Secular variation of the Earth's magnetic field from 18.5 to 15.0 ka BP, as recorded in a Vancouver Island stalagmite

Abstract

A record of secular variation has been obtained from a stalagmite from Vancouver Island, British Columbia, Canada, covering the period 18.5–15.0 ka BP. The ages, obtained by the U–Th method, were not fully constrained because of the low U content of the sample. The record contributes to a regional type curve obtained from the sediments of Bessette Creek (31–19 ka BP), and to which it shows similar features. In particular, a 1600 year long signal of easterly bias and shallow inclinations is similar to three earlier such features, attributed by M. E. Evans to oscillating geomagnetic sources to the west of North America. The later part of the composite record correlates fairly well with other western North American lake records. There is no evidence for a geomagnetic excursion during this period for the western North American continent.