PALEOMAGNETIC STRATIGRAPHY OF THE MEADOWCLIFFE TILL, SCARBOROUGH BLUFFS, ONTARIO - LATE PLEISTOCENE EXCURSION

The 12 m thick Meadowcliffe Till was sampled in 5 vertical profiles spread horizontally over 400 m in the Scarborough Bluffs near Toronto, Ontario. This paleomagnetic study of ≃700 specimens yielded a normal segment in all 5 profiles and an excursive segment in 3 profiles. The normal zones give, in most cases, significantly different directions which suggests that they are not strictly coeval and that deposition rates in this till are highly variable from one point to the next. Overall, they give a virtual geomagnetic pole located at 273.1°W, 73.0°N (δp = 1.7°, δm = 2.6°). Similarly the 3 excursive zones are not exactly coeval. Assuming the remanence reflects a single excursion then the pole appears to swing from mid‐Africa to mid‐South Pacific, and then back to the normal Arctic pole. This polar sequence and the apparent paleofield intensities are notably similar to those found in aboriginal fireplaces at Lake Mungo, Australia. The Meadowcliffe Till is the first Ontario till to yield evidence of recording a geomagnetic field excursion(s). Accordingly its paleomagnetic age is set at 30,500 ± 1,500 yr B.P. which is within the 8,000 yr window permitted by the single radiocarbon dates from below and above the till. Copyright 1979 by the American Geophysical Union.