Volume 13, numéro 1, march 1986

EN :

Past attempts to subdivide the Canadian Shield into provinces and subprovinces have relied primarily on variations in structural trends and styles, and to a lesser degree on isotopic ages of rock units and events. In the Superior Province, subdivisions based on all, or combinations of, structural trends and styles, lithology, absolute and relative ages of rock units and events, metamorphic grade,metal logenesis, and geophysical characteristics, leads to recognition of several different types of litho-tectonic domains, including volcano-plutonic, metasedimentary, plutonic, and high-grade gneiss subprovinces. These are considered to represent the primary components assembled in the Late Archean to form the Superior Province craton. The Superior Province is thus seen to consist of northern and southern high-grade gneiss terrains, in part at least of Early Archean age, and a broad central region consisting of elongate, east-west trending volcano-plutonic and metasedimentary subprovinces.

EN :

The use of thermoluminescence (TL) for dating Quaternary sediments (both heated and unheated) is expanding rapidly, and is poised to become routine for deposits previously considered barren of datable material or that are inaccessible to other absolute chrono-metric methods (e.g. "C, K-Ar, fission-track dating). Especially significant advances in procedures, applications, understanding and technology have been made within the pastf ew years. It is now possible to date the cooling of airfall glass in tephra, and the last exposure to light of feldspars within loess, buried soils and in some waterlaid silts. Sand-sized quartz from beach and dune deposits, and silt-sized feldspar from peats, offer potential. Perhaps outshining this substantial progress in application of TL methods to un-healed sediments is a potentially revolutionary technique, demonstrated at Simon Fraser University, that uses laser light rather than heat to stimulate the luminescent signal inminerals. This new technique is expected to be sensitive, simple and speedy. Furthermore, it has the potential to date unheated sediments that have received very brief (e.g.minutes) exposure to sunlight at deposition time.

EN :

The first collections of Quaternary fossil plants in Canada were made by Sir William Dawson in 1857. His collections were probably the first in North America and among the first in the world. Noteworthy contributions by D.P. Penhallow laid the foundation of Quaternary botany in Canada with his studies on the fossils from the famous Sangamonian Don Formation at Toronto and late Wisconsinan nodules at Green Creek, Ottawa, in addition to numerous miscellaneous collections from across Canada. A re-examination of these early collections and new samples from some of the same localities reveals a high standard of identification and interpretation. Interestingly, current Canadian Quaternary botanists have no links with the early pioneers; they came here during the 1950's from European and American lineages.