised and their magnetic direction had been reset at the time of the massive dolerite intrusions during the Jurassic period. The reson for this is not clear and further investigation were conducted. Only the red beds which occur at two periods within the
... Beacon Supergroup were sampled. The first period is near the base of the section - the Terra Cotta siltstone and probably Lower Devonian in age. The second is in the Upper Devonian, near the boundary with the Permian, called the Aztec siltstone. The Terra Cotta siltstone outcrops at Mt Kempe, Table Mountain and Knobhead were sampled and the Aztec siltstone outcrops at Portal Mountain, Alligator Peak and Mount Crean were sampled. Rock samples were collected using rock coring equipment. In addition, samples of the dykes (of Ordovician age) in the Wright and Miers Valley and the volcanic of Ross Island (strongly magnetised basalt from a series of flows on Observation Hill) were also collected. Palaeomagnetic measurements were made on all samples. 
