Paleomagnetism of the Monteregian Hills: New results

Paleomagnetic directions were obtained for seventy-four stably and homogeneously magnetized cores drilled at sixteen sites on four of a group of eight basic intrusive plugs located in southeast Quebec and known as the Monteregian Hills. A statistical analysis of these data shows that the mean directions (regardless of polarity) of magnetization of the four sampled bodies were not significantly distinct after the cores were ‘cleaned’ in an alternating field of 250 oe. The circle of confidence about the mean of the sixteen site means (each given unit weight) has a radius, α95, of 3.8°. Because of the high precision of these data it is proposed that they supersede a set of data obtained from the same series of rocks and published five years ago. The seventy-four directions yielded a paleomagnetic pole at 171.2°W, 69.9°N. This pole position is in remarkably good agreement with the poles derived from six different areas in North America and at present regarded as reliable estimates for the Cretaceous period. The high coherency of the Cretaceous poles so far estimated from North American rocks strongly supports the view that the earth's magnetic field was dipolar at that time.