Lionel E. Jackson

Cosmogenic 36Cl dating of the Foothills erratics train, Alberta, Canada

The Foothills erratics train of Alberta was carried into place during coalescence between montane glaciers and the Laurentide ice sheet. Its age has been controversial: Late Wisconsinan and pre-Wisconsinan ages have been assigned to it. Cosmogenic 36 Cl exposure dating was carried out on erratics over a 130 km segment of the erratics train. Seven of eight age determinations support emplacement during the late Wisconsinan glaciation. These ages eliminate the possibility of an ice-free corridor during the last glacial maximum. They are also consistent with the hypothesis that the Laurentide ice sheet was the most extensive of all Pleistocene continental ice sheets in western Canada.

Chapter 45 - Limits of Successive Middle and Late Pleistocene Continental Ice Sheets, Interior Plains of Southern and Central Alberta and Adjacent Areas

Abstract The limit of glaciation by continental ice sheets in Alberta dates to the climax of the Late Wisconsinan Glaciation. Stratigraphy in buried valleys indicates that Illinoian ice sheets covered only the eastern third of Alberta. This fits the model of progressive expansion of the western margins of continental ice sheets through the Pleistocene in North America.

Gold Run tephra: a Middle Pleistocene stratigraphic and paleoenvironmental marker across west-central Yukon Territory, Canada

Gold Run tephra has been found at Thistle Creek, Sixtymile River, and the Klondike goldfields of west-central Yukon, Canada. It is a hornblende-bearing rhyolitic tephra with thicknesses of up to 10...

A holocene zinc orebody formed by supergene replacement of mosses

Abstract An extensive deposit of secondary zinc minerals has been formed at Howards Pass, Yukon by replacement of mosses and as a cement within talus. The deposits are of Holocene age (younger than 9610 yr. B.P.) and occur in blanket peat bogs percolated by zinc-rich springwaters. Buried moss strata undergo cell by cell replacement forming zincian clacite, smithsonite and hemimorphite. The last is the most important secondary mineral in both mosses and talus.

Revision of the tephrostratigraphy of the lower Sixtymile River area, Yukon Territory, Canada

Five distinctive tephra beds are preserved in fine-grained sediments on a prominent terrace strath along the lower Sixtymile River of the Yukon Territory. Commencing with the oldest unit, they are TA, SM3, Gold Run, Hollis 2, and Flat Creek tephra beds. The uppermost three tephra beds have rhyolitic compositions, the other two are bimodal with a much more basic glass phase. Three glass fission-track age determinations point to deposition during the early-Middle Pleistocene. We correct an error in an earlier study by clarifying that Flat Creek tephra is younger than Gold Run tephra, TA tephra is older.

The COMCOM Process: Informing and Transforming Communities in the Developing World Through Geotechnical Information

Following destructive landslide movement in 1999, the community of Reinaldo Espinosa in Loja, Ecuador was facilitated by a community communication process to address the problem. The government agencies involved each added value to their respective inputs by articulating resources, listening to the demands and experiences of the Reinaldo Espinosa community, and working together with them to identify and implement the most relevant, pertinent and convenient solutions. The result was the positive transformation of the Reinaldo Espinosa community and its people and appropriate solutions to the landslide problem.