Palaeosecular Variation of the Geomagnetic Field in the Aleutian Islands, Alaska

Sequences of late Tertiary to Quaternary lava flows at six Aleutian Island sites were sampled for palaeosecular variation (PSV) measurement using palaeomagnetic methods. Due to limitations in probable time span represented by each sequence of flows and statistical constraints, data from only two sites are considered in themselves to be reliable indicators of PSV. When all the data are combined to give greater statistical significance, an angular standard deviation of palaeofield directions of = 10.8° is obtained. This is compatible with other Pacific Ocean PSV data and points to the persistence of the present secular variation low in this region at least into Quaternary time.